72, P = 0.046) and an interaction of Speed × Trial (F1,15 = 4.55, P = 0.05). To disentangle this interaction, the data were collapsed across Modality, and two repeated-measures t-tests were conducted, one comparing the switch-fast condition to the switch-slow condition, and one comparing the repeat-fast to the repeat-slow condition. The comparison of switch-fast vs. switch-slow indicated a significant difference between these two conditions (t15 = 2.57, P = 0.021), reflecting the fact that the success rate was greater
on switch fast [0.93 (0.06)] vs. switch-slow [0.88 (0.08)] conditions. The comparison of repeat fast vs. repeat-slow did not cross the significance threshold (t15 = 1.48, P = 0.158).
The results of this analysis indicate Selleckchem MDV3100 that fast-switch trials were accompanied by a greater proportion of hits to FAs than were slow-switch trials, suggesting that RT latency does at least partially reflect the completeness of a given task-set reconfiguration. That this relationship was specific to switch trials and did not extend to repeat trials Everolimus datasheet adds further weight to this contention. With this established, we next sought to investigate alpha oscillatory deployment on fast and slow trials. From Fig. 6 it is evident that on auditory-switch fast relative to auditory-switch slow trials a punctate increase in alpha power is evident in the last ~150 ms prior to S2 onset over frontal and parietal regions. This effect was wholly absent in the SCPs comparing auditory-repeat fast to auditory-repeat slow. In the cue-visual conditions, both switch and repeat comparisons exhibited
greater alpha desynchronisations on Fast trials than on Slow trials. However, on observation of the SCPs, repeat trials showed a more focal effect over parietal-occipital areas while this effect on switch trials was present over frontal regions as well. We set out to assess the role of anticipatory alpha-band mechanisms during preparation for the first instance of a new task relative to a repeated instance of that same task, on the premise that a key component of initial task-set reconfigurations 3-mercaptopyruvate sulfurtransferase would involve a vigorous and selective suppression of processing within circuits responsible for the ‘old’ task. Indeed, when we compared the differential deployment of anticipatory alpha-band activity on switch vs. repeat trials by contrasting anticipatory alpha-band power between sensory modalities (i.e. preparing for an auditory vs. preparing for a visual task), we found considerably greater differential activity between modalities during switch trials. Further, this differential modulation began earlier and had a considerably more extensive topographical distribution across the scalp, with clear additional foci evident over more frontal cortical regions.