Term
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Definition
| the phase of development where diffusible substances produced by underlying tissue induce growth of cells; an example of how the cells & tissues interact during development |
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Term
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Definition
| a period during which the primitive neurons & glial precursors divide mitotically |
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Term
| Why do primitive neurons migrate? |
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Definition
| to get from the site of proliferation to their final position in the nervous system |
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Term
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Definition
| the development of structural & functional features that makes cells different from each other |
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Term
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Definition
| the phase where the axons must find their way & recognize the neurons with which they are going to establish synaptic contact |
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Term
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Definition
| the phase where many neurons are eliminated at the time their axons are establishing synaptic contacts; occurs in many parts of the nervous system |
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Term
| Does the elimination of axon collaterals occur at the same time as selective cell death? |
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Definition
| no! in some systems, it occurs at a later stage |
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Term
| 2 things that neuronal activity is necessary for in development |
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Definition
1. the proper development of axonal ramifications
2. formation of synapses |
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Term
| use-dependent synaptic plasticity |
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Definition
| developmental processes that require proper use of the relevant neural networks |
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Term
| Assembly of neurons into nuclei & establishment of their interconnections are largely _____ determined |
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Definition
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Term
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Definition
| bends of the neural tube that occur because different parts grow at different rates |
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Term
| In the fourth week of development, three _____ take shape |
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Definition
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Term
| What are the three vesicles that form in week 4 of brain development? |
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Definition
1. prosencephalon (most cranial)
2. mesencephalon (middle one)
3. rhombencephalon (caudal-most one) |
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Term
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Definition
| a ventrally directed bend that arises at the junction between the rhombencephalon & the spinal cord |
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Term
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Definition
| arises between the rhombencephalon & the mesencephalon |
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Term
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Definition
| a dorsally directed bend that later divides the rhombencephalon into two parts |
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Term
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Definition
| each segment that is formed in the segmentation of the cranial end of the neural tube |
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Term
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Definition
| the segmentation formed in the rhombencephalon |
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Term
| What 2 things does the prosencephalon develop into? |
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Definition
1. diencephalon
2. cerebral hemispheres |
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Term
| 3 things that the rhombencephalon develops into |
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Definition
1. medulla oblongata
2. pons
3. cerebellum |
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Term
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Definition
| two vesicles that are produced in the rostral end of the prosencephalon; later becomes the cerebral cortex & the basal ganglia |
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Term
| Where does the olfactory bulb arise from? |
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Definition
| the ventral aspect of the telencephalon |
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Term
| Where do the eye vesicles arise from? |
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Definition
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Term
| What does the myelencephalon form? |
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Definition
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Term
| What 2 things does the metencephalon form? |
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Definition
1. pons
2. most of the cerebellum |
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Term
| 2 formations that bind the layer of cylindrical neuroepithelial cells that make up the wall of the neural tube |
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Definition
1. external limiting membrane
2. internal limiting membrane |
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Term
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Definition
| the innermost layer of the neural tube that border the cavity |
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Term
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Definition
| future neurons; migrate outward from the neural tube to form the mantle zone that later becomes the gray matter |
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Term
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Definition
| a layer without neurons that forms external to the mantle zone & becomes the white matter |
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Term
| What are the last cells to be produces by the neuroepithelial cells? |
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Definition
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Term
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Definition
| tufts invaginated from the wall into the cavity that fill the cavity with CSF & are eventually covered by ependymal cells |
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Term
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Definition
| a large ventral thickening on the neural tube produced by the neuroblasts in the mantle zone |
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Term
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Definition
| a smaller dorsal thickening on the neural tube produced by the neuroblasts in the mantle zone |
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Term
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Definition
| a shallow furrow that marks the border between the basal plate & the alar plate |
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Term
| What plate does the cerebellum develop from? |
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Definition
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Term
| motor cranial nerve nuclei |
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Definition
| innervate visceral arch muscles |
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Term
| Where do spinal nerves leave the vertebral canal? |
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Definition
| through the intervertebral foramina |
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Term
| Where does the thalamus originate from? |
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Definition
| the lateral wall in the diencephalon |
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Term
| What 2 structures does the floor plate of the diencephalon form? |
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Definition
1. hypothalamus
2. posterior pituitary |
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Term
| What is produced by the roof plate of the diencephalon through evagination? |
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Definition
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Term
| Do the eye vesicles retain connection with the diencephalon throughout development? |
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Definition
| yes! through the optic nerve |
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Term
| How does the development of the cerebral hemispheres start? |
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Definition
| the appearance of one vesicle on each side of the prosencephalon |
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Term
| 2 parts that the basal ganglia primordium is divided into by descending axons from the cerebral cortex |
