Memory

Question 1

Morris (1989)

Answer 1

Looked at spatial learning in rats
Placed them in opaque water and they learnt where a platform was
The more they were placed in the water the less time it took them to find the platform (escape latency)
Bilateral injection of NMDA anatagonist into hippocampus (high or low dose)
High dose significantly lengthened the escape latency and almost completely blocked LTP
Low dose had no effect
First correlational evidence of animals ability to learn to induce LTP and suggest a relationship between the 2

Question 2

Wilson and Tonegawa (1997)

Answer 2

Used knockout mice and a complicated genetic technology to remove one of the subunits of NMDA receptors from CA1 region or hippocampus (where LTP has been widely demonstrated) making it useless
OR could
Insert a dye to show where CA1 region was

Question 3

Castro et al (1989)

Answer 3

Idea that if you induce LTP at synapses before animal is put into a situation and needs to learn it should block the ability to learn when it needs to as there’s no more capacity in the system for learning (theoretically) - saturation of synapses hopefully to show synapses would normally be involved in learning
Found there was no evidence of learning
When LTP was decayed the synapses began to depotentiate and show the ability to learn evidenced by decreased escape latency
Showed evidence against a link between hippocampal LTP and memory but could be that there is and it’s just not very strong

Question 4

Abeliovich et al (1993)

Answer 4

Knockout mice lacking protein kinase C (important mediator in effects of calcium so involved in LTP)
Found these mice failed to show LTP as the lack of protein kinase C blocked ability to produce LTP in hippocampus
BUT when in the morris water maze they could still learn where the platform was - blocking ability to produce LTP in CA1 doesn’t block ability to learn

Question 5

Conditioned fear and LTP

Answer 5

Hippocampus is very complicated so can’t know for sure if LTP is involved but evidence suggests it’s not for memory so look at a more simple form of learning - classical conditioning
Conditioning fear involves the amygdala complex - closely related to the hippocampus