Lecture 4 - Neurons Neural Processes

Neurons & Neural Processes

Overview

  • Neurons are specialized cells that communicate through electrical and chemical signals.

Housekeeping

  • Concept Map for Chapter 2 due soon.

  • Chapter 3 due February 6th next week.

  • Chapter 1 Quiz due Sunday at 11:59 PM.

Introduction to the Brain and Neuron

  • Brain Functions:

    • Information Processing: Similar to a computer.

    • Receives Sensory Inputs: Information from the environment.

    • Activates Behavioral Outputs: Initiates responses.

    • Short and Long-Term Storage: Retains memories and experiences.

    • Software: Refers to cognition, emotion, personality, etc.

    • Hardware: Comprises the brain and nervous system (e.g., cortex, hippocampus, cerebellum).

Neuron Composition

  • Neurons: Approximately 100 billion neurons in adults.

  • Each neuron connects to up to 1,000 neighboring neurons, leading to trillions of connections.

  • They serve as the building blocks of psychological phenomena but cannot think or feel individually.

Neuron Structure and Function

Basic Units of the Nervous System

  1. Neuron Functions:

    • Reception, Conduction, Transmission.

    • Connections are determined by maturation and experience.

Glial Cells

  • Support Cells:

    • Astrocytes: Assist in CNS damage and support communication.

    • Oligodendrocytes/Schwann Cells: Generate and repair myelin sheaths.

    • Microglia: Role in infections, inflammation, and brain development.

Parts of a Neuron

  • Dendrites: Receive signals from other cells.

  • Cell Body: Organizes and maintains cell functionality.

  • Cell Membrane: Protects the cell; selectively permeable to ions.

  • Axon Hillock: Generates impulses in the neuron.

  • Nucleus: Controls the neuron.

  • Node of Ranvier: Allows ionic diffusion.

  • Myelin Sheath: Increases signal speed.

  • Axon Terminal (Buttons): Forms junctions with other cells.

The Neural Impulse

Resting Potential

  • Characteristics:

    • Neuron is negatively charged at rest (resting potential = -70 mV).

    • Sodium/Potassium (Na+/K+) Pumps maintain ion balance.

Action Potential

  • Communication style; occurs when voltage shifts from -70mV to +40mV.

    • Triggered when channels open allowing Na+ influx at threshold potential (-55 mV).

    • Depolarization: The process where the internal charge of the neuron becomes positive.

    • Refractory Period: Follows firing where the neuron is unable to fire again.

Communication Speed

  • Affected by:

    • Axon length and myelination.

    • Range of 1 mph to 270 mph.

Neural Communication

Synapse and Neurotransmitters

  • Synapse: Space between axon terminal of one neuron and dendrites of another.

  • Neurotransmitters: Chemicals that transmit signals across synapses, leading to excitation or inhibition of the postsynaptic cell.

Mechanisms of Neurotransmission

  • Agonists: Enhance neurotransmitter activity (e.g., increase production, block reuptake).

  • Antagonists: Inhibit neurotransmitter activity (e.g., decrease production, block receptor sites).

Effects of Key Neurotransmitters

  • GABA: Inhibits communication.

  • Glutamate: Promotes communication.

  • Dopamine: Involved in reward and motor control.

  • Serotonin: Influences mood and appetite.

  • Acetylcholine: Important for muscle movement and memory.

  • Epinephrine/Norepinephrine: Related to energy and stress response.

The Endocrine System

Overview

  • Glands communicate via hormones, impacting development, behavior, and mood.

  • Key Functions:

    • Hormones regulate physical states and motivate behaviors.

Major Glands and Hormones

  • Hypothalamus: Controls the pituitary gland.

  • Pituitary Gland: Influences other glands and regulates various bodily functions.

  • Key Hormones:

    • Oxytocin: Aids in birth and promotes bonding.

    • Insulin: Regulates blood sugar levels.

    • Estrogens & Androgens: Involved in sex characteristics.

Conclusion

Questions

  • See you next time!