Figure 6.

Summary schematic of dynamic coding for working memory (WM)-dependent behaviour. The initial input triggers a specific pattern in activity state that in turn alters the underlying hidden state of the network via a temporary shift in functional connectivity (e.g., short-term synaptic plasticity [25], or coherence [35]). Activity-dependent changes in hidden state drive a dynamic trajectory during the initial high-energy phase via the reciprocal interaction between hidden states and the activity states that modulate them [43,44]. After activity has relaxed to baseline levels, the hidden state remains patterned according to the WM item. Although in principle this temporary hidden state could be ‘activity silent’, any spontaneous activity in the network will be patterned according to the WM context, resulting in a WM-specific activity state during spontaneous firing [44]. This kind of ‘baseline emission’ could help explain the content-specific delay activity observed under some circumstances [32]. Increasing the level of network activity via attention/rehearsal mechanisms could increase the discriminability of the activity state, resulting in ‘ramp-up’ delay activity [19,20] or task-dependent ‘reactivations’ [22]. Finally, when the critical memory cue is presented, the context-dependent response maps activity states for WM-guided behaviour (e.g., match/non-match decision; see [44]).