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318 Cards in this Set
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The mechanism we use to detect & react to stimuli, transforming environmental stimulation into information the nervous system can use.
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Sense
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The conversion of physical energy into a neural impulse.
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Transduction
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A process involving a specific pattern of neural activity that contains information about stimuli in the environment.
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Coding
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The type of coding in which information about a stimulus is determined by the particular receptor reacting to the stimulus.
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E.g., certain receptors are sensitive to bitter & sweet.
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Labeled Line Coding
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The type of coding in which information about a stimulus is determined by the pattern of neural impulses.
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E.g., taste of bittersweet candy.
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Across-Fiber Pattern Coding
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Cross sensory wiring.
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Synesthesia
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Letters or numbers perceived as inherently colored.
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Word-Color Synesthesia
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Individual letters & numbers are perceived as inherently colored.
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Grapheme-Color Synesthesia
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Individuals experience colors in response to tones or other aspects of musical stimuli.
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Music-Color Synesthesia
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Individual words & sounds of spoken language evoke the sensations of taste in the mouth.
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Lexical-Gustatory Synesthesia
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Synesthesia runs strongly in families, possibly inherited as a(n) ___ trait.
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X-Linked Dominant
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Synesthesia occurs in about ___ of population.
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4%
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1/23 Persons
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The receptor cell at the back of the eye that transduces light into a neural impulse.
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Photoreceptor
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The transparent outer layer of the eyeball.
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Cornea
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A clear fluid similar to blood plasma which fills the anterior chamber of the eye.
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Aqueous Humor
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A structure consisting of bands of muscle covered by colored tissue.
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Iris
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An opening in the iris that light passes through (size is regulated by ANS).
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Pupil
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The ___ consists of transparent, onion-like layers of tissue whose function is to focus the light passing through the pupil on the retina.
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Lens
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Contract to control the shape of the lens.
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Ciliary Muscles
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Change in the shape of the lens to maintain focus of an image on the retina.
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Accommodation
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A clear, jelly-like fluid between the lens & the retina.
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Vitreous Humor
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The interior lining at the back of the eye that contains the photoreceptors.
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Retina
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An upside down & reversed image focused on the retina.
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Retinal Image
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A cell between a photoreceptor & a ganglion cell in the retina.
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Bipolar Cell
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A cell in the third layer of cells in the retina.
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Ganglion Cell
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The central region of the retina where cones are most concentrated.
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Fovea
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Rods & cones are:
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Photoreceptors
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A type of photoreceptor located in the peripheral part of the eye which operates in low light.
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Rod
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A type of photoreceptor relatively concentrated in the center of the retina which detects fine details & colors in bright light.
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Cone
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___ have better acuity; ___ have more light sensitivity due to a process called ___.
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Cones; Rods; Convergence
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Located mostly in the periphery of the retina.
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Relatively sensitive to light.
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Rods
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Operate under low light levels (at night).
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Achromatic (colorless) vision.
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Rods
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Low visual acuity.
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High convergence of information.
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Rods
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Located mostly in the center of the retina.
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Relatively insensitive to light.
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Cones
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Operates under high light levels (during the day).
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Chromatic (color) vision.
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Cones
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High visual acuity.
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Low convergence of information.
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Cones
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There are 120 million ___ & 6 million ___ in each human retina.
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Rods; Cones
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An area in the back of the eye where axons of the ganglion cells come together where an object cannot be seen.
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Optic Disk (Blind Spot)
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___ enter the eye at the optic disc & ___ exit.
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Arteries; Veins
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You cannot see an object focused at the ___; however, movement of the eye eliminates the ___.
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Optic Disc; Blind Spot
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Formed by the axons of ganglion cells.
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Optic Nerve
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The location of the crossing of the 2 optic nerves to opposite sides of the brain.
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In humans about 50% of the fibers cross here.
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Optic Chiasm
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The fibers that originate in the ___ half of each retina cross over to the ___ of the brain.
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Nasal; Contralateral (Opposite) Side
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The fibers that originate in the ___ half of each retina stay on the ___ of the brain.
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Lateral; Ipsilateral (Same) Side
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The continuation of the optic nerves past the optic chiasm.
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About 80% project to the lateral geniculate nucleus (LGN) of the thalamus.
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Optic Tracts
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The parvocellular layers are the top 4 layers & the magnocellular layers are the bottom 2 layers of the ___.
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LGN
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___ are the 4 top layers of the LGN.
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Parvocellular Layers
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The 2 bottom layers of the LGN.
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Magnocellular Layers
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The parvocellular layers are composed of a type of neuron with small cell bodies that receive projections from a type of ganglion cell called a(n) ___.
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These cells originate from the central portion of the retina (fovea) that contains mostly cones.
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X Ganglion Cell
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The magnocellular layers are ccomposed of neurons with large cell bodies that receive input from a(n) ___.
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These cells originate mostly from the periphery of the retina which suggests that their input is primarily from rods.
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Y Ganglion Cell
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Both the LGN & primary visual cortex are organized spatially like a map of the retina so the representation of an image remains intact as it is sent to the ___.
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Primary Visual Cortex
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About 25% of the ___ receives representation from the ___ (a disproportional amount) which helps to account for the greater acuity of objects seen in bright light.
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Primary Visual Cortex; Fovea
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About 80% of the optic tract fibers go to the ___;
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The remaining 20% to the ___.
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LGN; Superior Colliculus
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Is responsible for attention to visual stimuli & eye movement.
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Superior Colliculus
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The area of the cerebral cortex that detects features of the visual environment.
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Also called area V1 or striate cortex.
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Primary Visual Cortex
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The primary visual cortex has ___ layers like the LGN.
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6
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A cluster of neurons in the primary visual cortex that are sensitive to specific colors.
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Blobs
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An inability to see objects in a specific part of the visual field.
