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
Activates NMDA receptors lead to ___. New ___ receptors inserted into postsynaptic membrane leads to ___ transmission.
Ca2+ influx
AMPA
stronger
Immature synapses cluster
___ receptors and have few ___ receptors. Electrically active synapses gain ___ receptors.
NMDA
AMPA
AMPA
activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer following a long patterned stimulus
long- term depression (LTD)
____ activity (i.e., noise) results in fewer ___ receptors.
uncorrelated
AMPA
Monocular deprivation: eyelid closure prevents image formation on retina, which replaces ____ ganglion cell activity with noise. This rarely evokes strong response in cortex –> weakly activates ____ receptors –> removal of ___ receptors and loss of ____ from closed eye.
well-correlated
NMDA
AMPA
synapses
After ____, monocular deprivation has little effect on ocular dominance.
critical period
time during an organism’s life span when it’s most sensitive to environmental influences or stimulation; suggested for vision, language, music, etc.
critical period
In children, ___ impedes brain development; leads to a high risk for variety of ____
neglect
social and behavioral abnormalities
Mike May was light-sensitive before his vision was restored. What can he see and not see after his surgery?
Can see 2D forms and shapes but has no constructive perception; depth perception but no shading, lacks perspective and transparency perception; fine with motion but poor with object and face recognition
Order and approximate timing of the appearance of visual abilities is common to all infants. Use ___, attention to novel stimuli within a week of birth. ___ cues (binocular stereo) develop within 4-12 weeks. The form ___ categories at 3-4 months. They recreate ___ from memory at 5-9 years. They ___ (detect partially hidden objects): 10- 17 years. ___ cues develop very early.
size cue depth perceptual spatial layouts separate an image into parts motion
Why is motion important in infant vision?
infants use motion cues to detect and recognize objects, estimate 3D shape
What is the hypothesis surrounding Mike May’s ability to see certain things?
Mike May is good at using motion cues, which were well developed before accident, did not decay afterwards. Other things like face recognition underwent pruning (plasticity) and that brain area was adapted for something else
process by which we acquire knowledge
about the world
learning
encoded knowledge that is stored and later retrieved
memory
memory without experience
instinct
What are the 3 stages of memory?
- encoding (i.e., initial processing of information)
- storage (i.e., permanent record)
- recall (i.e., accessing information)
memory of facts and events, and refers to those memories that can be consciously recalled (daily episodes, word meanings, history)
declarative memory
Patient H.M. underwent removal of bilateral hippocampus and medial temporal lobes for seizures. What was the outcome of this surgery?
- seizures were much improved
- devastating memory deficit
- normal short-term memory but no consolidation of short-term declarative memory into long-term
- long-term memory of events prior to 1953 largely intact
- intelligence unaffected
- procedural memory intact
- spatial orientation severely affected
___ and __ are crucial for memory, specifically episodic memory, spatial memory, and navigation.
MTL
hippocampus
repeating a complex activity over and over again until all of the relevant neural systems work together to automatically produce the activity
procedural learning
Procedural memory formation can occur without ___.
conscious awareness
memory of autobiographical events (times, places, associated emotions, and other contextual who, what, when, where, why knowledge) that can be explicitly stated or conjured
episodic memory
Recollection better for recent events than distant ones
– often reversed in ___.
elderly
forget events prior to trauma
retrograde amnesia
forget events since trauma
anterograde amnesia
sense of place and ability to navigate; highly organized in brain space; hippocampus required
spatial memory
cells located in the hippocampus that fire when animal reaches a certain place in the environment
place cells
cells located in entorhinal cortex; active in multiple places (i.e., regular spatial intervals); hexagonal arrangement; part of navigation system – measure distances
grid cells
How are place cells involved in episodic memory?
encode not only current spatial location but also where animal has been and where it’s going next
What happens with place cell activity during sleep or memory formation?
replay of place cell activity in reverse during memory formation and forward during sleep
____ is particularly useful in remembering spatial information.
posterior hippocampus
London taxi cab drivers showed an enlarged ____ but atrophy of ____.
posterior hippocampus
anterior hippocampus
In ___ of hippocampus, there are stem cells that can differentiate into neurons during spatial memory formation.
sub granular zone
What stimulates and inhibits hippocampal neurogenesis?
stimulates: exercise, enriched environments
inhibits: stress, corticosteroids
when we fill in most likely missing data and may even confabulate to make the memories make sense
false memories
