Studied by 14 people
nature–nurture issue
the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors. Today’s science views traits and behaviors as arising from the interaction of nature and nurture.
natural selection
the principle that the inherited traits enabling an organism to survive and reproduce in a particular environment will (in competition with other trait variations) most likely be passed on to succeeding generations.
evolutionary psychology
the study of the evolution of behavior and the mind, using principles of natural selection.
behavior genetics
the study of the relative power and limits of genetic and environmental influences on behavior.
mutation
a random error in gene replication that leads to a change.
environment
every nongenetic influence, from prenatal nutrition to our experiences of the people and things around us.
heredity
the genetic transfer of characteristics from parents to offspring.
genes
the biochemical units of heredity.
genome
the complete instructions for making an organism
identical (monozygotic) twins
individuals who developed from a single fertilized egg that split in two, creating two genetically identical organisms.
fraternal (dizygotic) twins
individuals who developed from separate fertilized eggs. They are genetically no closer than ordinary siblings, but they shared a prenatal environment.
interaction
the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).
epigenetics
“above” or “in addition to” (epi) genetics; the study of the molecular mechanisms by which environments can influence genetic expression (without a DNA change).
nervous system
the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.
central nervous system (CNS)
the brain and spinal cord.
peripheral nervous system (PNS)
the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.
nerves
bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sensory organs.
sensory (afferent) neurons
neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord.
motor (efferent) neurons
neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.
interneurons
neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs.
somatic nervous system
the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system.
autonomic nervous system (ANS)
the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.
sympathetic nervous system
the division of the autonomic nervous system that arouses the body, mobilizing its energy.
parasympathetic nervous system
the division of the autonomic nervous system that calms the body, conserving its energy.
reflex
a simple, automatic response to a sensory stimulus, such as the knee
neuron
a nerve cell; the basic building block of the nervous system.
cell body
the part of a neuron that contains the nucleus; the cell’s life
dendrites
a neuron’s often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body.
axon
the segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands.
myelin sheath
a fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speed as neural impulses hop from one node to the next.
glial cells (glia)
cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory.
action potential
a neural impulse; a brief electrical charge that travels down an axon.
threshold
the level of stimulation required to trigger a neural impulse.
refractory period
in neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state.
all-or-none response
a neuron’s reaction of either firing (with a full-strength response) or not firing.
synapse
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.
neurotransmitters
chemical messengers that cross the synaptic gap between neurons. When released by the sending neuron, _____ travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
reuptake
a neurotransmitter’s reabsorption by the sending neuron.
endorphins
“morphine within”; natural, opioid-like neurotransmitters linked to pain control and to pleasure.
agonist
a molecule that increases a neurotransmitter’s action.
antagonist
a molecule that inhibits or blocks a neurotransmitter’s action
endocrine
system the body’s “slow” chemical communication system; a set of glands and fat tissue that secrete hormones into the bloodstream.
hormones
chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.
psychoactive drug
a chemical substance that alters the brain, causing changes in perceptions and moods.
substance use disorder
a disorder characterized by continued substance use despite resulting life disruption.
depressants
drugs that reduce neural activity and slow body functions.
tolerance
the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug’s effect.
addiction
an everyday term for compulsive substance use (and sometimes for dysfunctional behavior patterns, such as out
withdrawal
the discomfort and distress that follow discontinuing an addictive drug or behavior.
barbiturates
drugs that depress central nervous system activity, reducing anxiety but impairing memory and judgment.
opioids
opium and its derivatives; they depress neural activity, temporarily lessening pain and anxiety.
stimulants
drugs that excite neural activity and speed up body functions.
hallucinogens
psychedelic (“mind-manifesting”) drugs that distort perceptions and evoke sensory images in the absence of sensory input.
near-death experience
an altered state of consciousness reported after a close brush with death (such as cardiac arrest); often similar to drug-induced hallucinations.
biological psychology
the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists.
biopsychosocial approach
an integrated approach that incorporates biological, psychological, and social
levels of analysis
the differing complementary views, from biological to psychological to social
neuroplasticity
the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.
lesion
tissue destruction. Brain _____ may occur naturally (from disease or trauma), during surgery, or experimentally (using electrodes to destroy brain cells).
