An enzyme required to convert testosterone to 5α-dihydrotestosterone.
Surgical removal of brain tissue.
Action potential
A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation.
Evolved solutions to problems that historically contributed to reproductive success.
Adoption study
A behavior genetic research method that involves comparison of adopted children to their adoptive and biological parents.
Afferent nerves
Nerves that carry messages to the brain or spinal cord.
A form of social interaction that includes threat, attack, and fighting.
Due to damage of Wernicke’s area. An inability to recognize objects, words, or faces.
Due to damage of the Broca’s area. An inability to produce or understand words.
Arcuate fasciculus
A fiber tract that connects Wernicke’s and Broca’s speech areas.
An enzyme that converts androgens into estrogens.
Autonomic nervous system
A part of the peripheral nervous system that connects to glands and smooth muscles. Consists of sympathetic and parasympathetic divisions.
Axial plane
See “horizontal plane.”
Part of the neuron that extends off the soma, splitting several times to connect with other neurons; main output of the neuron.
Basal ganglia
Subcortical structures of the cerebral hemispheres involved in voluntary movement.
Behavioral genetics
The empirical science of how genes and environments combine to generate behavior.
Brain stem
The “trunk” of the brain comprised of the medulla, pons, midbrain, and diencephalon.
Broca’s area
An area in the frontal lobe of the left hemisphere. Implicated in language production.
Surgical procedure in which the corpus callosum is severed (used to control severe epilepsy).
Case study
A thorough study of a patient (or a few patients) with naturally occurring lesions.
Cell membrane
A bi-lipid layer of molecules that separates the cell from the surrounding extracellular fluid.
Central sulcus
The major fissure that divides the frontal and the parietal lobes.
The distinctive structure at the back of the brain, Latin for “small brain.”
A nervous system structure behind and below the cerebrum. Controls motor movement coordination, balance, equilibrium, and muscle tone.
Cerebral cortex
The outermost gray matter of the cerebrum; the distinctive convolutions characteristic of the mammalian brain.
Cerebral hemispheres
The cerebral cortex, underlying white matter, and subcortical structures.
Consists of left and right hemispheres that sit at the top of the nervous system and engages in a variety of higher-order functions.
Usually refers to the cerebral cortex and associated white matter, but in some texts includes the subcortical structures.
Chromosomal sex
The sex of an individual as determined by the sex chromosomes (typically XX or XY) received at the time of fertilization.
Cingulate gyrus
A medial cortical portion of the nervous tissue that is a part of the limbic system.
Computerized axial tomography
A noninvasive brain-scanning procedure that uses X-ray absorption around the head.
Literally “opposite side”; used to refer to the fact that the two hemispheres of the brain process sensory information and motor commands for the opposite side of the body (e.g., the left hemisphere controls the right side of the body).
Converging evidence
Similar findings reported from multiple studies using different methods.
Coronal plane
A slice that runs from head to foot; brain slices in this plane are similar to slices of a loaf of bread, with the eyes being the front of the loaf.
The removal of the potential for female traits.
The removal of the potential for male traits.
Part of a neuron that extends away from the cell body and is the main input to the neuron.
Diffuse optical imaging (DOI)
A neuroimaging technique that infers brain activity by measuring changes in light as it is passed through the skull and surface of the brain.
The force on molecules to move from areas of high concentration to areas of low concentration.
Dihydrotestosterone (DHT)
A primary androgen that is an androgenic steroid product of testosterone and binds strongly to androgen receptors.
DNA methylation
Covalent modifications of mammalian DNA occurring via the methylation of cytosine, typically in the context of the CpG dinucleotide.
DNA methyltransferases (DNMTs)
Enzymes that establish and maintain DNA methylation using methyl-group donor compounds or cofactors. The main mammalian DNMTs are DNMT1, which maintains methylation state across DNA replication, and DNMT3a and DNMT3b, which perform de novo methylation.
The outermost layer of a developing fetus.
Efferent nerves
Nerves that carry messages from the brain to glands and organs in the periphery.
A technique that is used to measure gross electrical activity of the brain by placing electrodes on the scalp.
