The investigation of semantic memory in decompensated tinnitus indexed by N400 response

1. BackgroundMemory deficit and its supporting role in the persistence of tinnitus and in the increase in associated distress of tinnitus have been revealed through several studies. Semantic memory is another aspect of memory which is not investigated in tinnitus population. The N400 as a negative-going voltage deflection at 400 msec is an electrophysiological tool surveying semantic memory. Accordingly, the main purpose of the presentstudy was to investigate the semantic memory in decompensated tinnitus using N400 response. 2. Method The experimental groups consisted of 15 tinnitus subjects experiencing chronic tinnitus more than 6 months and 15 control comparison (NC) subjects having been matched in aspect of sex and age. The N400 response was recorded from 29 scalp electrodes in response to the semantic priming paradigm. The amplitudes,latencies, N400 effect, and the reaction times (RTs) were obtained in the region of interests (ROIs). 3. ResultsERP analyses revealed that the N400 amplitude in response to semantically unrelated pairs and N400 effect were significantly larger in normal subjects than the tinnitus group. In addition, RTs as a behavioral indicator of processing efficiency showed significant differences between the two groups. However, any significant difference was not founf for N400 latency.4. Conclusions Our study provides evidence that decompensated tinnitus has effect on the semantic memory. Indeed,tinnitus subjects had poor performance in using meaningful context to activate semantic memory. 5. ReferencesCouncil, N.R. (1982), National Academies Press) Laureano, M.R., et al (2014), PLoS One) Kutas, M., K.D. Federmeier (2000), Trends in cognitive sciences)