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PSYCHOLOGY
Fourth E d i t i o n
by
Robin Kowalski and Drew Westen
PowerPoint  Presentation
Chapter 3
BIOLOGICAL BASES OF
M E N T A L L I F E & B E H A V I OR
John Wiley & Sons, Inc.
Lecture Outline
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Neurons and nerve potentials
The Nervous system
Cerebral lateralization
Genetics & Evolution
© 2002 John Wiley & Sons, Inc.
Neurons
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Neurons are cells that specialize in the transfer
of information within the nervous system
Three classes of neurons:
 Sensory: Transmit information from sensory
receptors to the brain (afferent)
 Motor: Transmit commands from the brain to the
muscles and glands of the body (efferent)
 Interneurons: Interconnect neurons
© 2004 John Wiley & Sons, Inc.
Components of the Neuron
 Dendrites: receive
information from other
neurons
 Cell body: creates
transmitter molecules
 Axon
• Myelin insulates the nerve
cell, speeds up conduction
of nerve messages
• Terminal buttons of the axon
release transmitter
© 2004 John Wiley & Sons, Inc.
Neuron Resting Potentials
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The membrane of the neuron
separates charges
 The ions NA+ and Cl- are found
outside the membrane, whereas
the ion K+ is mostly inside the
membrane
 The membrane is slightly
permeable to K+ ions, so that at
rest, the inside is about -70
millivolts relative to the outside
 At rest, few NA+ ions are able to
cross the membrane
© 2004 John Wiley & Sons, Inc.
NA
Cl-
+
K+
INSIDE
Cross-section of nerve
cell showing
distribution of ions
across the membrane
Graded Potentials
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Stimulation of the nerve
membrane can open ion
channels in the
membrane
• NA+ ions flowing in will
depolarize the membrane
(movement from -70 mV to
say -60 mV
• K+ ions flowing out of
membrane will
hyperpolarize the
membrane (-70 mV to say
-90 mV)
© 2004 John Wiley & Sons, Inc.
The Action Potential
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Graded potentials are generated at the dendrites
and are conducted along the membrane to the
axon hillock
If the summated activity at the axon hillock raises
the membrane potential past threshold, an action
potential (AP) will occur
During the AP, NA+ ions flow into the cell raising
the membrane potential to +40 mV, producing the
spike
 The restoration of the membrane potential to -70 mV is
produced by an opening of channels to K+
 The AP is conducted along the axon toward the
terminals
© 2004 John Wiley & Sons, Inc.
Overview of the Action Potential
NA ions
in
© 2004 John Wiley & Sons, Inc.
K ions
out
Details of the Synapse
© 2004 John Wiley & Sons, Inc.
Synaptic Functioning
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Neurotransmitters (NTs) are chemicals
 NTs are stored within vesicles of the presynaptic
cell
 NTs are released in response to the action
potential sweeping along the presynaptic
membrane
 Transmitter molecules diffuse across the synaptic
cleft and bind to postsynaptic receptors
 Receptor binding opens or closes ion channels:
• NA channel opening: Depolarizes the membrane
• K+ channel opening: Hyperpolarizes the membrane
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Neuromodulators: Indirectly alter the activity
of other transmitter substances
© 2004 John Wiley & Sons, Inc.
Endocrine Systems
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Endocrine glands release
hormones into blood stream
 Have effects at diffuse target
sites throughout the body
 Hormones bind to receptors
 Hormones can have
organizational effects
(permanent change in structure
and function)
 Hormones can have
activational effects:
• Lack of testosterone lack reduces
sexual behavior
© 2004 John Wiley & Sons, Inc.
Psychoneuroimmunology
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Psychoneuroimmunology is the study of the
interactions among behavior, the nervous system, the
endocrine system, and the immune system
The immune cells (cytokines, t-cells, macrophages,
etc.) do not cross the blood-brain barrier. However,
they do affect at least one of the cranial nerves, the
vagus nerve.
© 2004 John Wiley & Sons, Inc.
