learning and memory---------- Flashcards
engram
The theory that memory is a strengthening of the connection between two brain areas.
what did LASHLEY find?
that learning and memory is equally distributed throughout brain.the cortex works as a whole. the more intact cortex, the better. was the first to get the biological structure for memory.
where is memory stored?
in the HIPPOCAMPUS, important for getting memory into cortex for long term storage.
ERIC KANDEL
won the nobel prize for memory in physiology for studying learning and memory. (her fav scientist)
studied APLYSIA.
(looked at cellular level)
aplysia
giant sea slug, nice ganglion circuts. very simplified nervous system. neurons are comprable to humans, so he studied cellular changes that occurred with learning and memory.
donald hebb
leading researcher- hypothesized what was in the brain to have learning and memory occur.
NEURONS THAT WIRE TOGETHER, FIRE TOGETHER.
-changes at synaptic level is what underlies learning and memory.
glutamate
main excitatory neurotransmitter in brain. very important to underlie biological basis of learning and memory
2 types of glutamate receptors
AMPA & NMDA
AMPA
sodium channel. when glutamate released from presynaptic, it binds to AMPA receptors and opens sodium channel, which depolarizes cell, leading to positive charge.
NMDA
respond to glutamate.
have sodium channel AND calcium channel. (ca++ was concentrated outside of cell) if NA/CA enter cell, it depolarizes cell, which leads to EPSP.
-when just resting it has 2 channels, which are blocked by MAGNESIUM ion.
where is glutamate released from
presynaptic channel.
what type of ion is blocking NMDA channels?
MAGNESIUM
how do we get magnesium ion out?
depolarize membrane by increasing positive charge inside cell by using AMPA receptors with small amount of glutamate release. depolarizes membrane, positive charge expells magnesium ion, causing it to pop out.
what causes a lot of glutamate release from presynaptic cell?
increase firing rate of presynaptic neuron, more glutamate is released.
what does calcium in the cells do?
it creates more AMPA receptors and more NMDA channels, which means more surface area, more sodium and higher EPSP
what happens if calcium enters the cell
- more AMPA
- more surface area
- more NMDA
calcium triggers what?
retrograde signaling
nitric oxide- triggers synthesis. can flow freely across cell membrane because its a gas. it diffuses back into neuron A and causes it to release more glutamate next time neuron B fires an action potential.
hebb said
that when neuron a fires to stimulate neuron B, causes cellular changes in neuron B or both that allows neuron A to more efficiently stimulate neuron B.
