Exam 2 - Development of the nervous system Flashcards
The first major phase of neurodevelopment is formation of the
A) neural tube.
B) neural grove.
C) growth cones.
D) neural plate.
D
The neural plate develops directly into the
A) neural embryo.
B) neural groove.
C) brain.
D) CNS.
B
In addition to radial migration of developing neurons, there is considerable __________
migration.
A) rapid
B) tangential
C) intermediate
D) circuitous
B
Cell adhesion molecules are thought to play a major role in
A) differentiation.
B) aggregation.
C) proliferation.
D) sprouting
B
In a classic study, Sperry cut the optic nerves of frogs, rotated their eyes 180e, and waited for
regeneration. Once the frogs regained their vision, there was evidence that
A) sprouts had grown out from undamaged nerves into available retinal target sites.
B) axons had grown back into the retinas from the optic tectums.
C) axonal connections had been reestablished in such a way that vision was perfectly normal,
despite the rotation of the eyes.
D) despite the eye rotation, each axon grew out from the retina to the same area of the optic
tectum to which it had originally been connected.
D
What are the phases of development of the nervous system?
- induction of neural plate
- neural proliferation
- migration and aggregation
- axon growth and synapse formation
- neuron death and synapse rearrangement
Ecoderm
outermost layer of embryonic cell, becomes skin
Mesoderm
middle layer of embryonic cell, becomes connective tissue
Endoderm
innermost layer of embryonic cell, becomes lining of organs
Totipotent
earliest cells have the ability to become any type of body cell
Stem cells
- unlimited capacity for self-renewal
- can develop into different mature cell types (multipotent)
Radial migration
towards the outer wall of the tube
Tangential migration
at a right angle to radial migration, parallel to the tube walls
What are the two methods of migration? Explain.
- somal - an extension develops that leads migration, cell body follows
- glial-mediated migration - cell moves along a radial glial network
Cell-adhesion molecules (CAMs), where are they found?
aid both migration and aggregation
- found on cell surfaces
What is the importance of the growth cone? What is the growth cone?
- at the growing tip of each extension, extends and retracts filopodia as if finding its way
- important for accurate axon growth
What are the filopodia that are retracted and extended by the growth cone guided by? What hypothesis explains this?
chemoaffinity hypothesis - postsynaptic targets release a chemical that guides axonal growth
Guidance molecules (chemoattractants and chemorepellants), what are they released by?
-released by glia
- chemoattractants attract growing axons
- chemorepellants repel them
Fasciculation
the tendency of developing axons to grow along the paths established by the pioneer growth cone’s path
Synaptogenesis, what type of cell is this dependent on, and high levels of what are needed for this?
- formation of new synapses
- glial cells - astrocytes
- cholesterol
Neutrophins
promote growth and survival, guide axons, stimulate synaptogenesis
Necrosis
- passive cell death
- cell death associated with injury
Apoptosis
- active cell death
- programmed cell death
- cleaner than necrosis
Prefrontal cortex
- working memory, planning and carrying out sequences of actions, inhibiting inappropriate responses
Neurons and synapses that are not activated by experience usually do, or do not survive?
do not survive
What does an enriched environment result in?
- thicker cortices
- greater dendritic development
- more synapses per neuron
What does early visual deprivation result in?
- underdeveloped visual cortex
- fewer synapses and dendritic spines in primary visual cortex
- deficits in depth and pattern vision
Tinnitus, what does this cause?
ringing in the ears
- major reorganization of primary auditory cortex
Savants
intellectually handicapped individuals who display specific cognitive or artistic abilities
Where is brain damage most commonly seen in autism?
cerebellum
__________ - if given early in pregnancy, increases chance of autism.
thalidomide
Evidence for a role in autism of a gene on which chromosome has been found?
chromosome 7
What are the 3 core symptoms of autism?
- reduced ability to interpret emotions and intentions
- reduced capacity for social interaction
- preoccupation with a single subject or activity
- also have trouble interacting
What are some characteristics of people with William’s syndrome?
- sociable, empathetic, and talkative
- exhibit language and music skills
- enhanced ability to recognize faces
What is severely impaired in people with William’s Syndrome?
spatial cognition (telling time)
A gene on which chromosome is associated with William’s Syndrome?
chromosome 7
People with William’s Syndrome will often have underdeveloped ________ and ________ cortex, and normal _____ and ______.
- occipital and parietal
- frontal and temporal
