In the other set of trials, the orientation of the stimulus was task relevant, and the color had to be ignored. A vertical stimulus was associated with an eye movement to the right and a horizontal stimulus with a saccade to the left. The key point is that the visual stimuli do not uniquely determine

the response required to obtain the reward—the monkeys needed to understand and apply the rules to pick the correct response. While the monkeys were performing this task, neuronal spike activity and local field potentials (LFPs), which reflect rhythmic activity in small populations around the electrode tip, were recorded from dorsolateral PFC. To quantify neural synchrony, Buschman et al. (2012) computed coherence among pairs of LFP recordings. In B-Raf assay addition, the degree of coupling between individual cells and the LFP was quantified by computing spike-field synchrony. Interestingly, LFP coherence showed rule-specific Venetoclax datasheet effects in two different frequency ranges: the beta and the alpha band (Figure 1B). While beta-band effects (around 20–30 Hz) occurred immediately after stimulus onset, alpha-band coherence changes (around 10 Hz) were maximal after presentation of the cue signaling the current rule. This suggests that the observed coherence changes were associated with rule selection. For most electrode pairs, beta-band LFP coherence was rule specific (i.e., stronger for either the orientation

or the color rule). Based on this, two assemblies could be identified: color and orientation (Figure 1B). For each assembly, beta-band synchrony increased in trials in which the rule preferred by the neurons was applied. Interestingly, these two assemblies were not completely PTPRJ disjunct; there were local populations that could couple, albeit with different strength, into either assembly. In agreement, analysis of spike-field synchrony showed that the strength of coupling of individual cells

into these two assemblies depended on the rule that applied. Thus, beta-band coupling of orientation-preferring cells to the LFP of the orientation assembly was stronger in orientation rule trials compared to color rule trials. Buschman et al. (2012) conclude that rule-specific beta-band coupling can dynamically link neurons involved in processing the same rule. Enhanced beta-band synchrony may then be relevant for dynamically selecting the assembly that is currently task relevant. Interestingly, orientation-specific cells showed higher alpha coherence when a switch to the color rule occurred, but color rule-specific cells did not increase alpha coherence during switches to the orientation rule (Figure 1B). Based on reaction times, the orientation rule was easier to apply for the animals and they had greater difficulty switching away from it, indicating behavioral dominance of the stimulus orientation. Buschman et al.