memory 2 Flashcards
what does the neural network model of learning suggest?
that learning is a distributed code
neurons A, B, C respond to all 3 faces, responses of a single neuron not enough to learn/remember one face (not specific)
what is the IT cortex?
- fired when presented with faces
- different neurons are selective for different faces
- neurons can change response to faces after multiple representations to acquire stimulus selectivity
how does our brain recognize a face?
- as a distributed code/unique response across many neurons
- through a specific ratio of neuron activation
what do changes in the synaptic strength indicate?
physical basis of information storage
- how memories are encoded
what are the forms of synaptic modification?
how do they relate
- potentiation=strengthening
- depression=weakening
how does information flow through the hippocampus?
1) Entorhinal cortex
2) dentate gyrus
3) CA3
4) CA1
what is LTP? (long term potentiation)
high NMDA receptor activation
- a long lasting enhancement of the effectiveness of synaptic transmission
what are LTP’s measured as?
how are they induced?
- they are measured as elevated EPSPs
- induced experimentally by tetanus (burst of high-frequency stimulation)
- brief tetanus can lead to prolonged LTP
what 2 factors are necessary for LTP?
1) temporal summation of EPSPs
- caused by stimulation at high enough frequencies
2) cooperativity/ spatial summation
- enough co-active synapses need to be active to cause spatial summation of EPSPs (neurons that fire together wire together)
how long does LTP last?
for years
what are AMPA cells triggered by?
what do they release?
triggered by - binding glutamate
release - Na+
what are NDMA cells triggered by?
what do they release?
triggered by
- depolarization which releases Mg+
- binding glutamate
release - Na+ & Ca++
what does the release of calcium from NMDA receptors cause?
protein kinases to activate
what do the protein kinase do?
- phosphorylate AMPA receptors to increase ion conductance of AMPA receptors
- insert new AMPA receptors to post synaptic membrane
what is LDP?
long term depression
- prolonged decrease in the magnitude of the ESP
what happens in LTD when there is low calcium?
weak NMDA activation
protein phosphatases are activated
- dephosphorilates
- internalization of AMPA receptors
what is inhibitory avoidance an example of?
modification to an episodic memory
how does protein synthesis coorelate with stimulation and salience?
salience leads to more stimulation which leads to increased protein transcription
why do you remember what you had for breakfast on a traumatic day?
because weak events are consolidated if they occur proximal to strong ones
how are long term memories sustained?
1) Protein Kinase M zeta - PKMZ is produced due to synaptic activation and RNA transcription
2) positive feedback which triggers additional synthesis of more proteins
how are long term memories erased?
zip peptide will block Protein Kinase M zeta, which completely disrupts and blocks memory by disrupting the positive feedback loop
