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Background Transcranial direct current stimulation (tDCS) is assumed to affect cortical excitability and dependent on the specific stimulation conditions either to increase or decrease learning. Objective The purpose of this study was to modulate implicit task sequence learning with tDCS. Methods As cortico-striatal loops are critically involved in implicit task sequence learning, tDCS was applied above the dorsolateral prefrontal cortex (DLPFC). In Experiment 1, anodal, cathodal, or sham tDCS was applied before the start of the sequence learning task. In Experiment 2, stimulation was applied during the sequence learning task. Consolidation of learning was assessed after 24 h. Results The results of both experiments showed that implicit task sequence learning occurred consistently but it was not modulated by different tDCS conditions. Similarly, consolidation measured after a 24 h-interval including sleep was also not affected by stimulation. Conclusions These results indicate that a single session of DLPFC tDCS is not sufficient to modulate implicit task sequence learning. This study adds to the accumulating evidence that tDCS may not be as effective as originally thought.

Tinnitus related distress is associated with increased activity in the anterior cingulate cortex (ACC). In a recent study, it was demonstrated that a single session of low frequency prefrontal TMS using a double-cone coil (DCC) modulating the ACC (AC/DC TMS, anterior cingulate cortex targeted modulation by Double-Cone coil) yields a transient improvement in subjects with chronic tinnitus. An increasing number of studies demonstrated that repeated sessions of low frequency TMS to the temporoparietal area can significantly improve tinnitus complaints. Our aim is to determine the extent to which repeated sessions of AC/DC TMS can modulate tinnitus in comparison to a single session. Seventy-three tinnitus patients received a single (N = 46) or repetitive (N = 27) session(s) of TMS using a DCC placed over the prefrontal cortex. Our results. indicate that both single sessions as well as multiple sessions (i.e. 8 sessions) of AC/DC TMS suppress both tinnitus distress (respectively 7.60% vs. 26.19%) and tinnitus intensity (respectively 7.12% vs. 19.60%) transiently. It was further shown that multiple sessions of AC/DC TMS generate a higher suppression effect in comparison to a single session of AC/DC TMS and that more patients responded to repeated sessions of 1 Hz stimulation in comparison to a single session. Our findings give further support to the fact that non-auditory areas are involved in tinnitus intensity and tinnitus distress and that more patients respond to repeated sessions with a higher suppression effect in comparison to patients who received a single session, suggesting that the approach of daily TMS sessions is relevant. (C) 2013 Elsevier Inc. All rights reserved.

s / Brain Stimulation 8 (2015) 343e359 349 learning paradigms, C57Bl6/J mice receive daily iTBS immediately prior to undergoing a skilled pellet-reaching task for 10 days. In a separate group; Thy1-GFPM mice undergo cranial window insertion overlying the right motor cortex to enable visualisation of excitatory cortical neurons in the upper layers of the motor cortex. Images of synaptic structures are collected at regular intervals before and after iTBS and analysed for alterations in connectivity resulting from stimulation. Preliminary analysis suggests daily iTBS significantly increases accuracy but not speed of pellet reaching, relative to sham stimulation (handling control). Preliminary analysis of the imaging data suggests a single session of iTBS does not alter dendritic spine density. These results will help characterise the biological mechanisms underlying rTMS, which will undoubtedly pave the way forward in the therapeutic applications of non-invasive brain stimulation in health and disease.