Effects Of Cerebellar tDCS Research Articles

Protocol for Cerebellar Stimulation for Aphasia Rehabilitation (CeSAR): A randomized, double-blind, sham-controlled trial.

In this randomized, double-blind, sham-controlled trial of Cerebellar Stimulation for Aphasia Rehabilitation (CeSAR), we will determine the effectiveness of cathodal tDCS (transcranial direct current stimulation) to the right cerebellum for the treatment of chronic aphasia (>6 months post stroke). We will test the hypothesis that cerebellar tDCS in combination with an evidenced-based anomia treatment (semantic feature analysis, SFA) will be associated with greater improvement in naming untrained pictures (as measured by the change in Philadelphia Picture Naming Test), 1-week post-treatment, compared to sham plus SFA. We will also evaluate the effects of cerebellar tDCS on naming trained items as well as the effects on functional communication, content, efficiency, and word-retrieval of picture description, and quality of life. Finally, we will identify imaging and linguistic biomarkers to determine the characteristics of stroke patients that benefit from cerebellar tDCS and SFA treatment. We expect to enroll 60 participants over five years. Participants will receive 15, 25-minute sessions of cerebellar tDCS (3-5 sessions per week) or sham tDCS combined with 1 hour of SFA treatment. Participants will be evaluated prior to the start of treatment, one-week post-treatment, 1-, 3-, and 6-months post-treatment on primary and secondary outcome variables. The long-term aim of this study is to provide the basis for a Phase III randomized controlled trial of cerebellar tDCS vs sham with concurrent language therapy for treatment of chronic aphasia. Trial registration: The trial is registered with ClinicalTrials.gov NCT05093673.

Facilitation of sensorimotor temporal recalibration mechanisms by cerebellar tDCS in patients with schizophrenia spectrum disorders and healthy individuals

Core symptoms in patients with schizophrenia spectrum disorders (SSD), like hallucinations or ego-disturbances, have been associated with a failure of internal forward models to predict the sensory outcomes of self-generated actions. Importantly, forward model predictions must also be able to flexibly recalibrate to changing environmental conditions, for example to account for additional delays between action and outcome. We investigated whether transcranial direct current stimulation (tDCS) can be used to improve these sensorimotor temporal recalibration mechanisms in patients and healthy individuals. While receiving tDCS on the cerebellum, temporo-parietal junction, supplementary motor area, or sham stimulation, patients with SSD and healthy control participants were repeatedly exposed to delays between actively or passively elicited button presses and auditory outcomes. Effects of this procedure on temporal perception were assessed with a delay detection task. Similar recalibration outcomes and faciliatory effects of cerebellar tDCS on recalibration were observed in SSD and healthy individuals. Our findings indicate that sensorimotor recalibration mechanisms may be preserved in SSD and highlight the importance of the cerebellum in both patients and healthy individuals for this process. They further suggest that cerebellar tDCS could be a promising tool for addressing deficits in action-outcome monitoring and related adaptive sensorimotor processes in SSD.

Brain-behavior analysis of transcranial direct current stimulation effects on a complex surgical motor task.

Transcranial Direct Current Stimulation (tDCS) has demonstrated its potential in enhancing surgical training and performance compared to sham tDCS. However, optimizing its efficacy requires the selection of appropriate brain targets informed by neuroimaging and mechanistic understanding. Previous studies have established the feasibility of using portable brain imaging, combining functional near-infrared spectroscopy (fNIRS) with tDCS during Fundamentals of Laparoscopic Surgery (FLS) tasks. This allows concurrent monitoring of cortical activations. Building on these foundations, our study aimed to explore the multi-modal imaging of the brain response using fNIRS and electroencephalogram (EEG) to tDCS targeting the right cerebellar (CER) and left ventrolateral prefrontal cortex (PFC) during a challenging FLS suturing with intracorporeal knot tying task. Involving twelve novices with a medical/premedical background (age: 22-28 years, two males, 10 females with one female with left-hand dominance), our investigation sought mechanistic insights into tDCS effects on brain areas related to error-based learning, a fundamental skill acquisition mechanism. The results revealed that right CER tDCS applied to the posterior lobe elicited a statistically significant (q < 0.05) brain response in bilateral prefrontal areas at the onset of the FLS task, surpassing the response seen with sham tDCS. Additionally, right CER tDCS led to a significant (p < 0.05) improvement in FLS scores compared to sham tDCS. Conversely, the left PFC tDCS did not yield a statistically significant brain response or improvement in FLS performance. In conclusion, right CER tDCS demonstrated the activation of bilateral prefrontal brain areas, providing valuable mechanistic insights into the effects of CER tDCS on FLS peformance. These insights motivate future investigations into the effects of CER tDCS on error-related perception-action coupling through directed functional connectivity studies.

