Synaptic Plasticity and Memory

Question 1

Criteria for assessing the synaptic plasticity and memory hypothesis

Answer 1

• Anterograde alteration: blocking changes in synaptic strength should block memory formation
• Retrograde alteration: reversing or scrambling changes in synaptic strength after learning should wipe out the memory stored
• Detectability: if synaptic changes happen during learning, should be able to detect them
• Mimicry: if you could go into the brain, should be able to engineer a memory for something that has never happened

(Martin, 2000)

Question 2

What experiment showed that NMDAR blockade impairs water maze memory formation?

Answer 2

(Morris, 1986)
Spatial learning in water maze: rats implanted with automatic pumps that gave either a vehicle or DL-AP5 (NMDA inhibitor) to the lateral ventricle (adjacent to hippocampus)
Vehicle - spent most time in quadrant that used to contain the platform (in training)
DL-AP5 - randomly searched every quadrant equally

LTP was measured in dentate gyrus:
Vehicle - LTP
DL-AP5 - complete lack of LTP

To check not other forms of memory were affected:
Two platforms in the maze (both visible, different colours, one stable, one unstable)
Both groups improved performance is selecting the right platform equally
-> This is discrimination learning (not in the hippocampus) -> was not affected