Contralesional cathodal tDCS appears feasible and well tolerated in childhood stroke patients. Additional safety trials with careful consideration of dosing, neurophysiology, and other variables are warranted. 3 Polarity-dependent effects of trans-cranial direct current stimulation (tDCS) in cerebellar learning depends on the state of neuronal network Suman Das a,b, * , Peter Holland b , Martijn Schonewille b , Chris de Zeeuw b , Maarten A. Frens b , Opher Donchin a,b a Department of Bio-medical Engineering, BGU, Beer Sheva, Israel b Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands *E-mail: s.das@erasmusmc.nl. Polarity-dependent modulation of network activity makes trans- cranial direct current stimulation (tDCS) increasingly popular as a promising possibility for non-invasive therapeutic interventions, in a wide range of neurological and psychiatric disorders. However, a thorough understanding of the neuronal mechanisms through which tDCS acts is needed to understand its clinical potential, as well as to maximize effects. As a step towards building such an understanding, we explored (i) how mutations in cerebellar cir- cuitry aff5ct the behavioral efficacy of tDCS and (ii) how neural activity reflects tDCS efficacy in both normal and mutated cere- bellum. We have focused specifically on efficacy of tDCS in modu- lating gain-down vestibule-occular reflex (VOR) adaptation, and compared the effects of tDCS on Parallel fiber (PF) and Purkinje cell (PC) long term potentiation (LTP) impaired mutants. In wild type mice, low intensity (113 mAmp for 10 min) anodal stimulation fa- cilitates learning whereas; low intensity cathodal stimulation pro- duces results indistinguishable from sham stimulation. Increasing the intensity of anodal stimulus-intensity further accelerates learning. In contrast, higher cathodal stimulation decreases both leaning rate and the total amount of learning. Strikingly, mice in which LTP at the PF-PC synapse is impaired showed the opposite effect: anodal stimulation have little effect while cathodal stimu- lation improved learning. Anodal stimulation increases neuronal firing rates, and cathodal stimulation reduces firing rates in awake non-behaving mice. Additionally, the effect of cathodal current has a longer post-stimulation duration than anodal current. Further analysis is needed to show the reversal effect in neuronal firing in mutants to correlate the altered behavioral response. 4 Far Field Effects of Cortical tDCS in the Cerebellum may Contribute to its Effects on Learning. Aaron P. Jones a,b,c,d, * , Michael Trumbo a,b , Brian Coffman a,b,c,f , Michael A. Hunter a,b,c,d,e , Alexander David g , Marom Bikson g , Vincent P. Clark a,b,c a Psychology Clinical Neuroscience Center, The University of New Mexico, Albuquerque, NM, USA b Department of Psychology, The University of New Mexico, Albuquerque, NM, USA c The Mind Research Network and LRRI, Albuquerque, NM, USA d Department of Psychiatry, The University of New Mexico School of Medicine, Albuquerque, NM, USA e New Mexico Raymond G. Murphy VA Healthcare System, Albuquerque, NM, USA f Department of Neurosciences, The University of New Mexico, Albuquerque, NM, USA g Department of Biomedical Engineering, The City College of New York, New York, NY, USA *E-mail: aaronjones@unm.edu. In previous studies, we have used imaging and tDCS to examine the brain basis of learning to detect objects hidden in a complex visual environment. Learning this task resulted in increased activity in right lateral frontal and parietal cortices, and reduced activity in occipital-temporal regions bilaterally. We hypothesized that anodal and cathodal stimulation over regions showing increased and decreased activity with learning, respectively, would both result in increased performance. In agreement with this, we found that both anodal F10 or P4 vs. cathodal contralateral arm stimulation (Clark et al., 2012; Coffman et al. 2012; Falcone et al. 2012), and cathodal T5 vs. anodal left arm stimulation were associated with increased performance (Clark et al., 2013). However, F10 anode vs. T5 cathode did not result in significantly increased performance. Modeling of these showed that the effective protocols using scalp vs. left arm electrodes produced effects in the cerebellum (with opposite po- larities), but the ineffective protocol (F10 anode vs. T5 cathode) did not. Therefore, it’s possible that the observed effects of tDCS on learning might have resulted from an effect of stimulation on the cerebellum, rather than an effect on cortex, or a combination of cerebellum and cortex. Cerebellar stimulation has previously been used to modulate motor control, cognition, learning, and aff5ct (Ferrucci et. al., 2013), all of which might influence performance on this task. We are currently planning studies to compare the effects of cerebellar vs. cortical stimulation on learning and performance of this task. 5 Efficacy of tDCS for Treating Working Memory Dysfunction and Depression in Patients with Temporal Lobe Epilepsy A. Jefferson a, * , A. Byant a , O. Devinsky a , H. Fusco a , M. Shafi b , W. Barr a , D. Friedman a , D. Press b , S. Herman b , M. O’Connor b , S.S. Schachter b , A. Pascual-Leone b , A.A. Liu a a NYU Comprehensive Epilepsy Center, New York University Langone Medical Center, New York, NY b Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA *E-mail: aj1141@nyu.edu. Background: Working memory dysfunction and depression are common complaints in patients with temporal lobe epilepsy. Pre- vious pilot studies have suggested that transcranial direct current stimulation (tDCS) can improve working memory and mood in healthy and neurologically impaired subjects. We aimed to deter- mine whether tDCS would improve working memory, mood, and quality of life in individuals with temporal lobe epilepsy. Methods: This is a randomized, double-blinded, sham-controlled pilot study with 24 adult patients (ages 18-62) with well-controlled temporal lobe epilepsy. Subjects randomized to the active tDCS arm received 5 consecutive sessions of 2 mA of direct current for 20 minutes. Anode was placed over the left dorsolateral prefrontal cortex (DLPFC) and cathode over the right supraorbital area. Verbal and visuospatial working memory (Rey Auditory Verbal Learning Test, Letter-Number Sequencing, Digit Span, Tower of London, Spatial Span), mood (Beck Depression Inventory, Neurological Dis- orders Depression Inventory for Epilepsy), quality of life (Quality of Life in Epilepsy), and seizure frequency were measured at baseline and after the last stimulation session. Results: Subjects randomized to the treatment arm were similar in educational background, verbal IQ, seizure frequency, and baseline working memory and mood scores compared to control subjects. Subjects receiving active tDCS demonstrated a significant Abstracts / Brain Stimulation 7 (2014) e1ee16 e3 View publication stats View publication stats