Transcript Introduction to Psychology, 7th Edition, James W. Kalat Chapter 3

Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Chapter 3
Biological Psychology
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Biological Psychology

In this chapter we will examine:
 What are the components of the nervous system?
 How does the brain create mental processes and
behavior?
“What we understand least is why brain activity produces
experience at all.” -- James W. Kalat
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Module 3.1

Neurons and Behavior
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Introduction

Reductionism?
 Scientists in many fields use a strategy called
reductionism; they attempt to explain complex
phenomena by reducing them to combinations of simpler
components.
 Chemists use atoms and molecules; physicists reduce
the subatomic world to the interactions of a few
fundamental forces.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Introduction

Reductionism?
 Does reductionism work in the science of psychology?
 Let’s find out as we try to explain behavior in terms of
the activity of the cells that comprise the nervous
system.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Neurons
 You experience yourself as a unitary entity.
 Neuroscientists have demonstrated that that experience
is the product of a nervous system made up of an
enormous number of discrete cells.
 The cells that make up your nervous system are called
neurons.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.1 Distribution of the estimated 100 billion neurons in the adult human central
nervous system. (Based on data of R. W. Williams & Herrup, 1988)
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Neurons and communication
 Neurons are a unique type of cell that can receive and
transmit information electrochemically.
 Sensory neurons carry information from sense organs
to the central nervous system.
 Neurons in the central nervous system process that
information, interpret it, and then send commands to
muscles, glands and organs.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells


