The difference between our current and our previous studies suggests state-dependency in the form of a task-dependent role for PMd during online performance and offline consolidation
of implicit sequence-specific learning of a visuomotor task. Given its anatomical location and functional connectivity, the PMd is a likely convergence CP-673451 solubility dmso point for cognition and motor control. PMd is generally associated with explicit declarative aspects of motor learning. While the PMd has been implicated in facilitating the transition between implicitly learned movements that constitute a sequence (Mushiake et al., 1991), activity in the PMd is reduced when explicit awareness of the implicit motor sequences is gained (Hazeltine et al., 1997; Honda et al., 1998). During online learning it is likely that the PMd serves to enhance implicit sequence-specific learning by linking specific movements which are dependent upon sensory cues (Nowak et al., 2009; Taubert et al., 2010). This role may be particularly important during interleaved practice and may explain why anodal transcranial direct current stimulation over the PMd during constant repetitive Ibrutinib manufacturer practice does not result in improved consolidation of performance gains (Nitsche
et al., 2003; Kantak et al., 2012). In contrast, early offline consolidation of information relating to sequencing of action selection may interfere with early consolidation of more procedural elements relating to individual ADAMTS5 movements, which are most likely represented in M1
(Muellbacher et al., 2002; Wilkinson et al., 2010). This may result from early offline consolidation of information being more reliant on a declarative memory and thus more explicit. This assumption is consistent with observations of differential rates of consolidation for explicit declarative memories relative to procedural memory (Brown & Robertson, 2007a; Ghilardi et al., 2009; Galea et al., 2010) and competition between procedural and declarative memory systems (Brown & Robertson, 2007a,b; Galea et al., 2010). Interference may occur even when explicit instruction is not given and participants have not autogenously acquired declarative knowledge of a sequence through practice (Vidoni & Boyd, 2007). Therefore, reducing the cortical excitability of PMd through 1 Hz rTMS during early offline consolidation may relieve suppression of procedural representations in M1 during this critical period and facilitate an early boost in procedural learning not seen at later stages of offline consolidation (Hotermans et al., 2008). Another interesting result was the lack of dissociation between implicit motor sequence learning for the 5 Hz and sham stimulation groups. Relative to the sham control group, one might expect the 5 Hz group to show the opposite effect to that induced by 1 Hz rTMS.