The Effect of Cerebellar tDCS on Static and Dynamic Balance of Inactive Elderly Men.

The aim of this study was investigating the effect of cerebellar transcranial direct current stimulation (tDCS) on static and dynamic balance of inactive older adults. Twenty-four older adults participated in this study. All participants underwent static and dynamic balance tests. In the Experimental group, anode electrode was positioned at the O point in the cerebellum and cathode electrode was positioned on the left eye socket (FP1). In the control group, the anode and cathode electrodes were positioned at O and FP1 points, respectively, but the current stimulation was stopped after 30 s. Then, the posttest was performed. Data analysis was done using MANCOVA. There was a significant difference between the Experimental and control groups in static balance (p = .12) and dynamic balance (p = .18) and the performance was better in the experimental group. It can be concluded that tDCS can improve static and dynamic balance in inactive older adults.

Trait aggression-dependent effects of cerebellar tDCS in a social dominance task

Trait aggression-dependent effects of cerebellar tDCS in a social dominance task

Effects of cerebellar transcranial direct current stimulation on upper limb motor function after stroke: study protocol for the pilot of a randomized controlled trial

BackgroundTranscranial direct current stimulation (tDCS) is a technique that can noninvasively modulate neural states in a targeted brain region. As cerebellar activity levels are associated with upper limb motor improvement after stroke, the cerebellum is a plausible target of tDCS. However, the effect of tDCS remains unclear. Here, we designed a pilot study to assess: (1) the feasibility of a study that aims to examine the effects of cerebellar tDCS combined with an intensive rehabilitation approach based on the concept of constraint-induced movement therapy (CIMT) and (2) the preliminary outcome of the combined approach on upper limb motor function in patients with stroke in the chronic stage.MethodsThis pilot study has a double-blind randomized controlled design. Twenty-four chronic stroke patients with mild to moderate levels of upper limb motor impairment will be randomly assigned to an active or sham tDCS group. The participants will receive 20 min of active or sham tDCS to the contralesional cerebellum at the commencement of 4 h of daily intensive training, repeatedly for 5 days per week for 2 weeks. The primary outcomes are recruitment, enrollment, protocol adherence, and retention rates and measures to evaluate the feasibility of the study. The secondary outcome is upper limb motor function which will be evaluated using the Action Research Arm Test, Fugl-Meyer Assessment, for the upper extremity and the Motor Activity Log. Additionally, neurophysiological and neuroanatomical assessments of the cerebellum will be performed using transcranial magnetic stimulation and magnetic resonance imaging. These assessments will be conducted before, at the middle, and after the 2-week intervention, and finally, 1 month after the intervention. Any adverse events that occur during the study will be recorded.DiscussionCerebellar tDCS combined with intensive upper limb training may increase the gains of motor improvement when compared to the sham condition. The present study should provide valuable evidence regarding the feasibility of the design and the efficacy of cerebellar tDCS for upper limb motor function in patients with stroke before a future large trial is conducted.Trial registrationThis study has been registered at the Japan Registry of Clinical Trials (jRCTs042200078). Registered 17 December 2020

Age- and task-dependent effects of cerebellar tDCS on manual dexterity and motor learning–A preliminary study

ObjectivesThe role of the cerebellum in motor learning of dexterous control and interaction with aging remains incompletely understood. We compared the effect of age and cerebellar transcranial direct current stimulation (CRB-tDCS) on motor learning in two different manual dexterity tasks, visuomotor force control vs. effector selection (independent finger movements). MethodsTwenty younger and 20 older adults were randomized (double-blinded) to anodal or sham CRB-tDCS during dexterity training over three consecutive days, and followed-up at day 10. Motor learning was measured as (i) overall learning (across 10 days), (ii) within-day (short-term) learning, (iii) between-day learning (consolidation), and (iv) retention (long-term learning; day 3 to day 10). ResultsYounger and older subjects showed significant overall learning in both tasks. Subjects with poor initial performance showed stronger learning. No effects of CRB-tDCS were observed in younger adults. A significant Age*CRB-tDCS interaction showed that CRB-tDCS improved within-day learning in finger independence (improved reaction time in effector selection) in older adults. However, a significant Age*CRB-tDCS interaction showed that CRB-tDCS impacted consolidation negatively in older subjects. No stimulation effects were found on retention. Finally, we found that degree of within-day learning in finger independence (change in reaction times) correlated with baseline (pre-training) reaction times in both young and old subjects. DiscussionThe results suggest that CRB-tDCS may improve short-term learning of manual dexterity in older adults in a task-dependent manner, specifically in difficult tasks requiring effector (action) selection. However, cerebellar tDCS stimulation may also interfere with consolidation in older subjects. These results need confirmation in a larger sample.

