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Cunillera T.,University of Barcelona | Fuentemilla L.,University of Barcelona | Fuentemilla L.,Institute of Biomedicine Research of Bellvitge IDIBELL | Brignani D.,Irccs Centro San Giovanni Of Dio Fatebenefratelli | And 3 more authors.
PLoS ONE | Year: 2014

Proactive and reactive inhibitory processes are a fundamental part of executive functions, allowing a person to stop inappropriate responses when necessary and to adjust performance in in a long term in accordance to the goals of a task. In the current study, we manipulate, in a single task, both reactive and proactive inhibition mechanisms, and we investigate the within-subjects effect of increasing, by means of anodal transcranial direct current stimulation (tDCS), the involvement of the right inferior frontal cortex (rIFC). Our results show a simultaneous enhancement of these two cognitive mechanisms when modulating the neural activity of rIFC. Thus, the application of anodal tDCS increased reaction times on Go trials, indicating a possible increase in proactive inhibition. Concurrently, the stop-signal reaction time, as a covert index of the inhibitory process, was reduced, demonstrating an improvement in reactive inhibition. In summary, the current pattern of results validates the engagement of the rIFC in these two forms of inhibitory processes, proactive and reactive inhibition and it provides evidence that both processes can operate concurrently in the brain. © 2014 Cunillera et al.

Fuentemilla L.,Institute of Biomedicine Research of Bellvitge IDIBELL | Fuentemilla L.,University of Barcelona | Miro J.,Institute of Biomedicine Research of Bellvitge IDIBELL | Miro J.,University Hospital Of Bellvitge | And 12 more authors.
Current Biology | Year: 2013

Recent accumulating evidence in animals and humans has shown that memory strengthening occurs, at least partially, during sleep [1, 2] and relies on the covert reactivation of individual memory episodes [3-5]. However, it remains to be determined whether the hippocampus critically promotes memory consolidation via the reactivation of individual memories during sleep. To investigate the hippocampal-dependent nature of this phenomenon in humans, we selected two groups of chronic temporal lobe epileptic (TLE) patients with selective unilateral (TLE+UHS) or bilateral (TLE+BHS) hippocampal sclerosis and a group of matched healthy controls, and we requested them to learn the association of sounds cueing the appearance of words. On the basis of other similar behavioral paradigms in healthy populations [4, 6], sounds that cued only half of the learned memories were presented again during the slow-wave sleep stage (SWS) at night, thus promoting memory reactivation of a select set of encoded episodes. A memory test administered on the subsequent day showed that the strengthening of reactivated memories was observed only in the control subjects and TLE+UHS patients. Importantly, the amount of memory strengthening was predicted by the volume of spared hippocampus. Thus, the greater the structural integrity of the hippocampus, the higher the degree of memory benefit driven by memory reactivation. Finally, sleep-specific neurophysiological responses, such as spindles and slow waves, differed between the sample groups, and the spindle density during SWS predicted the degree of memory benefit observed on day 2. Taken together, these findings demonstrate that the hippocampus plays a crucial role in the consolidation of memories via covert reactivation during sleep. © 2013 Elsevier Ltd. All rights reserved.

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