Genetics, Development, and Neuroplasticity Flashcards

Question

Explain why it might be an advantage that our brains take a long time to develop

Answer 1

our delayed cortical development is precisely what enables us to acquire the cultural building blocks, such as language, that make up the foundations of human achievement tradeoff between plasticity/flexibility and efficiency

Answer 2

Axons find their way to targets based on molecular cues

Answer 3

breathing, eye blinking, swallowing, grasping, Moro reflex (arms out) rooting (touch cheek, turn head and open mouth for nursing—"rooting reflex," an instinctive search for food)

Answer 4

ex: Held & Hein cats: raised cats in total darkness —> 1hr/day, kittens exposed to light —> one cat was able to walk, the other placed in box and moved around cylinder —> only the kitten who controlled its own motor movements (thus learning the proper relationship between action and visual feedback from the world) developed normal vision —> SHOWED NEURONAL NETWORKS ARE DEPENDENT ON EXPERIENCE (REQUIRE INTERACTION WITH WORLD) IN ORDER TO PROPERLY DEVELOP

Answer 5

strabismus: misaligned eye —> visual system did not wire up properly —> favor one eye/bad vision other eye (amblyoplia) —> dominant eye takes over weaker eye's territory constraint therapy —>correction of strabismus must occur during critical period for visual system development

Answer 6

Sound of mom’s voice boosts brain growth in premature babies Infants born prematurely are more than twice as likely to have difficulty hearing and processing words than those carried to full-term, likely because brain regions that process sounds aren’t sufficiently developed at the time of delivery —> babies exposed to mother's voice SIGNIFICANTLY THICKER AUDITORY CORTICES THAN CONTROL GROUP

Answer 7

neurotrophins promote neural growth and survival - proteins secreted by neuron targets that enable the development, survival, and function of neurons - enable neurons to make and keep connections - prevent neurons from initiating apoptosis currency over which the neurons and synapses compete for real estate —> drive neurons to makes connections then stabilize those connections —> promote growth, survival, guide axons, and stimulate development of new synapses

Answer 8

ex: enriched vs. deprived rat environments: animals raised in a complex and engaging environment have more dendrite development and more overall synapses than do animals who are raised in an environment with no stimulation

Answer 9

myelination= formation of myelin sheath around nerve fibers -Begins ~29 weeks gestation -many major tracts not fully myelinated until adolescence and beyond… some areas of the brain mature faster than others —> areas associated with reward, motivation, and impulsivity mature early —> prefrontal cortex matures later in life (logic, reason) —> teens therefore can be MORE PRONE TO RISKY/IMPULSIVE BEHAVIOR — less likely to think about consequences —> risk vs. reward: more likely to think the latter outweighs the former

Answer 10

old dogma —> neurogenesis/plasticity Dynamic changes in brain structure/function in response to interaction with the external environment or internal goals

Answer 11

ability for brain to change its neural pathways and develop new functions (in response to learning/experience/damage/etc.)

Answer 12

Rasmussen's encephalitis = inflammatory disease that affects 1/2 of brain —> causing severe epileptic seizures treatment: hemispherectomy remove 1/2 of brain/cerebrum —> empty half fills up with cerebrospinal fluid —> REMAINDER OF BRAIN REWIRES TO TAKE OVER MISSING FUNCTIONS

Answer 13

Blind more sensitive to touch and hearing —> cortical space that would have gone to visual input is taken over by other sensory mechanisms —> fMRI: auditory and tactile tasks activate visual cortex of early blind patients Brain makes use of available cortical area

Answer 14

not scientifically accurate cross-sensory phenomenon is known as synesthesia (heard vs. saw) subjects’ brains responded to the sound of their phones as they would respond to the presence or proximity of a girlfriend, boyfriend or family member causation vs. correlation

Answer 15

brain reflects animal’s actions/goals differences in behavior reflected anatomically Omega sign gyrus (present in musicians only, keyboard players had it on left, string players showed it on right) responsible for motor hand area

Answer 16

juggling training for 3 months: • MRI before training, during training, and after training changes in grey matter and white matter —> both increase significant expansion was found in two areas (the mid-temporal area and left posterior intraparietal sulcus) within the brains of jugglers (important in processing information related to moving objects) —> learning new skills can alter brain structure

Answer 17

basal forebrain = contains nucleus basilus, which distributes the cholinergic neurotransmitter [acetylcholine] broadly throughout the cortex