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Caused by damage to a region of the occipital lobe or the pathways leading to it.
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Visual Field Deficit
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The ability of an individual to respond to objects in a missing visual field without being conscious of seeing anything.
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Blindsight
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The area of the cerebral cortex that combines visual features into a recognizable visual perception.
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Also called area V2 or prestriate cortex.
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Secondary Visual Cortex
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___ occurs when the rods & cones change light energy into neural messages which are carried to the cerebral cortex.
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Transduction
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___ is related to the perceived characteristic of hue or color.
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Measured in nanometers (1 nm is a billionth of a meter).
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Wavelength
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___ is related to the perceived characteristic of brightness.
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Intensity
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___ refers to the number of wavelengths light contains.
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It is also related to the perceived characteristic of saturation.
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Purity
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Wavelength, intensity, & purity are characteristics of ___.
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Light
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A thin membranous disc in the outer layer of a photoreceptor.
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Lamella
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A chemical molecule in the lamellae of the eye that absorbs light.
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Photopigment
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The protein component of a photopigment.
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Opsin
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The lipid component of a photopigment.
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Synthesized from Vitamin A.
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Retinal
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The form of opsin found in the rods.
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Rod Opsin
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The photopigment in rods (rosy color before light exposure).
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Consists of rod opsin & retinal.
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Rhodopsin
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Rhodopsin, Opsin, Rod Opsin, Retinal, Lamella, & Photopigment are:
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Photoreceptor Structures
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A decrease in activity of one neuron caused by the stimulation of its neighbors.
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It allows us to sense edges by enhancing the contrast between an object & its background.
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Lateral Inhibition
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A region of the retina that, when stimulated, causes a change in activity of the cell.
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Receptive Field
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Ganglion cells stimulated when the center of the receptive field is illuminated.
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Center-On, Surround-Off
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Ganglion cells activated when the surround is illuminated.
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Center-Off, Surround-On
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A neuron in area V1 that responds to lines (edges) in a specific part of the visual field having a specific orientation.
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If the orientation of the line is changed, this cell doesn’t fire or has a drastically reduced response.
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Simple Cell
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Found in areas V1 & V2; these cells are sensitive to a line stimulus oriented in a certain direction.
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The stimulus can appear in several different locations & still activate the large receptive field of this cell. Some cells respond to line movement in a specific direction & others respond to line movement in any direction.
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Complex Cells
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Respond to visual stimuli of a particular orientation (line-tilt) within a relatively large receptive field.
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However, if the line stimulus extends beyond a specific point they do not respond (end-stopped).
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Hypercomplex Cells
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A column of cells in the visual cortex all having the same amount of dominance of input from either the right or left eye.
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Ocular Dominance Column
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A column of cells in the visual cortex all responding to the same orientation of a line stimulus (line-tilt).
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Orientation Column
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Cells of the visual cortex which respond to specific features of a visual scene.
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This may be due to responding to a different feature of the visual scene (its spatial features).
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Feature Detectors
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This theory proposes any visual scene can be broken into areas of lightness & darkness (represented by a sine-wave grating).
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Spatial-Frequency Theory
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Hubel & Wiesel (1963) found a critical period of stimulation required for normal development for cats (about 3 months).
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This period may last as long as 4 to 5 years or more in humans.
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Critical Period
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Amblyopia is produced by ___ & treated by forcing patients to use the “lazy” eye.
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Strabismus
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___ problems may be caused by damage within the cerebral cortex even though the sensory pathway is intact.
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Perceptual
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An inability to name an object presented visually (the ability to identify it by another sense, e.g., touch may be present).
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Visual Agnosia
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The region of the inferotemporal cortex most responsible for recognition of faces.
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Fusiform Face Area
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An impaired ability to recognize faces visually.
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A person with this problem may be unable to recognize their own face!
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Prosopagnosia
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___ cues to depth perception require only one eye in order to be detected.
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Examples: Relative size, Interposition, Gradient of texture, Relative height, Linear perspective.
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Monocular
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___ depth cues are provided by both eyes.
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Example: Retinal disparity.
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Binocular
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Certain neurons in the ___ are sensitive to various types of movements (horizontal, vertical, or motion perpendicular to one axis of orientation).
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Visual Cortex
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Neurons in area V1 that respond to movement in one direction.
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Component Direction-Selective Neurons
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Neurons in the middle temporal cortex that combine the information arriving from the primary visual cortex to recognize the direction in which an object is moving.
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Pattern Direction-Selective Neurons
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There are also neurons in the ___ that can detect the speed at which an object is moving.
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MST
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The theory that color perceptions come from a pattern of stimulation of three sets of color receptors in the eye.
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Problems with this theory include an explanation of why red-green color defect individuals don’t have difficulty detecting yellow.
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Young-Helmholtz Trichromatic Theory
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The theory that there are 3 receptor complexes operating in opponent fashion to yield a perception of color & brightness.
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This theory explains negative afterimages.
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Opponent-Process Theory
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There are different types of cones which are sensitive to different wavelengths as predicted by the trichromatic theory.
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Beyond the level of photoreceptors there are different types of ganglion cells & parvocellular neurons of the LGN that seem to operate by opponent-process theory.
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Integration of Young-Helmholtz Trichromatic Theory & Hering’s Opponent-Process Theory
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Refers to the phenomenon in which an object retains its known color despite changes in lighting conditions.
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Color Constancy
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The problem of how the brain binds together information to form a unified perception.
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The shape, structure, & spatial location of an object are formed into a unified perception of an object.
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Binding Problem
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The solution to the binding problem:
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The parts of the visual system involved in forming a unified perception of an object:
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Occipitotemporal Pathways & Occipitoparietal Pathways
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Vibrations in a material medium, such as air, water, or metal.
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Sound
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When objects vibrate, air molecules are set in motion. These molecules are pushed together & moved apart to create a wave of movement traveling away from the vibrating object.
