Notes From Reading
C HAPTER 3:T HE BIOLOGICAL BASIS OFB EHAVIOUR (PGS.84-135)
Communication in the Nervous System
Nervous Tissue: The Basic Hardware
Neurons – are individual cells in the nervous system that receive, integrate, and transmit
Soma (cell body) – contains the cell nucleus and much of the chemical machinery common
to most cells
Rest of neuron dedicated to handling info
Dendrites – branches that are specialized to receive info from other cells
Axon – fibre that carries signals away from soma to other cells
Myelin sheath – insulating material that encases some axons, may speed up transmission of
Terminal Buttons – small knobs at ends of axons that release neurotransmitters at synapses
o Synapse – point at which neurons connect. Junction where info is transmitted from
one neuron to another.
Gila – are cells found throughout the nervous system that provide various types of support
The Neural Impulse: Using Energy to Send Information
The Nueron at Rest: A Tiny Battery
o Neural impulse is a complex electrochemical reaction.
o The Resting Potential of a neuron – neuron‟s stable, negative charge when inactive
The Action Potential – voltage spike that travels along axon
Absolute Refractory Period – Brief time after action potential before another action
potential can begin
The All or None Law – a neuron either fires or doesn‟t
o Its action potentials are always the same. i.e. weaker stimuli don‟t produce smaller
o They can change the rate of action potentials. A stronger stimulus will make for
more rapid action potentials in a shorter period of time.
The Synapse: Where Neurons Meet
Sending Messages: Chemicals as Couriers
o Synaptic Cleft – a microscopic gap between the terminal button of one neuron and
the cell membrane of another neuron.
o Presynaptic Neuron – sends the signal, postsynaptic neuron receives the signal.
o Neurotransmitters – chemicals that transmit info from one neuron to another.
Receiving Signals: Postsynaptic Potentials
o Postsynaptic Potential (PSP) – a voltage change at a receptor site on a postsynaptic
o Graded – vary in size and increase/decrease the possibility of a neural impulse in the
receiving cell in proportion to the amount of voltage change.
o 2 Types of Signals:
Excitatory PSP is a positive voltage change that increases the likelihood that
postsynaptic neuron will fire action potentials.
Inhibitory PSP negative voltage change that decreases the likelihood that the
postsynaptic neuron will fire action potentials.
o Reuptake – process in which neurotransmitters are sponged up from the synaptic
cleft by the presynaptic membrane.
Integrating Signals: Neural Networks
1/6 Notes From Reading
C HAPTER 3:T HE BIOLOGICAL B ASIS OFBEHAVIOUR (PGS.84-135)
o State of a Neuron is the weighted balance between excitatory and inhibitory PSP‟s.
Neurotransmitters and Behavior
o Released by neurons that control skeletal muscles
o Contribute to the regulation of attention, arousal, and memory
o Agonist – is a chemical that mimics the action of a neurotransmitter
o Antagonist – is a chemical that opposes the action of a neurotransmitter
Monoamines – regulate everyday behaviour such as voluntary movements (Parkinson
Disease); linked to schizophrenia and psych disorders (depression)
o Includes 3 neurotransmitters – dopamine (DA), norepinephrine, and serotonin.
o Serotonin involves the regulation of sleep; abnormal levels linked to depression and
o Dopamine abnormal levels linked to schizophrenia; dopamine circuits activated by
cocaine and amphetamines
o Norepinephrine abnormal levels linked to depression; contributes to modulation of
mood and arousal
GABA and Glutamate
o GABA are inhibitory transmitters that contribute to regulation of anxiety
o Glutamate are excitatory transmitters linked to memory process of long-term
Endorphins – internally produced chemicals that resemble opiates in structure and effects
Organization of the Nervous System
The Peripheral Nervous System
Peripheral Nervous System – is made up of all those nerves that lie outside the brain and
spinal cord (divided into the Somatic NS and Autonomic NS)
Nerves – are bundles of neuron fibres (axons) that are routed together in the peripheral
Somatic Nervous System – nerves that connected to voluntary skeletal muscles and to
sensory receptors. (skin, muscles, joints)
o Afferent Nerve fibers are axons that carry info INWARD to the central nervous
system from the periphery of the body.
o Efferent Nerve Fibers – axons that carry info OUTWARD from the central nervous
system to the periphery of the body.
Autonomic Nervous System – nerves that connect to the heart, blood vessels, smooth
muscles and glands. (2 divisions)
o Separate, yet ultimately guided by the Central Nervous System.
o Controls automatic, involuntary functions that people don‟t normally think about, i.e.
heart rate, blinking, digestion
o Sympathetic Division – branch of the autonomous nervous system that mobilizes
the body‟s resources for emergencies (fight-or-flight)
o Parasympathetic division – branch of autonomic nervous system that generally
conserves bodily resources
The Central Nervous System
The Central Nervous System – Consists of brain and spinal cord. Protected by the
Cerebrospinal Fluid – nourishes the brain and provides a protective cushion for it
2/6 Notes From Reading
C HAPTER 3:T HE BIOLOGICAL BASIS OFB EHAVIOUR PGS .84-135)
Blood-brain barrier – a semipermeable membrane like mechanism that stops some
chemicals from passing between the bloodstream and the brain
Spinal Cord – connects the brain to the rest of the body through the peripheral nervous
system. i.e. extension of the brain
The Brain – most important part of the central nervous system
Looking Inside the Brain: Research Methods
Electroencephalograph (EEG) – monitor the electrical activity of the brain over time,
yielding line tracings called brain waves
Used in the clinical diagnosis of brain damage and neurological disorders.
Used to identify patterns of brain activity that occurs when participants engage in a specific
Can‟t control where damage occurs
Also plethora of variables in the person‟s cases.
Lesioning – destroying part of the brain to learn about its function
o Usually done through passing a high frequency current into an area to burn tissue
and disable structure.
Electrical Stimulation of the Brain
Electrical Stimulation of the Brain (ESB) – Sending a weak electric current into a brain
structure to stimulate it
Mostly occurs with animals
Transcranial Magnetic Stimulation
Transcranial Magnetic Stimulation – is a new technique that permits scientists to
temporarily enhance or depress activity in a specific area of the brain
Brain imaging Procedure
CT Scan – xray, computer enhanced of brain structure, combining many different x rays at
different angles, and creating one detailed, horizontal map of the brain.
PET scans examine brain activity, not structure. Using chemicals introduced to the brain
MRI uses magnetic fields, radio waves, and computerized enhancement to map out brain
o 3D at high resolution, can monitor blood and oxygen flow to find areas of high
activity – both Function and Structure
The Brain and Behavior
Includes the Cerebellum and 2 structures found in the lower part of the brainstem: the
medulla and the pons.
o Medulla – attached to spine, in charge of unconscious, but important functions like