2 Biological Bases

biological psychology

a branch of psychology concerned with the links between biology and behavior.

neuron

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

dendrites

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.

axon

the extension of a neuron, ending in branching terminal fibers through which messages pass to other neurons or to muscles or glands.

myelin sheath

a layer of fatty tissue segmentally encasing the fivers of many neurons; enables vastly greater transmission speed of neural impulses as the pulse hops from one node to the next.

action potential

a neural impulse; a brief electrical charge that travels down an axon.

refractory period

a period of inactivity after a neuron has fired

threshold

the level of stimulation required to trigger a neural impulse.

all-or-none response

a neuron’s reaction of either firing (with a full-strength response) or not firing at all.

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 the junction is called the synaptic gap or synaptic cleft.

neurotransmitters

chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, they travel across the synapse and bind to the 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, opiate-like neurotransmitters linked to pain control and to pleasure.

agonist

a molecule that, by binding to a receptor site, stimulates a response.

antagonist

a molecule that, by binding to a receptor site, inhibits or blocks a response.

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 sense of organs.

sensory (afferent) neurons

neurons that carry incoming information from the 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 that communicate internally and intervene between 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

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 in stressful situations.

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 response.

endocrine system

the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstreamblood stream.

adrenal glands

pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

lesion

tissue destruction; a brain lesion is a naturally or experimentally caused destruction of brain tissue.

electroencephalogram (EEG)

an amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.

CT (computed tomography) scans

a series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body. Also called CAT scan.

PET (positron emission tomography) scan

a visual display of brain activity that detects 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-generated images of soft tissue. Shows brain anatomy.

fMRI (functional MRI)

a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. Shows brain function.

brainstem

the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; is responsible for automatic survival functions.

limbic system

doughnut-shaped neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives.

glial cell

cells in the nervous system that support, nourish, and protect neurons.

association areas

areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.

plasticity

the brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

neurogenesis

the formation of new neurons

split brain

• a condition resulting from surgery that isolates the brain's two hemispheres by cutting the fibers (mainly those of the corpus callosum connecting them)

• Most often after repeated seizures (epilepsy)

consciousness

our awareness of ourselves and our environment.

cognitive neuroscience

the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).

dual processing

the principle that information is often simultaneously processed on separate conscious and unconscious tracks.

behavior genetics

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

environment

every non-genetic influence, from prenatal nutrition to the people and things around us.

chromosomes

threadlike structures made of DNA molecules that contain the genes.

DNA (deoxyribonucleic acid)

a complex molecule containing the genetic information that makes up the chromosomes

genes

the biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing a protein.

genome

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

identical twins

twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms.

fraternal twins

twins who develop from separate fertilized eggs. They are genetically no closer that brothers and sisters, but they share a fetal environment.

molecular genetics

the subfield of biology that studies the molecular structure and functions of genes.

heritability

the proportion of variation among individuals that we can attribute to genes. This may vary, depending on the range of populations and environments studied.

interaction

the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).

epigenetics

The study of environmental influences on gene expression that occurs without a DNA change

evolutionary psychology

the study of the evolution of behavior and the mind, using principles of natural selection.

natural selection

the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations.

mutation

a random error in gene replication that leads to a change.

cell body

the part of a neuron that contains the nucleus; the cell’s life-support centre

MEG (magnetoencephalography)

a brain imaging technique that measures magnetic fields from the brain’s natural electrical activity

blindsight

a condition in which a person can respond to a visual stimulus without consciously experiencing it

parallel processing

processing many aspects of a problem simultaneously; generally used to process well-learned information or to solve easy problems

sequential processing

processing one aspect of a problem at a time; generally used to process new information or to solve difficult problems

heredity

the genetic transfer of characteristics from parent to offspring

social script

a culturally modelled guide for how to act in various situations

aphasia

impairment of language, usually caused by left hemisphere damage either to Broca’s area (impaired speaking) or to Wernicke’s area (impaired meaning of sentences)

motor cortex

an area at the rear of the frontal lobes that controls voluntary movements

sensory cortex (somatosensory cortex)

• area at the front of the parietal lobes that registers and processes body touch and movement sensations

• receives information from skin surface and sense organs

parietal lobe

• portion of the cerebral cortex lying at the top of the head and toward the rear

• receives sensory input for touch and body position

  • proprioception

visual area

involved in processing of visual input

occipital lobe

• portion of the cerebral cortex lying at the back of the head

• includes areas that receive information from the visual fields.

Wernicke’s area

a brain area involved in language comprehension and expression; usually in the left temporal lobe

temporal lobe

• portion of the cerebral cortex lying roughly above the ears

• includes the auditory areas, each receiving information primarily from the opposite ear.

Broca’s area

a brain area involved in speaking

prefrontal cortex

• aids emotion regulation

• located in the forward part of the frontal lobes

• enables judgement, planning, and processing of new memories

• damage can impact ability to plan and control emotions

  • case study: Phineas Gage

frontal lobe

speaking, making plans and judgments, voluntary muscle movements

cerebrum

• largest part of brain

• handles a wide ranges of responsibilities

• Includes

  • Frontal lobe

  • Occipital lobe

  • Temporal lobe

  • Parietal lobe

cerebral cortex

• the body's ultimate control and information processing centre for higher-level thinking

• the intricate fabric of interconnected neural cells covering the cerebral hemispheres

thalamus

• part of the brain stem

• brain’s sensory switchboard

• directs messages to the sensory areas in the cortex and transmits replies to the cerebellum and medulla

corpus callosum

the large band of neural fibers connecting the two brain hemispheres and carrying messages between them

hippocampus

• part of the limbic system

• processes conscious, explicit memories

• as we age, size decreases and function declines

• can appear smaller after repeated concussions

amygdala

• two almond-shaped neural clusters

• part of the limbic system

• linked to emotions of fear and anger

• criminal behaviour can be linked to abnormalities of this structure

hypothalamus

• part of the limbic system

• hypo = lies below the thalamus

• directs several maintenance activities like eating, body temperature and control of emotions

• helps govern the endocrine system via the pituitary gland

• linked to reward centre

  • Rat experiment

pituitary gland

• the endocrine system’s most influential gland

• under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands

pons

• part of the brainstem

• helps coordinate movement

reticular formation

• Nerve network in the brainstem that plays an important role in controlling arousal as it filters important information

• Severed = coma

medulla oblongata

• Controls heartbeat and breathing

• Part of the brainstem

  • Located at the base of brainstem

cerebellum

• "little brain" attached to the rear of the brain stem

• processes sensory input and coordinates movement output and balance

• non-verbal memory

• negatively affected by alcohol

lateralization

the division of the brain into two hemispheres that differ in function

serial positioning effect

• tendency to remember the first and last elements of a series

  • primacy and recency

hormones

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

consciousness

our awareness of ourselves and our environment

hypnosis

a social interaction in which one person (the hypnotist) suggests to another (the subject) that certain perceptions, feelings, thoughts, or behaviours will spontaneously occur

posthypnotic suggestion

a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to help control undesired symptoms and behaviours

dissociation

a split in consciousness, which allows some thoughts and behaviours to occur simultaneously with others

circadian rhythm

the 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

alpha waves

the relatively slow brain waves of a relaxed, awake state