Chapter 4 (Module 4.2) - Development of the Brain Flashcards
(32 cards)
this term refers to a series of genes that regulate the expression of other genes and control the start of anatomical development, including such matters as which end is the front and which is the rear
homeobox genes
when does the human CNS begin to form?
when the embryo is about 2 weeks old
when do the first muscle movements start?
it starts at age 7 1/2 weeks
what chemicals guide neuron migration?
immunoglobulins and chemokines
this term refers to the production of new cells
proliferation
New receptor neurons form in which sensory system?
Olfaction
this term refers to the process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons
myelination
this term refers to the formation of synapses
synaptogenesis
Which comes first: migration, synaptogenesis, or myelination?
Migration occurs first
what protein promotes the survival and growth of the axon?
nerve growth factor (NGF)
this term refers to a chemical that promotes the survival and activity of neurons
neurotrophin
What evidence indicates that new neurons form in the human hippocampus and basal ganglia?
The mean C concentration of the DNA of human neurons in the hippocampus and basal ganglia corresponds to a level slightly more recent than the year the person was born, indicating that some of those neurons formed after birth
If axons from the retina were prevented from showing spontaneous activity during early development, what would be the probable effect on development of the thalamus?
The axons would attach based on a chemical gradient but could not fine-tune their adjustment based on experience. Therefore, the connections would be less precise.
this term refers to a condition marked by hyperactivity, impulsiveness, difficulty maintaining attention, varying degrees of mental retardation, motor problems,
heart defects, and facial abnormalities
fetal alcohol syndrome
what is apoptosis
a programmed mechanism of cell death
What was Sperry’s evidence that axons grow to a specific target instead of attaching at random?
If he cut a newt’s eye and inverted it, axons grew back to their original targets, even though the connections were inappropriate to their new positions on the eye.
What process assures that the spinal cord has the right number of axons to innervate all the muscle cells?
The nervous system builds more neurons than it needs and discards through apoptosis those that do not make lasting synapses
At what age does a person have the greatest number of neurons—early in life, during adolescence, or during adulthood?
The neuron number is greatest early in life
What class of chemicals prevents apoptosis in the sympathetic nervous system?
Neurotrophins, such as nerve growth factor
Name two kinds of evidence indicating that touch information from the fingers activates the occipital cortex of people blind since birth.
First, brain scans indicate increased activity in the occipital cortex while blind people perform tasks such as feeling two objects and saying whether they are the same or different.
Second, temporary inactivation of the occipital
cortex blocks blind people’s ability to perform that task, without affecting the ability of sighted people.
Anesthetic drugs and anxiety-reducing drugs increase activity of GABA, decreasing brain excitation.
Why would we predict that exposure to these drugs might be dangerous to the brain of a fetus?
Prolonged exposure to anesthetics or anxiety-reducing drugs might increase apoptosis of developing neurons.
Increased GABA activity decreases excitation, and developing neurons undergo apoptosis if they do not receive enough excitation.
In the ferret study, how did the experimenters determine that visual input to the auditory portions of the brain actually produced a visual sensation?
They trained the ferrets to respond to stimuli on the normal side, turning one direction in response to sounds and the other direction to lights. Then they presented light to the rewired side and saw that the ferret again turned in
the direction it had associated with lights.
this term refers to a condition marked by hyperactivity, impulsiveness, difficulty maintaining attention, varying degrees of mental retardation, motor problems,
heart defects, and facial abnormalities
fetal alcohol syndrome
An enriched environment promotes growth of axons and dendrites in laboratory rodents.
What is known to be one important reason for this effect?
Animals in an enriched environment are more active, and their exercise enhances growth of axons and dendrites.
