Chapter 9 - Development of the Nervous System

Question 1

five phases of Neurodevelopment

Answer 1

(1) induction of the neural plate, (2) neural proliferation, (3) migration and aggregation, (4) axon growth and synapse formation, and (5) neuron death and synapse rearrangement

Question 2

totipotent

Answer 2

the cell has the ability to develop into any class of cell in the body

Question 3

pluripotent

Answer 3

cells have the ability to develop into many, but not all, classes of body cells

Question 4

multipotent

Answer 4

Eventually, new cells can develop into different cells of only one class

Question 5

unipotent

Answer 5

hey can develop into only one type of cell (e.g., bipolar neurons)

Question 6

neural plate

Answer 6

small patch of ectodermal tissue on the dorsal surface of the vertebrate embryo, from which the neural groove, the neural tube, and ultimately, the mature nervous system develop

Question 7

neural tube

Answer 7

the tube that is formed in the vertebrate embryo when the edges of the neural groove fuse and that develops into the central nervous system

Question 8

ventricular zone

Answer 8

the region adjacent to the ventricle (the fluid-filled center of the tube)

Question 9

migration

Answer 9

the movement of cells from their site of creation in the ventricular zone of the neural tube to their appropriate target location
> During this period of migration, the cells are still in an immature
form, lacking the processes (i.e., axons and dendrites) that characterize mature neurons

Question 10

Radial migration

Answer 10

proceeds from the ventricular zone in a straight line outward toward the outer wall of the tube

Question 11

tangential migration

Answer 11

occurs at a right angle to radial migration—that is, paral- lel to the tube’s walls

Question 12

somal translocation

Answer 12

an extension grows from the developing cell in the direction of the migration; the extension seems to explore the immediate environment for attractive and repulsive cues as it grows. Then, the cell body itself moves into and along the extending process, and trailing processes are retracted

Question 13

glia-mediated migration

Answer 13

one of two major modes of neural migration during development, by which immature neurons move away from the central canal along radial glia cells

Question 14

radial glia cells

Answer 14

glia cells that exists in the neural tube during the period of neural migration and that from a network along which radial migration occurs; some radial cells are stem cells

Question 15

neural crest

Answer 15

structure situated just dorsal to the neural tube, It is formed from cells that break off from the neural tube as it is being formed;
> Neural crest cells develop into the neurons and glial cells of the peripheral nervous system as well as many other cell types in the body and thus many of them must migrate over considerable distances

Question 16

aggregation

Answer 16

Once developing neurons have migrated, they must align themselves with other developing neurons that have migrated to the same area to form the structures of the nervous system

Question 17

cell-adhesion molecules (CAMs)

Answer 17

molecules on the surface of cells that have the ability to recognize specific molecules on the surface of the other cells and adhere to them

Question 18

growth cone

Answer 18

amoebalike structure at the tip of each growing axon or dendrite that guides growth to the appropriate target

Question 19

retinal ganglion cells

Answer 19

retinal neurons whose axons leave the eyeball and form the optic nerve

Question 20

optic tectum

Answer 20

the main destination of retinal ganglion cells in non-mammalian vertebrates

Question 21

chemoaffinity hypothesis

Answer 21

the hypothesis that growing axons are attracted to the correct targets by different chemicals released by the target sites

Question 22

fasciculation

Answer 22

the tendency of developing axons to grow along the paths established by preceding axons

Question 23

topographic gradient hypothesis

Answer 23

the hypothesis that axonal growth is guided by the relative position of the cell bodies in intersecting gradients, rather than by point-to-point coding of neural connections

Question 24

synaptogenesis

Answer 24

the formation of new synapses

Question 25

neurotrophins

Answer 25

chemicals that are supplied to developing neurons by their targets and that promote their survival

Question 26

Nerve growth factor (NGF)

Answer 26

first neurotrophin to be isolated

Question 27

Perseveration

Answer 27

the tendency to continue making a formerly correct response when it is currently incorrect

Question 28

Permissive experiences

Answer 28

experiences that permit the information in genetic programs of brain development to be expressed and maintained

Question 29

Instructive experiences

Answer 29

particular experiences that contribute to the information in genetic programs and influence the course of development

Question 30

critical period

Answer 30

If it is absolutely essential (i.e., critical) for an experience to occur within a particular interval to influence development, the interval is called a critical period

Question 31

sensitive period

Answer 31

If an experience has a great effect on develop- ment when it occurs during a particular interval but can still have weak effects outside the interval, the interval is called a sensitive period

Question 32

Neurogenesis

Answer 32

the growth of new neurons

Question 33

Pattern separation

Answer 33

refers to our ability to separate distinct percepts into individual memories for storage

Question 34

Autism spectrum disorder (ASD)

Answer 34

a complex neurodevelopment disorder characterized by a reduced capacity for social interaction and communication and restricted and repetitive patterns of behavior, interests or activities

Question 35

Savants

Answer 35

persons with developmental disabilities who nevertheless display amazing and specific cognitive or artistic abilities

Question 36

Williams syndrome

Answer 36

a neurodevelopment disorder characterized by intellectual disability, accompanied by preserved language and social skills

Question 37

orbitofrontal cortex

Answer 37

the inferior area of frontal cortex near the orbits, or eye sockets

Question 38

superior temporal gyrus

Answer 38

the large gyrus of the temporal lobe adjacent to the lateral fissure; the location of the auditory cortex