biological approach glossary

Artifacts

something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the investigative procedure.

Bidirectional ambiguity

A problem with correlational research. We cannot be sure whether variable A causes a change in variable B or vice versa. It could also be that there is no cause-and-effect relationship in either direction, but that it is interactive or caused by another, underdetermined "third variable."

Cross-sectional design

Comparing two or more groups on a particular variable at a specific time. The opposite is a longitudinal design where the researcher measures a change in an individual over time.

Domino causality

cause and effect relationships where the effects become causes and there is a sequential unfolding of effects over time.

Double-blind testing

an experimental procedure in which neither the researcher doing the study nor the participants know the specific type of treatment each participant receives until after the experiment is over; a double-blind procedure is used to guard against both experimenter bias and placebo effects.

Longitudinal study

research over a period of time using observations, interviews or psychometric testing. (Similar to a repeated measures design in an experiment).

Meta-analysis

Pooling data from multiple studies of the same research question to arrive at one combined answer.

Placebo effect

a beneficial effect produced by a placebo drug or treatment, which cannot be attributed to the properties of the placebo itself, and must, therefore, be due to the patient's belief in that treatment.

Prospective research

A study that attempts to find a correlation between two variables by collecting data early in the life of participants and then continuing to test them over a period of time to measure change and development.

Reductionist approach

analyzes a complex behavior by studying the simplest, most basic mechanisms that are believed to be responsible for the behavior.

Retrospective research

A study of an individual after an important change or development. For example, the study of a person after a stroke. This requires the research to "reconstruct" the life of the individual prior to the event.

Single-blind testing

an experiment in which the researchers know which participants are receiving treatment and which are not; however, the participants do not know which condition they are in.

Triangulation

Using multiple data sources, multiple researchers, or multiple research methods in an investigation to reach a richer understanding of a behavior or cognitive process.

Acetylcholine

The most common neurotransmitter. Acetylcholine receptor sites are found in the hippocampus. It appears that acetylcholine plays a key role in memory consolidation from STM to LTM.

Adrenaline

Also called epinephrine, adrenaline is secreted by the adrenal glands and stimulates the sympathetic nervous system, and prepares the body for fight or flight.

Agonist

a chemical or a drug that binds to receptors in the brain and causes a reaction. Agonists can occur naturally in the body as neurotransmitters (endogenous agonists) or come from exterior sources like drugs and toxins (exogenous agonists).

Amygdala

Part of the limbic system, this part of the brain is believed to play a key role in emotion and memory. In addition, there is evidence that it plays a role in aggression, sexual orientation, trust, and alcoholism.

Antagonist

A chemical or drug that binds to receptors in the brain and prevents a neurotransmitter from having an effect on behavior. For example, scopolamine is an antagonist for acetylcholine.

Concordance rate

the probability that the same trait will be present in both members of a pair of twins.

Cortisol

a stress hormone that is secreted by the adrenal cortex. Responsible for the breakdown of glucose in the fight-or-flight response. Appears to be linked to hippocampal cell loss and memory dysfunction.

Dizygotic twins

The clinical term for fraternal twins; this occurs when two fertilized eggs are implanted in the uterus wall at the same time. When two eggs are independently fertilized by two different sperm cells, fraternal twins result. The genetic similarity is the same as any other siblings.

Dopamine

A neurotransmitter that helps control the brain's reward and pleasure centers. Dopamine also helps regulate emotional responses. Dopamine deficiency results in Parkinson's Disease and people with a lower number of dopamine receptor sites may be more prone to addiction.

Epigenetics

A branch of genetics that focuses on "gene expression" - that is, how environmental factors may "activate" genes.

Equal environment fallacy

environmental similarity between twins does not have much of an impact on trait similarity.

Excitatory function

When a neurotransmitter increases the likelihood that the neuron will fire an action potential. This depends on the receptor site. Many neurotransmitters are excitatory when they act on some receptor sites, and inhibitory when they act on others. For example, serotonin is an excitatory neurotransmitter that regulates sleep and wakefulness and is found in neurons in the pons and upper brain stem - but it is inhibitory in mood and emotion.

Family studies

Researchers trace a phenotype over several generations in a family tree to determine the likelihood that a behavior is inherited

Fight or flight response

a physiological reaction that occurs in response to perceived harm or threat to survival. It is triggered by the sympathetic nervous system activation that innervates the adrenal medulla, producing a hormonal cascade that results in the secretion of glucocorticoids. The animal is then reading for fighting or fleeing. This response is recognized as the first stage of Seyle's General Adaptation Syndrome.