The best current estimate is that the human nervous
system has nearly 100 billion neurons.
And they aren’t the only type of cell in the system.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Glia
 Glia support the neurons in many ways.
 They provide insulation, and remove waste products
and foreign bodies.
 They are 1/10th the size of the neurons, but about 10
times as numerous.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Anatomy of a neuron
 Neurons have a variety of shapes, but they all have 3
basic parts.
 A cell body that contains the nucleus and most of the
organelles.
 The dendrites, widely branching structures that
receive transmissions from other neurons.
 The axon, which is a single, long, thin fiber with
branches near its tip.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Axons
 The function of the axon is to send the electrochemical
message on to the next cell.
 Most axons transmit information to the dendrites or
cell bodies of neighboring neurons.
 Many axons have a coating of myelin, which speeds
up transmission.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Nerve cell growth
 Neurons do not have a fixed anatomy.
 Researchers have discovered that neurons are
constantly growing and losing branches to dendrites
and axons.
 This growth seems to be related to new experiences
and learning.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Action potentials
 Axons convey information by a combination of electrical
and chemical processes.
 This combination is called an action potential.
 An action potential is an excitation that travels along
the axon at a constant strength regardless of the
distance it must travel.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Action potentials
 The all-or-none law
 An action potential is an all-or-nothing process – it’s
either happening or not; there’s no “sort of” action
potential.
 This allows the message to reach the brain at full
strength, but does slow it down compared to regular
electrical conduction.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Action potentials
 How an action potential works:
 An un-stimulated axon has resting potential.
 Resting potential is an electrical polarization across
the membrane covering the axon.
 A polarized axon has an inside charge that is
negative (-70 millivolts) relative to the outside.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Action potentials
 How an action potential works:
 Resting potential is maintained by the mechanism
called the sodium-potassium pump.
 Sodium is mostly concentrated outside the neuron,
and potassium mostly inside, and they are held in
place by special “gates” while the polarization is
maintained by the action of the pump.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.4 The sodium and potassium gradients for a resting membrane. Sodium ions
are concentrated outside the neuron; potassium ions are concentrated inside.
Because of the negatively charged protein ions inside the neuron, the inside of the cell
is negatively charged relative to the outside of the cell. Protein and chloride ions (not
shown) bear negative charges inside the cell. At rest, very few sodium ions cross the
membrane except by the sodium-potassium pump. Potassium tends to flow into the
cell because of an electrical gradient, and tends to flow out because of the
concentration gradient.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Action potentials
 How an action potential works:
 The sodium-potassium pump sends positively
charged (+1) sodium ions out of the cell and brings in
a smaller number of positively charged (+1)
potassium ions.
 The result is that the outside of the cell has more
positive charges than the inside.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Action potentials
 How an action potential works:
 When a message from a neighboring cell excites part
of the axon’s membrane, some of the sodium gates
are opened and sodium can enter the axon.
 This makes the charge inside the cell positive.
Depolarization has taken place.
 The charge is now briefly the same inside and outside
the cell. This is the action potential.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.6 (a) During an action potential, sodium gates in the neuron
membrane open, and sodium ions enter the axon, bringing a positive charge
with them. (b) After an action potential occurs at one point along the axon, the
sodium gates close at that point and open at the next point along the axon.
When the sodium gates close, potassium gates open, and potassium ions
flow out of the axon, carrying a positive charge with them. (Modified from
Starr & Taggart, 1992)
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.6 (a) During an action potential, sodium gates in the neuron membrane open, and
sodium ions enter the axon, bringing a positive charge with them.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.6 (b) After an action potential occurs at one point along the axon, the sodium gates
close at that point and open at the next point along the axon. When the sodium gates close,
potassium gates open, and potassium ions flow out of the axon, carrying a positive charge with
them. (Modified from Starr & Taggart, 1992)
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Action potentials
 How an action potential works:
 The sodium gates shut very quickly and potassium
gates open to allow potassium ions to leave the cell.
 These ions take the positive charge out with them,
and bring the axon back to a polarized state.
 Eventually the action of the sodium-potassium pump
removes the excess sodium ions and recaptures the
exiled potassium ions.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check
If a hamster and a seven-foot-tall human step on a sharp
object, which will respond faster? Why?
The hamster, because the action potential has a shorter distance to
travel.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Synapses
 Communication between neurons occurs at the
synapses.
 A synapse is a specialized junction between two
neurons where chemical messages cross from one to
the other.
 The chemicals released by one will either excite or
inhibit the other, making it either more or less likely to
produce an action potential.
 This activity at the synapses is crucial to everything
the brain does.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Synaptic transmission
 The electrochemical messages carried by neurons either
increase or decrease the likelihood that the next cell will
continue to transmit.
 Excitatory messages increase the probability that the
next cell will “fire” - continue to carry the transmission.
 Inhibitory messages decrease the likelihood that
transmission will continue to travel – as in the case of
the brain sending a message to inhibit pain in an
injured extremity.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.8 The synapse is the junction of the presynaptic (message-sending) cell and
the postsynaptic (message-receiving) cell. At the end of the presynaptic axon is the
terminal bouton (or button), which contains many molecules of the neurotransmitter,
ready for release.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Synapses
 Synaptic communication:
 Each axon has a bulge at the end called a presynaptic ending or a terminal bouton (alternately
spelled “button.”)
 When the action potential reaches the terminal
bouton, molecules of a neurotransmitter are released.
 A neurotransmitter is a chemical that is stored in the
neuron. It activates special receptors of other
neurons.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Synapses
 Synaptic communication:
 Neurons use a variety of neurotransmitters, but each
individual neuron always uses a particular
neurotransmitter or combination of them.
 The neurotransmitter diffuses over the synapse to the
surface of the receiving neuron (called the
postsynaptic neuron.)
 The neurotransmitter attaches to receptors on the
dendrite or cell body of the receiving neuron and
either excites or inhibits it.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.9 The complex process of neural communication actually takes only 1–2
milliseconds.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Nervous System Cells

Synapses
 Synaptic communication:
 After the neurotransmitter has excited or inhibited the
receiving cell, it detaches from the receptor site,
ending the message.
 The neurotransmitter may be reabsorbed by the axon
that released (a process called reuptake) or diffuse
away, be metabolized and removed from the body as
a waste product, or remain the synapse and reattach
to the receptor.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check
Learning and environmental challenges sometimes produce
branching in axons and dendrites of an organism’s neurons.
How would that affect the number of synapses?
It would increase the number of synapses.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check

Dopamine is a neurotransmitter that excites postsynaptic
neurons. If a drug were injected into an animal that blocked
dopamine from attaching to its receptors, what would
happen to the postsynaptic neurons?
They would be less likely to produce further action potentials.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Neurotransmitters and Behavior

