Human Auditory and Adjacent Nonauditory Cerebral Cortices Are Hypermetabolic in Tinnitus as Measured by Functional Near-Infrared Spectroscopy (fNIRS)

Figure 5

Mean oxy-hemoglobin (HbO) concentration traces versus time (seconds) from ROI and non-ROI under conditions of tonal auditory stimulation (750 Hz and 8000 Hz) between tinnitus (dark lines) and control (gray lines). The unit of concentration is micromolar (μM). Standard deviations at each time point of the traces were calculated using the equation: with = standard deviation; = each value in the population; = the mean of the values; = the number of values. The panels represent brain activity during the 4–18-second time period during the respective experimental paradigm. In the figure, 0 corresponds to 4 seconds of the 18-second period. Left hand column demonstrates responses to 750 Hz in both ROI (a) and non-ROI (c). Despite variable responses no significant differences are seen between tinnitus and control. Right-hand column demonstrates responses to 8000 Hz in ROI (a) and non-ROI (b) in both groups. Again, despite variability in traces, no significant differences are seen between tinnitus and control. All traces are marked with standard errors calculated for the 4 channels (2 on the right and 2 on the left for both ROI and non-ROI).

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