p s y c h o l o g y t h i r d e d i t i o n by drew westen powerpoint presentation c h a p t e r 3...
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P S Y C H O L O G YT h i r d E d i t i o n
by
Drew Westen
PowerPoint Presentation
C h a p t e r 3 B I O L O G I C A L B A S E S O F
M E N T A L L I F E & B E H A V I OR
John Wiley & Sons, Inc.
Lecture Outline
Neurons and nerve potentials The Nervous system Cerebral lateralization Behavioral genetics
© 2002 John Wiley & Sons, Inc.
Neurons 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
© 2002 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
© 2002 John Wiley & Sons, Inc.
Neuron Resting Potentials 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
NA+
K+
Cl-
Cross-section of nerve cell showing distribution of ions across the membrane
INSIDE
© 2002 John Wiley & Sons, Inc.
Graded Potentials 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)
© 2002 John Wiley & Sons, Inc.
The Action Potential 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
© 2002 John Wiley & Sons, Inc.
Synaptic Functioning 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
Neuromodulators: Indirectly alter the activity of other transmitter substances
© 2002 John Wiley & 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)
Hormones can have activational effects:
• Lack of testosterone lack reduces sexual behavior
© 2002 John Wiley & Sons, Inc.
Autonomic Nervous System The Autonomic Nervous System (ANS) has
two divisions: 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)
© 2002 John Wiley & Sons, Inc.
Midline View of Human Brain
Medulla: Controls heart rate, respirationCerebellum: Coordinates smooth movements, balance, and posturePons: Involved in the control of sleep
© 2002 John Wiley & Sons, Inc.
Limbic System Functions 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)
© 2002 John Wiley & Sons, Inc.
Cerebral Cortex 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
Functional organization of cortex: Primary areas Association areas
© 2002 John Wiley & Sons, Inc.
Frontal Lobe Damage and Personality
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.
© 2002 John Wiley & 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
© 2002 John Wiley & Sons, Inc.
The Split-Brain Study 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
© 2002 John Wiley & Sons, Inc.
Behavioral Genetics
Behavioral genetics is concerned with the influence of genes on psychological function Genotype: Genetic structure (DNA located on
chromosomes) Phenotype: Observable psychological function
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
© 2002 John Wiley & Sons, Inc.
Heritability of Psychological Traits
Studies of twins raised apart suggest heritability coefficients of 0.15 to 0.50 for the traits of:
• Conservatism• Neuroticism• Aggressiveness• Intelligence• Likelihood of divorce• Job satisfaction• Vocational interests
© 2002 John Wiley & Sons, Inc.
Copyright
Copyright 2002 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.
© 2002 John Wiley & Sons, Inc.