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These waves are detected by ___ in the ear & are perceived as particular sounds.
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Auditory Receptors
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Sound waves vary along 3 dimensions:
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Frequency, Amplitude, & Timbre
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Refers to the number of vibrations per second.
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Measured in hertz (Hz).
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Frequency
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Humans can detect sounds with frequencies between ___ Hz (a low-pitched sound) & ___ kHz (a high-pitched sound).
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20; 20
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Refers to the loudness of a sound wave.
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Measured in decibels (dB).
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Amplitude
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The more intensely an object ___, the greater the amplitude.
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Vibrates
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Objects that produce small ripples are perceived as ___ sounds; objects that produce large ripples are perceived as ___ sounds.
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Soft; Loud
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Complex sounds consist of multiple frequencies.
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The combination of multiple frequencies gives each sound its characteristic quality, which we perceive as ___.
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Timbre
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Pinna to tympanic membrane.
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Outer Ear
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Membrane that divides the outer & middle parts of the ear.
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Tympanic Membrane (Eardrum)
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Tympanic membrane to oval window.
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Middle Ear
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The bone of the middle ear attached to the tympanic membrane & the incus.
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Malleus (Hammer)
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The bone of the middle ear attached to the malleus & stapes.
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Incus (Anvil)
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The bone of the middle ear attached to the incus & the oval window.
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Stapes (Stirrup)
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The part of the inner ear attached to the stapes.
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Oval Window
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Cochlea & vestibular system of the ear.
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Inner Ear
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A snail-shaped structure in the inner ear that contains the auditory receptors.
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Cochlea
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The primary receptor unit in cochlea.
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Organ of Corti
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A membrane in the organ of Corti to which auditory receptors are attached by Deiter’s cells.
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Basilar Membrane
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A membrane in the organ of Corti in which hair cell cilia are embedded or with which cilia make close contact.
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Tectorial Membrane
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The inner hair cells have a resting potential of -60 mV.
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When cilia bend in the direction of the longest cilium the membrane ___.
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Depolarizes
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Depolarization of the membrane leads to a rapid influx of Ca2+ ions into the hair cells, which results in the release of ___.
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Glutamate
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A nerve formed by the axons of bipolar cells in the spiral ganglion that synapse with the hair cells.
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Cochlear Nerve
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Cranial nerve VIII.
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The nerve that extends from the merging of the cochlear nerve & vestibular nerve.
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Auditory Nerve
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The first neurons in the medulla that receive neural messages from auditory receptors via the auditory nerve.
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Cochlear Nucleus
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A group of neurons in the medulla that receives neural messages from the cochlear nuclei.
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Superior Olivary Nucleus
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An area of the tectum of the midbrain that receives neural messages from both the cochlear nucleus & the superior olivary nucleus.
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Inferior Colliculus
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A group of neurons in the thalamus that receives neural impulses from the inferior colliculus.
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Medial Geniculate Nucleus (MGN)
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The area of the temporal lobe where the features of a sound are recognized.
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Primary Auditory Cortex
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The area surrounding the primary auditory cortex,
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Where pitch, loudness, & timbre are perceived & specific sounds are understood.
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Secondary Auditory Cortex
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The view that different sounds activate nerve fibers at different locations on the basilar membrane. High-pitched sounds activate the nerve fibers at the base of the membrane near the oval window; low-pitched sounds stimulate nerve fibers at the opposite end of the basilar membrane.
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While the details have proven incorrect, there is experimental support for the theory: Exposure to damaging sounds of a particular frequency can impair a person’s ability to detect that frequency. As the frequency of the damaging sound increases, damage to the basilar membrane moves closer to its base.
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Place Theory of Pitch Perception (Helmholtz)
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The view that the firing rate in the auditory nerve matches the frequency of the sound. That is, the basilar membrane vibrates in synchrony with the sound wave.
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We now know that the firing rate matches the frequency because of the volley principle. While one group of neurons in the auditory nerve is firing, another group is recovering from its previous activity, with the end result being that the combined firing of all the groups matches the frequency of the sound.
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Frequency Theory of Pitch Perception (Rutherford)
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Current theory: From 20 Hz to 400 Hz, ___ theory accounts for pitch perception (the firing rate of individual neurons in the auditory nerve directly matches the frequency of the sound).
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Frequency
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Current theory: From 400 Hz to 4 kHz, ___ principle takes over.
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Volley
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Current theory: Beyond 4 kHz, ___ theory comes into play (the place of maximal vibration on the basilar membrane determines the pitch that we perceive).
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Place
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Current theory: Additionally, both place theory & the volley principle work for sounds from about ___ kHz to ___ kHz (may explain our greater sensitivity to pitches within this range).
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1;4
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The nervous system has 2 mechanisms for determining the intensity of a stimulus:
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(1) The rate of firing of individual neurons. (2) The number of neurons firing.
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The higher the firing rate of neurons, or the greater the number of neurons firing, the more ___ the stimulus.
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Intense
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___ tones are sounds of only 1 frequency; ___ sounds have 2 or more frequencies.
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Pure; Complex
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Most sounds in our environment are ___.
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Complex
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___ of frequencies produces what we perceive as the timbre of a particular sound.
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Combination
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According to the place theory, because each sound frequency activates a specific part of the ___, a ___ sound produces a unique pattern of neural activity.
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Basilar Membrane; Complex
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For both low-pitched & high-pitched sounds, the cues to sound localization are based on differential time of arrival at the 2 ears.
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As long as the sound does not come from the ___, the sound will arrive at 1 ear slightly before it gets to the other ear, which allows us to locate the ___ from which a sound comes from.
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Median Plane; Direction
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A cue to the localization of high-pitched sounds;
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A sound is louder in the ear closer to it than in the ear farther away.
