Vocabulary

5α-reductase: An enzyme required to convert testosterone to 5α-dihydrotestosterone.
Ablation: Surgical removal of brain tissue.
Acceptance and commitment therapy: A therapeutic approach designed to foster nonjudgmental observation of one’s own mental processes.
Action potential: A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation.
Adoption study: A behavior genetic research method that involves comparison of adopted children to their adoptive and biological parents.
Affect: An emotional process; includes moods, subjective feelings, and discrete emotions.
Affect: Feelings that can be described in terms of two dimensions, the dimensions of arousal and valence (Figure 2). For example, high arousal positive states refer to excitement, elation, and enthusiasm. Low arousal positive states refer to calm, peacefulness, and relaxation. Whereas “actual affect” refers to the states that people actually feel, “ideal affect” refers to the states that people ideally want to feel.
Afferent nerves: Nerves that carry messages to the brain or spinal cord.
A-fibers: Fast-conducting sensory nerves with myelinated axons. Larger diameter and thicker myelin sheaths increases conduction speed. Aβ-fibers conduct touch signals from low-threshold mechanoreceptors with a velocity of 80 m/s and a diameter of 10 μm; Aδ-fibers have a diameter of 2.5 μm and conduct cold, noxious, and thermal signals at 12 m/s. The third and fastest conducting A-fiber is the Aα, which conducts proprioceptive information with a velocity of 120 m/s and a diameter of 20 μm.
Aggression: A form of social interaction that includes threat, attack, and fighting.
Agnosias: Due to damage of Wernicke’s area. An inability to recognize objects, words, or faces.
Agonists: A drug that increases or enhances a neurotransmitter’s effect.
Agoraphobia: A sort of anxiety disorder distinguished by feelings that a place is uncomfortable or may be unsafe because it is significantly open or crowded.
Allodynia: Pain due to a stimulus that does not normally provoke pain, e.g., when a light, stroking touch feels painful.
Alogia: A reduction in the amount of speech and/or increased pausing before the initiation of speech.
Amygdala: A region located deep within the brain in the medial area (toward the center) of the temporal lobes (parallel to the ears). If you could draw a line through your eye sloping toward the back of your head and another line between your two ears, the amygdala would be located at the intersection of these lines. The amygdala is involved in detecting relevant stimuli in our environment and has been implicated in emotional responses.
Amygdala: Two almond-shaped structures located in the medial temporal lobes of the brain.
Analgesia: Pain relief.
Anhedonia: Loss of interest or pleasure in activities one previously found enjoyable or rewarding.
Anhedonia/amotivation: A reduction in the drive or ability to take the steps or engage in actions necessary to obtain the potentially positive outcome.
Antagonist: A drug that blocks a neurotransmitter’s effect.
Anxiety: A mood state characterized by negative affect, muscle tension, and physical arousal in which a person apprehensively anticipates future danger or misfortune.
Aphasia: 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.
Aromatase: An enzyme that converts androgens into estrogens.
Attributional style: The tendency by which a person infers the cause or meaning of behaviors or events.
Automatic process: When a thought, feeling, or behavior occurs with little or no mental effort. Typically, automatic processes are described as involuntary or spontaneous, often resulting from a great deal of practice or repetition.
Automatic thoughts: Thoughts that occur spontaneously; often used to describe problematic thoughts that maintain mental disorders.
Autonomic nervous system: A part of the peripheral nervous system that connects to glands and smooth muscles. Consists of sympathetic and parasympathetic divisions.
Awareness: A conscious experience or the capability of having conscious experiences, which is distinct from self-awareness, the conscious understanding of one’s own existence and individuality.
Axial plane: See “horizontal plane.”
Axon: 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.
Binocular advantage: Benefits from having two eyes as opposed to a single eye.
Biological vulnerability: A specific genetic and neurobiological factor that might predispose someone to develop anxiety disorders.
Blood-oxygen-level-dependent (BOLD): The signal typically measured in fMRI that results from changes in the ratio of oxygenated hemoglobin to deoxygenated hemoglobin in the blood.
Bouncing balls illusion: The tendency to perceive two circles as bouncing off each other if the moment of their contact is accompanied by an auditory stimulus.
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.
Callosotomy: Surgical procedure in which the corpus callosum is severed (used to control severe epilepsy).
Cartesian catastrophe: The idea that mental processes taking place outside conscious awareness are impossible.
Case study: A thorough study of a patient (or a few patients) with naturally occurring lesions.
Catatonia: Behaviors that seem to reflect a reduction in responsiveness to the external environment. This can include holding unusual postures for long periods of time, failing to respond to verbal or motor prompts from another person, or excessive and seemingly purposeless motor activity.
Cell membrane: A bi-lipid layer of molecules that separates the cell from the surrounding extracellular fluid.
