HOW NEURONS WORK

Overview

What Do Neurons Have to Do With Psychology?

How Do Neurons Communicate? How Can Neurons Produce Complex

Processes? How is the Nervous System Organized?

What Do Neurons Have to do with Psychology?

Every perception, thought, emotion, and action is related to activity in the nervous system.

The nervous system is made up of neurons in the brain, spinal cord, and throughout the body.

Why This is Important

Every time you think something or do something, neurons are communicating.

It’s not possible to understand some issues about Psychology without knowing how neurons work

Example: Advances in the treatment of psychological disorders

What are Neurons?

Cells that are specialized for communication

Glial cells are cells that support, insulate, nourish, and regulate neurons

The human brain has about 100 billion neurons and 900 billion glial cells.

Neurons generally are not replaced after they die

How Do Neurons Communicate?

An electrochemical process Neurons receive input from other neurons

and from sensory organs Each neuron summarizes the input it

receives; this determines what message (if any) will be sent to other neurons

The Resting Potential

A neuron in its resting state has a negative electrical charge called the resting potential.

Receiving Input

Input from other neurons and/or sensory organs results in electrical changes

These changes are graded potentials Vary in strength Excitatory potentials bring the neuron closer

to threshold Inhibitory potentials take the neuron farther

away from threshold

Reaching Threshold

The threshold is the electrical charge at which a neuron will send an outgoing message

If the neuron receives sufficient excitatory graded potentials, it will reach threshold

This triggers a chain reaction of electrochemical changes

The Action Potential

The action potential is the outgoing message, sent along the neuron’s axon

The action potential is all-or-none A wave of electrochemical change Travels faster when the axon is

myelinated

The Action Potential

When the action potential reaches the tips of the axon, it causes the release of neurotransmitter molecules

The neurotransmitters travel across the synapse to the dendrites of another neuron

The neurotransmitters fit into receptor sites on the dendrites, causing graded potentials

How Neurons Do Complex Things

Neurons are arranged into neural circuits. The neural circuits are connected into

larger neural networks. How did our brains get this way?

Peripheral Nervous System

Somatic Nervous System - voluntary behavior

Autonomic Nervous System - mostly involuntary

Sympathetic - increases arousal Parasympathetic - decreases arousal

Central Nervous System

Spinal Cord Brain