5 Steps to a 5 AP Psychology, 2010-2011 Edition (22 page)

Geographically, the cerebral cortex can be divided into eight lobes, four on the left side and four on the right side:

Occipital lobes
—primary area for processing visual information.

Parietal lobes
—front strip is somatosensory cortex that processes sensory information including touch, temperature, and pain from body parts; association areas perceive objects.

Frontal lobes
—interpret and control emotional behaviors, make decisions, carry out plans; motor cortex strip just in front of somatosensory cortex initiates movements and integrates activities of skeletal muscles; produces speech (Broca’s area).

Broca’s area
—located in left frontal lobe, controls production of speech.

Temporal lobes
—primary area for hearing, understanding language (Wernicke’s area), understanding music/tonality, processing smell.

Wernicke’s area
—located in left temporal lobe, plays role in understanding language and making meaningful sentences.

Aphasia
—impairment of the ability to understand or use language.

Glial cells
—supportive cells of the nervous system that guide the growth of developing neurons, help provide nutrition for and get rid of wastes of neurons, and form an insulating sheath around neurons that speeds conduction.

Neuron
—the basic unit of structure and function of your nervous system. Neurons perform three major functions: receive information, process it, and transmit it to the rest of your body.

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Cell body
—also called the cyton or soma; the part of the neuron that contains cytoplasm and the nucleus, which directs synthesis of such substances as neurotransmitters.

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Dendrites
—branching tubular processes of neuron that have receptor sites for receiving information.

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Axon
—a long, single conducting fiber extending from the cell body of a neuron that transmits an action potential and that branches and ends in tips called terminal buttons (a.k.a. axon terminals, or synaptic knobs), which secrete neurotransmitters.

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Myelin sheath
—a fatty covering of the axon made by glial cells, which speeds up conduction of the action potential.

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Terminal buttons
(a.k.a. axon terminals, end bulbs, or synaptic knobs)—tips at the end of axons that secrete neurotransmitters when stimulated by the action potential.

Neurotransmitters
—chemical messengers released by the terminal buttons of the presynaptic neuron into the synapse.

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Acetylcholine (ACh
)—a neurotransmitter that causes contraction of skeletal muscles, helps regulate heart muscles, is involved in memory, and also transmits messages between the brain and spinal cord. Lack of ACh is associated with Alzheimer’s disease.

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Dopamine
—a neurotransmitter that stimulates the hypothalamus to synthesize hormones and affects alertness, attention, and movement. Lack of dopamine is associated with Parkinson’s disease; too much is associated with schizophrenia.

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Glutamate
—a neurotransmitter that stimulates cells throughout the brain, but especially in the hypothalamus, and is associated with memory formation and information processing.

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Serotonin
—a neurotransmitter associated with arousal, sleep, appetite, moods, and emotions. Lack of serotonin is associated with depression.

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Endorphin
—a neurotransmitter similar to the opiate morphine that relieves pain and may induce feelings of pleasure.

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Gamma-aminobutyric acid (GABA
)—a neurotransmitter that inhibits firing of postsynaptic neurons. Huntington’s disease and seizures are associated with malfunctioning GABA systems.

Action potential
—also called an impulse, the “firing” of a neuron; a net flow of sodium ions into the cell that causes a rapid change in potential across the membrane when stimulation reaches threshold.

All-or-none principle
—the law that the neuron either generates an action potential when the stimulation reaches threshold or doesn’t fire when stimulation is below threshold. The strength of the action potential is constant whenever it occurs.

Nodes of Ranvier
—spaces between segments of myelin on the axons of neurons.

Saltatory conduction
—rapid conduction of impulses when the axon is myelinated since depolarizations jump from node (of Ranvier) to node.

Synapse
—region of communication between the transmitting presynaptic neuron and receiving postsynaptic neuron, muscle, or gland, consisting of the presynaptic terminal buttons, a tiny space and receptor sites typically on the postsynaptic dendrites.

Excitatory neurotransmitter
—chemical secreted at terminal button that causes the neuron on the other side of the synapse to generate an action potential (to fire).

Inhibitory neurotransmitter
—chemical secreted at terminal button that reduces or prevents neural impulses in the postsynaptic dendrites.

Reflex
—the simplest form of behavior.

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Reflex arc
—the path over which the reflex travels, which typically includes a receptor, sensory or afferent neuron, interneuron, motor or efferent neuron, and effector.

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Sensory receptor
—cell typically in sense organs that initiates action potentials, which then travel along sensory/afferent neurons to the CNS.

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Afferent neuron
—also called sensory neuron; nerve cell in your PNS that transmits impulses from receptors to the brain or spinal cord.

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Interneuron
—nerve cell in the CNS that transmits impulses between sensory and motor neurons. Neural impulses travel one way along the neuron from dendrites to axons to terminal buttons, and among neurons from the receptor to the effector.

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Efferent neuron
—also called motor neuron, nerve cell in your PNS that transmits impulses from sensory or interneurons to muscle cells that contract or gland cells that secrete.

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Effector
—muscle cell that contracts or gland cell that secretes.

Endocrine system
—ductless glands that typically secrete hormones directly into the blood, which help regulate body and behavioral processes.

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Hormone
—chemical messenger that travels through the blood to a receptor site on a target organ.

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Pineal gland
—endocrine gland in brain that produces melatonin that helps regulate circadian rhythms and is associated with seasonal affective disorder.