Central nervous system: The part of the nervous system that consists of the brain and spinal cord.
Central sulcus: The major fissure that divides the frontal and the parietal lobes.
Cerebellum: A nervous system structure behind and below the cerebrum. Controls motor movement coordination, balance, equilibrium, and muscle tone.
Cerebellum: The distinctive structure at the back of the brain, Latin for “small brain.”
Cerebral cortex: The outermost gray matter of the cerebrum; the distinctive convoluti characteristic of the mammalian brain.
Cerebral hemispheres: The cerebral cortex, underlying white matter, and subcortical structures.
Cerebrum: Consists of left and right hemispheres that sit at the top of the nervous system and engages in a variety of higher-order functions.
Cerebrum: Usually refers to the cerebral cortex and associated white matter, but in some texts includes the subcortical structures.
C-fibers: C-fibers: Slow-conducting unmyelinated thin sensory afferents with a diameter of 1 μm and a conduction velocity of approximately 1 m/s. C-pain fibers convey noxious, thermal, and heat signals; C-tactile fibers convey gentle touch, light stroking.
Chromosomal sex: The sex of an individual as determined by the sex chromosomes (typically XX or XY) received at the time of fertilization.
Chronic pain: Persistent or recurrent pain, beyond usual course of acute illness or injury; sometimes present without observable tissue damage or clear cause.
Chronic stress: Discrete or related problematic events and conditions which persist over time and result in prolonged activation of the biological and/or psychological stress response (e.g., unemployment, ongoing health difficulties, marital discord).
Cingulate gyrus: A medial cortical portion of the nervous tissue that is a part of the limbic system.
Cochlea: Snail-shell-shaped organ that transduces mechanical vibrations into neural signals.
Cognitive bias modification: Using exercises (e.g., computer games) to change problematic thinking habits.
Cognitive-behavioral therapy (CBT): A family of approaches with the goal of changing the thoughts and behaviors that influence psychopathology.
Comorbidity: Describes a state of having more than one psychological or physical disorder at a given time.
Computerized axial tomography: A noninvasive brain-scanning procedure that uses X-ray absorption around the head.
Conditioned aversions and preferences: Likes and dislikes developed through associations with pleasurable or unpleasurable sensations.
Conditioned response: A learned reaction following classical conditioning, or the process by which an event that automatically elicits a response is repeatedly paired with another neutral stimulus (conditioned stimulus), resulting in the ability of the neutral stimulus to elicit the same response on its own.
Cones: Photoreceptors that operate in lighted environments and can encode fine visual details. There are three different kinds (S or blue, M or green and L or red) that are each sensitive to slightly different types of light. Combined, these three types of cones allow you to have color vision.
Conscious: Having knowledge of something external or internal to oneself; being aware of and responding to one’s surroundings.
Conscious experience: The first-person perspective of a mental event, such as feeling some sensory input, a memory, an idea, an emotion, a mood, or a continuous temporal sequence of happenings.
Contemplative science: A research area concerned with understanding how contemplative practices such as meditation can affect individuals, including changes in their behavior, their emotional reactivity, their cognitive abilities, and their brains. Contemplative science also seeks insights into conscious experience that can be gained from first-person observations by individuals who have gained extraordinary expertise in introspection.
Contralateral: 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).
Contrast: Relative difference in the amount and type of light coming from two nearby locations.
Contrast gain: Process where the sensitivity of your visual system can be tuned to be most sensitive to the levels of contrast that are most prevalent in the environment.
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.
Cortisol: A hormone made by the adrenal glands, within the cortex. Cortisol helps the body maintain blood pressure and immune function. Cortisol increases when the body is under stress.
C-pain or Aδ-fibers: C-pain fibers convey noxious, thermal, and heat signals
Crossmodal phenomena: Effects that concern the influence of the perception of one sensory modality on the perception of another.
Crossmodal receptive field: A receptive field that can be stimulated by a stimulus from more than one sensory modality.
Crossmodal stimulus: A stimulus with components in multiple sensory modalties that interact with each other.
C-tactile fibers: C-tactile fibers convey gentle touch, light stroking
Culture: Shared, socially transmitted ideas (e.g., values, beliefs, attitudes) that are reflected in and reinforced by institutions, products, and rituals.
Cutaneous senses: The senses of the skin: tactile, thermal, pruritic (itchy), painful, and pleasant.
Dark adaptation: Process that allows you to become sensitive to very small levels of light, so that you can actually see in the near-absence of light.
Defeminization: The removal of the potential for female traits.
Delusions: False beliefs that are often fixed, hard to change even in the presence of conflicting information, and often culturally influenced in their content.
Demasculinization: The removal of the potential for male traits.
Dendrite: Part of a neuron that extends away from the cell body and is the main input to the neuron.
Deoxygenated hemoglobin: Hemoglobin not carrying oxygen.
