Biological and Neuropsychological Foundations of Behavior and Brain Function

nature-nurture issue

The debate over the relative contributions of genetics (nature) and experience (environment) in shaping behavior and mental processes.

Charles Darwin

Naturalist who developed the theory of evolution by natural selection, foundational to evolutionary psychology.

natural selection

The process where organisms with traits better suited to their environment survive and reproduce more successfully, passing those traits to offspring.

evolutionary psychology

Study of how natural selection has shaped behavior and mental processes to solve problems of survival and reproduction.

behavior genetics

Study of the relative power and limits of genetic and environmental influences on behavior.

mutation

Random error in gene replication that leads to genetic variation; the raw material for natural selection.

environment

Every external influence on behavior and mental processes, from prenatal nutrition to social experiences.

heredity

The genetic transfer of characteristics from parents to offspring.

genes

Biochemical units of heredity that make up chromosomes; segments of DNA.

genome

The complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes.

identical (monozygotic) twins

Twins who develop from a SINGLE fertilized egg that splits; share 100% of DNA; same genetic makeup.

fraternal (dizygotic) twins

Twins who develop from TWO separately fertilized eggs; share 50% of DNA like regular siblings; genetically no more similar than siblings.

interaction

The interplay between genetic predispositions and environmental factors in determining traits and behaviors.

epigenetics

Study of environmental influences on gene expression that occur WITHOUT changes to DNA sequence; genes can be turned 'on' or 'off'.

molecular genetics

Study of the molecular structure and function of genes to identify specific genes influencing behavior.

central nervous system (CNS)

Brain and spinal cord; the body's decision-maker and command center.

peripheral nervous system (PNS)

Sensory and motor neurons connecting the CNS to the rest of the body; gathers info and carries out commands.

nerves

Bundled axons that form neural cables connecting the CNS with muscles, glands, and sense organs.

sensory (afferent) neurons

Neurons that carry incoming information FROM body tissues and sensory receptors TO the CNS ('Afferent Arrives').

motor (efferent) neurons

Neurons that carry outgoing information FROM the CNS TO muscles and glands ('Efferent Exits').

interneurons

Neurons within the CNS that communicate internally and process information between sensory inputs and motor outputs.

somatic nervous system

Division of PNS that controls voluntary movements of skeletal muscles.

autonomic nervous system (ANS)

Division of PNS that controls involuntary functions of glands and internal organs (heart, digestion).

sympathetic nervous system

ANS division that arouses and mobilizes body for action; 'fight or flight' response (speeds up heart, dilates pupils, inhibits digestion).

parasympathetic nervous system

ANS division that calms body and conserves energy; 'rest and digest' (slows heart, constricts pupils, stimulates digestion).

reflex

Simple, automatic response to a sensory stimulus (like pulling hand from hot stove); doesn't require brain involvement.

neuron

Nerve cell; basic building block of the nervous system that transmits information.

cell body

Part of neuron containing nucleus and life-support machinery; integrates incoming signals.

dendrites

Bushy, branching extensions of neuron that RECEIVE messages from other neurons and conduct them toward cell body.

axon

Extension of neuron that passes messages through its branches to other neurons, muscles, or glands; SENDS signals away from cell body.

myelin sheath

Fatty tissue layer insulating axons of some neurons; speeds up neural transmission (like insulation on electrical wire).

glial cells (glia)

Support cells in nervous system that provide nutrients, insulation, and cleanup; outnumber neurons.

action potential

Brief electrical charge that travels down an axon; neural impulse; the neuron 'firing'.

threshold

Level of stimulation required to trigger a neural impulse; must be reached for neuron to fire.

refractory period

Brief pause after action potential when neuron cannot fire again; like reloading after shooting.

all-or-none response

Neuron's reaction of either firing at full strength or not firing at all; no partial firings (like flushing a toilet).

synapse

Junction between axon tip of sending neuron and dendrite or cell body of receiving neuron; tiny gap where communication happens.

neurotransmitters

Chemical messengers that cross synapses to carry messages between neurons or from neurons to muscles/glands.

reuptake

Neurotransmitter is reabsorbed by the sending neuron; like vacuuming up excess chemicals from synapse.

endorphins

Natural morphine-like neurotransmitters linked to pain control and pleasure; 'runner's high'.

agonist

Molecule that mimics or increases a neurotransmitter's effects; like a key that fits and opens the lock.