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Intensity Difference
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A cue to localizing a low-pitched sound by the difference in the cycle of the sound wave when it reaches each ear.
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Phase Difference
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Auditory receptors encode sound ___, ___, ___.
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Frequency, Intensity, & Timbre
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Auditory receptors send encoded information to the ___.
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Primary Auditory Cortex
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In the auditory cortex, some ___ respond selectively to specific aspects of sounds; others react to more complex aspects of the sound stimulus.
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Neurons
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Sound is identified as the neural information moves through the ___ (from the primary auditory cortex to the anterior part of the lateral surface of the superior temporal gyrus).
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“What” Stream
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A.K.A. Occipitotemporal Pathways/ Ventral Stream
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Sound is localized as it moves through the ___ (to the posterior part of the superior temporal gyrus & then to the parietal cortex).
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“Where” Stream
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A.K.A. Occipitoparietal Pathways/ Dorsal Stream
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Damage to the ___ can lead to ___, which is the inability to recognize sounds, or Wernicke’s aphasia, which is an inability to understand language.
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Secondary Auditory Cortex; Auditory Agnosia
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___ is a device that transmits electrical impulses along the auditory nerve to the brain.
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It can restore speech reception & production, especially when it is done in prelingual children under 6 years old.
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Cochlear Implant
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___ include the gustatory (taste) & olfactory (smell) systems.
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Chemical Senses
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Both ___ & ___ are intermingled in our eating experiences, in that much of what we report as the taste of food actually comes from its odor.
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Gustatory (Taste); Olfactory (Smell) Systems
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The sense of taste.
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Gustatory Sense
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Tastes can be classified according to 4 primary sensations:
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Sweet, Sour, Bitter, & Salty
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___ stimulate sugar receptors; ___
stimulate H+ receptors; ___ stimulate alkaloid compound receptors; ___ stimulate NaCl receptors. |
Sweet, Sour, Bitter, Salty
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A small, visible bump on the tongue that contains taste buds.
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Papilla
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A cluster of taste receptors that lie either near or within a papilla.
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Taste Bud
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3 kinds of papillae contain taste buds:
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Foliate, Circumvallate, & Fungiform
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People differ in their sensitivity to bitter & some sweet tastes.
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These individual differences appear to be partly related to the number of ___ on the tongue.
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Taste Buds
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___ (25% of people) have the most taste buds (about 425 per square cm on the tongue tip).
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Supertasters
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___ (50% of people) have about 184 taste buds per square cm.
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Medium Tasters
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___ (25% of people) have about 96 per square cm.
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Non-Tasters
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The mechanism of ___ differs for each of the 4 basic tastes.
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Taste Reception
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___ food activates a taste receptor by causing Na+ ions to move through Na+ ion channels in the ___.
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Salty; Cell Membrane
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___ ions in sour foods & ___ molecules in sweet foods close the K+ ion channels in receptor membranes, preventing K+ ions from leaving the cell.
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H+; Sugar
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In bitter foods, ___ trigger the movement of Ca2+ ions into the cytoplasm from storage sites in the taste receptor, increasing the release of ___.
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Alkaloid Compounds; Neurotransmitters
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A branch of cranial nerve VII that conveys taste information from the posterior tongue & the palate & throat to the nucleus of the solitary tract.
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Chorda Tympani
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A group of neurons in the medulla that receives information from taste receptors.
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Nucleus of the Solitary Tract
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A group of neurons that receives taste information from the nucleus of the solitary tract & then transmits it to the primary gustatory cortex.
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Ventral Posteromedial Thalamic Nucleus
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An area located just ventral & rostral to the area representing the tongue in the somatosensory cortex.
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Primary Gustatory Cortex
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The sense of smell.
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Olfactory Sense
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Habituation can occur quickly with smells. Whether pleasant or unpleasant, we rapidly “get used to” smells.
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This sensory adaptation is caused by ___ responding by receptors when they are exposed to the same stimulus for a continuous period of time.
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Decreased
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The mucous membrane in the top rear of the nasal passage;
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Lined by olfactory receptors.
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Olfactory Epithelium
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A structure at the base of the brain that receives information about odor from olfactory receptors.
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Olfactory Bulb
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Axons of olfactory bulb neurons that project to the primary olfactory cortex.
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Olfactory Tract
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An area in the pyriform cortex in the limbic system that gives odors an emotional component.
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Primary Olfactory Cortex
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From the primary olfactory cortex, some olfactory messages are transmitted to the ___, where they become important in motivating approach or avoidance behavior related to food or drink.
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Hypothalamus
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Other olfactory messages go to the dorsomedial thalamus & then to the ___, which is thought to be responsible for odor identification.
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Orbitofrontal Cortex
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A change in the place or position of the body or a body part.
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Movement
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When the ___ of movement is working correctly, we can walk, run, swim, tie shoelaces, play the piano, & play golf.
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When it fails the result is a movement disorder such as myasthenia gravis, movement apraxia, ALS, Parkinson's disease, & Huntington's disease.
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Neurological Control
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___ can range from simple to complex.
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Movements
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The simplest movements are ___.
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E.g., withdrawing your hand after touching a hot stove, Blinking when something gets in your eye.
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Reflexive Reactions
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Other movements are more complex than reflexes, but less complex than other skills.
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E.g., maintaining posture, sitting,standing, walking, & eye movement.
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More complex movements canbe learned.
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E.g., playing the piano, riding a bike, & operating exercise equipment.
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The neural control of a particular movement operates on several different levels:
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Spinal Cord, Brain Stem Structures, Cerebral Cortex (And Other Structures)
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Most basic level of control is the ___ (e.g., spinal reflexes, such as the withdrawal reflex).
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Spinal Cord
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Next level of control involves ___ structures in the hindbrain & midbrain (e.g., visual pursuit of a light stimulus).