Depolarization: A change in a cell’s membrane potential, making the inside of the cell more positive and increasing the chance of an action potential.
Descending pain modulatory system: A top-down pain-modulating system able to inhibit or facilitate pain. The pathway produces analgesia by the release of endogenous opioids. Several brain structures and nuclei are part of this circuit, such as the frontal lobe areas of the anterior cingulate cortex, orbitofrontal cortex, and insular cortex; and nuclei in the amygdala and the hypothalamus, which all project to a structure in the midbrain called the periaqueductal grey (PAG). The PAG then controls ascending pain transmission from the afferent pain system indirectly through the rostral ventromedial medulla (RVM) in the brainstem, which uses ON- and OFF-cells to inhibit or facilitate nociceptive signals at the spinal dorsal horn.
Diagnostic criteria: The specific criteria used to determine whether an individual has a specific type of psychiatric disorder. Commonly used diagnostic criteria are included in the Diagnostic and Statistical Manual of Mental Disorder, 5th Edition (DSM-5) and the Internal Classification of Disorders, Version 9 (ICD-9).
Dialectical behavior therapy (DBT): A treatment often used for borderline personality disorder that incorporates both cognitive-behavioral and mindfulness elements.
Dialectical worldview: A perspective in DBT that emphasizes the joint importance of change and acceptance.
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.
Diffusion: 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.
Disorganized behavior: Behavior or dress that is outside the norm for almost all subcultures. This would include odd dress, odd makeup (e.g., lipstick outlining a mouth for 1 inch), or unusual rituals (e.g., repetitive hand gestures).
Disorganized speech: Speech that is difficult to follow, either because answers do not clearly follow questions or because one sentence does not logically follow from another.
Distractor task: A task that is designed to make a person think about something unrelated to an impending decision.
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.
Dopamine: A neurotransmitter in the brain that is thought to play an important role in regulating the function of other neurotransmitters.
Double flash illusion: The false perception of two visual flashes when a single flash is accompanied by two auditory beeps.
Early adversity: Single or multiple acute or chronic stressful events, which may be biological or psychological in nature (e.g., poverty, abuse, childhood illness or injury), occurring during childhood and resulting in a biological and/or psychological stress response.
Ectoderm: The outermost layer of a developing fetus.
EEG: (Electroencephalography) The recording of the brain’s electrical activity over a period of time by placing electrodes on the scalp.
Efferent nerves: Nerves that carry messages from the brain to glands and organs in the periphery.
Electroencephalogram: A measure of electrical activity generated by the brain’s neurons.
Electroencephalography: 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.
Emotions: Changes in subjective experience, physiological responding, and behavior in response to a meaningful event. Emotions tend to occur on the order of seconds (in contract to moods which may last for days).
Endocrine gland: A ductless gland from which hormones are released into the blood system in response to specific biological signals.
Endorphin: An endogenous morphine-like peptide that binds to the opioid receptors in the brain and body; synthesized in the body’s nervous system.
Enzyme: A protein produced by a living organism that allows or helps a chemical reaction to occur.
Enzyme induction: Process through which a drug can enhance the production of an enzyme.
Epigenetics: 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.
Epigenome: The genome-wide distribution of epigenetic marks.
Episodic memory: The ability to learn and retrieve new information or episodes in one’s life.
Estrogen: 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.
Eureka experience: When a creative product enters consciousness.
Event-related potentials: A physiological measure of large electrical change in the brain produced by sensory stimulation or motor responses.
Excitatory postsynaptic potentials: A depolarizing postsynaptic current that causes the membrane potential to become more positive and move towards the threshold of excitation.
Exposure therapy: A form of intervention in which the patient engages with a problematic (usually feared) situation without avoidance or escape.
External cues: Stimuli in the outside world that serve as triggers for anxiety or as reminders of past traumatic events.
Exteroception: The sense of the external world, of all stimulation originating from outside our own bodies.
Feelings: A general term used to describe a wide range of states that include emotions, moods, traits and that typically involve changes in subjective experience, physiological responding, and behavior in response to a meaningful event. Emotions typically occur on the order of seconds, whereas moods may last for days, and traits are tendencies to respond a certain way across various situations.
Feminization: The induction of female traits.
Fight or flight response: A biological reaction to alarming stressors that prepares the body to resist or escape a threat.
Fight or flight response: The physiological response that occurs in response to a perceived threat, preparing the body for actions needed to deal with the threat.
First-person perspective: Observations made by individuals about their own conscious experiences, also known as introspection or a subjective point of view. Phenomenology refers to the description and investigation of such observations.
Flashback: Sudden, intense re-experiencing of a previous event, usually trauma-related.
Flat affect: A reduction in the display of emotions through facial expressions, gestures, and speech intonation.
Forebrain: A part of the nervous system that contains the cerebral hemispheres, thalamus, and hypothalamus.