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Definition
1. lateral corpus striatum
2. medial corpus striatum |
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Term
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Definition
| descending axons from the cerebral cortex into the basal ganglia primordium |
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Term
| How does development of the hippocampus start? |
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Definition
| a thickening in the medial wall of the pallium just above the attachment of the choroid plexus that bulges into the lateral ventricle |
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Term
| What is the main thing that happens in the 8th week of development? |
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Definition
| neuroblasts from the mantle zone migrate into the marginal zone & start establishing the cortical plate which develops into the mature cerebral cortex |
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Term
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Definition
| neuroepithelial cells in the ventricular zone that have ceased dividing |
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Term
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Definition
| the exact time a neuron becomes postmitotic; decides which cortical later it will join |
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Term
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Definition
| radially oriented glial cells with processes extending from the ependyma to the pia that guide the migration of postmitotic neurons toward the cortex |
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Term
| Which are the earliest afferent fibers to arrive in the cerebral cortex? |
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Definition
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Term
| Where do prospective cortical interneurons arise from? |
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Definition
| subcortical sites in the ventral forebrain |
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Term
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Definition
| the differentiation of the cortical plate into distinct areas; depends on both genetic factors intrinsic to the developing cortical progenitor cells & extrinsic influences |
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Term
| If a target for motoneurons is expanded, does the amount of surviving motoneurons increase or decrease? |
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Definition
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Term
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Definition
| a growth-promoting substance needed by neurons to survive |
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Term
| Do more neurons die in the cerebral cortex or in the spinal cord? |
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Definition
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Term
| About what percentage of interneurons in the retina die? |
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Definition
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Term
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Definition
| cell death as a normal developmental process |
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Term
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Definition
| a substance that stimulates axonal growth in the PNS; a protein produced by the cells of the target organ |
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Term
| 2 substances that are part of the neurotrophin family |
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Definition
1. NGF
2. brain-derived neurotrophic factor |
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Term
| 2 receptors that neurotrophins bind to |
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Definition
1. tyrosine-kinase receptors
2. p75NTR |
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Term
| fibroblast growth factors |
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Definition
| a growth factor acting in the brain that influences differentiation & survival of several kinds of neurons |
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Term
| When does myelination of axons start? |
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Definition
| in the fourth month of gestation |
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Term
| Where does myelination start in the spinal cord? |
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Definition
| in the cervical region & proceeds in the caudal direction |
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Term
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Definition
| controls the most precise voluntary movements; is fully myelinated only about 2 years after birth |
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Term
| What connections in the brain are myelinated at the same time as the pyramidal tract? Why? |
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Definition
| connections between the cerebellum & the cerebral cortex; they are important for coordination of voluntary movements |
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Term
| Which cranial nerve is not myelinated at the same time as the others? |
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Definition
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Term
| Where does myelination begin in the cerebral cortex? |
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Definition
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Term
| Is most of the hard-wiring of the brain completed before/shortly after birth? |
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Definition
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Term
| neuronal-cell adhesion molecules |
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Definition
| expressed at the surface of axons with a common target to make them sticky |
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Term
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Definition
| when axons with common targets form bundles (fascicles) |
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Term
| Where do many trophic factors, "signpost" molecules, recognition molecules, & N-CAMs governing the establishment of specific connections mostly act? |
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Definition
| on the axonal growth cone |
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Term
| an example of an extracellular molecule with actions on the growth cone |
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Definition
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Term
| Would rats raised in an enriched environment be expected to have more or less dendritic arborizations in the cerebral cortex? |
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Definition
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Term
| Would rats raised in an enriched environment be expected to have more or less synaptic density in the hippocampus? |
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Definition
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Term
| Is there an association between synaptic plasticity & learning? |
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Definition
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Term
| Can parts of the brain change size as development goes on? |
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Definition
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Term
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Definition
| shortly after birth, neurons in the cortex segregate into groups with a dominant input from one eye & a weaker input from the other |
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Term
| Would rats raised with more caring mothers have more or less synaptic density in their hippocampus? |
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Definition
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Term
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Definition
| the region of the brain involved in emotional processing |
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Term
| sensitive period (critical period) |
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Definition
| the development of a particular function of the nervous system & the period when the system responsible for the function is maximally plastic (its capacity for structural & functional adaptations is at its highest) |
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Term
| The opening of a sensitive period coincides with _____ & _____ |
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Definition
| increased plasticity & intense use of neural networks responsible for the particular behavior |
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Term
| Are nervous structures more or less vulnerable during a sensitive period? |
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Definition
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Term
| Reduced levels of _____ can end a sensitive period |
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Definition
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