Combined effects of cerebellar tDCS and task-oriented circuit training in people with multiple sclerosis: A pilot randomized control trial.

Balance and mobility impairments are frequent in people with multiple sclerosis, partly due to cerebellar dysfunctions. Task-oriented behavioural approaches were previously shown to promote physical function. The possibility exists that cerebellar transcranial direct current stimulation (ctDCS) applied during training, known to increase the excitability of the brain, can boost rehabilitation effects through modulation of cerebellum-brain inhibition. To test the efficacy of cerebellar ctDCS stimulation combined with motor training on mobility and balance in people with multiple sclerosis. 16 subjects were randomly assigned to receive real- or sham-ctDCS and task-oriented training daily over two weeks in a double-blind, randomised clinical pilot trial. Functional mobility, balance, walking performance and quality of life were tested before and after treatment and at two-week follow-up. Effects of cerebellar stimulation on psychological and executive functions were also recorded. Walking performance, balance and quality of life improved for both groups at post-treatment assessment which was maintained at 2-weeks follow up. A two-way ANOVA revealed a significant time effect for balance and walking performance. A significant interaction effect of time-treatment (F = 3.12, df = 2,26; p = 0.03) was found for motor aspects of quality of life assessment in patients who received real-ctDCS. Task-oriented training improves balance and mobility in people with multiple sclerosis, but ctDCS does not boost motor training effects.

Effects of cerebellar tDCS on glycometabolic control

Effects of cerebellar tDCS on glycometabolic control

Long-term effects of cerebellar anodal transcranial direct current stimulation (tDCS) on the acquisition and extinction of conditioned eyeblink responses

Cerebellar transcranial direct current stimulation (tDCS) has been reported to enhance the acquisition of conditioned eyeblink responses (CR), a form of associative motor learning. The aim of the present study was to determine possible long-term effects of cerebellar tDCS on the acquisition and extinction of CRs. Delay eyeblink conditioning was performed in 40 young and healthy human participants. On day 1, 100 paired CS (conditioned stimulus)–US (unconditioned stimulus) trials were applied. During the first 50 paired CS–US trials, 20 participants received anodal cerebellar tDCS, and 20 participants received sham stimulation. On days 2, 8 and 29, 50 paired CS–US trials were applied, followed by 30 CS-only extinction trials on day 29. CR acquisition was not significantly different between anodal and sham groups. During extinction, CR incidences were significantly reduced in the anodal group compared to sham, indicating reduced retention. In the anodal group, learning related increase of CR magnitude tended to be reduced, and timing of CRs tended to be delayed. The present data do not confirm previous findings of enhanced acquisition of CRs induced by anodal cerebellar tDCS. Rather, the present findings suggest a detrimental effect of anodal cerebellar tDCS on CR retention and possibly CR performance.

Effects of cerebellar transcranial direct current stimulation (tDCS) on motor skill learning in swallowing

