Lecture Notes: Neurotransmission and Neurotransmitters

Overview

• Topic: Neurotransmission and neurotransmitters
• Context: Falls under brain and behavior in biological approach
• Exams: Important for SAQs and potentially LAQs in Paper 1 exam
• Previous Topic: Neuroplasticity (treated separately for this purpose)
• Recommended Research: Martinez & Kessner, Antonova, Privat et al.

Key Concepts

Neurotransmission

• Definition: Communication within the nervous system via electrochemical signals
• Process:
  1. Action potential initiated in presynaptic neuron
  2. Travels down axon to terminals
  3. Neurotransmitters released into synapse
  4. Bind to postsynaptic receptors causing excitatory or inhibitory reactions
  5. Neurotransmitters either broken down or re-absorbed

Neurotransmitters

• Role: Chemical messengers facilitating neural communication
• Excitatory vs. Inhibitory:
  • Excitatory: Cause depolarization, action potentials (e.g., Acetylcholine)
  • Inhibitory: Cause hyperpolarization, prevent action potentials (e.g., GABA)

Agonists and Antagonists

• Agonists: Chemicals (endogenous or exogenous) that initiate a response when binding to receptors
  • Endogenous: Naturally occurring in the body
  • Exogenous: Artificial or external chemicals (e.g., drugs)
• Antagonists: Chemicals that block agonists from receptor binding (e.g., Scopolamine)

Detailed Studies

Acetylcholine (ACH)

• Function: Excitatory neurotransmitter related to memory and cognitive processes
• Associated Conditions: Alzheimer's, Parkinson's
• Research: Martinez & Kessner
  • Method: Lab experiment with mice
  • Groups: Scopolamine (antagonist), Physostigmine (enzyme blocker), Control
  • Findings: ACH levels influence memory performance
  • Evaluation: High internal validity, concerns on external validity

GABA (Gamma-Aminobutyric Acid)

• Function: Inhibitory neurotransmitter balancing excitability
• Research: Privat et al.
  • Method: Y-shaped maze with mice
  • Groups: Benzodiazepine-treated impaired memory, Untreated impaired memory, Healthy control
  • Findings: Benzodiazepine improves memory, supports recent cell growth
  • Evaluation: High internal validity, limited generalizability

Summary

• Important Neurotransmitters: Acetylcholine, GABA
• Key Research: Use controlled experiments to establish neurotransmitter roles
• Relevance: Understanding neurotransmission is critical for explaining cognitive and behavioral processes in exams