GLOSSARY: Neuroethology Terms

A | B | C | D | E | F | G | H | I | K | L | M | N | O | P | R | S | T | V | W

A

Term Definition
Acetylcholine

​A neurotransmitter in both the brain, where it may help regulate memory, and in the peripheral nervous system, where it controls the actions of skeletal and smooth muscle.

Action Potential

This occurs when a neuron is activated and temporarily reverses the electrical state of its interior membrane from negative to positive. This electrical charge travels along the axon to the neuron’s terminal where it triggers or inhibits the release of a neurotransmitter and then disappears.

Adrenal Cortex

​An endocrine organ that secretes corticosteroids for metabolic functions: aldosterone for sodium retention in the kidneys, androgens for male sexual development, and estrogens for female sexual development.

Adrenal Medulla

An endocrine organ that secretes epinephrine and norepinephrine for the activation of the sympathetic nervous system​

Affective Psychosis

​A psychiatric disease relating to mood states. It is generally characterized by depression unrelated to events in the life of the patient, which alternates with periods of normal mood or with periods of excessive, inappropriate euphoria and mania.

Agonist

A neurotransmitter, a drug or other molecule that stimulates receptors to produce a desired reaction​

Amino Acid Transmitters

The most prevalent neurotransmitters in the brain, these include glutamate and aspartate, which have excitatory actions, and glycine and gamma-amino butyric acid (GABA) which have inhibitory actions​

Amnesia

“Inability to remember events or experiences. Memory loss. includes: 1) Anterograde amnesia: inability to retain the memory of events occurring after the time of the injury or disease which brought about the amnesic state. 2) Retrograde amnesia: inability to recall the memory of events which occurred prior to the time of the injury or disease which brought about the amnesic state.” [ref]

Amygdala

1. An almond-shaped structure in the forebrain that is an important component of the limbic system; involved in producing and responding to nonverbal signs of anger, avoidance, defensiveness, and fear. 2. A small mass of gray matter that inspires aversive cues, such as the freeze reaction, sweaty palms, and the tense-mouth display. 3.A primeval arousal center, originating in early fishes, which is central to the expression of negative emotions in man.

Androgens

Sex steroid hormones, including testosterone, found in higher levels in males than females. They are responsible for male sexual maturation.​

Anosognosia

Impaired awareness or denial of one’s disorder. A significant problem in several kinds of strokes and in neuropsychiatric disorders such as schizophrenia and bipolar disorder. It is strikingly manifest when a person with a paralysed limb claims it is still functioning. [One of Professor Ramachandran’s patients, who had suffered a stroke which had paralysed the left side of her body, refused to accept that her arm couldn’t move. Even though lucid in every other aspect (including awareness of the fact that she had suffered a stroke) she claimed her left arm was carrying out tasks even though clearly it wasn’t. An explanation may involve close analysis of the different roles of the left and right hemispheres of the brain.]

Antagonist

A drug or other molecule that blocks receptors. Antagonists inhibit the effects of agonists​

Aphasia

Disturbance in language comprehension or production, often as a result of a stroke​

Auditory Nerve

A bundle of nerve fibers extending from the cochlea of the ear to the brain, which contains two branches: the cochlear nerve that transmits sound information and the vestibular nerve that relays information related to balance​

Autonomic Nervous System

A part of the peripheral nervous system responsible for regulating the activity of internal organs. It includes the sympathetic and parasympathetic nervous systems​

Axon

The fiber-like extension of a neuron by which the cell sends information to target cells​

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B

Term Definition
Basal Ganglia

 Clusters of neurons, which include the caudate nucleus, putamen, globus pallidus and substantia nigra, that are located deep in the brain and play an important role in movement. Cell death in the substantia nigra contributes to Parkinsonian signs.  Interacts with cognition in selecting and organizing motor programs

Blindsight

Some patients who are effectively blind because of brain damage can carry out tasks which appear to be impossible unless they can see the objects. For instance they can reach out and grasp an object, accurately describe whether a stick is vertical or horizontal, or post a letter through a narrow slot . The explanation appears to be that visual information travels along two pathways in the brain. If only one is damaged, a patient may lose the ability to see an object but still be aware of its location and orientation​