Fornix: (plural form, fornices) A nerve fiber tract that connects the hippocampus to mammillary bodies.
Free association: In psychodynamic therapy, a process in which the patient reports all thoughts that come to mind without censorship, and these thoughts are interpreted by the therapist.
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 capacity: The ability to engage in self-care (cook, clean, bathe), work, attend school, and/or engage in social relationships.
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: A measure of changes in the oxygenation of blood flow as areas in the brain become active.
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.
Functional neuroanatomy: Classifying how regions within the nervous system relate to psychology and behavior.
Gene: A specific deoxyribonucleic acid (DNA) sequence that codes for a specific polypeptide or protein or an observable inherited trait.
Generalized anxiety disorder (GAD): Excessive worry about everyday things that is at a level that is out of proportion to the specific causes of worry.
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.
Genotype: 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.
Grandiosity: Inflated self-esteem or an exaggerated sense of self-importance and self-worth (e.g., believing one has special powers or superior abilities).
Gray matter: The outer grayish regions of the brain comprised of the neurons’ cell bodies.
Gray matter: Composes the bark or the cortex of the cerebrum and consists of the cell bodies of the neurons (see also white matter).
Gustation: The action of tasting; the ability to taste.
Gyri: (plural) Folds between sulci in the cortex.
Gyrus: (plural form, gyri) A bulge that is raised between or among fissures of the convoluted brain.
Gyrus: A fold between sulci in the cortex.
Hallucinations: Perceptual experiences that occur even when there is no stimulus in the outside world generating the experiences. They can be auditory, visual, olfactory (smell), gustatory (taste), or somatic (touch).
Hemoglobin: The oxygen-carrying portion of a red blood cell.
Heritability coefficient: An easily misinterpreted statistical construct that purports to measure the role of genetics in the explanation of differences among individuals.
Hippocampus: (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.
Hormone: 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.
Hormones: Chemicals released by cells in the brain or body that affect cells in other parts of the brain or body.
Hyperpolarization: A change in a cell’s membrane potential, making the inside of the cell more negative and decreasing the chance of an action potential.
Hypersomnia: Excessive daytime sleepiness, including difficulty staying awake or napping, or prolonged sleep episodes.
Hypothalamic-pituitary-adrenal (HPA) axis: A system that involves the hypothalamus (within the brain), the pituitary gland (within the brain), and the adrenal glands (at the top of the kidneys). This system helps maintain homeostasis (keeping the body’s systems within normal ranges) by regulating digestion, immune function, mood, temperature, and energy use. Through this, the HPA regulates the body’s response to stress and injury.
Hypothalamus: A brain structure located below the thalamus and above the brain stem.
Hypothalamus: 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.
Immunocytochemistry: A method of staining tissue including the brain, using antibodies.
Independent self: A model or view of the self as distinct from others and as stable across different situations. The goal of the independent self is to express and assert the self, and to influence others. This model of self is prevalent in many individualistic, Western contexts (e.g., the United States, Australia, Western Europe).
Ingroup: A social group to which an individual identifies or belongs.
Inhibitory postsynaptic potentials: A hyperpolarizing postsynaptic current that causes the membrane potential to become more negative and move away from the threshold of excitation.
Integrated: The process by which the perceptual system combines information arising from more than one modality.
Integrative or eclectic psychotherapy: Also called integrative psychotherapy, this term refers to approaches combining multiple orientations (e.g., CBT with psychoanalytic elements).
Integrative or eclectic psychotherapy: Also called integrative psychotherapy, this term refers to approaches combining multiple orientations (e.g., CBT with psychoanalytic elements).
Interaural differences: Differences (usually in time or intensity) between the two ears.
Interdependent self: A model or view of the self as connected to others and as changing in response to different situations. The goal of the interdependent self is to suppress personal preferences and desires, and to adjust to others. This model of self is prevalent in many collectivistic, East Asian contexts (e.g., China, Japan, Korea).
Internal bodily or somatic cues: Physical sensations that serve as triggers for anxiety or as reminders of past traumatic events.
Interoception: The sense of the physiological state of the body. Hunger, thirst, temperature, pain, and other sensations relevant to homeostasis. Visceral input such as heart rate, blood pressure, and digestive activity give rise to an experience of the body’s internal states and physiological reactions to external stimulation. This experience has been described as a representation of “the material me,” and it is hypothesized to be the foundation of subjective feelings, emotion, and self-awareness.
Interoceptive avoidance: Avoidance of situations or activities that produce sensations of physical arousal similar to those occurring during a panic attack or intense fear response.
Invasive Procedure: A procedure that involves the skin being broken or an instrument or chemical being introduced into a body cavity.
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 inhibition: A signal produced by a neuron aimed at suppressing the response of nearby neurons.
Lateral sulcus: The major fissure that delineates the temporal lobe below the frontal and the parietal lobes.
