Rodger’s and Kesner (2003)

Neurotransmitters

• Chemical messengers that transmit signals across synapses between neurons, influencing a variety of behaviours and processes such as learning, memory and emotion.

  Acetylcholine

• A neurotransmitter involved in learning and memory. Highly concentrated in the hippocampus and plays a key role in encoding of spatial memories and consolidation of new information.

  THEORY

• Acetylcholine facilitates memory encoding by enhancing communication between neutrons in the hippocampus a decrease in acetylcholine disrupts memory formation but does not significantly affect the retrieval of existing memories.

  AIM

• To investigate the role of acetylcholine in the encoding and retrieval of spatial memories.

  METHOD

• 30 rats acclimate to a hebb-Williams maze.

• Rats were randomly allocated to two groups

• Group 1 received a scopolamine injection (acetylcholine inhibitor)

• Group 2 received saline solution (placebo)

• Injections made directly into the hippocampus

• Encoding was assessed by comparing errors on the first 5 and last 5 trails on day 1

• Retrieval was assessed by comparing errors on the first 5 trails of day 2 to the last 5 trails on day 1

  FINDINGS

• Scopolamine significantly increased errors during encoding, showing impaired memory formation

• There was no significant difference in memory retrieval suggesting acetylcholine primarily affects memory encoding

  APPLICATIONS

• The finding support the development of treatments for neurodegenerative conditions like Alzheimer’s , which involve reduced acetylcholine levels

• The study provides insight into how neurotransmitters influence memory, contributing to the broader understanding of cognitive processes in the biological approach

  EVALUATION

  Strengths

• It is a controlled experiment, the use of placebo minimises confounding variables (stress from injection) Enhancing the validity of the study

• Targeted injection , injecting scopolamine directly into the hippocampus ensured the neurotransmitters effects were isolated

• Cause and effect relationship, the rigorous design allows researchers to establish a casual link between acetylcholine and memory encoding

  Limitations

• Reductionism, the study simplifies the complex process of memory by focusing solely on acetylcholine, excluding other factors like dopamine or glutamate

• Generalizability, animal models are limited in representing the complexity of human memory processes

• Ecological validity, the artificial maze task does not replicate real world memory challenges

  ETHICAL CONCIDERATIONS

• Injecting scopolamine directly into the hippocampus an conducting trails may have caused stress or discomfort

  UNANSWERED QUESTIOSN

• Would the same effects be observed in rats apply to humans?

  CONCLUSIONS

• Demonstrated that acetylcholine is crucial for encoding spatial memory but does not significantly impact memory retrieval .