Lecture Notes on Neuronal Connections and Synapses

Introduction

• Previous module covered:
  • Electrical properties of neurons
  • Membrane potentials
  • Action potentials (spikes)
• Importance of understanding single neurons, but need to analyze collective behavior of neurons.
• Neuroscience can be approached at different scales and complexity levels.

Topics to be Explored

• From single molecules (ion channels) to neurons’ electrical behavior.
• Collective behavior in circuits.
• Organization in large brain regions.

Neuronal Anatomy

• Neurons are polarized:
  • Dendrites: Receive inputs (tree-like branches, from Greek 'dendron').
  • Cell Body: Initiates action potential if depolarization is sufficient.
  • Axon: Sends action potential to another neuron.

Connecting Neurons

• Synapse: Interface between axon of one neuron and dendrite of another.
• Types of synapses:
  • Electrical Synapses:
    • Pores allowing ions to pass through.
    • Fast and synchronizes cells.
  • Chemical Synapses:
    • Electrical signal causes chemical release into synaptic cleft.
    • Chemical taken up by downstream neuron.
    • Slower, allows complex signaling.

Chemical Synapses

• Action potential triggers chemical release.
• Chemical signal affects downstream neuron:
  • Can depolarize membrane (convert back to electrical).
  • Can have other effects.
• Critical for neuronal computations.

Upcoming Topics

• Detailed exploration of chemical synapses.
• Networks of interconnected neurons and behavior.
• Role of synapses in neurological and psychiatric disorders.
• Synapses targeted by psychoactive drugs and poisons.
• Synaptic changes over time, learning, and memory.