Distinct Components of Spatial Learning Revealed by Prior T - PowerPoint Presentation

Slide1

Distinct Components of Spatial Learning Revealed by Prior Training and NMDA Receptor Blockade

D.M. Bannerman, M.A. Good, S.P. Butcher, M. Ramsay & R.G.M. Morris

GROUP A3

Bonnie Chan | Anastasia Christopher | Herman Gill

Marisa Leung | Sarah McNeil | Carol

RegoSlide2

Overall Evaluations

Methodological CritiquesUnexplored Pathway of LTP

Age and Gender Anomalies

Pharmacological Side EffectsAlternate Interpretation of the ResultsFurther Exploration

Table of Contents

Carol

RegoSlide3

Overall Evaluations

Carol

Rego

The purpose of the study was very non specific, which allowed for further exploration during the course of the study.Slide4

Experiment

Evaluation

Experiment

1

injection

of AP5 caused learning deficit



Experiment

2 found contradicting results where the AP5 rats learned quite well despite complete LTP blockade Experiment 3 NMDA receptors are not necessary for all hippocampus dependant spatial learning Experiment 4 AP5 rats, given non-spatial pretraining, a learning deficit was observed

Overall Evaluations

Carol

RegoSlide5

Overall Evaluations

Carol

Rego

NMDA receptors are not necessary for all hippocampus dependant spatial learning, but NMDA receptor dependant plasticity is dependent on the hippocampus for its expression.Slide6

Study focused on hippocampus

Actually three different pathways

Unexplored Pathway of LTP

Herman GillSlide7

Unexplored Pathway of LTP

Herman Gill

Pathway

Input

Perforant

Pathway

Entorhinal

Cortex II, III (EC2 & EC3)

Mossy Fibre Pathway

Dentate Gyrus (DG)Schaffer Collateral PathwayCornu

Ammonis

III (CA3)Slide8

Unexplored Pathway of LTP

Herman Gill

Perforant

Mossy Fibre

Schaffer CollateralSlide9

Unexplored Pathway of LTP

Herman Gill

Perforant

Mossy Fibre

Schaffer Collateral

LTP is NMDA-independent in mossy fibre pathwaySlide10

In CA1 and DGNMDA responsible for

LTM retrievalIn CA3NMDA responsible for

spatial recognition

Unexplored Pathway of LTP

Herman Gill

LTM Retrieval

Spatial RecognitionSlide11

Difference in performance with regards to age

Declines continuously beginning at earliest age

Age Anomalies

Bonnie ChanSlide12

Gender Anomalies

Bonnie Chan

Gender

Cues

Efficiency

Male

Geometric

Fast

FemaleLandmark/MultipleSlowSlide13

Common critique/concern

Effects of the drugs used to block NMDA receptors not well researchedSide effects may cause a decrease in performance

(i.e.) due to drowsiness, disorientation

Solution  Gene knockout?

Pharmacological Side Effects

Bonnie ChanSlide14

Stress Impairs Performance in Spatial Water Maze Learning Tasks (1999)

By Christian Holscher

Alternate Interpretation

Anastasia ChristopherSlide15

Stressful situations

Stress can impair performance on specific activitiesHow altered fear conditions and stress perception can account for the impaired spatial learning

Alternate Interpretation

Anastasia ChristopherSlide16

Findings:

Stress can cause amnesic symptoms in working memoryNon-handled rats were slower in a spatial learning task

Alternate Interpretation

Anastasia ChristopherSlide17

Alternate Interpretation

Anastasia ChristopherSlide18

Connection:

Alternative interpretations for this research paperExperiment 2  no deficit; handling

Experiment 3  stress was not an issue

Experiment 4  extramaze cues

Alternate Interpretation

Anastasia ChristopherSlide19

Further Studies

Sarah McNeil

Evidence

Supporting

Evidence Against

Same results found in gene knockout studies

In nature,

large scale EPSP’s do not occur during information processing

Training in the brain uses same

pathways as LTP and causes same synaptic efficiencyDrug and gene knockout can have other side effects that skew dataLTP can occur in other regions of the brain (i.e. amygdala)Unethical to test LTP in humans and cannot extrapolate data across speciesSlide20

There is lots of evidence to suggest that LTP might be similar to the neural mechanism that the brain uses in learning and memory but the conclusion can not be made that the mechanisms are the same.

Further Studies – Conclusion

Sarah McNeilSlide21

Provided subsequent analyses of their hypothesis creating a concrete conclusion

However:

Left several possible causal pathways unexplored

Failed to account for pharmacological side effects, age, and gender of subjects

Possible misinterpretation of results

Further studies have shown some validity in Bannerman et al results

Conclusion

Carol

Rego

Slide22

This concludes our presentation

We will be happy to address any questions you may have