Blindspot

Blindspots can be produced by a variety of factors. In fact everyone has a small blindspot in each eye caused by the area of the retina which connects to the optic nerve. These blindspots are often filled in by the brain using information based on the surrounding visual image. In some cases, patients report seeing unrelated images in their blindspots. One reported seeing cartoon characters. This phenomenon may involve other pathways in the brain

Brainstem

The major route by which the forebrain sends information to and receives information from the spinal cord and peripheral nerves. It controls, among other things, respiration and regulation of heart rhythms​

Broca’s Area

The brain region located in the frontal lobe of the left hemisphere that is important for the production of speech​

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C

Term Definition
Capgras’ delusion

A rare syndrome in which the patient is convinced that close relatives usually parents, spouse, children or siblings are impostors. It may be caused by damage to the connections between the areas of the brain dealing with face recognition and emotional response. A sufferer might recognise the faces of his loved ones but not feel the emotional reaction normally associated with the experience​

Catecholamines

The neurotransmitters dopamine, epinephrine and norepinephrine that are active both in the brain and the peripheral sympathetic nervous system. These three molecules have certain structural similarities and are part of a larger class of neurotransmitters known as monoamines​

Cerebral Cortex

The outermost layer of the cerebral hemispheres of the brain. It is responsible for all forms of conscious experience, including perception, emotion, thought and planning​

Cerebral Hemispheres

The two specialized halves of the brain. The left hemisphere is specialized for speech, writing, language and calculation; the right hemisphere is specialized for spatial abilities, face recognition in vision and some aspects of music perception and production​

Cerebrospinal Fluid

A liquid found within the ventricles of the brain and the central canal of the spinal cord​

Cholecystokinin

A hormone released from the lining of the stomach during the early stages of digestion which acts as a powerful suppressant of normal eating. It also is found in the brain​

Circadian Rhythm

A cycle of behavior or physiological change lasting approximately 24 hours​

Classical Conditioning

Learning in which a stimulus that naturally produces a specific response (unconditioned stimulus) is repeatedly paired with a neutral stimulus (conditioned stimulus). As a result, the conditioned stimulus can become able to evoke a response similar to that of the unconditioned stimulus​

Cochlea

A snail-shaped, fluid-filled organ of the inner ear responsible for transducing motion into neurotransmission to produce an auditory sensation​

Cognition

The process or processes by which an organism gains knowledge of or becomes aware of events or objects in its environment and uses that knowledge for comprehension and problem-solving.

Cone

A primary receptor cell for vision located in the retina. It is sensitive to color and used primarily for daytime vision​

Confabulate

to fabricate a narrative or experience; to “invent memories which are then taken as true” by the inventor; to form “false memories, perceptions, or beliefs about the self or the environment as a result of neurological or psychological dysfunction.[ref]” including a deficiency of viatmine B1 (thiamine) as a result of alcoholism [ref]. Associated with specific brain disfunctions (Korsakoff’s Syndrome, neuroal trauma-induced anosognosia…); recently covered in The Confabulating Mind: How the Brain Creates Reality By Armin Schnider,Oxford University Press: 2008

Conservative

when referring to the an organism’s traits, more ancient in an evolutionary sense. Traits are presumed to be maintained in descendents because of their service in meeting fundamental needs. In this sense, the more ancient a trait, the more fundamental the need it serves; this does not preclude the “retasking” of a trait to meet more “recent” needs

Cornea

A thin, curved transparent membrane on the surface of the front of the eye. It begins the focusing process for vision​

Corpus Callosum

The large bundle of nerve fibers linking the left and right cerebral hemispheres​

Cortisol

​A hormone manufactured by the adrenal cortex. In humans, it is secreted in greatest quantities before dawn, readying the body for the activities of the coming day

Cotard’s syndrome

A disorder in which a patient asserts that he is dead, claiming to smell rotting flesh or worms crawling over his skin. It may be an exaggerated form of Capgras’ delusion, in which not just one sensory area (ie face recognition) but all of them are cut off from the limbic system. This would lead to a complete lack of emotional contact with the world​

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D

Term Definition
Dendrite

A tree–like extension of the neuron cell body. Along with the cell body, it receives information from other neurons​

