Background: Residual inhibition (RI) is a temporary phenomenon that happens following offset
of appropriate complete or partial acoustical and electrical masking stimulations
in people who experience tinnitus. The biologic mechanisms associated with RI are
not yet fully understood. Few studies have been focused on RI. Auditory mismatch negativity
(MMN) as a change-detection tool may be an appropriate tool to explore the processing
changes because of tinnitus and RI.
Purpose: The purpose of this study was to investigate alterations in auditory change detection
and auditory sensory memory related to RI induced by auditory electrical stimulation
(AES) using MMN brain mapping in participants with tinnitus.
Research Design: This investigation was a single-blind randomized controlled clinical trial study.
Participants were randomly assigned into two groups: AES and placebo electrical stimulation
(PES).
Study Sample: Twenty-eight participants with chronic subjective tinnitus aged 22- to 45-yr-old
participated in the study.
Intervention: After randomization, all participants received both AES and PES for 1 min in different
sessions.
Data Collection and Analysis: Brain mapping of multifeature MMN paradigm was recorded from 29 scalp electrodes
pre- and post-AES and PES. Following AES, participants were categorized into two groups:
RI and nonresidual inhibition (NRI). The grand average MMN waveforms and isopotential
topographic maps were obtained in RI, NRI, and PES groups.
Results: Three MMN parameters for five deviants of frequency, intensity, duration, location,
and silent gap were compared among three groups of RI, NRI, and PES. Statistical analyses
revealed significant between-subject effects for AES on MMN amplitude of frequency
and duration deviant, MMN area under the curve of frequency, intensity, and duration
deviants.
Conclusions: Presence of RI can reestablish change-detection mechanisms in the central auditory
pathways. It is suggested that MMN is reliable for assessment of change-detection
system in people with tinnitus. It can be a useful technique in monitoring effects
of treatments and rehabilitation.
Key Words
tinnitus - residual inhibition - auditory MMN - change detection - sensory memory