Lateralized: 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).
Lesion: 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.
Lesions: Damage or tissue abnormality due, for example, to an injury, surgery, or a vascular problem.
Lesions: Abnormalities in the tissue of an organism usually caused by disease or trauma.
Limbic system: Includes the subcortical structures of the amygdala and hippocampal formation as well as some cortical structures; responsible for aversion and gratification.
Limbic system: A loosely defined network of nuclei in the brain involved with learning and emotion.
Magnetic resonance imaging: A set of techniques that uses strong magnets to measure either the structure of the brain (e.g., gray matter and white matter) or how the brain functions when a person performs cognitive tasks (e.g., working memory or episodic memory) or other types of tasks.
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).
Masculinization: The induction of male traits.
Maternal behavior: Parental behavior performed by the mother or other female.
McGurk effect: An effect in which conflicting visual and auditory components of a speech stimulus result in an illusory percept.
Medial prefrontal cortex: An area of the brain located in the middle of the frontal lobes (at the front of the head), active when people mentalize about the self and others.
Medulla oblongata: An area just above the spinal cord that processes breathing, digestion, heart and blood vessel function, swallowing, and sneezing.
Mentalizing: The act of representing the mental states of oneself and others. Mentalizing allows humans to interpret the intentions, beliefs, and emotional states of others.
Mere-exposure effects: The result of developing a more positive attitude towards a stimulus after repeated instances of mere exposure to it.
Metabolism: Breakdown of substances.
Metabolite: A substance necessary for a living organism to maintain life.
Mindfulness: A process that reflects a nonjudgmental, yet attentive, mental state.
Mindfulness-based therapy: A form of psychotherapy grounded in mindfulness theory and practice, often involving meditation, yoga, body scan, and other features of mindfulness exercises.
Motor cortex: Region of the frontal lobe responsible for voluntary movement; the motor cortex has a contralateral representation of the human body.
Multimodal: Of or pertaining to multiple sensory modalities.
Multimodal perception: The effects that concurrent stimulation in more than one sensory modality has on the perception of events and objects in the world.
Multimodal phenomena: Effects that concern the binding of inputs from multiple sensory modalities.
Multisensory convergence zones: Regions in the brain that receive input from multiple unimodal areas processing different sensory modalities.
Multisensory enhancement: See “superadditive effect of multisensory integration.”
Myelin: 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.
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.
Neural plasticity: The ability of synapses and neural pathways to change over time and adapt to changes in neural process, behavior, or environment.
Neuroblasts: Brain progenitor cells that asymmetrically divide into other neuroblasts or nerve cells.
Neurodevelopmental: Processes that influence how the brain develops either in utero or as the child is growing up.
Neuroendocrinology: The study of how the brain and hormones act in concert to coordinate the physiology of the body.
Neuroepithelium: The lining of the neural tube.
Neuroscience: The study of the nervous system.
Neuroscience methods: A research method that deals with the structure or function of the nervous system and brain.
Neurotransmitter: 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.
Neurotransmitter: A chemical substance produced by a neuron that is used for communication between neurons.
Neurotransmitters: Chemical substance released by the presynaptic terminal button that acts on the postsynaptic cell.
Nociception: The neural process of encoding noxious stimuli, the sensory input from nociceptors. Not necessarily painful, and crucially not necessary for the experience of pain.
Nociceptors: High-threshold sensory receptors of the peripheral somatosensory nervous system that are capable of transducing and encoding noxious stimuli. Nociceptors send information about actual or impending tissue damage to the brain. These signals can often lead to pain, but nociception and pain are not the same.
Nomenclature: Naming conventions.
Noninvasive procedure: A procedure that does not require the insertion of an instrument or chemical through the skin or into a body cavity.
Noxious stimulus: A stimulus that is damaging or threatens damage to normal tissues.
Nucleus: Collection of nerve cells found in the brain which typically serve a specific function.
Nucleus accumbens: A region of the basal forebrain located in front of the preoptic region.
Obsessive-compulsive disorder (OCD): A disorder characterized by the desire to engage in certain behaviors excessively or compulsively in hopes of reducing anxiety. Behaviors include things such as cleaning, repeatedly opening and closing doors, hoarding, and obsessing over certain thoughts.
Occipital lobe: The back part of the cerebrum, which houses the visual areas.
Occipital lobe: The back most (posterior) part of the cerebrum; involved in vision.
Ocial touch hypothesis: Proposes that social touch is a distinct domain of touch. C-tactile afferents form a special pathway that distinguishes social touch from other types of touch by selectively firing in response to touch of social-affective relevance; thus sending affective information parallel to the discriminatory information from the Aβ-fibers. In this way, the socially relevant touch stands out from the rest as having special positive emotional value and is processed further in affect-related brain areas such as the insula.
