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