The population count selleck inhibitor of response selective FOF cells therefore starts rising

very shortly after the end of the instruction signal, and rises continually until the Go signal (Figure 4F; compare to Figure 5B, top panel, of Gage et al., 2010). This suggests that orienting preparation signals are represented significantly earlier in the FOF than in M1. Consistent with the much weaker electrophysiological delay period signature found in M1, as compared to the FOF, unilateral pharmacological inactivations of M1 produced very different, and much weaker, behavioral effects than those found in FOF (Figure S2, compare to Figure 2). The difference is particularly strong for memory trials. FOF inactivation reduced contralateral memory trials Microbiology inhibitor to almost 50% correct performance (chance), but M1 inactivation impaired performance on these trials only to ∼75% correct. This was a saturated effect: doubling the dose of muscimol in M1 did not further impair performance (Figure S2). Much further work is required to draw and refine functional maps of the rat cortex during awake behaviors, but we do conclude that the role of the FOF in memory-guided orienting is not common across frontal motor cortex. We targeted the FOF based on

previous anatomical, lesion, and microstimulation studies that suggested a role for this area in orienting behaviors (Leonard, 1969, Cowey and Bozek, 1974, Crowne and Pathria, 1982, Sinnamon and Galer, 1984 and Corwin and Reep, 1998). However, a Methisazone different line of research, observing whisker movements in response to intracortical microstimulation in head-fixed, anesthetized rats, has described the same area as whisker motor cortex (Brecht et al., 2004). Nevertheless, the functional role of the FOF in awake animals is not firmly established: single-unit recordings from the area in awake animals remain very sparse (Carvell et al., 1996, Kleinfeld et al., 2002 and Mizumori et al., 2005). We asked whether

whisking played a role in our memory-guided orienting task, and found that it did not: removing the whiskers had little effect on performance (Figures 1D and 1F and associated text), unilaterally paralyzing the whiskers did not produce a lateralized or memory specific effect (Figures 1E and 1F), and video analysis of regular trials did not find evidence of asymmetric or lateralized whisking during the memory delay period. The video showed instead that whiskers are held quite still during the delay period (Figure S1 and Movie S2). We speculate that well-trained animals that are highly familiar with the spatial layout of the behavior apparatus do not use whisking to guide their movements during the task. In particular, whisking appears to play no role in the short-term memory component of the task (Movie S2).