Dopamine

A catecholamine neurotransmitter known to have multiple functions depending on where it acts. Dopamine-containing neurons in the substantia nigra of the brainstem project to the caudate nucleus and are destroyed in Parkinson’s victims. Dopamine is thought to regulate emotional responses, and play a role in schizophrenia and cocaine abuse​

Dorsal Horn

​An area of the spinal cord where many nerve fibers from peripheral pain receptors meet other ascending nerve fibers

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E

Term Definition
Endocrine Organ

An organ that secretes a hormone directly into the bloodstream to regulate cellular activity of certain other organs​

Endorphins

Neurotransmitters produced in the brain that generate cellular and behavioral effects like those of morphine​

Epinephrine (Epi)

​A hormone, released by terminal neurons of the sympathetic nervous system, incluiding the adrenal medulla, and the brain. Epi acts with norepinephrine when there is activation of the sympathetic division of the autonomic nervous system. It has significant behavioral as well as as physiological consequences. Important in acute stress. Produced when the norepinephrine molecule is slightly altered (by methylation), a process that is accelerated by the presence of glucocorticoid such as corticosterone. Sometimes called adrenaline. The ratio of epinephrine and norepinephrine may affect the precise action pattern selected

Estrogens

​A group of sex hormones found more abundantly in females than males. They are responsible for female sexual maturation and other functions

Evoked Potentials

A measure of the brain’s electrical activity in response to sensory stimuli. This is obtained by placing electrodes on the surface of the scalp (or more rarely, inside the head), repeatedly administering a stimulus, and then using a computer to average the results​

Excitation

​A change in the electrical state of a neuron that is associated with an enhanced probability of action potentials

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F

Term Definition
Follicle-Stimulating Hormone

A hormone released by the pituitary gland. It stimulates the production of sperm in the male and growth of the follicle (which produces the egg) in the female​

Forebrain

The largest division of the brain, which includes the cerebral cortex and basal ganglia. It is credited with the highest intellectual functions​

Frontal Lobe

​One of the four divisions (parietal, temporal, occipital) of each hemisphere of the cerebral cortex. It has a role in controlling movement and associating the functions of other cortical areas.

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G

Term Definition
Gamma-Amino Butyric Acid (GABA)

An amino acid transmitter in the brain whose primary function is to inhibit the firing of neurons​

Glia

​Specialized cells that nourish and support neurons

Glutamate

An amino acid neurotransmitter that acts to excite neurons. Glutamate probably stimulates N-methyl-D-aspartate (NMDA) receptors that have been implicated in activities ranging from learning and memory to development and specification of nerve contacts in a developing animal. Stimulation of NMDA receptors may promote beneficial changes, while overstimulation may be the cause of nerve cell damage or death in neurological trauma and stroke​

Gonad

Primary sex gland: testis in the male and ovary in the female​

Growth Cone

​A distinctive structure at the growing end of most axons. It is the site where new material is added to the axon

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H

Term Definition
Hippocampus

​A seahorse-shaped structure located within the brain and considered an important part of the limbic system. It functions in learning, memory and emotion

Hormones

Chemical messengers secreted by endocrine glands to regulate the activity of target cells. They play a role in sexual development, calcium and bone metabolism, growth and many other activities

Hypothalamus

1. A subcortical group of nuclei in the forebrain which serves a. the limbic system, b. the autonomic nervous system, and c. the endocrine system. 2. A thumbnail-sized neuro structure which organizes basic nonverbal responses, such as aggression, anger, sexuality, and fear. [Nonverbal Dictionary] The many nuclei have various functions which include regulating the activities of internal organs, monitoring information from the autonomic nervous system and controlling specific endocrine functions of the pituitary gland.

