Working memory (WM) is an important cognitive function that is necessary to perform our daily activities. The present review briefly describes the most accepted models underlying WM and the neural networks involved in its processing. The review focuses on how the neurophysiological mechanisms develop with age in the periods from childhood to adolescence and young adulthood. Studies using behavioral, neuroimaging, and electrophysiological techniques showed the progress of WM throughout the development. The present review focuses on the neurophysiology of the basic processes underlying WM operations, as indicated by electroencephalogram-derived signals, in order to take advantage of the excellent time resolution of this technique. Children and adults use similar cerebral mechanisms and areas to encode, recognize, and keep the stimuli in memory and update the WM contents, although adults rely more on anterior sites. The possibility that a functional reorganization of WM brain processing occurs around the adolescent period is suggested, and would partly justify the high prevalence of the emergence of mental pathology in the adolescent period.

The neural bases of the inter-trial validity/invalidity sequential effects in a visuo-auditory modified version of the Central Cue Posner's Paradigm (CCPP) are analyzed by means of Early Directing Attention Negativity (EDAN), Contingent Negative Variation (CNV) and Lateralized Readiness Potential (LRP). ERPs results indicated an increase in CNV and LRP in trials preceded by valid trials compared to trials preceded by invalid trials. The CNV and LRP pattern would be highly related to the behavioral pattern of lower RTs and higher number of anticipations in trials preceded by valid with respect to trials preceded by invalid trials. This effect was not preceded by a modulation of the EDAN as a result of the previous trial condition. The results suggest that there is a trial-by-trial dynamic modulation of the attentional system as a function of the validity assigned to the cue, in which conditional probabilities between cue and target are continuously updated.

In this study, we asked whether the event-related potentials associated to cue and target stimuli of a Central Cue Posner Paradigm (CCPP) may encode key parameters of Bayesian inference – prior expectation and surprise – on a trial-by-trial basis. Thirty-two EEG channel were recorded in a sample of 19 young adult subjects while performing a CCPP, in which a cue indicated (validly or invalidly) the position of an incoming auditory target. Three different types of blocks with validities of 50%, 64%, and 88%, respectively, were presented. Estimates of prior expectation and surprise were obtained on a trial-by-trial basis from participants’ responses, using a computational model implementing Bayesian learning. These two values were correlated on a trial-by-trial basis with the EEG values in all the electrodes and time bins. Therefore, a Spearman correlation metrics of the relationship between Bayesian parameters and the EEG was obtained. We report that the surprise parameter was able to classify the different validity blocks. Furthermore, the prior expectation parameter showed a significant correlation with the EEG in the cue-target period, in which the Contingent Negative Variation develops. Finally, in the post-target period the surprise parameter showed a significant correlation in the latencies and electrodes in which different event-related potentials are induced. Our results suggest that Bayesian parameters are coded in the EEG signals; and namely, the CNV would be related to prior expectation, while the post-target components P2a, P2, P3a, P3b, and SW would be related to surprise. This study thus provides novel support to the idea that human electrophysiological neural activity may implement a (Bayesian) predictive processing scheme.