EEG (electroencephalogram)
an amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.
MEG (magnetoencephalography)
a brain-imaging technique that measures magnetic fields from the brain’s natural electrical activity
CT (computed tomography) scan
a series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice of the brain’s structure.
PET (positron emission tomography)
a technique for detecting brain activity that displays where a radioactive form of glucose goes while the brain performs a given task.
MRI (magnetic resonance imaging)
a technique that uses magnetic fields and radio waves to produce computer
fMRI (functional MRI)
a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. show brain function as well as structure.
hindbrain
consists of the medulla, pons, and cerebellum; directs essential survival functions, such as breathing, sleeping, and wakefulness, as well as coordination and balance.
midbrain
found atop the brainstem; connects the hindbrain with the forebrain, controls some motor movement, and transmits auditory and visual information.
forebrain
consists of the cerebral cortex, thalamus, and hypothalamus; manages complex cognitive activities, sensory and associative functions, and voluntary motor activities.
brainstem
the central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions.
medulla
the hindbrain structure that is the brainstem’s base; controls heartbeat and breathing.
thalamus
the forebrain’s sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
reticular formation
a nerve network that travels through the brainstem into the thalamus; it filters information and plays an important role in controlling arousal.
cerebellum
the hindbrain’s “little brain” at the rear of the brainstem; its functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory
limbic system
neural system located mostly in the forebrain — below the cerebral hemispheres — that includes the amygdala, hypothalamus, hippocampus, thalamus, and pituitary gland; associated with emotions and drives.
amygdala
two lima-bean–sized neural clusters in the limbic system; linked to emotion.
hypothalamus
a neural center in the limbic system that helps process explicit (conscious) memories — of facts and events — for storage.
hippocampus
a neural center in the limbic system that helps process explicit (conscious) memories — of facts and events — for storage.
cerebral
the intricate fabric of interconnected neural cells covering the forebrain’s cerebral hemispheres; the body’s ultimate control and information-processing center.
frontal lobes
the portion of the cerebral cortex lying just behind the forehead. They enable linguistic processing, muscle movements, higher
parietal lobes
the portion of the cerebral cortex lying at the top of the head and toward the rear; it receives sensory input for touch and body position.
occipital lobes
the portion of the cerebral cortex lying at the back of the head; it includes areas that receive information from the visual fields.
temporal lobes
the portion of the cerebral cortex lying roughly above the ears; it includes the auditory areas, each of which receives information primarily from the opposite ear. They also enable language processing.
motor cortex
a cerebral cortex area at the rear of the frontal lobes that controls voluntary movements.
somatosensory cortex
a cerebral cortex area at the front of the parietal lobes that registers and processes body touch and movement sensations.
association areas
areas of the cerebral cortex that are not involved in primary motor or sensory functions, but rather are involved in higher mental functions such as learning, remembering, thinking, and speaking.
neurogenesis
the formation of new neurons.
corpus callosum
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.
split brain
a condition resulting from surgery that separates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.
consciousness
our subjective awareness of ourselves and our environment.
cognitive neuroscience
the interdisciplinary study of the brain activity linked with cognition (thinking, knowing, remembering, and communicating).
dual processing
the principle that information is often simultaneously processed on separate conscious and unconscious tracks.
blindsight
a condition in which a person can respond to a visual stimulus without consciously experiencing it.
parallel processing
processing multiple aspects of a stimulus or problem simultaneously.
sequential processing
processing one aspect of a stimulus or problem at a time; generally used to process new information or to solve difficult problems.
sleep
a periodic, natural loss of consciousness — as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation. (Adapted from Dement, 1999.)
circadian rhythm
our biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle.
REM sleep
rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active. (Sometimes called R sleep.)
alpha waves
the relatively slow brain waves of a relaxed, awake state.
NREM sleep
non-rapid eye movement sleep; encompasses all sleep stages except REM
hallucinations
false sensory experiences, such as seeing something in the absence of an external visual stimulus.
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