Olfaction: The sense of smell; the action of smelling; the ability to smell.
Omnivore: A person or animal that is able to survive by eating a wide range of foods from plant or animal origin.
Opponent Process Theory: Theory of color vision that assumes there are four different basic colors, organized into two pairs (red/green and blue/yellow) and proposes that colors in the world are encoded in terms of the opponency (or difference) between the colors in each pair. There is an additional black/white pair responsible for coding light contrast.
Orbital frontal cortex: A region of the frontal lobes of the brain above the eye sockets.
Orthonasal olfaction: Perceiving scents/smells introduced via the nostrils.
Outgroup: A social group to which an individual does not identify or belong.
Oxygenated hemoglobin: Hemoglobin carrying oxygen.
Oxytocin: A peptide hormone secreted by the pituitary gland to trigger lactation, as well as social bonding.
Pain: Defined as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage,” according to the International Association for the Study of Pain.
Panic disorder (PD): A condition marked by regular strong panic attacks, and which may include significant levels of worry about future attacks.
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.
Parasympathetic nervous system (PNS): One of the two major divisions of the autonomic nervous system, responsible for stimulation of “rest and digest” activities.
Parental behavior: Behaviors performed in relation to one’s offspring that contributes directly to the survival of those offspring
Parietal lobe: An area of the cerebrum just behind the central sulcus that is engaged with somatosensory and gustatory sensation.
Parietal lobe: The part of the cerebrum between the frontal and occipital lobes; involved in bodily sensations, visual attention, and integrating the senses.
Paternal behavior: Parental behavior performed by the father or other male.
Periaqueductal gray: The gray matter in the midbrain near the cerebral aqueduct.
Peripheral nervous system: The part of the nervous system that is outside the brain and spinal cord.
Person-centered therapy: A therapeutic approach focused on creating a supportive environment for self-discovery.
Phantom pain: Pain that appears to originate in an amputated limb.
Pharmacokinetics: The action of a drug through the body, including absorption, distribution, metabolism, and excretion.
Phenotype: 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.
Photoactivation: A photochemical reaction that occurs when light hits photoreceptors, producing a neural signal.
Phrenology: 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.
Pinna: Visible part of the outer ear.
Placebo effect: Effects from a treatment that are not caused by the physical properties of a treatment but by the meaning ascribed to it. These effects reflect the brain’s own activation of modulatory systems, which is triggered by positive expectation or desire for a successful treatment. Placebo analgesia is the most well-studied placebo effect and has been shown to depend, to a large degree, on opioid mechanisms. Placebo analgesia can be reversed by the pharmacological blocking of  opioid receptors. The word “placebo” is probably derived from the Latin word “placebit” (“it will please”).
Polypharmacy: The use of many medications.
Pons: 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: A particle having the same mass and numerically equal but positive charge as an electron.
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: A technique that uses radio-labelled ligands to measure the distribution of different neurotransmitter receptors in the brain or to measure how much of a certain type of neurotransmitter is released when a person is given a specific type of drug or does a particularly cognitive task.
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.
Posttraumatic stress disorder (PTSD): A sense of intense fear, triggered by memories of a past traumatic event, that another traumatic event might occur. PTSD may include feelings of isolation and emotional numbing.
Preoptic region: A part of the anterior hypothalamus.
Primary auditory cortex: A region of the cortex devoted to the processing of simple auditory information.
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.
Primary visual cortex: A region of the cortex devoted to the processing of simple visual information.
Primary visual cortex (V1): Brain region located in the occipital cortex (toward the back of the head) responsible for processing basic visual information like the detection, thickness, and orientation of simple lines, color, and small-scale motion.
Principle of Inverse Effectiveness: The finding that, in general, for a multimodal stimulus, if the response to each unimodal component (on its own) is weak, then the opportunity for multisensory enhancement is very large. However, if one component—by itself—is sufficient to evoke a strong response, then the effect on the response gained by simultaneously processing the other components of the stimulus will be relatively small.
Processing speed: The speed with which an individual can perceive auditory or visual information and respond to it.
Progesterone: A primary progestin that is involved in pregnancy and mating behaviors.
Progestin: A class of C21 steroid hormones named for their progestational (pregnancy-supporting) effects. Progesterone is a common progestin.
Prohormone: 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.
Prolactin: 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.
Psychoactive drugs: A drug that changes mood or the way someone feels.
Psychoanalytic therapy: Sigmund Freud’s therapeutic approach focusing on resolving unconscious conflicts.
Psychodynamic therapy: Treatment applying psychoanalytic principles in a briefer, more individualized format.
Psychological vulnerabilities: Influences that our early experiences have on how we view the world.
Psychomotor agitation: Increased motor activity associated with restlessness, including physical actions (e.g., fidgeting, pacing, feet tapping, handwringing).
