Lecture: Neurons and Neural Circuits

Introduction

• Prof. Dave introduces the lecture focusing on neurons and their organization.
• Aim: Understanding the hierarchy of neuron organization or neural integration.

Neuronal Organization

Neuronal Pools

• Small collections of neurons.
• Function: Integrate information to determine the forwarding of signals.

Zones of Neurons

• Discharge Zone: Neurons with many synaptic contacts; more likely to depolarize beyond the threshold and generate an action potential.
• Facilitated Zone: Neurons with fewer synaptic contacts; less likely to reach the action potential threshold unless receiving additional stimuli.

Neural Circuits

Types of Circuits

1. Diverging Circuit

   • One input, multiple outputs.
   • Signal amplification.
   • Example: Activation of numerous motor neurons by a single brain neuron.

2. Converging Circuit

   • Multiple inputs, one output.
   • Signal concentration.
   • Example: Sensory information traveling to the brain.

3. Reverberating Circuit

   • Chain of neurons with feed-back loops.
   • Controls rhythmic activities (e.g., breathing) and repetitive actions (e.g., walking).

4. Parallel After-Discharge Circuit

   • One input, diverges into parallel arrays, then converges on one output.
   • Produces a burst of multiple impulses due to time variance to the output.
   • Involved in complex brain activities, like coincidence detection.

Neural Processing Types

Serial Processing

• Characteristic: All-or-nothing signal transmission.
• Example: Reflexes.

Parallel Processing

• Characteristic: Input diverges into many pathways; each pathway processes the information uniquely.
• Example: Smells or songs triggering memories, thoughts, and emotions.
• Role: Behind higher-level brain activities like abstract thinking and planning.

Conclusion

• Brief transition to how the brain handles all the processed information.