Panel A of Fig. 3 shows the topography of the differential alpha-band (8–14 Hz) oscillatory activity between all attend-auditory and all attend-visual trials (auditory – visual) at 1000 ms (i.e. where switch and repeat trials are collapsed together). The parieto-occipital focus of differential alpha power was highly consistent with our previous findings (Foxe et al., 1998; Fu et al., 2001; Gomez-Ramirez et al., 2007). Panel B of Fig. 3 depicts

the alpha-band (8–14 Hz) TSE waveforms derived from the three highlighted parieto-occipital electrode sites (central head; panel A). A sustained divergence in TSE amplitude is seen starting at ~600 ms post-cue, Fulvestrant some 750 ms before the onset of the S2 task stimulus, which occurs at 1350 ms. Alpha-band activity was greater when subjects had

been cued to attend selectively to impending auditory stimulation (i.e. to ignore or suppress concurrent visual inputs). In panel C of Fig. 3, ABT-737 research buy the TSE waveforms for attend-auditory (red traces) and attend-visual (black traces) are further distinguished according to trial type [i.e. switch trials (dotted traces) vs. repeat trials (solid traces)]. If participants were required to reconfigure the task-set on switch trials, the divergence in TSE waveforms was seen to start ~200 ms earlier at ~400 ms post-cue and reached a maximum just before the S2 stimulus onset. Figure 4 depicts the TSE waveforms for attend-auditory and attend-visual trials at six representative electrodes over frontopolar and parieto-occipital scalp regions, broken out for Mannose-binding protein-associated serine protease switch trials (panel A) and repeat trials (panel B). The extended electrode representation reveals that the modulation of alpha-band activity showed a considerably broader topographic distribution from the more typical focus over the parieto-occipital

region, with clear divergence seen over frontal and frontopolar scalp regions when participants were preparing for a switch of task (panel A). Early and widespread TSE modulation for switch compared to repeat trials is also depicted in the SCP (far right column). For repeat trials there was one main cluster of activation starting at ~1100 ms post-cue and this was distributed over both frontal and parieto-occipital scalp regions. For switch trials, two main clusters of differential activation were evident, an early one starting at ~600 ms and a later one starting at ~1100 ms. Both the early and late clusters showed widespread scalp distributions over parieto-occipital, central and frontopolar scalp regions. Topographical mapping shows maximal distributions over the parieto-occipital region starting at ~700 ms and over more frontal regions starting at ~1000 ms; both were enhanced on switch trials (panel C).