Electroencephalography (EEG)
A neuroimaging technique that measures electrical brain activity via multiple electrodes on the scalp.
Electrostatic pressure
The force on two ions with similar charge to repel each other; the force of two ions with opposite charge to attract to one another.
Endocrine gland
A ductless gland from which hormones are released into the blood system in response to specific biological signals.
The study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence. Epigenetic marks include covalent DNA modifications and posttranslational histone modifications.
Heritable changes in gene activity that are not caused by changes in the DNA sequence. http://en.wikipedia.org/wiki/Epigenetics
The genome-wide distribution of epigenetic marks.
Error management theory (EMT)
A theory of selection under conditions of uncertainty in which recurrent cost asymmetries of judgment or inference favor the evolution of adaptive cognitive biases that function to minimize the more costly errors.
Any of the C18 class of steroid hormones, so named because of the estrus-generating properties in females. Biologically important estrogens include estradiol and estriol.
A physiological measure of large electrical change in the brain produced by sensory stimulation or motor responses.
Change over time. Is the definition changing?
Excitatory postsynaptic potentials
A depolarizing postsynaptic current that causes the membrane potential to become more positive and move towards the threshold of excitation.
The induction of female traits.
A part of the nervous system that contains the cerebral hemispheres, thalamus, and hypothalamus.
(plural form, fornices) A nerve fiber tract that connects the hippocampus to mammillary bodies.
Frontal lobe
The front most (anterior) part of the cerebrum; anterior to the central sulcus and responsible for motor output and planning, language, judgment, and decision-making.
Frontal lobe
The most forward region (close to forehead) of the cerebral hemispheres.
Functional magnetic resonance imaging
(or fMRI) A noninvasive brain-imaging technique that registers changes in blood flow in the brain during a given task (also see magnetic resonance imaging).
Functional magnetic resonance imaging (fMRI)
Functional magnetic resonance imaging (fMRI): A neuroimaging technique that infers brain activity by measuring changes in oxygen levels in the blood.
A specific deoxyribonucleic acid (DNA) sequence that codes for a specific polypeptide or protein or an observable inherited trait.
Gene Selection Theory
The modern theory of evolution by selection by which differential gene replication is the defining process of evolutionary change.
Genome-wide association study (GWAS)
A study that maps DNA polymorphisms in affected individuals and controls matched for age, sex, and ethnic background with the aim of identifying causal genetic variants.
The DNA content of a cell’s nucleus, whether a trait is externally observable or not.
Globus pallidus
A nucleus of the basal ganglia.
Gonadal sex
The sex of an individual as determined by the possession of either ovaries or testes. Females have ovaries, whereas males have testes.
Gray matter
Composes the bark or the cortex of the cerebrum and consists of the cell bodies of the neurons (see also white matter).
Gray matter
The outer grayish regions of the brain comprised of the neurons’ cell bodies.
(plural) Folds between sulci in the cortex.
(plural form, gyri) A bulge that is raised between or among fissures of the convoluted brain.
A fold between sulci in the cortex.
Heritability coefficient
An easily misinterpreted statistical construct that purports to measure the role of genetics in the explanation of differences among individuals.
(plural form, hippocampi) A nucleus inside (medial) the temporal lobe implicated in learning and memory.
Histone acetyltransferases (HATs) and histone deacetylases (HDACs)
HATs are enzymes that transfer acetyl groups to specific positions on histone tails, promoting an “open” chromatin state and transcriptional activation. HDACs remove these acetyl groups, resulting in a “closed” chromatin state and transcriptional repression.
Histone modifications
Posttranslational modifications of the N-terminal “tails” of histone proteins that serve as a major mode of epigenetic regulation. These modifications include acetylation, phosphorylation, methylation, sumoylation, ubiquitination, and ADP-ribosylation.
Homo habilis
A human ancestor, handy man, that lived two million years ago.
Homo sapiens
Modern man, the only surviving form of the genus Homo.
Horizontal plane
A slice that runs horizontally through a standing person (i.e., parallel to the floor); slices of brain in this plane divide the top and bottom parts of the brain; this plane is similar to slicing a hamburger bun.
