Lecture: Neurotransmitters vs Neuromodulators

Introduction

• Neuromodulators are a subclass of neurotransmitters.
• Released from a presynaptic cell.
• Impact signal transmission across a broad population of neurons.

Key Differences

Standard Neurotransmitter

• Released from presynaptic cell.
• Binds to a target receptor on an adjacent single cell.
• Works via inotropic receptors.
  • Immediate effect by opening ion channels.
  • Alters resting potential by allowing ion permeation.
• Examples include:
  • GABA (inhibitory, decreases firing potential).
  • Glutamate (excitatory, increases firing potential).

Neuromodulator

• Also released from presynaptic cell.
• Can impact tens of thousands of neurons over a broad area.
• Works via metabotropic receptors.
  • Indirect effect by altering protein synthesis.
  • Causes longer-lasting changes in postsynaptic cells.
• Examples include:
  • Serotonin (impact on mood).
  • Dopamine (role in reward and addiction).

Synaptic Transmission Process Overview

1. Presynaptic Cell
   • Houses neurotransmitters or neuromodulators.
   • Releases these chemicals in response to action potentials.
2. Synapse
   • Junction where neurotransmitters/neuromodulators are released.
3. Postsynaptic Cell
   • Contains dendrites and receptor sites.
   • Binding alters cell activity.

Mechanism of Action

• Inotropic Receptors:
  • Neurotransmitters bind directly.
  • Opens ion channels immediately.
  • Allows ions to change cell resting potential rapidly.
• Metabotropic Receptors:
  • Neuromodulators bind.
  • Influences protein synthesis affecting ion channel behavior.
  • Causes lasting effects on neuron behavior and activity.

Conclusion

• Neurotransmitters: Instant effect, localized impact, quick response.
• Neuromodulators: Delayed, widespread, and prolonged influence.
• Both have specific roles in brain function, behavior, and neural responses.