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Brain Stem
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Highest level of control involves the ___ & structures such as the dorsolateral prefrontal cortex, the primary & secondary motor cortex, & the somatosensory cortex.
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Cerebral Cortex
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Influences movement by smoothing out & refining it (gets rid of extraneous movement & acts to ensure that the selected movement occurs with sufficient, but not excessive, force);
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Also responsible for muscle tone & postural adjustments.
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Basal Ganglia
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Plays a central role in translating uncoordinated movements into a skilled action;
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Receives feedback from sensory receptors that monitor movement & brain stem structures that initiate movement.
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Cerebellum
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3 types of muscle tissue in the body:
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Smooth, Cardiac, & Skeletal
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Control the movement of internal organs (we’re not aware of this type of movement).
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Smooth Muscles
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These heart muscles actively work to pump blood through the circulatory system.
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Cardiac Muscles
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Enable us to perform the movements necessary to exercise & engage in other activities.
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Attached to bones by tendons.
Many of these muscles work in opposing pairs. |
Skeletal Muscles
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Skeletal muscles are attached to bones by ___, which are strong bands of connective tissue that, when contracted, cause the movements of bones.
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Tendons
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Many skeletal muscles work in ___; in other words, when 1 muscle of a pair contracts or shortens, the other must lengthen in order for the bone to move.
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Opposing Pairs
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___ of skeletal muscles can be illustrated in the extension & flexion of a limb.
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Opposing Action
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Contracting an extensor muscle produces ___ of the limb (movement away from the body).
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Contracting a flexor muscle causes ___ (brings the extended limb back toward the body).
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Extension; Flexion
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Muscles that work in opposition to each other (e.g., biceps & triceps) are called ___ muscles;
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Muscles whose contraction results in the same movement are called ___ muscles.
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Antagonistic; Synergistic
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1 of the units comprising a skeletal muscle;
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About 10-100 micrometers in diameter.
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Muscle Fibers
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1 of the units comprising a muscle fiber;
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Cylindrical structures about 1-2 micrometers across.
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Myofibrils
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A component of a myofibril.
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Myofilament
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There are 2 kinds of myofilament in myofibrils:
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Myosin & Actin
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The protein component of thick myofilaments.
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Myosin
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The protein component of thin myofilaments.
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Actin
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The functional unit of a myofibril, consisting of overlapping bands of thick myosin filaments & thin actin filaments.
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This gives skeletal muscles a striped appearance, which is why they are sometimes called striated muscles.
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Sarcomere
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The ___ of the PNS control the skeletal muscles.
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Motor Neurons
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The ___ of motor neurons are located in the gray matter of the ventral horn of the spinal cord & in different parts of the brain stem.
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Cell Bodies
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Motor neurons with a long axon that leaves the ventral root of the spinal cord or brain stem & synapse with individual muscle fibers.
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Their axons conduct information rapidly (220 m/second).
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Alpha Motor Neurons
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A muscle fiber controlled by an alpha motor neuron.
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Extrafusal Muscle Fiber
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A specialized synapse between an alpha motor neuron & an extrafusal muscle fiber.
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Neuromuscular Junction
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The flattened area of an extrafusal muscle fiber where a motor neuron & the muscle fiber synapse.
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Motor End Plate
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Transmission of a neural impulse from ___ to ___ at the neuromuscular junction is similar to the transmission of neural impulses between neurons.
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Motor Neuron; Muscle Fiber
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Motor neuron releases ACh into the synaptic cleft. ACh binds to receptor proteins on the postsynaptic membrane (the muscle fiber). EPSPs are then produced; upon sufficient excitation, an action potential is generated.
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As the action potential travels down the muscle fiber, it increases the permeability of the fiber membrane to Ca2+ ions, which causes ___ to form cross bridges with ___.
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Myosin Heads; Actin Filaments
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At this point, the myosin head pivots, causing the myosin & actin filaments to slide past 1 another. The cross bridges then detach & reattach at a new position, which results in the sarcomere & the entire muscle fiber shortening.
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Thus, the muscle contracts, the attached bone moves, & the limb moves. When the muscle ___, the myosin & actin myofilaments slide back to their initial positions & the muscle fiber returns to its original ___.
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Relaxes; Length
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A chronic autoimmune neuromuscular disease. Characterized by varying degrees of weakness of the skeletal (voluntary) muscles that increases during periods of activity & improves after periods of rest.
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Muscles that control eye & eyelid movements, facial expression, chewing, talking, & swallowing are often, but not always, involved. The muscles that control breathing & neck & limb movements may also be affected.
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Myasthenia Gravis
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Myasthenia gravis is caused by ___ produced by the body's own immune system block, alter, or destroy the receptors for ___.
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Antibodies; Acetylcholine
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The first noticeable symptoms of myasthenia gravis may be weakness of the eye muscles, difficulty in swallowing, or slurred speech.
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Symptoms vary in type & severity.
Myasthenia gravis is not directly ___ nor is it ___. |
Inherited; Contagious
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Each branch of an axon synapses with a single muscle fiber.
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Collectively, a motor neuron & the muscle fibers it controls form a ___.
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Motor Unit
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An alpha motor neuron & the muscle fibers it controls.
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Motor Unit
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When the axon of an alpha motor neuron has few branches & controls only a few muscle fibers, ___ is possible.
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Fine Motor Control
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When the axon of an alpha motor neuron has many branches & controls many muscle fibers, ___ is possible.
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Gross Limb Movement
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Different types of ___ facilitate diverse abilities.
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Muscles
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A muscle fiber that contracts & fatigues slowly;
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Produces slower contractions that can be maintained for long periods of time without fatiguing.
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Slow-Twitch Muscle
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A muscle fiber that contracts & fatigues quickly;
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Produces rapid contractions that tire quickly.
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Fast-Twitch Muscle
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A muscle fiber that contracts at a lower rate than fast-twitch & a higher rate than slow-twitch muscles;
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Produces contractions of moderate speed & duration.
