PSY1EFP: EXPERIMENTAL FOUNDATIONS
OF PSYCHOLOGICAL SCIENCE
BRAIN-BEHAVIOUR RELATIONSHIPS
SESSION 1: HOW DOES THE NERVOUS SYSTEM OPERATE?
Session 1: How does the nervous system operate?
Today’s big question: Myelin is like butter: what happens when it melts?
In this face to face session we will:
• Distinguish between the two basic divisions of the nervous system.
• Distinguish between the functions of distinct types of neurons.
• Describe the structure of the neuron.
• Describe the electrical and chemical changes that occur when neurons communicate.
• Identify the major neurotransmitters and their primary functions.
• Clinical case example: Multiple Sclerosis.
The nervous system has two basic divisions
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Central nervous system (CNS): brain and spinal cord
Peripheral nervous system (PNS): all nerve cells in the body that are not part of the central
nervous system. The peripheral nervous system includes the somatic and autonomic
nervous systems.
Neurons are specialized for communication
Nerve cells are powered by electrical impulses and communicate with other nerve cells through
chemical signals.
 Three basic phases
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Reception: Chemical signals are received from neighbouring neurons.
Integration: Incoming signals are assessed.
Transmission: Signals are passed on to other receiving neurons.
Types of neurons
Sensory neurons: These neurons detect information
from the physical world and pass that information to the brain.
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Somatosensory nerves provide information from the skin and muscles.
Motor neurons: These neurons direct muscles to contract or relax, thereby producing
movement.
Interneurons: These neurons communicate within local or short-distance circuits.
Neuron Structure
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Dendrite: detects chemical signals from neighbouring neurons
Cell body (soma): collects and integrates information
Axon: transmits electrical impulses
Terminal buttons: bulbous end of an axon
Synapse: supports chemical communication between neurons
Synaptic cleft: narrow gap between terminal button (presynaptic membrane) and dendrite
(postsynaptic membrane) of neighbouring neuron
Myelin sheath: encases and insulates axons
Composed of glial cells
Nodes of Ranvier: Spaces between glial cells
The resting membrane potential is negatively charged
Resting membrane potential: the electrical charge of a neuron when it is not active
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Polarized: when a neuron has more negative ions inside it than outside
Polarization: creates the electrical energy necessary to power the firing of the neuron
Action potentials cause neural communication
Action potential (neural firing): the electrical signal that passes along the axon and subsequently
causes the release of chemicals from the terminal buttons
Case example: Multiple sclerosis (MS) is an autoimmune disease
Symptoms of MS/ Loss of myelin and its consequences
Neurotransmitters bind to receptors across the synapse
Neurotransmitters: chemical substances that transmit signals from one neuron to another
Receptors: In neurons, specialized protein molecules on the postsynaptic membrane;
neurotransmitters bind to these molecules after passing across the synapse.
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The binding of a neurotransmitter with a receptor produces an excitatory or inhibitory
signal.
Neurotransmitters Influence Mental Activity and Behaviour
Drugs and toxins can alter neurotransmitter
action.
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Agonists: enhance the actions of neurotransmitters
Antagonists: inhibit the actions of neurotransmitters
Researchers often inject agonists or antagonists into animals’ brains to assess how
neurotransmitters affect behaviour.