Lecture 05

Brain 2

1. Evolution of the Nervous System
2. Electrochemical Communication
1. Neurons produce electrical signals
2. Electrical signals are generated by chemical changes
3. Resting Phase
1. Distribution of potassium and sodium ions
2. Negative electrical change (~-70mV)
4. Action Potentials
1. Depolarization
2. Repolarization
3. Propagation
4. All or None Principle
5. Transmission Speed

Overview

Psychological phenomena are generated by electrical signals. The process underlies all aspects of psychological life, including emotion, behavior, dreams, and memory, and has remained unchanged for several hundred million years. Billions of neurons have been firing in the time it has taken you to read this paragraph and consider its implications. Neurons communicate by means of an electrical signal called the Action Potential. These signals are produced by sudden reversals in a neuron's electrical charge. These reversals are produced by the movement of ions across a neuronal membrane. This process is called electrochemical communication: Chemical changes produce electrical signals.

Specifics

• Identity two main factors that influence the distribution of ions within and outside of a neuron.
• Know the relative distribution of potassium and sodium ions during a neuron's resting phase, and the (approximate) electrical current the flow of these ions creates.
• Describe what happens to the distribution of potassium and sodium ions during depolarization (along with the factors that create this distribution), and know the (approximate) electrical current the flow of these ions creates.
• Be familiar with the following terms as they pertain to the flow of the electrical current through a neuron: Hyperpolarization, propagation, and the "all or none principle."
• Identify two factors that influence how fast an electrical charge travels through a neuron.