Activity related to transient reduction of fMRI acquisition noise. (A) Statistical parametric maps activated by noise reduction in the pre-fatigue session (random-effect analysis, P < 0.05, corrected). Anatomical locations were mapped on template brains. Axial (left), coronal (middle), and sagittal (left) sections passing through auditory cortices are shown. Crossing line indicates the local activity maximum of the brain regions. The right (R) and left (L) sides are indicated. (B) Statistical parametric maps activated by fMRI noise reduction (red) and visual search (green) in the pre-fatigue session (random effect analysis, P < 0.05, corrected). Combined statistical parametric maps were superimposed on surface-rendered high-resolution MRIs viewed from right and left. (C) Time course of normalised activity in the auditory cortices during fatigue-inducing period in the normal and CFS patient groups. To evaluate the time course of the auditory responses, we divided the fatigue-inducing period into 6-min sections, and measured activity of the brain regions that had been activated by transient reduction of fMRI noise in the pre-fatigue session. Magnitude of the activity was calculated as the peak signal change (%) averaged across the activated areas. Normalised activity was calculated as activity in a given section divided by that in the first section. Data are mean and SEM. Closed circles, normal subjects; open circles, CFS subjects.