An organic chemical messenger released from endocrine cells that travels through the blood to interact with target cells at some distance to cause a biological response.
Part of the diencephalon. Regulates biological drives with pituitary gland.
Identical twins
Two individual organisms that originated from the same zygote and therefore are genetically identical or very similar. The epigenetic profiling of identical twins discordant for disease is a unique experimental design as it eliminates the DNA sequence-, age-, and sex-differences from consideration.
A method of staining tissue including the brain, using antibodies.
Inhibitory postsynaptic potentials
A hyperpolarizing postsynaptic current that causes the membrane potential to become more negative and move away from the threshold of excitation.
Intersexual selection
A process of sexual selection by which evolution (change) occurs as a consequences of the mate preferences of one sex exerting selection pressure on members of the opposite sex.
Intrasexual competition
A process of sexual selection by which members of one sex compete with each other, and the victors gain preferential mating access to members of the opposite sex.
Ion channels
Proteins that span the cell membrane, forming channels that specific ions can flow through between the intracellular and extracellular space.
Ionotropic receptor
Ion channel that opens to allow ions to permeate the cell membrane under specific conditions, such as the presence of a neurotransmitter or a specific membrane potential.
Lateral geniculate nucleus
(or LGN) A nucleus in the thalamus that is innervated by the optic nerves and sends signals to the visual cortex in the occipital lobe.
Lateral sulcus
The major fissure that delineates the temporal lobe below the frontal and the parietal lobes.
To the side; used to refer to the fact that specific functions may reside primarily in one hemisphere or the other (e.g., for the majority individuals, the left hemisphere is most responsible for language).
A region in the brain that suffered damage through injury, disease, or medical intervention.
Lesion studies
A surgical method in which a part of the animal brain is removed to study its effects on behavior or function.
Limbic system
A loosely defined network of nuclei in the brain involved with learning and emotion.
Limbic system
Includes the subcortical structures of the amygdala and hippocampal formation as well as some cortical structures; responsible for aversion and gratification.
Magnetic resonance imaging
Or MRI is a brain imaging noninvasive technique that uses magnetic energy to generate brain images (also see fMRI).
Magnification factor
Cortical space projected by an area of sensory input (e.g., mm of cortex per degree of visual field).
The induction of male traits.
Maternal behavior
Parental behavior performed by the mother or other female.
Medulla oblongata
An area just above the spinal cord that processes breathing, digestion, heart and blood vessel function, swallowing, and sneezing.
A substance necessary for a living organism to maintain life.
Motor cortex
Region of the frontal lobe responsible for voluntary movement; the motor cortex has a contralateral representation of the human body.
Fatty tissue, produced by glial cells (see module, “Neurons”) that insulates the axons of the neurons; myelin is necessary for normal conduction of electrical impulses among neurons.
Myelin sheath
Substance around the axon of a neuron that serves as insulation to allow the action potential to conduct rapidly toward the terminal buttons.
Natural selection
Differential reproductive success as a consequence of differences in heritable attributes.
Neural crest
A set of primordial neurons that migrate outside the neural tube and give rise to sensory and autonomic neurons in the peripheral nervous system.
Neural induction
A process that causes the formation of the neural tube.
Brain progenitor cells that asymmetrically divide into other neuroblasts or nerve cells.
The lining of the neural tube.
A chemical messenger that travels between neurons to provide communication. Some neurotransmitters, such as norepinephrine, can leak into the blood system and act as hormones.
Chemical substance released by the presynaptic terminal button that acts on the postsynaptic cell.
Naming conventions.
Collection of nerve cells found in the brain which typically serve a specific function.
Occipital lobe
The back most (posterior) part of the cerebrum; involved in vision.
Occipital lobe
The back part of the cerebrum, which houses the visual areas.
A peptide hormone secreted by the pituitary gland to trigger lactation, as well as social bonding.
A nine amino acid mammalian neuropeptide. Oxytocin is synthesized primarily in the brain, but also in other tissues such as uterus, heart and thymus, with local effects. Oxytocin is best known as a hormone of female reproduction due to its capacity to cause uterine contractions and eject milk. Oxytocin has effects on brain tissue, but also acts throughout the body in some cases as an antioxidant or anti-inflammatory.
