Biological Bases of
Behavior: 3B—The Brain
UNIT PREVIEW
The brain’s increasing complexity arises from new brain systems built on top of old. Within the
brainstem are the oldest regions, the medulla and the reticular formation. The thalamus sits atop
the brainstem and the cerebellum extends from the rear. The limbic system includes the
amygdala, the hippocampus, and the hypothalamus. The cerebral cortex, representing the
highest level of brain development, is responsible for our most complex functions.
Each hemisphere of the cerebral cortex has four geographical areas: the frontal, parietal,
occipital, and temporal lobes. Although small, well-defined regions within these lobes control
muscle movement and receive information from the body senses, most of the cortex—its
association areas—are free to process other information. Experiments on splitbrain patients
suggest that,
for most people, the left hemisphere is the more verbal and the right hemisphere excels in visual
perception and the recognition of emotion. Studies of people with intact brains indicate that each
hemisphere makes unique contributions to the integrated functions of the brain.
Consciousness is our awareness of ourselves and our environment. Cognitive neuroscientists
study the links between brain activity and mental processes. Research indicates that we have a
two-track mind. Conscious information processing enables us to exercise control and to
communi
cate our mental states to others. Beneath the surface, unconscious processing occurs
simultaneously on many parallel tracks. Our awareness focuses on a limited aspect of all that we
experience.
UNIT GUIDE
Introducing the Brain and The Tools of Discovery
Lectures: Brain Puzzles, Models, and Molds; Neuroimaging Techniques; A Neurosociety and Your Brain on Politics;
Assessing Awareness in Brain-Injured Patients
Exercises: Building a Play-Doh Brain; A Portable Brain Model; Mastering Brain Structure; Case Studies in
Neuroanatomy
ActivePsych: Scientific American Frontiers, 3rd ed.: Neuroimaging: Assessing What’s Cool
PsychSim 5: Brain and Behavior
Videos: Video Clip 2 of Digital Media Archive, Psychology, 1st ed.: Brain Structures; Inside Information—The Brain
and How It Works; Video Clip 3 of Digital Media Archive: Psychology, 1st ed.: Brain Imaging; Segments 5 and 6 of the
Scientific American Frontiers series, 2nd ed.: Mind Reading and Image-Guided Surgery
Psychology Video Tool Kit: Mapping the Brain Through Electrical Stimulation
16 Unit 3B The Brain
1.
Describe several techniques for studying the brain. The oldest method of studying the
brain involved observing the effects of brain diseases and injuries. Powerful new techniques now
reveal brain structures and activities in the living brain. By surgically lesioning and electrically
stimulating specific brain areas, by recording electrical activity on the brain’s surface (EEG),
and by looking inside the living brain to see its activity (CT, PET, MRI, and fMRI),
neuroscientists examine the connections between brain, mind, and behavior.
Older Brain Structures
Lecture: Why Can’t We Tickle Ourselves?
Exercise: Individual Differences in Physiological Functioning and Behavior
Videos: Module 1 of The Brain series, 2nd ed.: Organization and Evaluation of Brain Function
2. Describe the components of the brainstem, and summarize the functions of the
brainstem, thalamus, and cerebellum.
The brainstem, the brain’s oldest and innermost region, is responsible for automatic survival
functions. It includes the medulla, which controls heartbeat and breathing, and the reticular
formation, which plays an important role in controlling arousal. Just above the medulla sits the
pons, which helps coordinate movements.Atop the brainstem is the thalamus, the brain’s sensory
switchboard. It receives information from all the senses, except smell, and sends it to the higher
brain regions that deal with seeing, hearing, tasting, and touching. The cerebellum, attached to
the rear of the brainstem, coordinates voluntary movement (with the help of the pons) and
balance and helps process sensory information. It also enables one type of nonverbal learning
and memory and helps us judge time, modulate our emotions, and discriminate sounds and
textures.
These older brain functions all occur without any conscious effort. This illustrates a
recurring theme: Our brain processes most information outside of our awareness.
Lecture/Video: The Case of Clive Wearing
ActivePsych: Digital Media Archive, 2nd ed.: The Brain’s Reward Center
Videos: Module 6 of The Mind series, 2nd ed.: Brain Mechanisms of Pleasure and Addiction; Video Clip 26 of Digital
Media Archive: Psychology, 1st ed.: Self-Stimulation in Rats
Psychology Video Tool Kit: Compulsive Gambling and the Brain’s Pleasure Center
3. Describe the structures and functions of the limbic system, and explain how one of these
structures controls the pituitary gland.
