Memory Flashcards

1
Q

What is Donald Hebb’s proposal for associative learning?

A

When axon of cell A excites cell B and repeatedly/persistently takes part in firing it, A’s efficiency, as one of the cells firing B, is increased - cells that fire together, wire together

Synaptic strength might be enhanced by concurrent activation in pre- and post-synaptic neurons

LTP is this exact phenomenon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the Morris water maze?

A

Tests for spatial memory

Opaque liquid ie milk (great, torture animals in the products of animal torture - 10/10 neuroscience), submerged escape platform, over sequential submersions rats to learn location of platform based off cues in the room

Measures:
Escape latency - how long to get out over time
Spatial transfer test - remove platform, see where stays most
- both of these are disrupted by hippocampal lesions..

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What did Morris 1989 study?

NDMA antagonists

A

Morris water maze

3x days training, 8x2mins/day

Before training: two groups had bilateral injections of NMDA antagonist (negatively impacts LTP) into dentate gyrus in hippocampus - one high/one low; one control group

High dose = longer escape latency on at 3 + blocked LTP; low dose = nil effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What did Wilson and Tonegawa 1997 study? (Knockout mice)

A

NMDAR1 receptor knockout mice in CA1 neurons only = non-functional

Tetanic stimulation of Schaffer colatteral - CA1 synapses failed to induce LTP

Placed in Morris water maze - no evidence for learning

(correlational evidence)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What did Castro et al 1989 study?

Prior LTP

A

Induction of LTP prior to learning should disrupt learning

3 groups - one control + 2 tetanised: measured EPSPs using test tetanised pulses at baseline for 5 days before being tetanised

This induced LTP in dentate gyrus and looked at Morris water maze performance at peak EPSP level (most saturated synapses, potentiation peak) at day 19 - no improvement in escape latency in tetansied group

Tested again after decay of LTP - found control levels of escape latency

(more causative)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What did
Albeliovich et al 1993 study?

(Protein kinase C)

A

An example of contrasting results

Protein kinase C knockouts - failed to show LTP in hippocampus but unimpairment in Morris water maze

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why is there a difference in the findings of studies concerning LTP and spatial memory?

A

Not enough is known about hippocampal role in it - combination of memory + proprioception = complex - how do we manipulate properly?

Maybe no relationship between the two… (unlikely)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the role of the amygdala in memory?

A

Classical conditioning = formation of a very simple memory:
US->UR; CS + US -> UR; CS -> CR

May also involve LTP processes..

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What did Rogan et al 1997 study?

Conditioned fear

A

Foot shock -> freeze can be conditioned to a tone

Tone evokes a field potential in amygdala - early ‘dip’ = thalamo-amygdala auditory information transfer

Conditioned tone to be associated with foot shock - when fear response learned = larger ‘dip’ ; when repeated presentation of tone alone = extinction of fear response + decrease in size of dip

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What did Schroeder and Shinnick-Gallagher 2005 study?

LTP and long term fear

A

Conditioned fear to white noise

Fear response in amygdala tightly controlled by frontal cortex - frontal lesions = cant learn fear; lesion once learned = cant extinguish response

Fear related EPSPs still greater 10 days after pairing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an alternative hypothesis for the role of LTP in memory?

A

Shors and Matzel 1997

LTP = arousal/attention device - increasing the gain of salient environmental stimuli = indirect impact on learning

No positive evidence but may explain negative findings?

Need to ensure we’re not seduced by superficial appeal of the relationship

How well did you know this?
1
Not at all
2
3
4
5
Perfectly