Unit 1, Part 1: Biological Bases of Behavior (CED Aligned)

nature-nurture issue

the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors.

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.

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.

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.

nervous system

the body's speedy, electrochemical communication network.

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 (ANS) nervous system

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-jerk reflex.

neuron

a nerve cell; the basic building block of the nervous system.

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

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.

neurotransmitters

chemical messengers that cross the synaptic gap between neurons.

reuptake

a neurotransmitter's reabsorption by the sending neuron.

endorphins

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 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-of-control gambling) that continue despite harmful consequences.

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 drugs that distort perceptions and evoke sensory images in the absence of sensory input.

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 lesions 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.

fmri (functional mri)

a technique for revealing blood flow and, therefore, brain activity by comparing successive mri scans. this technique scans show brain function as well as structure.

brainstem

the central core of the brain, responsible for automatic survival functions.

medulla

the hindbrain structure that controls heartbeat and breathing.

thalamus

the sensory control center, directs messages to sensory receiving areas in the cortex.

reticular formation

a nerve network that plays an important role in controlling arousal.

cerebellum

the hindbrain's "little brain" responsible for processing sensory input, coordinating movement and balance.

limbic system

neural system that includes the amygdala, hypothalamus, and hippocampus; associated with emotions and drives.

amygdala

two neural clusters in the limbic system linked to emotion.

hypothalamus

a neural structure directing maintenance activities, linked to emotion and reward.

hippocampus

a neural center in the limbic system that helps process explicit memories for storage.

cerebral cortex

the body's ultimate control and information-processing center.

frontal lobes

responsible for higher-order thinking, linguistic processing, and executive functioning.

parietal lobes

process sensory input for touch and body position.

occipital lobes

responsible for visual information processing.

temporal lobes

process auditory information and enable language processing.

motor cortex

controls voluntary movements.

somatosensory cortex

registers and processes body touch and movement sensations.

association areas

involved in higher mental functions such as learning, remembering, and speaking.

corpus callosum

the large band of neural fibers connecting the two brain hemispheres.

split brain

a condition resulting from surgery that separates the brain's two hemispheres.