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Titolo:
Lateralized tinnitus studied with functional magnetic resonance imaging: Abnormal inferior colliculus activation
Autore:
Melcher, JR; Sigalovsky, IS; Guinan, JJ; Levine, RA;
Indirizzi:
Massachusetts Eye & Ear Infirm, Eaton Peabody Lab, Boston, MA 02114 USA Massachusetts Eye & Ear Infirm Boston MA USA 02114 , Boston, MA 02114 USA Harvard Univ, Sch Med, Dept Otol & Laryngol, Boston, MA 02114 USA Harvard Univ Boston MA USA 02114 pt Otol & Laryngol, Boston, MA 02114 USA Harvard Univ, MIT, Div Hlth Sci & Technol, Speech & Hearing Sci Program, Cambridge, MA 02139 USA Harvard Univ Cambridge MA USA 02139 Sci Program, Cambridge, MA 02139 USA Massachusetts Gen Hosp, Neurol Serv, Boston, MA 02114 USA Massachusetts Gen Hosp Boston MA USA 02114 rol Serv, Boston, MA 02114 USA
Titolo Testata:
JOURNAL OF NEUROPHYSIOLOGY
fascicolo: 2, volume: 83, anno: 2000,
pagine: 1058 - 1072
SICI:
0022-3077(200002)83:2<1058:LTSWFM>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
DORSAL COCHLEAR NUCLEUS; SALICYLATE-INDUCED CHANGES; EVENT-RELATED POTENTIALS; PRIMARY AUDITORY-CORTEX; NOISE-INDUCED TINNITUS; STEM-EVOKED-RESPONSES; HIGH-INTENSITY SOUND; BRAIN-STEM; NEURAL ACTIVITY; HEARING-LOSS;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
119
Recensione:
Indirizzi per estratti:
Indirizzo: Melcher, JR Massachusetts Eye & Ear Infirm, Eaton Peabody Lab, 243 CharlesSt, Boston,MA 02114 USA Massachusetts Eye & Ear Infirm 243 Charles St Boston MA USA 02114
Citazione:
J.R. Melcher et al., "Lateralized tinnitus studied with functional magnetic resonance imaging: Abnormal inferior colliculus activation", J NEUROPHYS, 83(2), 2000, pp. 1058-1072

Abstract

Lateralized tinnitus studied with functional magnetic resonance imaging: abnormal inferior colliculus activation. J. Neurophysiol. 83. 1058-1072, 2000. Tinnitus, the perception of sound in the absence of external stimuli, isa common and often disturbing symptom that is not understood physiologically. This paper presents an approach for using functional magnetic resonanceimaging (fMRI) to investigate the physiology of tinnitus and demonstrates that the approach is effective in revealing tinnitus-related abnormalities in brain function. Our approach as applied here included 1) using a maskingnoise stimulus to change tinnitus loudness and examining the inferior colliculus (IC) for corresponding changes in activity, 2) separately considering subpopulations with particular tinnitus characteristics, in this case tinnitus lateralized to one ear, 3) controlling for intersubject differences in hearing loss by considering only subjects with normal or near-normal audiograms, and 4) tailoring the experimental design to the characteristics of the tinnitus subpopulation under study. For lateralized tinnitus subjects, we hypothesized that sound-evoked activation would be abnormally asymmetricbecause of the asymmetry of the tinnitus percept. This was tested using two reference groups for comparison. nontinnitus subjects and nonlateralized tinnitus subjects. Binaural noise produced abnormally asymmetric IC activation in every lateralized tinnitus subject (n = 4). In reference subjects (n= 9), activation (i.e., percent change in image signal) in the right versus left IC did not differ significantly. Compared with reference subjects, lateralized tinnitus subjects showed abnormally low percent signal change inthe IC contralateral, but not ipsilateral, to the tinnitus percept. Consequently, activation asymmetry (i.e., the ratio of percent signal change in the IC ipsilateral versus contralateral to the tinnitus percept) was significantly greater in lateralized tinnitus subjects as compared with reference subjects. Monaural noise also produced abnormally asymmetric IC activation in lateralized tinnitus subjects. Two possible models are presented to explain why IC activation was abnormally low contralateral to the tinnitus percept in lateralized tinnitus subjects. Both assume that the percept is associated with abnormally high ("tinnitus-related'') neural activity in the contralateral IC. Additionally, they assume that either 1) additional activityevoked by sound was limited by saturation or 2) sound stimulation reduced the level of tinnitus-related activity as it reduced the loudness of (i.e.,masked) the tinnitus percept. In summary, this work demonstrates that fMRIcan provide objective measures of lateralized tinnitus and tinnitus-related activation can be interpreted at a neural level.

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Documento generato il 26/01/20 alle ore 17:03:53