Parasympathetic nervous system
A division of the autonomic nervous system that is slower than its counterpart—that is, the sympathetic nervous system—and works in opposition to it. Generally engaged in “rest and digest” functions.
Parental behavior
Behaviors performed in relation to one’s offspring that contributes directly to the survival of those offspring
Parietal lobe
The part of the cerebrum between the frontal and occipital lobes; involved in bodily sensations, visual attention, and integrating the senses.
Parietal lobe
An area of the cerebrum just behind the central sulcus that is engaged with somatosensory and gustatory sensation.
Paternal behavior
Parental behavior performed by the father or other male.
The pattern of expression of the genotype or the magnitude or extent to which it is observably expressed—an observable characteristic or trait of an organism, such as its morphology, development, biochemical or physiological properties, or behavior.
A now-discredited field of brain study, popular in the first half of the 19th century that correlated bumps and indentations of the skull with specific functions of the brain.
A bridge that connects the cerebral cortex with the medulla, and reciprocally transfers information back and forth between the brain and the spinal cord.
Positron Emission Tomography
(or PET) An invasive procedure that captures brain images with positron emissions from the brain after the individual has been injected with radio-labeled isotopes.
Positron emission tomography (PET)
A neuroimaging technique that measures brain activity by detecting the presence of a radioactive substance in the brain that is initially injected into the bloodstream and then pulled in by active brain tissue.
Primary Motor Cortex
A strip of cortex just in front of the central sulcus that is involved with motor control.
Primary Somatosensory Cortex
A strip of cerebral tissue just behind the central sulcus engaged in sensory reception of bodily sensations.
A primary progestin that is involved in pregnancy and mating behaviors.
A class of C21 steroid hormones named for their progestational (pregnancy-supporting) effects. Progesterone is a common progestin.
A molecule that can act as a hormone itself or be converted into another hormone with different properties. For example, testosterone can serve as a hormone or as a prohormone for either dihydrotestosterone or estradiol.
A protein hormone that is highly conserved throughout the animal kingdom. It has many biological functions associated with reproduction and synergistic actions with steroid hormones.
Psychological adaptations
Mechanisms of the mind that evolved to solve specific problems of survival or reproduction; conceptualized as information processing devices.
Quantitative genetics
Scientific and mathematical methods for inferring genetic and environmental processes based on the degree of genetic and environmental similarity among organisms.
A chemical structure on the cell surface or inside of a cell that has an affinity for a specific chemical configuration of a hormone, neurotransmitter, or other compound.
Resting membrane potential
The voltage inside the cell relative to the voltage outside the cell while the cell is a rest (approximately -70 mV).
A front-back plane used to identify anatomical structures in the body and the brain.
Sagittal plane
A slice that runs vertically from front to back; slices of brain in this plane divide the left and right side of the brain; this plane is similar to slicing a baked potato lengthwise.
Sex determination
The point at which an individual begins to develop as either a male or a female. In animals that have sex chromosomes, this occurs at fertilization. Females are XX and males are XY. All eggs bear X chromosomes, whereas sperm can either bear X or Y chromosomes. Thus, it is the males that determine the sex of the offspring.
Sex differentiation
The process by which individuals develop the characteristics associated with being male or female. Differential exposure to gonadal steroids during early development causes sexual differentiation of several structures including the brain.
Sexual selection
The evolution of characteristics because of the mating advantage they give organisms.
​Sexual strategies theory
A comprehensive evolutionary theory of human mating that defines the menu of mating strategies humans pursue (e.g., short-term casual sex, long-term committed mating), the adaptive problems women and men face when pursuing these strategies, and the evolved solutions to these mating problems.
Sodium-potassium pump
An ion channel that uses the neuron’s energy (adenosine triphosphate, ATP) to pump three Na+ ions outside the cell in exchange for bringing two K+ ions inside the cell.
Cell body of a neuron that contains the nucleus and genetic information, and directs protein synthesis.
Somatic nervous system
A part of the peripheral nervous system that uses cranial and spinal nerves in volitional actions.
