| event-related potentials, p300 | A late-appearing component of the event-related potential. P stands for positive voltage potential and 300 represents 300 millisecond poststimulus. Its amplitude increases with unpredictable, unlikely, or highly significant stimuli and thereby constitutes an index of mental activity. (12 Dec 1998) |
|---|---|
| excitatory postsynaptic potentials | The change in potential produced in the membrane of the next neuron when an impulse which has an excitatory influence arrives at the synapse; it is a local change in the direction of depolarisation; summation of these potentials can lead to discharge of an impulse by the neuron. (12 Dec 1998) |
| audiometry, evoked response | A form of electrophysiologic audiometry in which an analog computer is included in the circuit to average out ongoing or spontaneous brain wave activity. A characteristic pattern of response to a sound stimulus may then become evident. Evoked response audiometry is known also as electric response audiometry. (12 Dec 1998) |
| visual evoked potential | Voltage fluctuations that may be recorded from the occipital area of the scalp as the result of retinal stimulation by a light flashing at 1/4-second intervals; commonly summated and averaged by computer. (05 Mar 2000) |
| somatosensory evoked potential | The computer-averaged cortical and subcortical responses to repetitive stimulation of peripheral nerve sensory fibres. (05 Mar 2000) |
| evoked potential | An event-related potential, elicited by, and time-lockied to a stimulus. See: evoked response. (05 Mar 2000) |
| evoked response | An alteration in the electrical activity of a region of the nervous system through which an incoming sensory stimulus is passing; may be somatosensory (SER), auditory (BAER), or visual (VER). See: evoked potential. (05 Mar 2000) |
| evoked response audiometry | A type of electrophysiologic audiometry in which electrical potentials of neural impulses from the cochlear nerve and various levels in the brain in response to acoustic stimulation are used to localise the site of a lesion causing a hearing loss. (05 Mar 2000) |
| air cells of auditory tube | Occasional small air cells in the inferior wall of the auditory tube, near the tympanic orifice, communicating with the tympanic cavity. Synonym: cellulae pneumaticae tubae auditivae, air cells of auditory tube. (05 Mar 2000) |
| auditory | <otolaryngology> Pertaining to the sense of hearing. Origin: L. Auditorius (18 Nov 1997) |
| auditory agnosia | The inability to recognise sounds, words, or music; caused by a lesion of the auditory cortex of the temporal lobe. (05 Mar 2000) |
| auditory alternans | Alternation in the intensity of heart sounds or murmurs in the presence of a regular cardiac rhythm as a result of alternation of the heart. Synonym: auditory alternans. (05 Mar 2000) |
| auditory aphasia | An impairment in comprehension of the auditory forms of language and communication, including the ability to write from dictation in the presence of normal hearing. Spontaneous speech, reading, and writing are not affected. Synonym: acoustic aphasia, word deafness. (05 Mar 2000) |
| auditory area | Area of the temporal lobe concerned with hearing. (12 Dec 1998) |
| auditory canal | The passage leading inward through the tympanic portion of the temporal bone, from the auricle to the tympanic membrane; it consists of a bony (inner) portion and a fibrocartilaginous (outer) portion, the cartilaginous external acoustic meatus. Synonym: meatus acusticus externus, acoustic meatus, antrum auris, auditory canal, external auditory meatus. (05 Mar 2000) |