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Intermediate-Twitch Muscle
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We use primarily ___ or ___-twitch muscles when we stand or walk; ___-twitch muscles when we run.
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Slow; Intermediate; Fast
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A simple, automatic response to a sensory stimulus.
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Reflex
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A reflex in which tapping the tendon of the knee stretches 1 of the muscles that extends the leg,
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& the resulting muscle contraction causes the leg to kick outward.
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Patellar Reflex
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Most reflexes are produced by the ___ without involvement of the ___.
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Spinal Cord; Brain
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A spinal reflex with a single synapse between the sensory receptor & the muscle effector.
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Monosynaptic Stretch Reflex
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A structure embedded within an extrafusal muscle fiber than enables the CNS to contract a muscle to counteract the stretching of the extrafusal muscle fiber.
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Muscle Spindle
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A muscle fiber that extends the length of the muscle spindle that is surrounded by annulospiral endings.
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Intrafusal Muscle Fiber
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Sensory receptors in the central part of the muscle fiber.
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Annulospiral Endings
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When the extrafusal muscle fibers are stretched, so are the intrafusal fibers; stimulates the annulospiral endings, causing them to fire more rapidly.
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This increased neural activity travels along the Ia fibers (or axons) of the annulospiral endings, entering the dorsal root of the spinal cord & synapsing with ___.
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Alpha Motor Neurons
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The Ia fibers have an ___ influence on alpha motor neurons, causing the extrafusal muscle fibers to ___.
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Excitatory; Contract
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A spinal reflex with more than 1 synapse between the sensory receptor & the muscle effector.
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These reflexes are more common than monosynaptic reflexes.
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Polysynaptic Reflex
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The automatic withdrawal of a limb from a painful stimulus.
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Withdrawal Reflex
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Although reflexes usually occur without mediation from the brain, the brain can influence the execution of ___ reflexes.
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Polysynaptic
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The ___ can also inhibit reflexes to prevent damage to our muscles.
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Spinal Cord
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Receptor located among the fibers of tendons that measures the total amount of force exerted by the muscle on the bone to which the tendon is attached.
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Enables motor system to control extent of muscle contraction.
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Golgi Tendon Organs
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___ of muscle contraction reflects the ___ exerted by the muscle on the bone—the greater the contraction of the muscle fibers, the greater the force on the bone.
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Strength; Force
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With too much force, Golgi tendon organs reduce the contraction of ___, resulting in the muscle exerting ___ pressure on the tendon & bone.
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Extrafusal Muscle Fibers; Less
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An inhibitory interneuron excited by an alpha motor neuron that causes it to stop firing, preventing excessive muscle contraction.
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Combats muscle damage that can result from fatigue, which results from muscles contracting often in a short period of time.
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Renshaw Cell
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___ does not always lead to movement. In fact, all of our muscles remain contracted (tense) even when no movement is occurring.
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Contraction
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A neuron that synapses with intrafusal muscle fibers to produce continuous muscle tension.
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Gamma Motor Neuron
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Continuous activity of gamma motor neurons produces a constant contraction of extrafusal muscle fibers (muscle tone).
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This muscle tone is maintained at all times, except during ___.
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REM sleep
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The gamma motor system also gives us the ability to ___ certain movements & react ___.
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Anticipate; Quickly
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3 principles govern the system responsible for voluntary movement:
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It is hierarchically organized, beginning with the dorsolateral prefrontal cortex. Sensory input primarily integrated by the posterior parietal cortex. Learning changes the locus of control over the movements.
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The top executive in the perception-action cycle in nonhuman primates & humans;
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Cells in this area integrate sensory information across time with motor actions needed to deal with the information.
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Dorsolateral Prefrontal Cortex
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Consisting of the supplementary motor area & the premotor cortex;
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Involved in the planning & sequencing of voluntary movements.
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Secondary Motor Cortex
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Receives input from the posterior parietal cortex & the somatosensory cortex.
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Supplemental Motor Area
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receives input mostly from the visual cortex.
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Premotor Cortex
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___ seems to plan & sequence movements guided by internally generated stimuli (intentions);
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___ does the same for externally guided movements.
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Supplemental Motor Area; Premotor Cortex
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Because most movements are guided by both intentions & external stimuli, the connections between the supplementary motor area & the premotor cortex coordinate ___.
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Movement Planning
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Neurons in the primate premotor cortex that are activated by performing an action or by watching another monkey or person performing an action.
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Also seems to exist in humans, in Broca’s area & the primary motor cortex.
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Mirror Neuron System
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Humans learn many actions through the observation & imitation of the actions of others & the ___ provides a possible mechanism through which observation can be translated into action.
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Mirror Neuron System
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Area in the precentral gyrus of the frontal lobe that initiates voluntary movements; directly involved in the control of motor neurons.
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Stimulation of the area results in movements involving groups of muscles, not individual muscles.
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Primary Motor Cortex
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The movement of different body parts is elicited by stimulation of different regions of the ___.
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There is greater cortical representation of some body parts than of others.
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Primary Motor Cortex
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Body parts that produce ___ movements (e.g., hands & mouth) have greater representation than do parts that produce ___ movements (e.g., arms & legs).
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Precise; Gross
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The primary motor cortex shows great ___ in its response to sensory & motor changes.
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Plasticity
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The sensory receptors in the muscles & joints send information about the external environment to the ___ & ___.
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Somatosensory Cortex; Posterior Parietal Cortex
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After information is sent to the somatosensory cortex & the posterior parietal cortex, it goes to the ___, the ___, & then the ___.
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Dorsolateral Prefrontal Cortex; Secondary Motor Cortex; Primary Motor Cortex
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The ___ becomes aware of the status of the muscles that must be activated & the location of the body parts that must be moved in order to exert the right amount of force.
