On ways to overcome the magical capacity limit of working memory.

The ability to simultaneously process and maintain multiple pieces of information is limited. Over the past 50 years, observational methods have provided a large amount of insight regarding the neural mechanisms that underpin the mental capacity that we refer to as "working memory." More than 20 years ago, a neural coding scheme was proposed for working memory. As a result of technological developments, we can now not only observe but can also influence brain rhythms in humans. Building on these novel developments, we have begun to externally control brain oscillations in order to extend the limits of working memory

Medial prefrontal cortex involvement in aesthetic appreciation of paintings: a tDCS study

Among the brain regions involved in the aesthetic evaluation of paintings, the prefrontal cortex seems to play a pivotal role. In particular, consistent neuroimaging evidence indicates that activity in the dorsolateral prefrontal cortex (mainly in the left hemisphere) and in medial and orbital sectors of the prefrontal cortex is linked to viewing aesthetically pleasing images. In this study, we focused on the contribution of the medial prefrontal cortex (mPFC) in mediating aesthetic decisions about paintings. We found that enhancing excitability in this region via anodal tDCS led participants to judge paintings as more beautiful. Although significant, the effects were moderate, possibly due to the neutral affective value of the artworks we used, suggesting that activity in mPFC may be critically dependent on the affective impact of the paintings.This work was supported by a PRIN Grant (2015WXAXJF) by Italian Ministry of Education, University and Research to Z.C and by Mondino Foundation “Ricerca Corrente” funds

Induced neural phase precession through exogenous electric fields

Abstract The gradual shifting of preferred neural spiking relative to local field potentials (LFPs), known as phase precession, plays a prominent role in neural coding. Correlations between the phase precession and behavior have been observed throughout various brain regions. As such, phase precession is suggested to be a global neural mechanism that promotes local neuroplasticity. However, causal evidence and neuroplastic mechanisms of phase precession are lacking so far. Here we show a causal link between LFP dynamics and phase precession. In three experiments, we modulated LFPs in humans, a non-human primate, and computational models using alternating current stimulation. We show that continuous stimulation of motor cortex oscillations in humans lead to a gradual phase shift of maximal corticospinal excitability by ~90°. Further, exogenous alternating current stimulation induced phase precession in a subset of entrained neurons (~30%) in the non-human primate. Multiscale modeling of realistic neural circuits suggests that alternating current stimulation-induced phase precession is driven by NMDA-mediated synaptic plasticity. Altogether, the three experiments provide mechanistic and causal evidence for phase precession as a global neocortical process. Alternating current-induced phase precession and consequently synaptic plasticity is crucial for the development of novel therapeutic neuromodulation methods

The mean accuracies (%) were significantly higher for both the parietal and the temporal groups compared with the sham stimulation group.

<p>Error bars represent standard error of the mean. Asterisks indicate significant differences.</p

The experimental procedure for the encoding A) and for the recognition B) phase of the verbal learning task.

<p>The experimental procedure for the encoding A) and for the recognition B) phase of the verbal learning task.</p

The summary of the fixed effects of the final model taking reaction-time as dependent variable (N = 5691; log-likelihood = -39621).

<p>Note: Random effect for subject intercept had SD of 148.7. SE: standard error of mean; df: degrees of freedom.</p><p>The summary of the fixed effects of the final model taking reaction-time as dependent variable (N = 5691; log-likelihood = -39621).</p

The summary of the fixed effects of the final model taking accuracy as dependent variable (N = 8448; log-likelihood = -5269.6).

<p>Note: Random effect for subject intercept had SD of 0.16. SE: standard error of mean.</p><p>The summary of the fixed effects of the final model taking accuracy as dependent variable (N = 8448; log-likelihood = -5269.6).</p

The summary of the fixed effects of the final model taking confidence rating as dependent variable (N = 7787; log-likelihood = 35888).

<p>Note: Random effect for subject intercept had SD of 12.49. SE: standard error of mean; df: degrees of freedom.</p><p>The summary of the fixed effects of the final model taking confidence rating as dependent variable (N = 7787; log-likelihood = 35888).</p

D’ values were significantly and marginally higher for the temporal and parietal groups respectively, compared with the sham stimulation group.

<p>D’ value is zero at random choice. Error bars represent standard error of the mean. Asterisk indicates significant differences; the plus sign indicates marginally significant differences.</p