5.1.1 Development Of The Brain 2 Flashcards
A program mechanism of cell death is called ____. It is distinct from necrosis, which is death caused by an injury or a toxic substance.
apoptosis
The brains system of over producing neurons and then applying apoptosis enables the CNS to ____ the number of incoming axons to the number of receiving cells.
match
When the sympathetic nervous system begins sending axons toward the muscles and glands, it doesn’t know the exact size of the muscles or glands. It makes ____ neurons than necessary and discards the excess.
more
The new growth factor is a ____, meaning a chemical that promotes the survival and activity of neurons.
neurotrophin
In addition to NGF, the nervous system responds to ____ ____ ____ ____ (BDNF) and several other neurotrophins.
brain derived neurotrophic factor
Neurotrophins are not necessary for survival of brain neurons, but they are ____ for growth of axons and dendrites, formation of new synapses, and learning.
essential
The early stages of brain development are ____. A mutation in one identified gene needs to any of a wide variety of defects in brain development.
critical
The developing brain is also highly vulnerable to ____, ____ ____, and ____ that would produce only mild problems at later ages.
malnutrition, toxic chemicals, and infections
The infant brain is highly vulnerable to damage by ____.
Alcohol
Children of mothers to drink heavily during pregnancy are born with ____ ____ ____, a condition marked by hyperactivity, impulsiveness, difficulty maintaining attention, varying degrees of mental retardation, motor problems, heart defects, and facial abnormalities.
fetal alcohol syndrome
Even in milder cases of fetal alcohol syndrome those were exposed to ____ alcohol show impairments in learning, memory, language, and attention.
prenatal
Alcohol suppresses of the release of ____, the brains main excitatory transmitter, and enhances activity of ____, the main inhibitory transmitter. Consequently, many neurons received less excitation and neurotrophins than normal, and they undergo apoptosis.
glutamate : GABA
Prenatal exposure to other substances can be dangerous too. On average, children of mothers to use cocaine or smoke cigarettes during pregnancy have an increased risk of ____ ____ and other behavioural deficits.
attention-deficit disorder
Children whose mother used antidepressants during pregnancy have increased risk of ____ ____.
heart problems
Finally, the immature brain is highly responsive to influences from the mother. ____ to the mother changes her behaviour in ways to change her offsprings behaviour. Children of impoverished and abused woman have, on average, increased problems in both the academic and social lives.
Stress
Neurons in different brain areas differ in ____ and ____.
shape and chemistry
Immature neurons experimentally ____ from one part of the developing cortex to another develop properties characteristic of the new location. However, neurons transplanted at a slightly later stage develop some new properties while retaining some old ones.
transplanted
Our brains have the ability to ____ themselves (with limits) in response to our experience.
remodel
Decades ago, researchers doubted that adult neurons substantially changed their shape. We now know that axons and dendrites continue to modify their structure ____ life.
throughout
We might suppose that neuronal changes in an enriched environment depend on new and interesting experiences, and many of them do. For example, after practice of particular skills, the connections relevant to those skills ____, while other connections retract.
proliferate
Much of the enhancement produced by enriched environment is due to ____ ____. Activity also improves learning and memory.
physical activity
Educators have long operated on the assumption that training children to do something difficult will enhance their intellect in general. The idea is to teach one thing and hope students get smarter than other ways too. This is called ___ ____.
far transfer
In general, far transfer is weak and hard to demonstrate. ____ ____ is training on one task and finding improvement on a very similar task.
Near transfer
One of the best-documented ways to maintain intellectual vigour in old age is the same thing that worked so well for laboratory animals – ____ ____.
physical activity
Being blind does not change the touch receptors in the fingers or the receptors in the ears. However, it increases attention to touch and sound, and the brain ____ to that attention.
adapts
Investigators asked sighted and blind people to feel the difference between two braille objects. On average, ____ people performed more accurately then ____ people, as you would guess.
blind : sighted
PET and fMRI scans indicated substantial activity in the ____ cortex of the blind people while they perform these tasks.
occipital
In people blind since birth or early childhood, auditory stimuli also produced increased responses in what we usually ____ areas of the cortex.
visual
In short, blind people, unlike sighted people, use the occipital cortex to help identify what they ____.
feel