Answer 18

although it is said that practice makes perfect…practicing a task is not enough to change the brain in absence of the plasticity-enhancing powers of cholinergic neurons lesioning the nucleus basilus in the basil forebrain of group of rats —> task: grab sugar pellets through slot —> two weeks of practice in control group led to 30% increase in the size of the cortical area devoted to forepaw movement and MOTOR SKILLS AND SPEED IMPROVED —> cortical area shrank in affected group by 22% and accuracy for reaching for sugar pellets never improved THE BASIS FOR PLASTICITY AND IMPROVED PERFORMANCE IS NOT SIMPLY REPEATING A TASK, BUT ALSO REQUIRES NEUROMODULATORY SYSTEMS TO ENCODE THE RELEVANCE OF THE TASK ~~ Adaptive coding

Answer 19

rapid changes to the brain's circuitry suggests that there does not need to be large-scale rewiring, but instead there are inhibited connections that need to be unmasked there are many neural connections that already exist —> but bc they are inhibited, they have no effect —> when dominant pathways lose active input, previously-masked ones take over

Answer 20

longer-term changes are thought to involve the growth of axons in new areas and the sprouting of new connections growth of new axons and synapses

Answer 21

the brain can essentially turn plasticity on and off in particular places at particular times, according to the animal's needs (relevance) this is called gating —> (the ability to allow changes to occur only when something important happens) attention causes widespread cholinergic release, which allows for changes in tissue—this is counterbalanced with inhibition in areas that should not change cholinergic release tends to be broadly distributed, not precise, and is counterbalanced by inhibitory neurotoassnmitiers of self-modulation neuromodulators are neurotransmitters that are not reabsorbed by the pre-synaptic neuron or broken down ex: acetylcholine ~~ neurons that release acytylcholine are called cholinergic (basal forebrain)

Answer 22

perceptually distinct units of sound

Answer 23

EXPERIMENT 1: cortical map adjusts itself to available brain tissue —>nerves from the eye travel to optic tectum (each nerve fibre has preassigned address in the optic tectum) —> to understand the principles of plasticity, researchers removed half of the optic tectum during development, before the optic nerves had arrived —> a full retinotopic map developed on a smaller piece of real estate SPERRY'S EXPERIMENT 2: —-> Sperry inserted a third eye into tadpole —> inputs shared the same tectum SHOWED THAT CORTICAL MAPS CAN COMPRESS OR EXPAND DEPENDING ON AMOUNT OF REAL ESTATE — MAXIMIZING SPACE NEUROPLASTICITY: BRAIN ADAPTS TO ENVIRONMENT TO MAXIMIZE COMPETITION AND EFFICIENCY

Answer 24

brain development: PMDSAP (practice moving different series around me) 1. proliferation (cells are reproducing themselves) 2. migration (cells are traveling to their destination) 3. differentiation (cells specializing for different functions) 4. synaptogenesis (creation of new synapses between cells) 5. apoptosis and pruning (selective cell death and paring back of synapses) 6. myleination (insulting axons to improve speed/efficiency/stability)

Answer 25

Critical period: time in which stimuli MUST occur in order for normal development ex: developing proper sight * **correction of strabismus must occur during critical period for visual system development Sensitive period: time when particular development occurs most easily ex: learning second language pathways are developing and refining most rapidly, when brain is most plastic

Answer 26

Synaptic connections between neurons are believed to be altered in autism. There can be too many or too few synapses (see left and center), or synapses may be too strong or too weak or even occur at the wrong place. What’s more, the balance between excitatory and inhibitory synapses may be abnormal (see right). That balance is thought to be important for establishing critical periods—the developmental windows where our environment has the most influence on our brain circuits.

Answer 27

Gray matter = cell bodies White matter = axons/myelin gray matter is where all the thinking happens, the "processing center" —> gray matter develops quickly in childhood, slows in adolescence —> then declines (makes the adolescent brain very versatile) U-SHAPE GROWTH white matter is the "super highway" transferring information to different parts of brain —> develops continuously from birth onwards, slight increase in puberty LINEAR GROWTH

Answer 28

some areas of the brain mature faster than others —> areas associated with reward, motivation, and impulsivity mature early —> prefrontal cortex matures later in life (logic, reason) —> teens therefore can be MORE PRONE TO RISKY/IMPULSIVE BEHAVIOR — less likely to think about consequences —> risk vs. reward: more likely to think the latter outweighs the former

Answer 29

if short-term/rapid connections (unmasking) are found useful to animal, then long-term/slow connections (growth of new axons) will follow

Genetics, Development, and Neuroplasticity Flashcards

(53 cards)