chapter in review
The dendrite and soma of a neuron combine neural input and send it down the axon to the axon terminals for output across the synapse to other neurons.
• The firing of an action potential (nerve impulse) is basically an electrical event.
• Communication between neurons is chemical: Neurotrans-mitters cross the synapse, attach to receptor sites, and excite or inhibit the receiving cell.
• Chemicals called neuropeptides regulate activity in the brain.
• All behavior can be traced to networks of neurons.
• The brain’s circuitry is not static. The brain can “rewire” itself and even grow new nerve cells in response to changing envi-ronmental conditions.
The nervous system can be divided into the central nervous system (CNS) and the peripheral nervous system (PNS), which includes the somatic (bodily) and autonomic (involuntary) nervous systems.
• The brain carries out most of the “computing” in the nervous system.
• The spinal cord connects the brain to the peripheral nervous system and can process simple reflex arcs.
• The peripheral nervous system carries sensory information to the brain and motor commands to the body.
• “Vegetative” and automatic bodily processes are controlled by the autonomic nervous system, which has a sympathetic branch and a parasympathetic branch.
A major brain research strategy involves the localization of function to link specific structures in the brain with specific psychological or behavioral functions.
• Biopsychologists study how processes in the body, brain, and nervous system relate to behavior.
• To map the brain, researchers activate or disable specific areas and observe changes in behavior.
• Brain structure is investigated though dissection and less intru-sive CT scans and MRI scans.
• Brain function is investigated through clinical case stud-ies, electrical stimulation, ablation, deep lesioning, electrical recording, and microelectrode recording, as well as less intru-sive EEG recordings, PET scans, and fMRI scans.
The human cerebral cortex is largely responsible for our ability to use language, make tools, acquire complex skills, and live in complex social groups. The cerebral cortex is divided into left and right hemispheres connected by the corpus callosum. Each hemisphere is divided into four lobes: the frontal lobes, the parietal lobes, the temporal lobes, and the occipital lobes.
• The human brain is marked by advanced corticalization, or enlargement of the cerebral cortex.
• The left cerebral hemisphere contains speech or language
“centers” in most people. It also specializes in writing, cal-culating, judging time and rhythm, and ordering complex movements.
• The right hemisphere is largely nonverbal. It excels at spatial and perceptual skills, visualization, and recognition of pat-terns, faces, and melodies.
• The left hemisphere is good at analysis and it processes small details sequentially. The right hemisphere detects overall patterns; it processes information simultaneously and holistically.
• “Split brains” can be created by cutting the corpus callosum.
The split-brain individual shows a remarkable degree of inde-pendence between the right and left hemispheres.
• The most basic functions of the lobes of the cerebral cortex are as follows: frontal lobes — motor control, speech, abstract thought, and sense of self; parietal lobes — bodily sensation;
temporal lobes — hearing and language; occipital lobes — vision. Damage to any of these areas will impair the named functions.
• Primary sensory and motor areas are found on the lobes of the cerebral cortex.
• Association areas on the cortex are neither sensory nor motor in function. They are related to more complex skills such as language, memory, recognition, and problem solving.
• Damage to either Broca’s area or Wernicke’s area causes speech and language problems known as aphasias.
The brain can be subdivided into the forebrain, midbrain, and hind-brain. The subcortex includes hindbrain and midbrain brain structures as well as the lower parts of the forebrain, below the cortex.
• The medulla contains centers essential for reflex control of heart rate, breathing, and other “vegetative” functions.
• The cerebellum maintains coordination, posture, and muscle tone.
• The reticular formation directs sensory and motor messages, and part of it, known as the RAS, acts as an activating system for the cerebral cortex.
• The thalamus carries sensory information to the cortex.
• The hypothalamus exerts powerful control over eating, drink-ing, sleep cycles, body temperature, and other basic motives and behaviors.
• The limbic system is strongly related to emotion. It also contains distinct reward and punishment areas and an area known as the hippocampus that is important for forming memories.
Endocrine glands serve as a chemical communication system within the body. The ebb and flow of hormones from the endocrine glands entering the bloodstream affect behavior, moods, and personality.
• Many of the endocrine glands are influenced by the pituitary (the “master gland”), which is in turn influenced by the hypo-thalamus. Thus, the brain controls the body through both the fast nervous system and the slower endocrine system.
The vast majority of people are right-handed and therefore left-brain dominant for motor skills. More than 90 percent of right-handed persons and about 70 percent of the left-handed also produce speech from the left hemisphere.
• Brain dominance and brain activity determine if you are right-handed, left-right-handed, or ambidextrous.
• Most people are strongly right-handed. A minority are strongly left-handed. A few have moderate or mixed hand preferences or they are ambidextrous. Thus, handedness is not a simple either/or trait.
• Left-handed people tend to be less strongly lateralized than right-handed people (their brain hemispheres are not as specialized).
Interactive Learning
Introduction to Psychology: Gateways to Mind and Behavior Book Companion Website
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Web Resources
For an up-to-date list of direct links to interesting sites, including those listed here, visit the student companion site for this book at www.cengage.com/psychology/coon
Neural Transmission View a series of animations about neural trans-mission illustrating the action potential and the resting potential.
Synaptic Transmission Read more detail about synaptic transmis-sion or view an animation.
The Nervous System Explore an overview of the major divisions of the nervous system.
The Whole Brain Atlas View images of various parts of the brain.
The PET Scan Read more about PET scans.
fMRI for Newbies Learn about fMRI; includes fMRI images.
Split Brain Consciousness Explore the cerebral hemispheres and what happens when they are split.
Probe the Brain Explore the motor homunculus of the brain interactively.
Brain Maps Information on the functions of a healthy cortex and also some effects of brain injury.
The Patient’s Journey: Living With Locked-In Syndrome Meet Nick, who lives with locked-in syndrome after suffering brainstem damage.
Endo 101: The Endocrine System A description of the endocrine system and hormones.
Anabolic Steroid Abuse An article on steroids and steroid abuse from the National Institute on Drug Abuse.
What Is “Handedness”? Information about handedness and brain laterality, including a list of famous left handers.
The Sinister Hand Interview on handedness with Dr. Michael Corballis.
Left Brain, Right Brain Article on popular conceptions of the differ-ences between brain hemispheres.
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Gateway Questions
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How do heredity and environment affect development?•
What can newborn babies do?•
Of what significance is a child’s emotional bond with adults?•
How important are parenting styles?•
How do children acquire language?•
How do children learn to think?•
Why is the transition from adolescence to adulthood especially challenging?•
How do we develop morals and values?•
What are the typical tasks and dilemmas through the life span?•
What is involved in well-being during later adulthood?•
How do people typically react to death?•
How do effective parents discipline and communicate with their children?C H A P T E R 3
Human Development
Gateway Theme
The principles of development help us better understand not only children, but our own behavior as well.
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Identical twins. Twins who share identical genes (identical twins) demonstrate the powerful influence of heredity. Even when they are reared apart, identical twins are strikingly alike in motor skills, physical development, and appearance. At the same time, twins are less alike as adults than they were as children, which shows environmental influences are at work (Larsson, Larsson, & Lichtenstein, 2004).