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I

Term Definition
Immediate Memory

A phase of memory that is extremely short-lived, with information stored only for a few seconds. It also is known as short-term and working memory​

Inhibition

In reference to neurons, it is a synaptic message that prevents the recipient cell from firing​

Ions

Electrically charged atoms or molecules​

Iris

A circular diaphragm that contains the muscles which alter the amount of light that enters the eye by dilating or constricting the pupil. It has an opening in its center​

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K

Term Definition
Korsakoff’s Syndrome

A disease associated with chronic alcoholism, resulting from a deficiency of vitamin B-1. Patients sustain damage to part of the thalamus and cerebellum. Symptoms include inflammation of nerves, muttering delirium, insomnia, illusions and hallucinations and a lasting amnesia. ​

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L

Term Definition
Limbic System

1. Those interlinked modules and pathways of the brain in charge of emotions, feelings, and moods. 2. The “entire neuronal circuitry that controls emotional behavior and motivational drives” (Guyton 1996:752). 3. The emotional core of the human nervous system (Cytowic 1993). A group of brain structures – including the amygdala, hippocampus, septum and basal ganglia – that work to help regulate emotion, memory and certain aspects of movement

Long-Term Memory

The final phase of memory in which information storage may last from hours to a lifetime​

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M

Term Definition
Mania

A mental disorder characterized by excessive excitement. A form of psychosis with exalted feelings, delusions of grandeur, elevated mood, psychomotor overactivity and overproduction of ideas.

MAO

Monoamine Oxidase (see below)

Melatonin

Produced from serotonin, melatonin is released by the pineal gland into the bloodstream. It affects physiological changes related to time and lighting cycles​

Memory Consolidation

The physical and psychological changes that take place as the brain organizes and restructures information in order to make it a permanent part of memory​

Metabolism

The sum of all physical and chemical changes that take place within an organism and all energy transformations that occur within living cells​

Mitochondria

Small cylindrical particles inside cells that provide energy for the cell by converting sugar and oxygen into special energy molecules​

Monoamine Oxidase (MAO)

The brain and liver enzyme that normally breaks down the catecholamines norepinephrine, serotonin and dopamine. MAO inhibitors increase levels of those neurotransmitters at the synapse. MAOIs are antidepressants which can help treat atypical depression (vegitative symptoms, anxiety, initial insomnia, etc), panic disorder, anxiety and (recently discovered) borderline personality disorder​

Motor Neuron

A neuron that carries information from the central nervous system to the muscle​

Motor Neuron

Nerve cell. It is specialized for the transmission of information and characterized by long fibrous projections called axons, and shorter, branch-like projections called dendrites​

Myasthenia Gravis

​A disease in which acetylcholine receptors on the muscle cells are destroyed, so that muscles can no longer respond to the acetylcholine signal in order to contract. Symptoms include muscular weakness and progressively more common bouts of fatigue. Its cause is unknown but is more common in females than in males and usually strikes between the ages of 20 and 50

Myelin

Compact fatty material that surrounds and insulates axons of some neurons​

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N

Term Definition
Nerve Growth Factor

A substance whose role is to guide neuronal growth during embryonic development, especially in the peripheral nervous system​

Neurotransmitter

A chemical released by neurons at a synapse for the purpose of relaying information via receptors​

Nociceptors

In animals, nerve endings that signal the sensation of pain. In humans, they are called pain receptors​

Norepinephrine

A catecholamine neurotransmitter, produced both in the brain and in the peripheral nervous system (sympathetic branch of the autonomic system). It seems to be involved in arousal, reward and regulation of sleep and mood, and the regulation of blood pressure. Also released from the adrenal medulla, often in concert with epinephrine during acute stress episodes

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O

Term Definition
Organelles

​Small structures within a cell that maintain the cells and do the cells’ work

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P

Term Definition
Parasympathetic Nervous System

​A branch of the autonomic nervous system concerned with the conservation of the body’s energy and resources during relaxed states

Parietal Lobe

​One of the four subdivisions of the cerebral cortex. It plays a role in sensory processes, attention and language

Peptides

Chains of amino acids that can function as neurotransmitters or hormones​

Periaqueductal Gray Area

A cluster of neurons lying in the thalamus and pons. It contains endorphin-producing neurons and opiate receptor sites and thus can affect the sensation of pain​

Peripheral Nervous System

A division of the nervous system consisting of all nerves not part of the brain or spinal cord​

Phosphorylation

A process that modifies the properties of neurons by acting on an ion channel, neurotransmitter receptor or other regulatory molecule. During phosphorylation, a phosphate molecule is placed on another molecule resulting in the activation or inactivation of the receiving molecule. It may lead to a change in the functional activity of the receiving molecule. Phosphorylation is believed to be a necessary step in allowing some neurotransmitters to act and is often the result of second messenger activity​