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Primary Motor Cortex
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Integrates input from the visual, auditory, & skin senses & relays it to the primary motor cortex, which uses the information to guide our movements.
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Damage results in difficulty responding to visual, auditory, or somatosensory stimuli presented to the contralateral (opposite) side of the body.
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Posterior Parietal Cortex
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Damage to the posterior parietal cortex that results in difficulty responding to visual, auditory, or somatosensory stimuli presented to the contralateral side of the body.
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Contralateral Neglect
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The primary motor cortex uses information from the posterior parietal cortex, somatosensory cortex, & secondary motor cortex to initiate movement.
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From the primary motor cortex & other cortical areas, 2 fiber tracts travel through the ___ & ___ & connect with the PNS in order to produce movement.
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Midbrain; Hindbrain
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Motor pathway that controls movements of fingers, hands, arms, trunk, legs, feet.
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Corticospinal Tract
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The axons of the corticospinal tract that cross over in the medulla to connect to the opposite side of the spinal cord, controlling the movement of the fingers, hands, arms, lower legs, & feet on the opposite side of the body.
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Lateral Corticospinal Tract
|
|
|
The noncrossing axons that control the movements of the trunk & upper legs on the same side of the body.
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Ventral Corticospinal Tract
|
|
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A motor pathway that controls movements of the face & tongue.
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Corticobulbar Tract
|
|
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Corticospinal tract (lateral corticospinal tract & ventral corticospinal tract) & corticobulbar tract are motor tracts that originate in the ___.
|
Motor Cortex
|
|
|
Caused by the degeneration of corticospinal & corticobular tracts.
Unable to function, the muscles gradually weaken, waste away (atrophy). |
Symptoms include twitching & cramping of muscles (fasciculation), loss of motor control in hands & arms, impaired use of the arms & legs, weakness & fatigue, tripping & falling, slurred speech, & difficulty breathing or swallowing.
|
Amyotrophic Lateral Sclerosis (ALS)
|
|
In most cases, ALS patients do not experience impaired intellectual reasoning, vision or hearing. Eye & bladder muscles, along with sexual function & drive, are not normally affected.
|
The brain eventually loses its ability to ___ & ___ voluntary movement.
There is no cure for ALS. |
Initiate; Control
|
|
The incidence of ALS is ___ times higher than Huntington's disease & about equal to multiple sclerosis.
|
___ people throughout the U.S. currently have ALS, & ___ new cases are diagnosed each year.
|
5; 30,000; 8,000
|
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1 of 4 motor pathways originating in different parts of the subcortex that control movements of the trunk & limbs.
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Ventromedial Tract
|
|
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A ventromedial tract that plays a central role in posture.
|
Vestibulospinal Tract
|
|
|
A ventromedial tract that controls upper trunk (shoulder) & neck movements & coordinates the visual tracking of stimuli.
|
Tectospinal Tract
|
|
|
A ventromedial tract that activates the flexor muscles of the legs.
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Lateral Reticulospinal Tract
|
|
|
A ventromedial tract that activates the extensor muscles of the legs.
|
Medial Reticulospinal Tract
|
|
|
A motor pathway that controls movements of the hands, lower arms, lower legs, & feet.
|
Rubrospinal Tract
|
|
|
The brain area responsible for developing rapid, coordinated responses or habits.
|
Located behind & beneath the cerebral cortex; outer surface is extremely convoluted; represents 10% of the brain’s mass, but contains more than half of its neurons.
|
Cerebellum
|
|
A habitual, rapid, well-practiced movement that does not depend on sensory feedback;
|
Controlled by the cerebellum.
|
Ballistic Movement
|
|
Input to/output from the cerebellum is conveyed by large bundles of axons called ___.
|
Peduncles
|
|
|
This integrates information about motor activity, balance & head position, limb position & extent of muscle contraction & determines whether ongoing movements are deviating from their intended course.
|
If movements begin to deviate, the ___ can correct them by sending signals to other structures, such as the deep cerebellar nuclei.
|
Cerebellum
|
|
An output cell from the cerebellar cortex, which has an exclusively inhibitory effect.
|
Purkinje Cells
|
|
|
A cerebellar neuron that has an inhibitory influence on Purkinje cells.
|
Basket Cell
|
|
|
Damage to the cerebellum: Difficulty maintaining a stable posture, making movements such as walking unsteady, slurred speech, & uncoordinated eye movements.
|
Research suggests that the cerebellum plays a significant role in ___ in addition to its role in fine-tuning motor movements & in motor learning.
|
Cognitive Behaviors
|
|
___ in the cerebellum are sensitive to alcohol; alcohol intoxication can lead to signs of cerebellar malfunction.
|
Neurons
|
|
|
Group of structures that integrates movement & controls postural adjustments & muscle tone.
|
Consists of 3 subcortical nuclei: Caudate nucleus (part of neostriatum)
Putamen (part of neostriatum) Globus pallidus (paleostriatum) |
Basal Ganglia
|
|
Part of the basal ganglia consisting of the caudate nucleus & putamen.
