Contextual coordination of the eyes and head is readily observed in both humans and monkeys (e.g. Oommen et al., 2004; Monteon et al., 2012), and recent neurophysiological results have detailed a potential role for the FEF in contextual coupling of the NSC 683864 cell line eyes and head (Knight, 2012; Monteon et al., 2012). Our observations that neck muscle responses evoked by ICMS-SEF also vary with context (see also Chen
& Walton, 2005), in this case with the instruction to prepare for a pro- or anti-saccade, is consistent with the possibility that the SEF may also provide a substrate for the flexible implementation of strategic contexts with oculomotor plans. How can we explain the seemingly paradoxical effects of ICMS-SEF on anti-saccade behavior and neck muscle recruitment? We speculate that our findings arise from both feedforward and feedback influences of ICMS-SEF throughout Kinase Inhibitor Library screening the oculomotor system. We illustrate our speculations in Fig. 7 by showing plausible activity profiles within the SEF, the SC (as an intermediary oculomotor area downstream from the SEF) and at the neck. Our speculative mechanism is an extension of that proposed by Kunimatsu & Tanaka (2012), with added considerations of the comparative effect of consolidation of task instruction to make a
pro- or anti-saccade task, and activity profiles at the downstream SC and neck. For this example, ICMS-SEF is delivered shortly after cue onset, before the arrival of visual information. SEF activity is higher on anti- vs. pro-saccade trials at the time of ICMS-SEF (Schlag-Rey et al., 1997; Amador et al., 2004). Accordingly, we assume that greater amounts of activity are evoked in the SEF, and fed forward to
downstream areas such as the SC. To our knowledge, there is no direct evidence for this assumption from the SEF (i.e. recording in a downstream structure during or after ICMS-SEF), but many studies have reported greater oculomotor effects of stimulation to the SEF or the FEF when delivered at a presumed time of greater activity (Tehovnik et al., 1999; Gold & Shadlen, 2000; Opris et al., 2001; Moore & Armstrong, 2003; Chen & Tehovnik, 2007); short-duration stimulation of 4-Aminobutyrate aminotransferase the SC delivered later during a gap interval also evokes larger neck muscle responses, paralleling the level of endogenous SC activity at the time of stimulation (Corneil et al., 2007). While SC activity preceding ICMS-SEF is higher on pro- vs. anti-saccade trials (Everling et al., 1999), we suggest that the stimulation-evoked activity arising from ICMS-SEF drives the SC to a higher level of activity on anti-saccade trials. This would then feed down to the neck via a polysynaptic pathway, producing greater amounts of lateralized neck muscle recruitment on anti- vs. pro-saccade trials, despite the greater amount of baseline activity on pro-saccades.