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50 Cards in this Set
- Front
- Back
- 3rd side (hint)
Genie |
Denied normal human interactions during a critical period, never learned to speak or be 'normal'.
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Prenatal Stages and Times
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Zygote (0-2 weeks)
Embryo (2-8 weeks) Fetus (9-birth) |
3
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Phases of Brain Development
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Induction of Neural Plate
Neural Proliferation Migration and Aggregation Axon Growth and Synapse Formation Neuron Death and Synapse Rearrangement |
5
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What becomes the neural plate?
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Patch of tissue on the dorsal surface of the embryo.
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How is neural plate induction induced and when is it visible?
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By chemical signals, and at three weeks after conception.
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Neural Plate Cells
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Toti- into multi-potent, often referred to as embyonic stem cells, have an unlimited capacity for cell renewable.
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3
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How is the neural tube formed?
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Neural plate folds to form the neural groove, which then fuses to form the neural tube.
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What is inside the neural tube?
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Cerebral ventricles and central canal.
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How do neural tubes proliferate in humans?
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Three swellings at the anterior end in humans will become the forebrain, midbrain, and hindbrain.
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Migration
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Once cells have been created through cell division in the vebtricular zone of the neural tube, they migrate.
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Migrating cells
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They lack dendrites and axons.
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Types of neural tube migration
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Radial (moving out, usually via radial glial cells)
Tangential migration (moving up) |
2
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Methods of migration
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Somal (extension develops and shoots out, drags cell body behind it)
Glial-mediated (cell moves along a radial glial network) |
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Aggregation
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After migration, cell align themselves with other cells and form structures.
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Cell-Adhesion Molecules
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CAMs aid in migration and aggregation. They recognize and adhere to molecules.
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2
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Axon Growth and Synapse Formation
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Once migration is complete and aggregation has began, axons and dendrites begin to form.
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Growth Cone
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At the growing tip of each extension during AGSF, extends and retracts filopodia as if finding its way.
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Chemoaffinity Hypothesis
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Hypothesis that says that during AGSF, axons grow and find their way due to postsynaptoc targets release of chemicals. Does not explain circuitous routes that are often taken.
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The role and origin of chemical signals during axonal growth.
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Chemical signals exist across the way, attracting and repeling. Such molecules are often released by glia. Adjacent growing axons also provide signals.
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3
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Are mechanisms underlying axonal growth different across species?
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Nope.
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What is needed during synapse formation?
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The presence of glial cells, especially astrocytes. Chemical signal exchange between pre- and post-synaptic neurons.
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Neuron Death and Synapse Rearrangement
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50% more neurons than needed are produced; death is normal.
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Neural Darwinism
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Cell death and synaptic pruning are like natural selection, the outcome of competition for neural connections and metabolic resources.
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How do neurons die during NDSR?
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Failure to compete for chemicals provided by targets. More targets, fewer cell deaths, etc...
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What happens to cells that fail to establish connections?
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Neurons that fail to establish connections are likely to die. They undergo apoptosis and are thus pruned in an experience-dependent manner.
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Synapse Rearrangement
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Space left after apoptosis is filled by sprouting axon terminals of surviving neurons. This leads to an increased selectivity of transmission.
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What is postnatal cerebral growth and consequence of?
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Synaptogenesis, increased dendric branches, different myelination times.
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3
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Possible reason for greater plasticity of younger brains?
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Overproduction of synapse.
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Does every area take the same amount of time to myelinate?
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No. Myelination of sensory areas then motor areas; myelination of prefrontal cortex continues into adolescence.
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3
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What can experience effect in neural development?
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Early development, maintenance, and reorganization of neural circuits.
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3
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Are effects of experience on development time-dependent?
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Yes. Critical period and sensitive period.
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Critical Period
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Development 'window' during which some event has a long-lasting influence on the brain. eg, imprinting.
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What doe enriched environments produce?
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Thicker cortexes, greater dendritic development, more synapses per neuron.
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Early deprivation of sensory/social experience causes what:?
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Sensory: Atrophy of dendrites
Social: Negative affect on intellectual and social behavioursn |
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Stress in early life has been associated with?
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Bigger amygdala, smaller hippocampus, anxiety/depression later in life.
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Can deprivation be overcome?
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Only if it is short, eg a few months.
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Problems with neural development and include and can cause
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Austism, mental retardation, injury during development causing FAS.
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Romanian Orphanage Study
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Dr. Nathan Fox followed a group of children who lived as babies in orphanages around Romania. Kids in orphanages had less gray/white matter, and lower quality brain activity. Also discovered the sensitive period for social development.
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4
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When are behavioural effects of brain damage to a certain area seen?
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Not until that particular area fully matures, ex: becomes myelinated, etc.
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What is there evidence of, regarding drugs on a prenatal brain?
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Psychoactive drugs may increase later drug use. Nicotine/caffeine increase change of learning disabilities and hyperactivity. Drugs also increasr birth defects and produce lower birth weights.
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Worst and better times for brain injury in humans
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Worst: Last half of fetal period and first few months after birth.
Better: First few years after birth. |
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Fetal Alcohol Syndrome
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Causes learning disabilities, hyperactivity and social problems. Varies depending on when and how much alcohol is consumed.
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Mental Retardation
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Impaired cognitive functioning due to abnormal brain development.
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Causes of mental retardation
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Genetic abnormalities, prenatal exposure to infections/toxins, birth trauma, malnutrition, environmental abnormalities.
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Three core symptoms of autism
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Reduced ability to interpret emotions/intentions.
Reduced capacity for social interactions. Preoccupation with a single subject/activity. |
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Autism facts
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Intensive behavioural therapy may improve function.
Often considered a spectrum disorder; heterogenous. |
2
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Autistic Savants
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Intellectually handicapped individuals who display cognitive or artistic abilities.
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Neural machanisms of autism has implicated:
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Cerebellum, amygdala, frontal cortex.
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Lines of research on cortical involvement in autism
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Possibly dificient in mirror neuron function.
Abnormal response to faces. |
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How do any of us develop a normal brain?
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Plasticity.
Range of normality. Plasticity occurs jnto older adulthood. |
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