The limbic system has been linked primarily to memory, emotions, and drives. For example, one
of its neural centers, the hippocampus, processes memory. Another, the amygdala, influences
aggression and fear. A third, the hypothalamus, has been linked to various bodily maintenance
functions and to pleasurable rewards. Its hormones influence the pituitary gland, and thus it
provides a major link between the nervous and endocrine systems.
The Cerebral Cortex
Lectures: Einstein’s Brain and Genius; Kim Peek’s Brain; Hemispherectomy;
Exercises: Neuroscience and Moral Judgments; The Sensory Homunculus
Project: The Human Brain Coloring Book
ActivePsych: Scientific American Frontiers, 3rd ed.: Brain and Behavior: Phineas Gage Revisited and Brain Plasticity:
Rewiring the Visual Cortex
Videos: Segment 8 of the Scientific American Frontiers series, 2nd ed.: Old Brain, New Tricks; Module 7 of The Mind
series, 2nd ed.: The Frontal Lobes: Cognition and Awareness; Module 25 of The Brain series, 2nd ed.: The Frontal Lobes and
Behavior: The Story of Phineas Gage; Program 10 of Moving Images: Exploring Psychology Through Film: Sensation Without
Perception: Visual Prosopagnosia; Module 18 of The Mind series, 2nd ed.: Effects of Mental and Physical Activity on
Brain/Mind
Unit 3B The Brain
4. Describe the structure of the cerebral cortex, and explain the various functions of the four lobes. The
cerebral cortex, a thin surface layer of interconnected neural cells, is our body’s ultimate control and
information-processing center. Glial cells support, nourish, and protect the nerve cells of the cerebral
cortex. The frontal lobes, just behind the forehead, are involved in speaking, muscle movements, and
planning and making judgments. The parietal lobes, at the top of head and toward the rear, receive
sensory input for touch and body position. The occipital lobes, at the back of the
head, include visual areas. The temporal lobes, just above the ears, include auditory areas. Each
lobe performs many functions and interacts with other areas of the cortex.
5. Summarize some of the findings on the functions of the motor cortex and the sensory cortex, and
discuss the importance of the association areas. The motor cortex, an arch-shaped region at the rear of
the frontal lobes, controls voluntary muscle movements on the opposite side of the body. Body parts
requiring the most precise control occupy the greatest amount of cortical space. In an effort to find the
source of motor control, researchers have recorded messages from brain areas involved in planning
and intention, leading to the testing of neural prosthetics for paralyzed patients. The sensory cortex, a
region at the front of the parietal lobes, registers and processes body sensations. The most sensitive
body parts require the largest amount of space in the sensory cortex.
The association areas are not involved in primary motor or sensory functions. Rather, they integrate
and act on information processed by the sensory areas. They are involved in higher mental
functions, such as learning, remembering, thinking, and speaking. Association areas are found in all
four lobes. Complex human abilities, such as memory and language, result from the intricate
coordination of many brain areas.
Lecture The Smart-Talk Syndrome Videos: Module 16 of Psychology: The Human Experience: Language Centers in the
Brain; Video Clip 22 of Digital Media Archive, 1st ed.: Psychology: Gleason’s Wug Test; Modules 6 and 8 of The Brain, 2nd
ed.: Language and Speech: Broca’s and Wernicke’s Areas and Language Processing in the Brain
6. Identify the brain areas involved in language, and explain how these areas coordinate to produce
speech.
Language depends on a chain of events in several brain regions. When we read aloud, the words
(1) register in the visual area, (2) are relayed to the angular gyrus, which transforms the words into
auditory code, which is (3) received and understood in nearby Wernicke’s area and sent (4) to Broca’s
area, which (5) controls the motor cortex as it creates the pronounced word. Depending on which link
in this chain is damaged, a different form of aphasia occurs. For example, damage to the angular gyrus
leaves the person able to speak and understand but unable to read. Damage to Wernicke’s area disrupts
understanding. Damage to Broca’s area disrupts speaking. What we experience as a continuous
experience is the visible tip of a subdivided information-processing iceberg, most of which is outside
our awareness. More generally, language processing illustrates how the mind’s subsystems are
localized in particular brain regions, yet the brain acts as a unified whole.
Videos: Modules 7 and 32 of The Brain series, 2nd ed.: Brain Anomaly and Plasticity: Hydrocephalus and
Neurorehabilitation; Psychology: The Human Experience, Modules 4 and 5: A Case Study of Brain Damage and Brain Plasticity
Psychology Video Tool Kit: Planning, Life Goals, and the Frontal Lobe; Language and Brain Plasticity; Rewiring the
Brain
7.
