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 Rego

 Overall Evaluations  Methodological Critiques ◦ Unexplored Pathway of LTP ◦ Age and Gender Anomalies ◦ Pharmacological Side Effects  Alternate Interpretation of the Results  Further Exploration Carol Rego

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

ExperimentEvaluation 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  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.

 Study focused on hippocampus  Actually three different pathways Herman Gill

PathwayInput Perforant PathwayEntorhinal Cortex II, III (EC2 & EC3) Mossy Fibre PathwayDentate Gyrus (DG) Schaffer Collateral PathwayCornu Ammonis III (CA3)

Herman Gill Perforant Mossy Fibre Schaffer Collateral

Herman Gill Perforant Mossy Fibre Schaffer Collateral LTP is NMDA-independent in mossy fibre pathway

 In CA1 and DG ◦ NMDA responsible for LTM retrieval  In CA3 ◦ NMDA responsible for spatial recognition Herman Gill LTM Retrieval Spatial Recognition

 Difference in performance with regards to age  Declines continuously beginning at earliest age Bonnie Chan

GenderCuesEfficiency MaleGeometricFast FemaleLandmark/MultipleSlow

 Common critique/concern  Effects of the drugs used to block NMDA receptors not well researched  Side effects may cause a decrease in performance ◦ (i.e.) due to drowsiness, disorientation  Solution  Gene knockout? Bonnie Chan

 Stress Impairs Performance in Spatial Water Maze Learning Tasks (1999) ◦ By Christian Holscher Anastasia Christopher

 Stressful situations ◦ Stress can impair performance on specific activities  How altered fear conditions and stress perception can account for the impaired spatial learning Anastasia Christopher

 Findings: ◦ Stress can cause amnesic symptoms in working memory ◦ Non-handled rats were slower in a spatial learning task Anastasia Christopher

 Connection: ◦ Alternative interpretations for this research paper  Experiment 2  no deficit; handling  Experiment 3  stress was not an issue  Experiment 4  extramaze cues Anastasia Christopher

Sarah McNeil Evidence SupportingEvidence 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 efficiency Drug and gene knockout can have other side effects that skew data LTP can occur in other regions of the brain (i.e. amygdala) Unethical to test LTP in humans and cannot extrapolate data across species

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. Sarah McNeil

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 Carol Rego 

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