3. Biological Foundations: Roots in Neurons and Genes

Question 1

active gene–environment association

Answer 1

People’s genes encourage them to seek out experiences compatible with their inherited tendencies.

Question 2

allele

Answer 2

An alternative form of a gene; typically, a gene has two alleles, one inherited from the offspring’s mother and one from the father.

Question 3

attention-deficit/hyperactivity disorder (ADHD)

Answer 3

A disorder characterized by a persistent pattern of inattention and hyperactivity or impulsivity.

Question 4

attunement

Answer 4

A pattern of mutual engagement between care- giver and infant by which the caregiver maintains attention and responds warmly to the infant’s signals.

Question 5

autism

Answer 5

A disorder that begins in childhood, lasts a lifetime, and disrupts social and communication skills.

Question 6

cerebral cortex

Answer 6

The covering layer of the cerebrum, which contains the cells that control specific functions such as seeing, hearing, moving, and thinking.

Question 7

cerebral hemispheres

Answer 7

The two halves of the brain’s cerebrum, left and right.

Question 8

cerebrum

Answer 8

The two connected hemispheres of the brain.

Question 9

corpus callosum

Answer 9

The band of nerve fibers that connects the two hemispheres of the brain.

Question 10

dizygotic

Answer 10

Fraternal twins from two different eggs, fertilized by two different sperm, producing two different zygotes.

Question 11

evocative gene–environment association

Answer 11

People’s inherited tendencies elicit certain environmental responses.

Question 12

experience-dependent processes

Answer 12

Brain processes that are unique to the individual and responsive to particular cultural, community, and family experiences.

Question 13

experience-expectant processes

Answer 13

Brain processes that are universal, experienced by all human beings across evolution.

Question 14

externalizing problems

Answer 14

A type of childhood behavior prob- lem in which the behavior is directed at others, including hitting, stealing, vandalizing, and lying.

Question 15

gene

Answer 15

A portion of DNA located at a particular site on a chro- mosome and coding for the production of a specific type of protein.

Question 16

genotype

Answer 16

The particular set of genes a person inherits from his or her parents.

Question 17

glial cells

Answer 17

A cell that supports, protects, and repairs neurons.

Question 18

heritability factor

Answer 18

A statistical estimate of the contribution heredity makes to a particular trait or ability.

Question 19

heterozygous

Answer 19

Alleles for a particular trait from each parent are different.

Question 20

homozygous

Answer 20

Alleles for a particular trait from each parent are the same.

Question 21

human behavior genetics

Answer 21

The study of the relative influences of heredity and environment on individual differences in traits and abilities.

Question 22

internalizing problems

Answer 22

A type of childhood behavior problem in which the behavior is directed at the self rather than others, including fear, anxiety, depression, loneliness, and withdrawal.

Question 23

lateralization

Answer 23

The process by which each half of the brain be- comes specialized for certain functions—for example, the control of speech and language by the left hemisphere and of visual-spatial processing by the right.

Question 24

mirror neuron

Answer 24

A nerve cell that fires both when a person acts and when a person observes the same action performed by someone else, as if the observer himself or herself were acting.

Question 25

modifier genes

Answer 25

Genes that exert their influence indirectly by affecting the expression of other genes.

Question 26

monozygotic

Answer 26

Identical twins created when a single zygote splits in half and each half becomes a distinct embryo with nearly the same genes; both embryos come from one zygote.

Question 27

myelination

Answer 27

The process by which glial cells encase neurons in sheaths of the fatty substance myelin.

Question 28

neural migration

Answer 28

The movement of neurons within the brain that ensures that all brain areas have a sufficient number of neural connections.

Question 29

neuron

Answer 29

A cell in the body’s nervous system, consisting of a cell body, a long projection called an axon, and several shorter projections called dendrites; neurons send and receive neural impulses, or messages, throughout the brain and nervous system.

Question 30

neuron proliferation

Answer 30

The rapid formation of neurons in the developing organism’s brain.

Question 31

niche picking

Answer 31

Seeking out or creating environments compatible with one’s genetically based predispositions.

Question 32

nonshared environment

Answer 32

A set of conditions or activities experienced by one child in a family but not shared with another child in the same family.

Question 33

passive gene–environment association

Answer 33

Environment created by parents with particular genetic characteristics encourages the expression of these tendencies in their children.

Question 34

phenotype

Answer 34

The visible expression of a person’s particular physical and behavioral characteristics created by the interaction of the person’s genotype with the environment.

Question 35

programmed neuronal death

Answer 35

The naturally occurring death of immature nerve cells during early development of the nervous system.

Question 36

reaction range

Answer 36

The range of possible developmental outcomes established by a person’s genotype in reaction to the environment in which development takes place.

Question 37

shared environment

Answer 37

A set of conditions or activities experienced by children raised in the same family.

Question 38

synapse

Answer 38

A specialized site of intercellular communication that exchanges information between nerve cells, usually by means of a chemical neurotransmitter.

Question 39

synaptic pruning

Answer 39

The brain’s disposal of the axons and dendrites of a neuron that is not often stimulated.

Question 40

synaptogenesis

Answer 40

The forming of synapses.

Question 41

temperament

Answer 41

An individual’s typical mode of response including activity level, emotional intensity, and attention span; used particularly to describe infants’ and children’s behavior.