Discuss the brain’s plasticity following injury or illness. Research indicates that some neural
tissue can reorganize in response to damage. When one brain area is damaged, others may in time
take over some of its function. For example, if you lose a finger, the sensory cortex that received its
input will begin to receive input from the adjacent fingers, which become more sensitive. Our brains
are most plastic when we are young children.
18 Unit 3B The Brain
Constraint-induced therapy rewires the brain by restraining a fully functioning limb and forcing
use of the “bad hand” or the uncooperative leg. Eventually, the therapy reprograms the brain,
improving the dexterity of a brain-damaged child or even an adult stroke victim. New evidence
reveals that adult humans can also generate new brain cells. Monkey brains illustrate
neurogenesis by forming thousands of new neurons each day.
Our Divided Brain
Exercise: Behavioral Effects of the Split-Brain Operation
Exercise/Project: The Wagner Preference Inventory
Lecture: The Wada Sodium Amobarbital Test
Psychology Video Tool Kit: The Split Brain: Lessons on Language, Vision, and Free Will; The Split Brain: Lessons on
Cognition and the Cerebral Hemispheres
ActivePsych: Scientific American Frontiers, 3rd ed.: Achieving Hemispheric Balance: Improving Sports Performance
PsychSim 5: Hemispheric Specialization
Videos: Segment 7 of the Scientific American Frontiers series, 2nd ed.: Severed Corpus Callosum; Module 5 of The
Brain series, 2nd ed.: The Divided Brain
8. Describe split-brain research, and explain how it helps us understand the functions of our left
and right hemispheres.
A split brain is one in which the corpus callosum, the wide band of axon fibers that connects the
two brain hemispheres, has been severed. Experiments on split-brain patients have refined our
knowledge of each hemisphere’s special functions (called hemispheric specialization or
lateralization). In the laboratory, investigators ask a split-brain patient to look at a designated
spot, then send information to either the left or right hemisphere (by flashing it to the right or left
visual field).
Right-Left Differences in the Intact Brain
9. (text and Close-Up) Describe the distinct functions of the brain’s two hemispheres, and
discuss research findings on brain organization and handedness.
Quizzing each hemisphere separately, researchers have confirmed that for most people, the left
hemisphere is the more verbal and the right hemisphere excels in visual perception and the
recognition of emotion. Studies of people with intact brains have confirmed that the right and left
hemispheres each make unique contributions. For example, the left hemisphere makes quick,
literal interpretations of language, and the right hemisphere excels in making inferences.
Lectures: Left-Handedness; The Right Brain Movement
Exercise: Handedness and Health
Project/Exercise: Hemispheric Specialization About 10
percent of us are left-handed. Almost all righthanders process speech primarily in the left hemisphere. Left-handers are more diverse. Seven in ten
process speech in the left hemisphere and the rest either process speech in the right hemisphere or use
both hemispheres. Left-handers are more numerous among those with reading disabilities, allergies, and
migraine headaches. Left-handedness is also more common among musicians, mathematicians,
professional baseball and
cricket players, architects, and artists. The advantages and disadvantages of being a lefty
seem roughly equal.
Unit 3B The Brain
The Brain and Consciousness
Lectures: The Mind-Body Problem; Automatic Processing; Psychological Distance and Evaluative Judgments; The
Deliberation-Without-Attention Effect
Exercise: The Dualism Scale
ActivePsych: Scientific American Frontiers, 3rd ed.: Hidden Prejudice: The Implicit Association Test
10. Describe research that leads cognitive neuroscientists to infer how the brain’s dualprocessing affects our perception, memory, and attitudes on conscious and unconscious
levels.
Consciousness is our awareness of ourselves and our environment. Cognitive neuroscience, the
interdisciplinary study of how brain activity is linked with our mental processes, is helping us to
understand how specific brain states relate to conscious experiences. Most cognitive
neuroscientists are exploring and mapping the conscious functions of the cortex. Based on our
cortical activation patterns, they are beginning to “read our minds.” For example, they can tell
which of 10 similar objects we are viewing.
Cognitive neuroscientists and others studying the brain activity underlying consciousness have
discovered a two-track human mind, each with its own neural processing. Perception, memory,
thinking, language, and attitudes all operate on two levels—a conscious, deliberate “high road”
and an unconscious, automatic “low road.” Researchers call this dual processing. Conscious
information processing enables us to exert voluntary control and to communicate our mental
states to others. Beneath the surface, faster unconscious processing occurs simultaneously on
many parallel tracks. Clearly, much of our everyday thinking, feeling, and acting occurs outside
our conscious awareness.