Our understanding of the role of neurotransmitters has
revolutionized medicine, particularly psychiatry.
 A drug that can be designed to act on a particular kind of
receptor in the nervous system can also have specific
effects on an organism’s functioning and behavior.
 It can be hypothesized that unusual behavior or
problems in functioning may be due to lack or excess of
a particular neurotransmitter.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Neurotransmitters and Behavior

Parkinson’s disease
 Parkinson’s disease is a condition in which the individual
has trouble executing voluntary movements, and has
tremors, rigidity and a depressed mood.
 This condition has been linked to a gradual decay in a
system of axons that release the neurotransmitter
dopamine.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Neurotransmitters and Behavior

Parkinson’s disease
 Dopamine is a neurotransmitter that promotes activity
levels and facilitated movement.
 Symptoms of Parkinson’s disease can be managed in
mild cases with a drug called L-dopa, which is
synthesized into dopamine by the neurons.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.11With Parkinson’s disease, axons from the substantia nigra gradually die.
(a) Normal brain (b) Brain of person with Parkinson’s disease. Green = excitatory
path; red = inhibitory.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Neurotransmitters and Behavior

The link is not always so clear though.
 The symptoms of a disorder such as attention-deficit
disorder or ADD include impulsive, agitated behavior
and a short attention span.
 These symptoms would suggest an oversupply of
dopamine.
 But there doesn’t seem to be any relationship between
dopamine and ADD.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check
People suffering from schizophrenia are given haloperidol, a
drug that blocks activity at dopamine synapses. How would
haloperidol affect a person with Parkinson’s Disease?
It would make the symptoms worse.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Neurotransmitters and Behavior


The neurotransmitter, whether it is in over-, under- or
normal supply, is just one part of a complex system.
What alleviates the problem may not necessarily tell us
what originally caused the problem.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Module 3.2

The Nervous System and Behavior
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Major Divisions of the Nervous System

The central nervous system and the peripheral nervous
system
 The central nervous system consists of the brain and the
spinal cord.
 The central nervous system communicates with the rest
of the body via the peripheral nervous system.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.12 The nervous system has two major divisions: the central nervous system
and the peripheral nervous system. Each of these has major subdivisions, as shown.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Major Divisions of the Nervous System

The central nervous system and the peripheral nervous
system
 The peripheral nervous system is composed of bundles
of axons between the spinal cord and the rest of the
body.
 There are two sets of subdivisions of the peripheral
nervous system.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Peripheral Nervous System

The somatic nervous system and autonomic nervous
system
 The somatic nervous system is made up of the
peripheral nerves that communicate with the skin and
muscles.
 The autonomic nervous system controls the involuntary
actions of the heart, stomach and other organs.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Central Nervous System

Embryological development
 During the embryonic stage, the vertebrate nervous
system forms out of a simple tube with three lumps:
 The forebrain that becomes the cerebral cortex and
other higher structures.
 The midbrain and hindbrain become the brainstem.
 The forebrain is especially dominant in human
beings.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.13 The human brain begins development as three lumps. By birth the
forebrain has grown much larger than either the midbrain or the hindbrain, although all
three structures perform essential functions.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Forebrain

General structure
 The forebrain
 The forebrain has two separate hemispheres, left and
right.
 Each hemisphere controls sensation and motor
functioning on the opposite side of the body.
 The hemispheres of the brain communicate with each
other through a thick bundle of axons crossing
between them, called the corpus callosum.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Forebrain

Cerebral cortex
 The cerebral cortex
 The outer covering of the forebrain is known as the
cerebral cortex.
 It is made up of the gray matter, the cell bodies of the
cortical neurons.
 The interior of the forebrain is made up of white
matter or axons of cortical neurons. It is white
because of the myelin that coats axons.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Forebrain

Cerebral cortex
 The four lobes of the cerebral cortex
 It’s customary to represent the areas of the cerebral
cortex as four lobes: occipital, parietal, temporal, and
frontal.
 The occipital lobe is at the rear of the head, and
contains many specialized areas for interpreting
visual sensory information.
 There are areas both inside and outside the occipital
lobes for shape, color and motion vision.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Forebrain

Cerebral cortex
 The four lobes of the cerebral cortex
 The parietal lobe is directly in front of the occipital
lobe.
 It contains the primary somatosensory cortex, the
area of the brain that is specialized for body senses
and awareness of the location of body parts.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Forebrain

