Neural Communications (2_17_25)

Neural Communication

Overview

• Brain's complexity

  • Human brain constitutes 2% of body weight but consumes 20% of oxygen and 25% of body's glucose.

  • Critical for all conscious and unconscious experiences, indicating its vast energy requirements.

Basic Concepts

• Neural Communication

  • Involves billions of neurons, an information system that operates the same across different brains.

Neurons

• Definition: Basic units of the nervous system.

• Functions:

  • Receive, integrate, and transmit information.

  • Communication occurs via electrochemical processes.

Anatomy of Neurons

• Parts of a Neuron:

  • Dendrites: Receive messages from other cells.

  • Cell Body: Life-sustaining center of the cell.

  • Axon: Conveys messages away from the cell body.

  • Terminal Branches of Axon: Connects with other cells.

  • Myelin Sheath: Insulates the axon, enhancing signal speed.

  • Neural Impulse: Electrical signals traveling down the axon.

Phases of Neural Communication

1. Neuron sends signal to receiving neurons.

2. Receiving neurons take in signals from adjacent neurons.

3. Neurons evaluate incoming signals.

Electrical Properties of Neurons

• Resting State: Negative internal charge, positive external charge.

• Input Effects:

  • Excitatory Input: Reduces negativity, making it more likely to fire.

  • Inhibitory Input: Increases negativity.

  • Neurons integrate these inputs to determine whether to fire.

Action Potential

• Characteristics:

  • All-or-nothing response; consistent size, varies in frequency.

  • Triggered when excitatory input surpasses the threshold.

  • Associated with changes from negative to positive charge, sending signals down the axon.

Myelin and Speed of Transmission

• Function:

  • Myelin sheath enhances efficiency and speed of electrical impulses.

Transmission Across Synapses

• Synaptic Communication:

  • Chemicals released from the sending neuron's terminal buttons deposit into synapse and bind to receptor sites on neighboring neurons.

  • This binding can encourage action potentials in receiving neurons.

Synaptic Transmission Steps

1. Neurotransmitter Release: Triggered by action potentials fusing vesicles with the presynaptic membrane.

2. Binding to Receptors: Neurotransmitters only bind if they fit specific receptors, likened to a key fitting a lock.

3. Termination: By reuptake, enzyme deactivation, or autoreception to stop the neurotransmission.

After Neurotransmitter Release

• Reuptake: Absorption back into the presynaptic neuron.

• Autoreception: Self-regulation by presynaptic neurons.

• Enzyme Deactivation: Enzymes break down excess neurotransmitters.

Neural Communication Summary

• Neurons begin in a resting state, collecting data from others.

• Fire when enough excitation is present, generating an action potential that releases neurotransmitters into the synapse.

• Signal intensity is conveyed through the frequency of firing.

Major Neurotransmitters and Their Functions

• Acetylcholine: Motor control, learning, and memory.

• Norepinephrine: Arousal and attention.

• Serotonin: Emotional regulation and sleep.

• Dopamine: Reward pathways and motor control.

• GABA: Main inhibitory neurotransmitter; reduces anxiety.

• Glutamate: Primary excitatory neurotransmitter; important for memory.

• Endorphins: Pain reduction and mood elevation.

Agonist and Antagonist Molecules

• Agonists: Enhance neurotransmitter action by increasing production, binding to receptors, or blocking reuptake.

• Antagonists: Inhibit neurotransmitter action by decreasing production, blocking receptors, or promoting breakdown.