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Central neural activity in rats with tinnitus evaluated with manganese-enhanced magnetic resonance imaging (MEMRI).
- Source :
-
Hearing research [Hear Res] 2007 Jun; Vol. 228 (1-2), pp. 168-79. Date of Electronic Publication: 2007 Feb 23. - Publication Year :
- 2007
-
Abstract
- The pathophysiology of tinnitus, the perception of sound in the absence of acoustic stimulation, is largely unknown, although several lines of research implicate long-term neuroplastic loss of inhibition. The evidence to date suggests that the neuroplastic alterations are likely to be found in multiple brain structures. The present study used manganese-enhanced magnetic resonance imaging (MEMRI) to assess the pattern of neural activity in the central auditory pathway of rats with psychophysical evidence of chronic acoustic-exposure-induced tinnitus. Manganese, an activity-dependent paramagnetic contrast agent, accumulates in active neurons through voltage-gated calcium channels, primarily at synapses, and serves as both a structural and functional indicator. Comparison images were obtained from normal subjects exposed to external tinnitus-like sound, and from tinnitus subjects treated with vigabatrin, a GABA agonist shown to eliminate the psychophysical evidence of tinnitus in rats. MEMRI indicated: (1) In rats with evidence of tinnitus, activity was generally elevated in the auditory brainstem, with significant elevation in the cerebellar paraflocculus, the posterior ventral cochlear nucleus, and the inferior colliculus; in general forebrain structures showed decreased activity, although MEMRI may be a less sensitive indicator of forebrain activity than brainstem activity; (2) in normal rats exposed to a tinnitus-like sound, a similar pattern of elevated brainstem activity and decreased forebrain activity was evident, with the notable exception of the paraflocculus, where artificial tinnitus had no effect and (3) vigabatrin, decreased brainstem activity to control levels, in rats with prior evidence of tinnitus, and decreased forebrain activity to below control levels. It was concluded that chronic tinnitus in rats is associated with focal activity elevation in the auditory brainstem and increased activity in the paraflocculus that may be unique to tinnitus.
- Subjects :
- Animals
Auditory Pathways physiopathology
Auditory Perception
Auditory Threshold
Behavior, Animal
Brain Stem drug effects
Cochlear Nucleus physiopathology
Disease Models, Animal
Evoked Potentials, Auditory, Brain Stem
GABA Agonists pharmacology
Inferior Colliculi physiopathology
Male
Neural Inhibition
Neuronal Plasticity
Noise adverse effects
Pitch Perception
Psychoacoustics
Rats
Rats, Long-Evans
Tinnitus etiology
Tinnitus psychology
Vigabatrin pharmacology
Brain Stem physiopathology
Chlorides
Magnetic Resonance Imaging methods
Manganese Compounds
Prosencephalon physiopathology
Tinnitus physiopathology
Subjects
Details
- Language :
- English
- ISSN :
- 0378-5955
- Volume :
- 228
- Issue :
- 1-2
- Database :
- MEDLINE
- Journal :
- Hearing research
- Publication Type :
- Academic Journal
- Accession number :
- 17382501
- Full Text :
- https://doi.org/10.1016/j.heares.2007.02.003