Psychomotor retardation: A slowing of physical activities in which routine activities (e.g., eating, brushing teeth) are performed in an unusually slow manner.
Psychopathology: Illnesses or disorders that involve psychological or psychiatric symptoms.
Psychophysiological methods: Any research method in which the dependent variable is a physiological measure and the independent variable is behavioral or mental (such as memory).
Psychotropic drug: A drug that changes mood or emotion, usually used when talking about drugs prescribed for various mental conditions (depression, anxiety, schizophrenia, etc.).
Quantitative genetics: Scientific and mathematical methods for inferring genetic and environmental processes based on the degree of genetic and environmental similarity among organisms.
Reappraisal, or Cognitive restructuring: The process of identifying, evaluating, and changing maladaptive thoughts in psychotherapy.
Receptive field: The portion of the world to which a neuron will respond if an appropriate stimulus is present there.
Receptor: 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.
Reinforced response: Following the process of operant conditioning, the strengthening of a response following either the delivery of a desired consequence (positive reinforcement) or escape from an aversive consequence.
Resting membrane potential: The voltage inside the cell relative to the voltage outside the cell while the cell is a rest (approximately -70 mV).
Retronasal olfaction: Perceiving scents/smells introduced via the mouth/palate.
Rods: Photoreceptors that are very sensitive to light and are mostly responsible for night vision.
Rostrocaudal: A front-back plane used to identify anatomical structures in the body and the brain.
Rubber hand illusion: The false perception of a fake hand as belonging to a perceiver, due to multimodal sensory information.
SAD performance only: Social anxiety disorder which is limited to certain situations that the sufferer perceives as requiring some type of performance.
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.
Schema: A mental representation or set of beliefs about something.
Sensitization: Increased responsiveness of nociceptive neurons to their normal input and/or recruitment of a response to normally subthreshold inputs. Clinically, sensitization may only be inferred indirectly from phenomena such as hyperalgesia or allodynia. Sensitization can occur in the central nervous system (central sensitization) or in the periphery (peripheral sensitization).
Sensory modalities: A type of sense; for example, vision or audition.
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.
Simulation: Imaginary or real imitation of other people’s behavior or feelings.
Social anxiety disorder (SAD): A condition marked by acute fear of social situations which lead to worry and diminished day to day functioning.
Social categorization: The act of mentally classifying someone into a social group (e.g., as female, elderly, a librarian).
Social constructivism: Social constructivism proposes that knowledge is first created and learned within a social context and is then adopted by individuals.
Social support: A subjective feeling of psychological or physical comfort provided by family, friends, and others.
Social touch hypothesis: Proposes that social touch is a distinct domain of touch. C-tactile afferents form a special pathway that distinguishes social touch from other types of touch by selectively firing in response to touch of social-affective relevance; thus sending affective information parallel to the discriminatory information from the Aβ-fibers. In this way, the socially relevant touch stands out from the rest as having special positive emotional value and is processed further in affect-related brain areas such as the insula.
Social zeitgeber: Zeitgeber is German for “time giver.” Social zeitgebers are environmental cues, such as meal times and interactions with other people, that entrain biological rhythms and thus sleep-wake cycle regularity.
Socioeconomic status (SES): A person’s economic and social position based on income, education, and occupation.
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.
Soma: 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.
Somatosensory cortex: Consists of primary sensory cortex (S1) in the postcentral gyrus in the parietal lobes and secondary somatosensory cortex (S2), which is defined functionally and found in the upper bank of the lateral sulcus, called the parietal operculum. Somatosensory cortex also includes parts of the insular cortex.
Somatotopically organized: When the parts of the body that are represented in a particular brain region are organized topographically according to their physical location in the body (see Figure 2 illustration).
Spatial principle of multisensory integration: The finding that the superadditive effects of multisensory integration are observed when the sources of stimulation are spatially related to one another.
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.
Spatial resolution: The degree to which one can separate a single object in space from another.
Specific vulnerabilities: How our experiences lead us to focus and channel our anxiety.
Spina bifida: A developmental disease of the spinal cord, where the neural tube does not close caudally.
Spines: Protrusions on the dendrite of a neuron that form synapses with terminal buttons of the presynaptic axon.
Spinothalamic tract: Runs through the spinal cord’s lateral column up to the thalamus. C-fibers enter the dorsal horn of the spinal cord and form a synapse with a neuron that then crosses over to the lateral column and becomes part of the spinothalamic tract.
Split-brain patient: A patient who has had most or all of his or her corpus callosum severed.
Stereotypes: The beliefs or attributes we associate with a specific social group. Stereotyping refers to the act of assuming that because someone is a member of a particular group, he or she possesses the group’s attributes. For example, stereotyping occurs when we assume someone is unemotional just because he is man, or particularly athletic just because she is African American.
