Development of the Brain (Psy. 202)

ectoderm

the outer cellular layer of the developing embryo, giving rise to the skin and the nervous system

3

the embryo consists of _____ layers of cells: endoderm, mesoderm, and ectoderm at 18 days old

ectoderm (thickening Q)

a thickening of the _________ leads to development of the neural plate

neural groove

at 20 days the ______ _______ begins to develop

neural tube

at 22 days the groove has closed to form the ______ ____, with the beginning of the brain at the anterior end.

discernible

at 24 days, three major divisions of the brain—forebrain, midbrain, and hindbrain—are ___________

neural tube

an embryonic structure with subdivisions that correspond to the future brain and spinal cord

forebrain

the front division of the neural tube and brain, which in the mature vertebrates contains the cerebral hemispheres, the thalamus, and the hypothalamus

midbrain

the middle division of the brain

hindbrain

the rear division of the brain, which in the mature vertebrate contains the cerebellum, pons, and medulla

embryo

the earliest stage in a developing animal (first 10 weeks)

fetus

a developing individual after the embryo stage

neurogenesis

the mitotic division of nonneuronal cells to produce neurons

cell migration

the massive movements of nerve cells or their precursors to establish distinct nerve cell populations (nuclei in the CNS, layers of the cerebral cortex, and so on)

cell differentiation

the refining of cells into distinctive types of neurons or glial cells

synaptogenesis

the establishment of synaptic connections as axons and dendrites grow

neuronal cell death

the selective death of many nerve cells that begins well before birth

synapse rearrangement

the loss of some synapses and the development of others, to refine synaptic connections, which extends throughout our lifespan

mitosis

the process of division of somatic cells that involves duplication of DNA

ventricular zone

also called ependymal layer. a region lining the cerebral ventricles that displays mitosis, providing neurons early in development and glial cells throughout life

gene expression

the process by which a cell makes an mRNA transcript of a particular gene; the turning on or off of specific genes

cell-cell interactions

the general process during development in which one cell affects the differentiation of other, usually neighboring, cells

stem cells

a cell that is undifferentiated and therefore can take on the fate of any cell that a donor organism can produce

adult neurogenesis

the creation of new neurons in the brain of an adult

700

___ new neurons are produced everyday in the adult hippocampus

cell death

also called apoptosis, the developmental process during which “surplus” cells die

neurotrophic factors

also called simply trophic factor, a target-derived chemical that acts as if it feeds certain neurons to help them survive

synapse rearrangement

also called synaptic remodeling, the loss of some synapses and the development of others

intellectual disability

a disability characterized by significant limitations in intellectual functioning and adaptive behavior

fragile X syndrome

a condition that is a frequent cause of inherited intellectual disability and is produced by a fragile site on the X chromosome that seems prone to breaking because the DNA there is unstable

amblyopia

reduced visual acuity of one eye that is not caused by optical or etinal impairments

binocular deprivation

depriving both eyes of form vision, as by sealing the eyelids

sensitive period

also called critical period, the period during development in which an organism can be permanently altered by a particular experience or treatment

monocular deprivation

depriving one eye of light

ocular dominance histogram

a graph that portrays the strength of response of a brain neuron to stimuli presented to either the left eye or the right eye

hebbian synapses

a synapse that is strengthened when it successfully drives the postsynaptic cell

protein

genes direct the production of every ______ the cell can make

genotype

the sum of all the intrinsic, genetic information that an individual has inherited

phenotype

the sum of an individual’s physical characteristics at one particular time

genetic disorders

hundreds of ______ ________ affect the metabolism of proteins, carbohydrates, or lipids, having a profound impact on the developing brain. the genetic defect usually results in the absence of a particular enzyme that controls a critical biochemical step in the synthesis or breakdown of a vital body product

PKU (phenylketonuria)

an inherited disorder in which the absence of an enzyme leads to a toxic buildup of phenylalanine metabolites, causing intellectual disability

clones

asexually produced organisms that are genetically identical

epigenetics

the study of factors that affect gene expression without making any changes in the nucleotide sequence of the genes themselves

methylation

a chemical modification of DNA that does not affect the nucleotide sequence of a gene but makes that gene less likely to be expressed

alzheimer’s disease

a form of dementia that may appear in middle age but is more frequent among the aged

dementia

drastic failure of cognitive ability, including memory failure and disorientation

amyloid plaques

also called senile plaque, a small area of the brain that has abnormal cellular and chemical patterns. amyloid plaques correlate with dementia

beta-amyloid

a protein that accumulates in amyloid plaques in alzheimer’s disease

neurofibrillary tangles

an abnormal whorl of neurofilaments within nerve cells that is seen in alzheimer’s disease