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Hypothalamus
—portion of brain part that acts as endocrine gland and produces hormones that stimulate (releasing factors) or inhibit secretion of hormones by the pituitary.

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Pituitary gland
(sometimes called “master gland”)—endocrine gland in brain that produces stimulating hormones, which promote secretion by other glands including TSH–thyroid-stimulating hormone; ACTH–adrenocorticotropic hormone, which stimulates the adrenal glands; FSH, which stimulates egg or sperm production; ADH (antidiuretic hormone) to help retain water in your body; and HGH (human growth hormone).

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Thyroid gland
—endocrine gland in neck that produces thyroxine, which stimulates and maintains metabolic activities.

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Parathyroids
—endocrine glands in neck that produce parathyroid hormone, which helps maintain calcium ion level in blood necessary for normal functioning of neurons.

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Adrenal glands
—endocrine glands atop kidneys. Adrenal cortex—the outer layer—produces steroid hormones such as cortisol, which is a stress hormone. Adrenal medulla—the core—secretes adrenaline (epinephrine) and noradrenaline (norepinephrine), which prepare the body for “fight or flight” like the sympathetic nervous system.

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Pancreas
—gland near stomach that secretes the hormones insulin and glucagon, which regulate blood sugar that fuels all behavioral processes. Imbalances result in diabetes and hypoglycemia.

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Ovaries and testes
—gonads in females and males respectively that produce hormones necessary for reproduction and development of secondary sex characteristics.

Nature-nurture controversy
—deals with the extent to which heredity and the environment each influence behavior.

Evolutionary psychologists
—study how Charles Darwin’s theory of natural selection favored behaviors that contributed to survival and spread of our ancestors’ genes; evolutionary psychologists look at universal behaviors shared by all people.

Behavioral geneticists
—study the role played by our genes and our environment in mental ability, emotional stability, temperament, personality, interests, etc.; they look at the causes of our individual differences.

Zygote
—fertilized egg.

Studies of twins help separate the contributions of heredity and environment.

Identical twins
—also called monozygotic twins; two individuals who share all of the same genes/heredity because they develop from the same zygote.

Fraternal twins
—also called dizygotic twins; siblings that share about half of the same genes because they develop from two different zygotes.

Heritability
—the proportion of variation among individuals in a population that is due to genetic causes.

When twins grow up in the same environment, the extent to which behaviors of monozygotic twins are behaviorally more similar than dizygotic twins reveals the contribution of heredity to behavior.

If monozygotic twins are separated at birth and raised in different environments (adoption studies), behavioral differences may reveal the contribution of environment to behavior; similarities reveal the contribution of heredity.

In adoption studies, if the children resemble their biological parents, but not their adoptive families, with respect to a given trait, researchers infer a genetic component for that trait.

Gene
—each DNA segment of a chromosome that determines a trait.

Chromosome
—structure in the nucleus of cells that contains genes determined by DNA sequences.

Human cells contain 23 pairs of chromosomes, 23 of which come from the sperm of the father and 23 of which come from the egg of the mother at fertilization. If the father contributes a Y sex chromosome, the baby is male; otherwise the baby is female.

Errors during fertilization can result in the wrong number of chromosomes in cells of a baby.

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Turner’s syndrome
—females with only one X sex chromosome who are short, often sterile, and have difficulty calculating.

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Klinefelter’s syndrome
—males with XXY sex chromosomes.

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Down syndrome
—usually with three copies of chromosome-21 in their cells, individuals who are typically mentally retarded and have a round head, flat nasal bridge, protruding tongue, small round ears, a fold in the eyelid, and poor muscle tone and coordination.

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Genotype
—the genetic make-up of an individual.

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Phenotype
—the expression of the genes.

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Homozygous
—the condition when both genes for a trait are the same.

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Heterozygous
—also called hybrid, the condition when the genes for a trait are different.

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Dominant gene
—the gene expressed when the genes for a trait are different.

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Recessive gene
—the gene that is hidden or not expressed when the genes for a trait are different.

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Tay-Sachs syndrome
—recessive trait that produces progressive loss of nervous function and death in a baby.

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Albinism
—recessive trait that produces lack of pigment and involves quivering eyes and inability to perceive depth with both eyes.

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Phenylketonuria (PKU)
—recessive trait that results in severe, irreversible brain damage unless the baby is fed a special diet low in phenylalanine.

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Huntington’s disease
—dominant gene defect that involves degeneration of the nervous system, characterized by tremors, jerky motions, blindness, and death.

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Sex-linked traits
—recessive genes located on the X chromosome with no corresponding gene on the Y chromosome, which result in expression of recessive trait, more frequently in males.

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Color blindness
—sex-linked trait with which individual cannot see certain colors, most often red and green.

IN THIS CHAPTER

Summary:
If you had to give up one of your senses, which one would it be? Most people choose the sense of smell or taste; no one ever chooses sight or hearing. What we see and hear are more essential for our survival than what we smell and taste. Vision is the most studied sense, and has the largest area of our cerebral cortex devoted to it of all of our senses.

All species have developed special sensory mechanisms for gathering information essential for survival.
Sensation
is the process by which you detect physical energy from your environment and encode it as neural signals.
Perception
is the process that organizes sensory input and makes it meaningful. What you perceive is influenced by your memory, motivation, emotion, and even culture. The study of sensation and perception is rooted in physics.
Psychophysics
is the study of the relationship between physical energy and psychological experiences. Psychophysics asks questions about our sensitivity to stimuli.