Download Chapter 3

Psychology: Brain, Mind,
and Culture, 2e
by
Drew Westen
Paul J. Wellman
Texas A&M University
John Wiley and Sons, Inc.
PowerPoint  Presentation: Chapter 3
Biological Bases of Mental Life and Behavior
Lecture Outline
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Neurons and nerve potentials
Neurotransmitters
The Nervous system
Cerebral lateralization
Behavioral genetics
© 1999 John Wiley and Sons, Inc.
Neurons
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Neuron: A cell that specializes 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
© 1999 John Wiley and Sons, Inc.
Components of the Neuron
 Dendrites: receive
information
 Cell body
 Axon
• Myelin insulates the
nerve cell, speeds up
conduction of nerve
messages
• Terminal buttons of the
axon release transmitter
© 1999 John Wiley and 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 inside
the membrane
 The membrane is slightly
permeable to K+, so that at
rest, the inside is about -70
millivolts relative to the outside
 At rest, little NA+ crosses the
membrane
© 1999 John Wiley and 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 +40
channels in the membrane 0
• NA+ ions flowing in will
depolarize the membrane
(movement from -70 mV to say-70
-60 mV
• K+ ions flowing out of
membrane will hyperpolarize
the membrane (-70 mV to say
-90 mV)
© 1999 John Wiley and Sons, Inc.
RMP
Time
K+
The Action
Potential
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NA+
If the graded potential passes threshold, 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+
© 1999 John Wiley and Sons, Inc.
Details of the Synapse
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The synapse is
the physical gap
that separates the
axon terminal
from the dendrite
 Presynaptic vs.
postsynaptic
membranes
© 1999 John Wiley and Sons, Inc.
Neurotransmitters
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Neurotransmitters are chemicals
• Stored within vesicles of the presynaptic cell
• 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
© 1999 John Wiley and Sons, Inc.
Endocrine Systems
 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)
© 1999 John Wiley and Sons, Inc.
Overview of the Nervous System
© 1999 John Wiley and Sons, Inc.
The Autonomic Nervous System (ANS)
 Two branches of the ANS:
• Sympathetic: Emergency
system
• Parasympathetic: Vegetative
functions (e.g. digestion)
 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)
© 1999 John Wiley and Sons, Inc.
Overview of the Spinal Cord
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Evolution of the Brain
(Figure adapted from Kolb & Wishaw, 1990)
© 1999 John Wiley and 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
© 1999 John Wiley and Sons, Inc.
Anatomy of the Limbic System
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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)
© 1999 John Wiley and 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
© 1999 John Wiley and Sons, Inc.
The Cortical Lobes of
the Human Brain
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Organization of Sensory and
Motor Cortex
(Figure adapted from Penfield & Rasmussen, 1978)
© 1999 John Wiley and Sons, Inc.
Frontal Lobe Damage and Personality
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Frontal lobes are involved in
movement, attention, planning,
memory, and personality.
Frontal lobe function in personality is
evident in the case of Phineas Gage
• Gage suffered frontal lobe damage after an
accident involving a dynamite tamping rod
• Gage was a railroad supervisor prior to the
damage; after the damage he became childish
and irreverent, could not control his impulses,
and could not effectively plan.
© 1999 John Wiley and Sons, Inc.
Cerebral Lateralization
 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
© 1999 John Wiley and 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
only reaching one
hemisphere
(Figure adapted from Gazzaniga, 1967)
© 1999 John Wiley and Sons, Inc.
Behavioral Genetics
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Behavioral genetics is concerned with the
influence of genes 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
© 1999 John Wiley and 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
© 1999 John Wiley and Sons, Inc.
Copyright
Copyright 1999 by John Wiley and Sons, 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.
© 1999 John Wiley and Sons, Inc.