Genome-wide association studies (GWAS)

an examination of a genome-wide set of genetic variants in a large sample of individuals to see if any variant is associated with a trait.

Glucocorticoids

stress hormones that help with the metabolism of glucose. They are released during stress to assist with the "Fight or Flight" response.

Hippocampus

Part of the limbic system, this part of the brain appears to play a key role in the consolidation of memory from short-term to long-term, as well as play a role in spatial navigation. There are several acetylcholine receptor sites in the hippocampus. Hippocampal cell loss plays a role in dementia, including Alzheimer's Disease.

Hormone

A chemical released by a gland directly into the bloodstream which has an effect on behavior.

HPA axis

a complex set of interactions between two parts of the brain—the hypothalamus and the pituitary glands—and the adrenal glands that are located at the top of each kidney. This is the basis of the human stress response.

Human Genome Project

the international, collaborative research program whose goal was the complete mapping and understanding of all the genes of human beings. All our genes together are known as our "genome."

Inhibitory function

When a neurotransmitter decreases the likelihood that the neuron will fire an action potential. This depends on the receptor site. Many neurotransmitters are inhibitory when they act on some receptor sites, and excitatory when they act on others. For example, serotonin is an inhibitory neurotransmitter when it is involved in emotion and mood, but excitatory in sleep and wakefulness.

Linkage analysis

Matching genetic variations (polymorphisms) with the frequency of a behavior

Melatonin

Secreted by the pineal gland, melatonin forms part of the system that regulates the sleep-wake cycle by chemically causing drowsiness and lowering the body temperature.

Monozygotic twins

The clinical term for identical twins; they share 100% of their DNA.

Natural selection

the process whereby organisms better adapted to their environment tend to survive and produce more offspring

Neural network

Usually called a neural circuit, a group of neurons interconnected by synapses to carry out a specific function when activated.

Neural pruning

Usually referred to as synaptic pruning refers to the process by which extra neurons and synaptic connections are eliminated in order to increase the efficiency of neuronal transmissions.

Neuroplasticity

the brain’s ability to alter its own structure following changes within the body or in the external environment.

Neurotransmitter

A neurotransmitter is a chemical messenger that carries signals between neurons. Neurotransmitters are released from the terminal buttons at the end of an axon after the action potential has sent an electrical charge down the neuron. The neurotransmitter then crosses the synaptic gap to reach the receptor site on another neuron.

Nucleus Accumbens

A section of the basal forebrain, the nucleus accumbens plays a key role in addiction, pleasure, reinforcement learning, aggression, impulsivity, and the placebo effect. The nucleus accumbens has a significant number of dopamine receptors.

Oxytocin

Secreted by the pituitary gland, oxytocin plays a role in social recognition, pair bonding, and maternal attachment. For this reason, it is sometimes referred to as the "love hormone". There is some evidence that oxytocin promotes trust and empathy in in-groups.

Permissive effect

When the mere presence of the hormone allows for a behavior, rather than the amount of the hormone. In the case of testosterone, Sapolsky argues that it is not how much testosterone an animal has that determines whether it is aggressive, it is whether they have testosterone.

Pheromone

a chemical substance produced and released into the environment by an animal affecting the behavior or physiology of others of its own species.

Polymorphism

a genetic variation (mutation) resulting in the occurrence of several different forms or types of individuals among the members of a single species

Reuptake

The reabsorption of a neurotransmitter by the terminal buttons of the pre-synaptic neuron after it has performed its function of transmitting a neural impulse. This prevents further activity of the neurotransmitter. Prozac is an SSRI - that is, a selective serotonin reuptake inhibitor, allowing more serotonin to remain in the synaptic gap.

Selective placement

a limitation of adoption studies in which children are placed with families that are very similar to the original family.

Serotonin

A neurotransmitter that works to regulate mood, appetite, and sleep. Low levels of serotonin have been linked to Clinical Unipolar depression and high levels of aggression. High levels of serotonin have been linked to hallucinations.

Sexual selection

natural selection arising through preference by one sex for certain characteristics in individuals of the other sex

Testosterone

The male sex hormone. Secreted by the testes in males and the ovaries in females.

Transgenic mice

a mouse that has had a single gene changed or removed

Theories in biology

Diathesis-stress model

attempts to explain a disorder as the result of an interaction between a predisposition and stress caused by life experiences.

Genetic vulnerability

An underlying inherited susceptibility - that is, the theory that you may have genes that may make you more likely to have certain traits if those genes are exposed to the appropriate environmental stressors.

Localization of function

The theory that specific behaviors may have their origin in specific parts of the brain