Pineal Gland

An endocrine organ found in the brain. In some animals, it seems to serve as a light-influenced biological clock​

Pituitary Gland

An endocrine organ closely linked with the hypothalamus. In humans, it is composed of two lobes and secretes a number of hormones that regulate the activity of other endocrine organs in the body​

Pons

A part of the hindbrain that, with other brain structures, controls respiration and regulates heart rhythms. The pons is a major route by which the forebrain sends information to and receives information from the spinal cord and peripheral nervous system​

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R

Term Definition
Reafference

The component of sensory input an animal receives as a consequence of its own movements. (Thus, in the case of movement of the limbs, reafference is the proprioceptive or visual sensation that arises as a direct consequence of the motor act. (“process of relaying messages from limbic system via entorhinal cortex to sensory cortices, in parallel with limbic commands to motor systems, serving (1) to compensate in advance for changes in sensory input accompanying actions, and (2) to sustain states of expectancy and attention.” — from Freeman, Societies of Brains)

Receptor Cell

Specialized sensory cells designed to pick up and transmit sensory information​

Receptor Molecule

A specific molecule on the surface or inside of a cell with a characteristic chemical and physical structure. Many neurotransmitters and hormones exert their effects by binding to receptors on cells​

Reticular System

area in brainstem that regulates arousal and activity in higher brain areas. Signals from various sources are filtered. Much information goes to (or through) the thalamus to influence the cerebral cortex. Medial nuclei are the elements of the “ascending reticular system”

Reuptake

​A process by which released neurotransmitters are absorbed for subsequent re-use

Rod

A sensory neuron located in the periphery of the retina. It is sensitive to light of low intensity and specialized for nighttime vision​

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S

Term Definition
Second Messengers

Recently recognized substances that trigger communications between different parts of a neuron. These chemicals are thought to play a role in the manufacture and release of neurotransmitters, intracellular movements, carbohydrate metabolism and, possibly, even processes of growth and development. Their direct effects on the genetic material of cells may lead to long-term alterations of behavior, such as memory​

Sensitization

A change in behavior or biological response by an organism that is produced by delivering a strong, generally noxious, stimulus.

Serotonin

A monoamine neurotransmitter believed to play many roles including, but not limited to, temperature regulation, sensory perception and the onset of sleep. Neurons using serotonin as a transmitter are found in the brain and in the gut. A number of antidepressant drugs are targeted to brain serotonin systems​

Short-Term Memory

A phase of memory in which a limited amount of information may be held for several seconds to minutes​

Stimulus

​An environmental event capable of being detected by sensory receptors

Stroke

The third largest cause of death in America, stroke is an impeded blood supply to the brain. It can be caused by a blood clot forming in a blood vessel, a rupture of the blood vessel wall, an obstruction of flow caused by a clot or other material, or by pressure on a blood vessel (as by a tumor). Deprived of oxygen, which is carried by blood, nerve cells in the affected area cannot function and die. Thus, the part of the body controlled by those cells, cannot function either. Stroke can result in loss of consciousness and brain function, and death​

Sympathetic Nervous System

A branch of the autonomic nervous system responsible for mobilizing the body’s energy and resources during times of stress and arousal​

Synapse

A gap between two neurons that functions as the site of information transfer from one neuron to another.

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T

Term Definition
Temporal Lobe

​One of the four major subdivisions of each hemisphere of the cerebral cortex. It functions in auditory perception, speech and complex visual perceptions

Thalamus

A structure consisting of two egg-shaped masses of nerve tissue, each about the size of a walnut, deep within the brain. It is the key relay station for sensory information flowing into the brain, filtering out only information of particular importance from the mass of signals entering the brain​

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V

Term Definition
Ventricles

Of the four ventricles, comparatively large spaces filled with cerebrospinal fluid, three are located in the brain and one in the brainstem. The lateral ventricles, the two largest, are symmetrically placed above the brainstem, one in each hemisphere​

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W

Term Definition
Wernicke’s Area

A brain region responsible for the comprehension of language and the production of meaningful speech​

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