Lecture 10 Flashcards
Most neurons are born in excess, about __ die later in development. Dying is ___, neurons need a ___ to survive.
half
default
signal
The number of neurons is ___ to target size. The target secretes a __ needed for survival. If you remove synaptic target, ___. Therefore, the cues presented by target ___.
directly proportional
limited amount of factor
neurons die
regulate survival
There are multiple growth factors involved in neural development. Specificity arises from ___.
receptor expression on growth cone.
Programmed cell death (___) is not a passive process, it’s an active process held in check by ____.
apoptosis
trophic factors
___ is a growth factor that showed growth in DRG, NG, and SG. ___ showed growth in DRG and NG. ___ showed growth in DRG and SG.
NT-3
BDNF
NGF
What sets human brains apart from other species?
synaptic plasticity
Brain circuitry simplifies as the animal ___. Target cell receives the same number of synapses, but the ___ has changed (_____). This is ___-based and occurs before and after birth.
matures
pattern
synaptic rearrangement
activity
At birth, ganglion cells show ___ innervation of immature muscle. In maturity,
___ motor neuron innervates ___ motor fiber. Elimination of synapse occurs with ____ and ____.
polyneuronal one one axonal atrophy axonal retraction
___, ___, and____ all known to have extra axonal branches that are ____ in development (probably everywhere). More axons innervate each target cell in ___ animals (convergence ____ with age). More targets are innervated by each axon at a ___ age (divergence ___ with age).
NMJ cerebellum retinogeniculate autonomic nuclei pruned young decreases younger decreases
At birth, most neurons are present yet the brain continues to grow. What continues to grow in the brain after birth?
new glia
new neural connections
Brain development is ___-dependent. Every experience excites some neural circuits and leaves others alone. Circuits used over and over ___; those that are not used are ___.
activity
strengthen
pruned
misalignment of the eyes (4% of children)
strabismus
visual impairments without physical problems in the eye; 1⁄2 children with untreated strabismus develop this
amblyopia
How do you treat strabismus?
strengthen muscles in misaligned eye –> force use by patching good eye (timing is critical!!)
input from both eyes to visual cortex
binocular vision
Monocular deprivation test: close one eye –> ___
no cells activated by deprived eye; death of corresponding cells
What is Hebb’s postulate?
When an axon of cell A is near enough to excite cell B or repeatedly or consistently takes part in firing it, some growth or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased; “cells that fire together wire together”
Inputs from two eyes ____.
Each input has a different ___. Highly ____ activity wins out – synapse is strengthened; others weaken and are ____. Therefore, ___ strengthens synaptic connections.
converge on single cell activity pattern correlated eliminated coordinated activity
In neural plasticity, neurotransmitter at all these synapses is ___ – receptors can be ___ or ___.
glutamate
metabotropic (AMPA)
ionotropic (NMDA)
NMDA receptors are unique: ___ – glutamate + depolarization. NMDA receptors also allow ___ to pass; the magnitude of this ion signals level of ___.
voltage-gated (Mg2+ block)
Ca2+
synaptic activity
___ leads to strengthening of synapses.
long-term potentiation (LTP)
patterns of synaptic activity that produce a long-lasting increase in signal transmission between two neurons
long-term potentiation