Overview of the Nervous System
© 2004 John Wiley & Sons, Inc.
Peripheral Nervous Systems
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Somatic Nervous System
Autonomic Nervous System
© 2004 John Wiley & Sons, Inc.
Autonomic Nervous System
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The Autonomic Nervous System (ANS) has
two divisions:
 Sympathetic: Emergency system
 Parasympathetic: Vegetative functions (e.g.
digestion)
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The two systems often act in opposition (as
in the control of heart rate)
Can act in concert (as in the control of
sexual reflexes)
© 2004 John Wiley & Sons, Inc.
Autonomic Nervous System
© 2004 John Wiley & Sons, Inc.
Overview of the Spinal Cord
© 2004 John Wiley & Sons, Inc.
Development of the Brain
(Figure adapted from Kold & Wishaw, 1990)
© 2004 John Wiley & Sons, Inc.
Midline View of Human Brain
Medulla: Controls heart rate, respiration
Cerebellum: Coordinates smooth movements, balance, and posture
Pons: Involved in the control of sleep
© 2004 John Wiley & Sons, Inc.
Limbic System Functions
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Septal area is involved in pleasure and in
relief from pain
Amygdala is involved in learning and
recognition of fear
Hippocampus is involved in memory
• Patient H.M. shows anterograde amnesia
(cannot learn new information)
© 2004 John Wiley & Sons, Inc.
Cerebral Cortex
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Functions of cerebral cortex:
 Provides for flexible control of patterns of
movement
 Permits subtle discrimination among complex
sensory patterns
 Makes possible symbolic thinking
• Symbolic thought is the foundation of human thought and
language
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Functional organization of cortex:
 Primary areas
 Association areas
© 2004 John Wiley & Sons, Inc.
The Cortical Lobes of
the Human Brain
© 2004 John Wiley & Sons, Inc.
Cerebral Lateralization
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The structures of the cortex and sub-cortex appear
to specialize in function:
 Hemispheric Specialization
• Left hemisphere is dominant for language, logic, and complex
motor behavior.
• Right hemisphere is dominant for non-linguistic functions
including recognition of faces, places, and sounds (music)
• The hemispheric specializations are evident from studies of
– Damage to one hemisphere (I.e. Broca’s area)
– Split-brain subjects
 Gender differences in brain lateralization
• Issue is whether the brains of males and females may be
organized differently and whether such organization might have
functional significance
© 2004 John Wiley & Sons, Inc.
The Split-Brain Study
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Information from the one visual field is usually
transmitted to the opposite visual cortex
The corpus callosum serves to integrate the
two hemispheres
Cutting the corpus callosum can result in
information reaching only one hemisphere
 Language is a left-hemisphere function
 Information reaching the left hemisphere will be
reported by the subject, but not information
reaching the right hemisphere
© 2004 John Wiley & Sons, Inc.
Split-Brain Studies
(Figure adapted from Gazzaniga, 1967)
© 2004 John Wiley & Sons, Inc.
Genetics & Evolution
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Behavioral genetics is concerned with the
influence of genetics on psychological function
 Genotype: Genetic structure (DNA located on
chromosomes)
 Phenotype: Observable psychological function
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Relatedness is the probability of sharing a gene
with parents and others
Heritability: Quantifies the extent to which
variations in a trait across persons can be
accounted for by genetic variation
© 2004 John Wiley & Sons, Inc.
Heritability of Psychological
Traits
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Studies of twins raised apart suggest
heritability coefficients of 0.15 to 0.50 for the
traits of:
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Conservatism
Neuroticism
Aggressiveness
Intelligence
Likelihood of divorce
Job satisfaction
Vocational interests
© 2004 John Wiley & Sons, Inc.
Copyright
Copyright 2004 by John Wiley & Sons, Inc., New
York, NY. All rights reserved. No part of the
material protected by this copyright may be
reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying,
recording, or by any information storage and
retrieval system, without written permission of the
copyright owner.
© 2004 John Wiley & Sons, Inc.