Nonetheless, in both monkeys, these movements were again not randomly distributed, but were instead modulated by the behavioral relevance of the cue and EPZ5676 clinical trial foil: there was a higher frequency of microsaccades directed towards either the cued or foil locations than to neither location at trial end (Fig. 10A). This result is consistent with previous

observations from the same two monkeys, albeit with many more behavioral trials (Hafed et al., 2011). During peripheral SC inactivation, this bias of late microsaccades towards the behaviorally relevant cued and foil locations was disrupted. Figure 10B shows the distribution of microsaccade directions for movements occurring within 70 ms from motion pulse onset, but now during SC inactivation, and with the CYC202 clinical trial cue placed in the affected region. In this case, we classified movements as being directed either towards the region affected by SC inactivation (cue), towards the quadrant diametrically opposite that region (foil), or towards neither location.

In both monkeys, the normal biases towards the cued and foil quadrants at the expense of ‘neither’ quadrants was all but eliminated after SC inactivation. Moreover, the individual monkey effects looked similar to the effects earlier in the early post-cue intervals of Figs 8 and 9. For example, monkey J showed a pronounced increase in ‘neither’ movements relative to the case without muscimol injection, as was the case in

Fig. 9, whereas monkey M did not show this effect so strongly. When the cue was in the unaffected region (Fig. 10C), microsaccade directions were more similar to the pre-injection data of Fig. 10A, especially in monkey M, although the rarity of movements near trial end (Hafed et al., 2011) meant that this observation did not always reach statistical significance. Thus, the results of Fig. 10 combined indicate that, in both monkeys, inactivation Selleckchem Enzalutamide disrupted the normal bias of late microsaccades, which was in favor of the behaviorally relevant stimulus locations (cue and foil) and against the irrelevant ones (neither). Instead, the microsaccades that did occur near trial end in the task seemed to have equal likelihoods of being directed towards the behaviorally relevant quadrants and towards the remaining two locations. These results, combined with our earlier observations shown in Figs 8 and 9, indicate that peripheral SC inactivation had the effect of disrupting the correlations between microsaccades and both cue-induced (Figs 8 and 9) and sustained (Fig. 10) attentional allocation. Microsaccades in humans and monkey have been recently found to show predictable changes in rate and direction during a variety of experiments involving different aspects of cognition (Martinez-Conde et al., 2009; Rolfs, 2009; Hafed, 2011). However, the neural bases for these effects are so far unknown.