Cerebral Cortex
 The four lobes of the cerebral cortex
 The temporal lobes are located on the sides of the
head, near the ears.
 They are the main processing areas for hearing and
complex aspects of vision.
 The left temporal lobe contains important areas for
language processing and comprehension.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Forebrain

Other structures that lie under or near the temporal lobe
include the hypothalamus, amygdala and hippocampus.
 The hypothalamus helps to regulate emotional and
motivated behavior.
 The amygdala, an almond-shaped structure that is
crucial for emotional processing, is deep inside the
temporal lobes.
 The hippocampus is a vital structure for memory
processing.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Forebrain

Cerebral cortex
 The four lobes of the cerebral cortex
 The frontal lobes are at the front of the brain.
 They contain the primary motor cortex, and area that
is important for control of fine movements.
 The foremost part of the frontal lobes, the prefrontal
cortex, is responsible for organization, planning of
action, and aspects of memory.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.17 The four lobes of the human cerebral cortex, with indications of
some of their major functions.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check
Which lobe is damaged if…
A person is unable to feel or locate the left side of her body?
Right parietal lobe
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check

Which lobe is damaged if…

A person has difficulty with fine movements with the right
hand?
Left frontal lobe
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check

Which lobe is damaged if…

A person has loss of vision in the right visual field?
Left occipital lobe
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Concept Check

Which lobe is damaged if…

A person has impaired emotional experience and some
hearing loss?
Temporal lobe
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Between the Spinal Cord and the Forebrain

The hindbrain & midbrain
 The medulla, pons and midbrain contain the reticular
activating system (or reticular formation).
 This structure regulates levels of arousal in the brain.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
How the Cerebral Cortex Communicates with
the Body

The hindbrain
 The cerebellum is important for coordination and timing.
 It is also in charge of tasks that requiring shifting of
attention and discrimination between stimuli.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
How the Cerebral Cortex Communicates with
the Body

The hindbrain
 The medulla oblongata and the pons are two important
structures in the hindbrain.
 They contain the axons that control breathing and heart
rate.
 They are also in charge of relaying sensory information
from the head and sending motor messages back to it.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.14 (a) The major divisions of the human central nervous system, as seen
from the midline.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
How the Cerebral Cortex Communicates with
the Body

The spinal cord
 The spinal cord
 Both reflex and voluntary responses are conducted
through the spinal cord.
 A reflex is a rapid, automatic response to a stimulus.
The spinal cord is usually the origination point of
these responses.
 A voluntary response originates in the brain and
travels through the spinal cord to the muscles needed
to carry out the movements.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
How the Cerebral Cortex Communicates with
the Body

The spinal cord
 The spinal cord
 The spinal cord communicates with the body below
the head by means of sensory and motor neurons.
 The sensory neurons carry information received by
the senses from the extremities of the body to the
spinal cord.
 The motor neurons transmit messages from the
central nervous system to the muscles and glands.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.20 The spinal cord receives sensory information from all parts of
the body except the head. Motor nerves in the spinal cord send messages to
control the muscles and glands.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Peripheral Nervous System

The autonomic nervous system
 The autonomic nervous system
 A division of the peripheral nervous system that is
closely associated with the spinal cord is the
autonomic nervous system.
 The individual has very little control over the
responses in this division, thus the name, autonomic.
 The autonomic nervous system has two subdivisions.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Peripheral Nervous System

The autonomic nervous system
 The divisions of the autonomic nervous system
 The sympathetic nervous system is the crisis
management center.
 It increases heart and respiration rate and prepares
the body for fight or flight.
 A chain of neurons lying just outside the spinal cord
controls it.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Peripheral Nervous System

The autonomic nervous system
 The divisions of the autonomic nervous system
 The parasympathetic nervous system is in charge of
long-term survival related functions, nutrition and
energy conservation.
 It decreases heart rate, increases digestive activities
and promotes processes in the body that take place
during rest.
 It is controlled by neurons at the upper and lower
levels of the spinal cord.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.21 The sympathetic nervous system prepares the body for brief bouts of
vigorous activity; the parasympathetic nervous system promotes digestion and other
nonemergency functions. Although both systems are active at all times, the balance can
shift from a predominance of one to a predominance of the other.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Endocrine System