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Corpus Striatum
|
|
|
Integrates movement through interconnections with the primary motor cortex, the cerebellum, substantia nigra, red nucleus, & other motor centers in the brain.
|
Damage to this structure results in impairments in muscle tone, postural instability, poorly integrated movements, & difficulty performing voluntary movements (e.g., standing & walking).
|
Basal Ganglia
|
|
A degenerative neurological disorder characterized by rigidity of the limbs & muscle tremors.
|
Parkinson’s Disease
|
|
|
A movement disorder characterized by slow movement.
|
Bradykinesia
|
|
|
A tendency in a movement disorder to speed up a walking pace to running.
|
Festination
|
|
|
First signs of the disease may include a tremor in 1 hand or some stiffness in the muscles of a leg. Over time, tremors & rigidity worsen; movement becomes increasingly impaired.
|
___ are caused by the degeneration of the DA- producing cells of the substantia nigra that synapse with the basal ganglia.
|
Motor Disturbances
|
|
Other symptoms of Parkinson's disease include: difficulty in speaking, lack of facial expression, apathy, lack of spontaneous blinking, cognitive deficits (e.g., problems with learning, memory, attention, & judgment).
|
Damage to the nigrostriatal dopaminergic system leads to the ___, whereas the rigidity & tremors are believed to result from excessive activity in a ___ extending from the ventrolateral thalamus to the primary motor cortex.
|
Bradykinesia; Neural Loop
|
|
Suggested causes: Genetic basis; encephalitis; arteriosclerosis; Carbon monoxide or manganese poisoning; trauma to the head; Syphilitic damage to the brain; environmental toxins
|
Possible treatments: Levodopa—L-dopa; a drug converted to DA in the brain, increasing levels of DA depleted by the disease. Effective in decreasing rigidity & improving movement, but less effective in reducing tremors. High dosages can result in schizophrenic-like symptoms. Possible treatments:
Thalamotomy—Psychosurgical treatment that relieves tremors & improves rigidity; does not relieve bradykinesia. Pallidotomy—Psychosurgical treatment that reduces tremors, rigidity, & bradykinesia. Deep brain stimulation. Transplantation of fetal tissue into the corpus striatum (highly controversial). |
Parkinson's Disease
|
|
An inherited neurological disorder characterized by a slow, progressive deterioration of motor control, cognition, & emotion. Caused by a dominant, defective gene on the short arm of chromosome 4.
|
Symptoms usually begin between the ages of 30-50, usually with a decline in physical activity & loss of interest in activities (apathy).
Other symptoms include: involuntary movements of whole limbs or parts of a limb, interference of voluntary movements like walking, writing, swallowing, speaking, & cognitive deficits (e.g., impaired storage & retrieval of information, poor abstract reasoning, & diminished cognitive flexibility). Symptoms worsen over 15 years or so, & death eventually results from a loss of muscle control. Inability to control voluntary movements is caused by atrophy of the cerebral cortex & basal ganglia. The death of neurons in the basal ganglia decreases GABA & ACh levels, which increases activity in the nigrostriatal dopaminergic pathway. This causes the appearance of the involuntary movements that characterize the disease. |
Huntington’s Disease
|
|
In 1 study, more than __% of right-handed people showed ___ dominance for language, as did __% of left-handed people.
|
95; left hemisphere; 70
|
|
|
The remaining left-handed people were equally split between ___ & right hemisphere language dominance.
|
equal dominance
|
|
|
Damage to either hemisphere impairs language in most ___ people, whereas ___ people may show no language impairment following damage to the ___ hemisphere.
|
left-handed; right-handed; right
|
|
|
An acquired impairment in the use of language.
|
Caused by traumatic damage to neural areas involved in receiving (understanding) & /or expressing (producing) language.
|
aphasia
|
|
With aphasia, impairment is limited to language, leaving nonverbal processes such as ___ & ___ intact.
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reasoning; memory
|
|
|
Difficulty producing fluent, well-articulated, & self-initiated speech.
|
nonfluent aphasia
|
|
|
Themost prevalent type of nonfluent aphasia.
|
Broca’s aphasia
|
|
|
A difficulty selecting the correct word for either written or spoken language. Language comprehension remains relatively intact.
|
Caused by damage to the left cerebral hemisphere rostral to the base of the primary motor cortex; an inability to initiate well-articulated conversational speech.
|
anomia
|
|
A severe depression of all language functioning. Exhibit poor speech comprehension & difficulty repeating words or remembering names; speech may be limited to a jargon phrase repeated in all contexts or to a phrase used inappropriately. Words are rarely used in a functional or meaningful way; do not understand the language of others.
|
Caused by damage extending beyond Broca’s area into Wernicke’s area.
|
global aphasia
|
|
Sparse, self-initiated speech with relatively good language comprehension. Person does not usually initiate speech, speaking only if strongly encouraged.
When speech does occur, it tends to be nonfluent & agrammatical. Speech consists of only 1 or 2 words & complete sentences are rare. Can repeat long and complex sentences fluently; has good language comprehension. |
Caused by damage to regions of the premotor cortex anterior & superior to Broca’s area, which is not damaged.
|
transcortical motor aphasia
|
|
An inability to understand the language of others & the production of less meaningful speech than normal.
|
fluent aphasia
|
|
|
An inability to comprehend language. Person can speak fluently but speech is less meaningful. Uses jargon, leaves out key words, substitutes words, & includes extra words; poor reading comprehension; unintelligible writing.
|
Caused by damage to the posterior portion of the superior & middle temporal gyrus & the temporoparietal cortex.
|
Wernicke’s aphasia
|
|
Speech characterized by the use of inappropriate morphemes.
|
paragrammatical speech
|
|
|
Difficulty repeating verbal (orally presented) information;
|
Degree of impairment depends on the length of the phrase to be repeated.
|
conduction aphasia
|
|
An error in speaking
phonemic paraphasia—The substitution of a similar sounding word. Anomic aphasia—A consistent difficulty finding names and substituting indefinite nouns and pronouns for substantive words. Person has good language comprehension with fluent and grammatical speech. Absence of crucial words makes it difficult to follow what the person is saying. Though exact cause is not known, because it is a very rare condition, it appears to be caused by damage at the left temporo-occipital junction. Transcortical sensory aphasia—Characterized by fluent speech, poor comprehension, and anomia, along with an unusual tendency to repeat verbal stimuli. Echolalia—A repetition of something someone has just said. Person can repeat a sound without understanding it. Caused by damage to areas that surround and include Wernicke’s area. |
Language comprehension remains relatively good & conversational speech is only mildly impaired.
|
paraphasia
|