Somatosensory (body sensations) cortex
The region of the parietal lobe responsible for bodily sensations; the somatosensory cortex has a contralateral representation of the human body.
Spatial resolution
A term that refers to how small the elements of an image are; high spatial resolution means the device or technique can resolve very small elements; in neuroscience it describes how small of a structure in the brain can be imaged.
Spina bifida
A developmental disease of the spinal cord, where the neural tube does not close caudally.
Protrusions on the dendrite of a neuron that form synapses with terminal buttons of the presynaptic axon.
Split-brain patient
A patient who has had most or all of his or her corpus callosum severed.
Structures that lie beneath the cerebral cortex, but above the brain stem.
(plural) Grooves separating folds of the cortex.
(plural form, sulci) The crevices or fissures formed by convolutions in the brain.
A groove separating folds of the cortex.
Sympathetic nervous system
A division of the autonomic nervous system, that is faster than its counterpart that is the parasympathetic nervous system and works in opposition to it. Generally engaged in “fight or flight” functions.
Junction between the presynaptic terminal button of one neuron and the dendrite, axon, or soma of another postsynaptic neuron.
Synaptic gap
Also known as the synaptic cleft; the small space between the presynaptic terminal button and the postsynaptic dendritic spine, axon, or soma.
Synaptic vesicles
Groups of neurotransmitters packaged together and located within the terminal button.
Target cell
A cell that has receptors for a specific chemical messenger (hormone or neurotransmitter).
Temporal lobe
The part of the cerebrum in front of (anterior to) the occipital lobe and below the lateral fissure; involved in vision, auditory processing, memory, and integrating vision and audition.
Temporal lobe
An area of the cerebrum that lies below the lateral sulcus; it contains auditory and olfactory (smell) projection regions.
Temporal resolution
A term that refers to how small a unit of time can be measured; high temporal resolution means capable of resolving very small units of time; in neuroscience it describes how precisely in time a process can be measured in the brain.
Terminal button
The part of the end of the axon that form synapses with postsynaptic dendrite, axon, or soma.
The primary androgen secreted by the testes of most vertebrate animals, including men.
A part of the diencephalon that works as a gateway for incoming and outgoing information.
Threshold of excitation
Specific membrane potential that the neuron must reach to initiate an action potential.
Transcranial direct current stimulation (tDCS)
A neuroscience technique that passes mild electrical current directly through a brain area by placing small electrodes on the skull.
Transcranial magnetic stimulation (TMS)
A neuroscience technique whereby a brief magnetic pulse is applied to the head that temporarily induces a weak electrical current that interferes with ongoing activity.
A process in which physical energy converts into neural energy.
Transverse plane
See “horizontal plane.”
Twin studies
A behavior genetic research method that involves comparison of the similarity of identical (monozygotic; MZ) and fraternal (dizygotic; DZ) twins.
Vagus nerve
The 10th cranial nerve. The mammalian vagus has an older unmyelinated branch which originates in the dorsal motor complex and a more recently evolved, myelinated branch, with origins in the ventral vagal complex including the nucleus ambiguous. The vagus is the primary source of autonomic-parasympathetic regulation for various internal organs, including the heart, lungs and other parts of the viscera. The vagus nerve is primarily sensory (afferent), transmitting abundant visceral input to the central nervous system.
A nine amino acid mammalian neuropeptide. Vasopressin is synthesized primarily in the brain, but also may be made in other tissues. Vasopressin is best known for its effects on the cardiovascular system (increasing blood pressure) and also the kidneys (causing water retention). Vasopressin has effects on brain tissue, but also acts throughout the body.
Visual hemifield
The half of visual space (what we see) on one side of fixation (where we are looking); the left hemisphere is responsible for the right visual hemifield, and the right hemisphere is responsible for the left visual hemifield.
Wernicke’s area
A language area in the temporal lobe where linguistic information is comprehended (Also see Broca’s area).
White matter
The inner whitish regions of the cerebrum comprised of the myelinated axons of neurons in the cerebral cortex.
White matter
Regions of the nervous system that represent the axons of the nerve cells; whitish in color because of myelination of the nerve cells.
Working memory
Short transitory memory processed in the hippocampus.