The endocrine system is under the control of the nervous
system.
 The endocrine system is a system of glands that release
hormones into the bloodstream.
 Hormones are chemicals that affect mood, behavior and
even anatomy.
 Some neurotransmitters act as hormones when released
into the bloodstream. An example of one of these is
epinephrine, which is called adrenaline when it is acting
as a hormone.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.22 Glands in the endocrine system produce hormones and release them into the
bloodstream. This shows only some of the endocrine glands and some of their most abundant
hormones.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Measuring brain activity

Methods for looking at and mapping the brain include:
 Electroencephalographs and Magnetoencephalographs
(EEGs and MEGs) record electrical and magnetic
activity in the brain.
 These readouts do not allow the viewing of brain activity.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Measuring brain activity

Methods for looking at and mapping the brain include:
 Positron emission tomography (PET) provides a highresolution picture of brain activity using radioactivity from
chemicals injected into the bloodstream.
 The color of the image indicates the level of activity: red
areas are most active, followed by yellow, green and
blue for the least active areas.
 PET scans provide fascinating information, but are
expensive and can be risky to the subject.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Measuring brain activity

Methods for looking at and mapping the brain include:
 Functional magnetic resonance imaging (fMRI) uses magnetic
detectors outside the head to measure the amounts of hemoglobin
and oxygen in different areas of the brain.
 Highly active areas of the brain appear to use more oxygen in fMRI
images.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Experience and the Brain

Nerve cell generation
 Neurons can be generated later in life (to a limited
extent).
 It was once thought that all neurons developed well
before birth.
 Researchers have discovered stem cells undifferentiated cells growing in some brain areas
that are capable of developing into neurons in older
organisms.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Experience and the Brain

Nerve cell generation
 Neuronal generation is generally very limited in scope.
 The action of stem cells seems to be stimulated after
some types of brain damage, so their purpose may
be in part compensatory.
 The growth of new neurons is much more limited than
that which occurs in skin and hair cells.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Experience and the Brain

Learning changes the brain
 We now know, because we can “see” the brain, and its
activity that practicing behaviors (learning to play a
musical instrument, for example) can change the
structure of the brain by altering the cortical neurons.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Experience and the Brain

The “binding problem”
 We still don’t understand precisely how all the different
parts of the brain allow us to have a unified experience
of objects or events, since the areas of the brain that
help us analyze our experience are often not directly
connected to each other.
 It is amazing that people can lose just one aspect of
vision, for example, color, motion, or the ability to
recognize faces.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Experience and the brain

The two halves of the brain
 Work with individuals who have had the “split-brain”
operation (severing the corpus callosum) to control
seizures provides evidence that the two hemispheres
are highly specialized.
 The right hemisphere needs to communicate with the left
in order to name the objects in its visual field.
 The left hemisphere needs the right in order to
synthesize details into a whole picture (the parts of a
face into a whole recognizable image).
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.26 The corpus callosum is a large set
of axons that convey information between the
two hemispheres of the cerebral cortex. (a) A
midline view showing the location of the corpus
callosum. (b) A horizontal section showing how
each axon of the corpus callosum links one spot
in the left hemisphere to a corresponding spot in
the right hemisphere.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.27 In the human visual system
(viewed here from above), light from either
half of the world crosses through the pupils to
strike the opposite side of each retina. Axons
from the left half of each retina travel to the
left hemisphere of the brain; axons from the
right half of each retina travel to the right
hemisphere of the brain.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
Figure 3.28 (a) A man with a severed corpus callosum cannot name something he
sees in his left visual field but can find the corresponding object with his right hand.
(b) When the word hatband is flashed on a screen, a man with a split brain can
report only what his left hemisphere saw, “band.” However, with his left hand he
can point to a hat, which is what the right hemisphere saw.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Brain and the Self
We are still learning about the brain, but we now understand
that your brain is composed of many separate areas with
separate abilities.
Introduction to Psychology, 7th Edition, James W. Kalat
Chapter 3: Biological Psychology
The Brain and the Self
If you lose part of the brain, you lose part of your unique
experience.
Brain activity and mind are inseparable. One is the other.