Motor Unit - Ancient Brain, Glossary of Terms - Psychophysiology

Lecture

Motor unit - a single motoneuron together with the muscle fibers it innervates.
Motor cortex - an area of the cerebral cortex whose electrical stimulation elicits motor reactions in certain parts of the body.
Direction-sensitive cells - detector neurons that respond to the movement of a stimulus in a particular direction and at a particular speed
Motor centers - areas of the cerebral cortex where the cortical end of the motor analyzer is localized.
Motor analyzer - a neurophysiological system that performs the analysis and synthesis of signals arising in the organs of movement of humans and animals. The motor analyzer consists of a peripheral division, specific nerve fibers, subcortical structures, and a cortical division located in the frontal lobes of the cerebral cortex.
De... - a prefix denoting: 1) separation, removal, cancellation; 2) downward movement, decrease.
Deafferentation - the cessation of sensory impulse conduction from the periphery to the center as a result of a disruption of the anatomical or physiological integrity of the sensory nerves.
Deviation - departure from the norm.
Dis... - a prefix denoting the destruction, removal, or absence of something.
Disintegration - the breaking down or dismembering of a whole into its constituent parts.
Decortication - the removal or functional shutdown of the cerebral cortex, used to study the functions of the cortex and its interrelation with subcortical formations.
Decompensation - a disturbance of the activity of the organism, of one of its functional systems, or of an organ, resulting from a breakdown or exhaustion of adaptive mechanisms; after some time the organism may adapt to the new conditions of existence, and compensation sets in.
Decrement - a characteristic of the weakening of excitation as it propagates along nerve pathways.
Delirium - a disturbance of consciousness, a distorted reflection of reality, accompanied by hallucination, delusion, and motor agitation.
Delta rhythm - one of the components of the EEG rhythm spectrum, with a frequency ranging from 0.5 to 4.0 Hz and an amplitude in the range of 20 to 200 microvolts.
Dementia - acquired mental deficiency characterized by difficulties in the sphere of thinking. Judgment of situations and critical functions are impaired; the range of interests narrows, and adaptation to life conditions decreases.
Dendrite - a branching process of a neuron that receives excitation signals from other neurons or directly from receptor cells that perceive external stimuli.
Denervation - disruption of innervation by cutting or damaging the nerves that innervate particular organs.
Depolarization - a decrease in membrane potential compared with the resting level.
Depression - an affective state characterized by a negative emotional background, changes in the motivational sphere, cognitive representations, and general passivity of behavior.
Alpha rhythm depression - see Alpha rhythm blockade.
Deprivation - sensory insufficiency that can lead to a loss of the organism's orientation in the environment.
Derivative - something derived, having originated from something that previously existed.
Desensitization - the reduction or elimination of an organism's increased sensitivity to the action of some substance.
Desynchronization - the replacement of temporally ordered (synchronous) high-amplitude potentials on the EEG by faster, lower-amplitude ones; serves as an indicator of increased activity of the nervous system.
Descriptor - an indicator, a describer.
Destruction - the destruction or disruption of the normal structure of something, annihilation.
Lie detector - a conventional name for a whole range of instruments for the objective recording of physiological indicators such as EDA, EEG, tremor, plethysmogram, etc.
Determine - to define, to condition.
Deterministic model - a conception implying that the forms of behavior and emotional reactions of living beings are determined by environmental factors that acted in the past or are acting at the present moment.
Definitive - final, mature.
Definition - a brief statement of some concept, reflecting the essential features of an object or phenomenon.
Deceleration - the process opposite to acceleration.
Decerebration - transection of the brainstem between the anterior and posterior colliculi of the quadrigeminal body, used for the experimental study of the activity of the mammalian CNS. In this case the diencephalon and all higher-lying divisions of the brain turn out to be separated from the lower-lying ones.
Divergence - a type of morphological organization of a neural network in which the axon of one neuron addresses many neurons.
Digestive - relating to digestion.
Dys.., dis... - a prefix denoting separation, division, negation, destruction (corresponding in meaning to the Russian "раз...", "не...").
Dysarthria - a disorder of articulation, difficulties in pronouncing speech sounds.
Dys(s)graphia - a writing disorder.
Dys(s)lexia - a speech disorder manifested in difficulty pronouncing words, leading to an inability to learn owing to extreme difficulties in mastering reading.
Dys(s)ergasia - a disturbance of behavior and mental activity resulting from organic brain lesions.
Sexual dimorphism - biological differences due to belonging to the male or female sex.
Variance - a statistical measure of the variability of some characteristic, the main descriptor of the deviation of a characteristic's value from its mean value.
Dysplasia - abnormal development of organs and tissues during the pre- and postnatal development of the organism.
Dissimilation - the breakdown of complex organic substances in the organism, accompanied by the release of energy used in vital processes. Dissimilation, together with assimilation, constitutes metabolism.
Dissolution - a phenomenon of a peculiar "return" in ontogenesis, in which reduced functions and outdated skills reappear, creating interference in the realization of new functions. The phenomenon is well known clinically: in severe stroke patients, sucking, grasping, and other automatisms acquired in infancy often reappear.
Distal - located at the periphery, at a distance from the midline of the body.
Distress - stress that has a negative effect on activity.
Dysfunction - a disorder, a disruption of some function.
Difference threshold - the minimal difference between two stimuli that is perceived subjectively.
Differentiation - the process by which undifferentiated cells acquire morphological and functional specialization.
Diffusion - the transfer of a substance across a cell membrane, proceeding along an electrochemical gradient, that is, without the expenditure of energy.
Dichotic listening - the auditory perception of messages differing in content or sound, one of which is presented (through headphones) to the left ear and the other to the right.
Diencephalic - relating to the diencephalon.
Diencephalic animal - an animal after transection of the brain along the anterior border of the diencephalon.
Dominant focus - a focus of excitation in the central nervous system that temporarily determines the character of the organism's response to external and internal stimuli and thereby gives behavior a definite direction. The term was introduced by A.A. Ukhtomsky. The dominant focus is regarded as a general principle of the brain's operation.
Dominance - the prevailing role of a structure and/or function in a living system.
Eye dominance - the greater contribution of one of the two eyes to the formation of a visual image, arising as a result of the differing effectiveness of eye stimulation upon excitation of simple, complex, and hypercomplex cells of the visual cortex.
Cerebral hemisphere dominance - the relative predominance of the functional activity of one of the hemispheres as a result of their joint activity.
Dominant EEG rhythm - the rhythm whose index exceeds the index of other rhythms in a given segment of the EEG recording.
Supplementary motor area - an area of the motor cortex located on the medial surface of the cerebral cortex.
Dorsal - situated at, or facing, the dorsal surface of an animal's body (see Ventral).
Dopamine - an intermediate product of catecholamine biosynthesis, secreted, along with adrenaline and noradrenaline, by the adrenal medulla; in the CNS it functions as a neurotransmitter.
Dopaminergic system of the brain - networks of neurons in which dopamine serves as the neurotransmitter.
Ancient brain (reptilian brain) - a group of nervous structures forming the "lower floor" of the human brain, corresponding to the first stage of brain development in phylogeny, up to and including reptiles.