Stress: A threat or challenge to our well-being. Stress can have both a psychological component, which consists of our subjective thoughts and feelings about being threatened or challenged, as well as a physiological component, which consists of our body’s response to the threat or challenge (see “fight or flight response”).
Stria terminalis: A band of fibers that runs along the top surface of the thalamus.
Subcortical: Structures that lie beneath the cerebral cortex, but above the brain stem.
Suicidal ideation: Recurring thoughts about suicide, including considering or planning for suicide, or preoccupation with suicide.
Sulci: (plural) Grooves separating folds of the cortex.
Sulcus: A groove separating folds of the cortex.
Sulcus: (plural form, sulci) The crevices or fissures formed by convolutions in the brain.
Superadditive effect of multisensory integration: The finding that responses to multimodal stimuli are typically greater than the sum of the independent responses to each unimodal component if it were presented on its own.
Superior temporal sulcus: The sulcus (a fissure in the surface of the brain) that separates the superior temporal gyrus from the middle temporal gyrus. Located in the temporal lobes (parallel to the ears), it is involved in perception of biological motion or the movement of animate objects.
Sympathetic nervous system: A branch of the autonomic nervous system that controls many of the body’s internal organs. Activity of the SNS generally mobilizes the body’s fight or flight response.
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.
Sympathetic nervous system (SNS): One of the two major divisions of the autonomic nervous system, responsible for stimulation of “fight or flight” activities.
Synapse: The tiny space separating neurons.
Synapse: 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.
Synesthesia: The blending of two or more sensory experiences, or the automatic activation of a secondary (indirect) sensory experience due to certain aspects of the primary (direct) sensory stimulation.
Target cell: A cell that has receptors for a specific chemical messenger (hormone or neurotransmitter).
Temporal lobe: An area of the cerebrum that lies below the lateral sulcus; it contains auditory and olfactory (smell) projection regions.
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 parietal junction: The area where the temporal lobes (parallel to the ears) and parieta lobes (at the top of the head toward the back) meet. This area is important in mentalizing and distinguishing between the self and others.
Temporal resolution: The degree to which one can separate a single point in time from another.
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.
Testosterone: The primary androgen secreted by the testes of most vertebrate animals, including men.
Thalamus: A structure in the midline of the brain located between the midbrain and the cerebral cortex.
Thalamus: A part of the diencephalon that works as a gateway for incoming and outgoing information.
Third-person perspective: Observations made by individuals in a way that can be independently confirmed by other individuals so as to lead to general, objective understanding. With respect to consciousness, third-person perspectives make use of behavioral and neural measures related to conscious experiences.
Thought-action fusion: The tendency to overestimate the relationship between a thought and an action, such that one mistakenly believes a “bad” thought is the equivalent of a “bad” action.
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.
Transduction: The mechanisms that convert stimuli into electrical signals that can be transmitted and processed by the nervous system. Physical or chemical stimulation creates action potentials in a receptor cell in the peripheral nervous system, which is then conducted along the axon to the central nervous system.
Transduction: A process in which physical energy converts into neural energy.
Transverse plane: See “horizontal plane.”
Trichromacy theory: Theory that proposes that all of your color perception is fundamentally based on the combination of three (not two, not four) different color signals.
Twin studies: A behavior genetic research method that involves comparison of the similarity of identical (monozygotic; MZ) and fraternal (dizygotic; DZ) twins.
Tympanic membrane: Ear drum, which separates the outer ear from the middle ear.
Unconditional positive regard: In person-centered therapy, an attitude of warmth, empathy and acceptance adopted by the therapist in order to foster feelings of inherent worth in the patient.
Unconscious: Not conscious; the part of the mind that affects behavior though it is inaccessible to the conscious mind.
Unimodal: Of or pertaining to a single sensory modality.
Unimodal components: The parts of a stimulus relevant to one sensory modality at a time.
Unimodal cortex: A region of the brain devoted to the processing of information from a single sensory modality.
Universalism: Universalism proposes that there are single objective standards, independent of culture, in basic domains such as learning, reasoning, and emotion that are a part of all human experience.
Vestibulo-ocular reflex: Coordination of motion information with visual information that allows you to maintain your gaze on an object while you move.
Visual cortex: The part of the brain that processes visual information, located in the back of the brain.
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.
Voltage: The difference in electric charge between two points.
Wernicke’s area: A language area in the temporal lobe where linguistic information is comprehended (Also see Broca’s area).
What pathway: Pathway of neural processing in the brain that is responsible for your ability to recognize what is around you.
Where-and-How pathway: Pathway of neural processing in the brain that is responsible for you knowing where things are in the world and how to interact with them.
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.
White matter: The inner whitish regions of the cerebrum comprised of the myelinated axons of neurons in the cerebral cortex.
Working memory: The ability to maintain information over a short period of time, such as 30 seconds or less.
Working memory: Short transitory memory processed in the hippocampus.