antagonist

Molecule that blocks or decreases a neurotransmitter's effects; like jamming the lock so the key won't work

endocrine system

Body's slow chemical communication system; network of glands that secrete hormones into bloodstream

hormones

Chemical messengers manufactured by endocrine glands that travel through bloodstream and affect other tissues; slower but longer-lasting than neurotransmitters

biological psychology

Study of the links between biological (genetic, neural, hormonal) processes and psychological processes

biopsychosocial approach

Integrated approach considering biological, psychological, and social-cultural factors in understanding behavior and mental processes

levels of analysis

Different complementary views (biological, psychological, social-cultural) for analyzing any given phenomenon

neuroplasticity

Brain's ability to change and reorganize itself by forming new neural connections throughout life; especially after damage

lesion

Tissue destruction; brain lesion is naturally or experimentally caused destruction of brain tissue used to study brain function

EEG (electroencephalogram)

Recording of electrical activity in brain's neurons using electrodes on scalp; shows brain waves; good for sleep/seizure studies

MEG (magnetoencephalography)

Records magnetic fields from brain's electrical activity; more precise than EEG for localizing brain activity

CT (computed tomography) scan

X-ray technique that produces 3D images of brain structure by taking multiple X-rays from different angles

PET (positron emission tomography)

Visual display of brain activity detecting where radioactive glucose goes while brain performs task; shows function

MRI (magnetic resonance imaging)

Uses magnetic fields and radio waves to produce detailed images of soft brain tissue; shows structure clearly

fMRI (functional MRI)

MRI technique that shows brain activity by detecting changes in blood flow; reveals which areas are active during tasks

hindbrain

Lowest brain region including medulla, pons, and cerebellum; controls basic survival functions

midbrain

Small region above hindbrain; involved in arousal, pain, and some movement

forebrain

Largest, most complex brain region including thalamus, hypothalamus, limbic system, and cerebral cortex

brainstem

Oldest, central core of brain beginning where spinal cord enters skull; includes medulla, pons, reticular formation; automatic survival functions

medulla

Base of brainstem; controls heartbeat and breathing; damage is fatal

thalamus

Brain's sensory relay station (except for smell); receives info from senses and routes it to appropriate brain areas

reticular formation

Nerve network in brainstem that plays role in arousal, attention, and sleep; filters incoming stimuli

cerebellum

"Little brain" at rear of brainstem; coordinates voluntary movement, balance, and enables nonverbal learning and memory

limbic system

Neural system (amygdala, hypothalamus, hippocampus) beneath cerebral hemispheres; associated with emotions and drives

amygdala

Two lima-bean-sized clusters in limbic system; linked to emotion, especially fear and aggression; damage removes fear response

hypothalamus

Neural structure below thalamus; directs maintenance activities (eating, drinking, body temp); helps govern endocrine system via pituitary; linked to emotion and reward

hippocampus

Neural center in limbic system; crucial for forming new memories; damage prevents new memory formation

cerebral cortex

Intricate fabric of interconnected neural cells covering cerebral hemispheres; body's ultimate control and information-processing center

frontal lobes

Portion of cerebral cortex behind forehead; involved in speaking, muscle movements, planning, judgment, personality

parietal lobes

Portion of cerebral cortex at top/rear of head; receives sensory input for touch and body position

occipital lobes

Portion of cerebral cortex at back of head; includes areas that receive information from visual fields

temporal lobes

Portion of cerebral cortex above ears; includes auditory areas receiving information primarily from opposite ear

motor cortex

Area at rear of frontal lobes that controls voluntary movements; different parts control different body parts

somatosensory cortex

Area at front of parietal lobes that registers and processes body touch and movement sensations

association areas

Areas of cerebral cortex not involved in primary motor or sensory functions; involved in higher mental functions (learning, memory, thinking, speaking)

neurogenesis

Formation of new neurons; occurs in hippocampus and olfactory bulb throughout life

corpus callosum

Large band of neural fibers connecting brain's two hemispheres and carrying messages between them

Roger Sperry

Researcher who studied split-brain patients to understand hemispheric specialization; won Nobel Prize

Michael Gazzaniga

Researcher who worked with Sperry on split-brain research and continued studying brain lateralization

split brain

Condition resulting from surgery that isolates brain's two hemispheres by cutting corpus callosum; done to treat severe epilepsy