g., no instructions to strategically recode 19•• and 26]), MVPA typically reveals a stable set of regions to represent Idelalisib chemical structure memoranda across the duration of a delay-period. However, the activity patterns within these regions can be dynamic. For example, with auditory STM, the frequency-specific pattern of elevated stimulus-evoked activity transitions to become a pattern of negative activity during the delay period [30]. For visual STM, a classifier trained on a time point early in the trial will often perform progressively worse as it is slid forward across the remainder of the delay period, the converse being true for a classifier trained on a late-in-the-delay time point and slid backwards (Figure 1b). This suggests

a temporal evolution of the neural code underlying the short-term retention of a subjectively ‘stable’ mental representation 11•• and 31•]. It remains to be determined whether these observations from fMRI relate in a meaningful way to the finding of dynamic coding in populations of neurons in monkeys performing tasks requiring sustained attention to an object 32 and 33]. Another neural effect that has influenced models of visual STM capacity limitation is the contralateral delay activity (CDA), an ERP component that scales monotonically with STM load, but asymptotes at the psychophysically estimated capacity of an individual [34]. The

CDA is Ivacaftor research buy widely interpreted as an index of the short-term retention of information (e.g., [35]), such that, for example, the presence of a CDA during visual search has been taken as evidence for ‘memory in search’ 36 and 37], and the

diminution of the CDA across consecutive trials requiring search for the same target as evidence for the ‘handoff’ of the mnemonic representation of the search template from STM to LTM [38]. Not unlike with univariate analyses of fMRI data, however, there can be problems with equating a 1-D, signal intensity-based measure like the CDA with a single psychological construct (in this case, the short-term retention of information). For example, empirically, the CDA can be observed during tasks for which it is unclear that the short-term retention of information is required, such as during multiple object tracking [39], or during change detection ‘even when the observers know that the objects will not disappear from the visual field’ [40] (p. Anacetrapib 8257). Further, the CDA during STM and during visual search is markedly reduced after intensive visual working memory training, despite the fact that STM capacity is increased and search performance improves with training [41•]. Under these conditions, a physiological marker specific to the short-term retention of information would be expected to increase in intensity. An additional challenge to the idea that the CDA is specific to the short-term retention of information comes from the proposal that it may, in fact, be the consequence of averaging across trials containing asymmetric amplitude modulation of alpha-band oscillations [42].