Objective This study evaluated the effects of cerebellar tDCS on motor learning for swallowing. Methods In a double-blind RCT, 39 healthy adults received either sham, anodal tDCS, or cathodal tDCS in two sessions on two consecutive days. Following 20 min cerebellar tDCS (2 mA) or sham, they underwent swallowing skill training that targeted control of timing and magnitude of submental muscle activation during swallowing. Linear mixed models were used to identify the effects of stimulation on timing and magnitude accuracy as measured by the change in task performance for each training session, and for skill retention on days 3 and 10 post-intervention. Results Only the sham group had a reduced temporal error from baseline to all following timepoints. When compared to error changes in the sham group, changes from baseline in temporal errors were higher at all timepoints post-intervention for the anodal group, and higher at both retention assessments for the cathodal group. Amplitude errors were smaller for all conditions at all timepoints post-intervention compared to baseline. Conclusions Cerebellar tDCS was found to inhibit temporal aspects of motor skill learning in swallowing. For the tDCS parameters used in this study, there is no support for use of tDCS to facilitate swallowing rehabilitation. Trial Registry Number (https://www.anzctr.org.au/): ACTRN12615000451505. IMPLICATIONS FOR REHABILITATION Cerebellar tDCS, in combination with motor skill training, has been demonstrated to increase motor skill learning in healthy individuals and neurologically impaired patients. In this study, cerebellar tDCS applied prior to swallowing skill training adversely affected timing measures of submental muscle activation during swallowing. In contrast to published outcomes in the corticospinal literature, both anodal and cathodal tDCS resulted in a relative inhibitory effect on motor skill learning in swallowing when compared to the sham condition. Swallowing skill training without tDCS produced increased accuracy in outcomes.

Lack of cerebellar tDCS effects on learning of a complex whole body dynamic balance task in middle-aged (50\u201365\u2009years) adults

BackgroundCerebellar transcranial direct current stimulation (tDCS) is widely considered as a promising non-invasive tool to foster motor performance and learning in health and disease. The results of previous studies, however, are inconsistent. Our group failed to provide evidence for an effect of cerebellar tDCS on learning of a complex whole body dynamic balance task in young and healthy participants. Ceiling effects in the young study population are one possible explanation for the negative findings.MethodsIn the present study, we therefore tested 40 middle-aged healthy participants between the ages of 50 to 65 years. Participants received either anodal or sham cerebellar tDCS using a double-blinded study design while performing a balance task on a Lafayette Instrument 16,030 stability platform®. Mean platform angle and mean balance time were assessed as outcome measures.ResultsSignificant learning effects were found in all participants. Balancing performance and learning rate was significantly less in the group of middle-aged adults compared to our previous group of young adults. No significant effects of cerebellar tDCS were observed.ConclusionsOur findings are in line with other studies that have failed to prove robust effects of cerebellar tDCS on motor learning. The present findings, however, do not exclude cerebellar tDCS effects. tDCS effects may be more prominent after repeated stimulation, using other stimulus parameters, in patient populations, or in other motor learning tasks.Trial registrationNot applicable.

Beneficial effects of cerebellar tDCS on motor learning are associated with altered putamen-cerebellar connectivity: A simultaneous tDCS-fMRI study

Non-invasive transcranial stimulation of cerebellum and primary motor cortex (M1) has been shown to enhance motor learning. However, the mechanisms by which stimulation improves learning remain largely unknown. Here, we sought to shed light on the neural correlates of transcranial direct current stimulation (tDCS) during motor learning by simultaneously recording functional magnetic resonance imaging (fMRI). We found that right cerebellar tDCS, but not left M1 tDCS, led to enhanced sequence learning in the serial reaction time task. Performance was also improved following cerebellar tDCS compared to sham in a sequence production task, reflecting superior training effects persisting into the post-training period. These behavioral effects were accompanied by increased learning-specific activity in right M1, left cerebellum lobule VI, left inferior frontal gyrus and right inferior parietal lobule during cerebellar tDCS compared to sham. Despite the lack of group-level changes comparing left M1 tDCS to sham, activity increase in right M1, supplementary motor area, and bilateral middle frontal cortex, under M1 tDCS, was associated with better sequence performance. This suggests that lack of group effects in M1 tDCS relate to inter-individual variability in learning-related activation patterns. We further investigated how tDCS modulates effective connectivity in the cortico-striato-cerebellar learning network. Using dynamic causal modelling, we found altered connectivity patterns during both M1 and cerebellar tDCS when compared to sham. Specifically, during cerebellar tDCS, negative modulation of a connection from putamen to cerebellum was decreased for sequence learning only, effectively leading to decreased inhibition of the cerebellum. These results show specific effects of cerebellar tDCS on functional activity and connectivity in the motor learning network and may facilitate the optimization of motor rehabilitation involving cerebellar non-invasive stimulation.

Effects of Cerebellar tDCS on Inhibitory Control: Evidence from a Go/NoGo Task

Response inhibition as an executive function refers to the ability to suppress inappropriate but prepotent responses. Several brain regions have been implicated in the process underlying inhibitory control, including the cerebellum. The aim of the present study was to explore the role of the cerebellum in executive functioning, particularly in response inhibition. For this purpose, we transitorily inhibited cerebellar activity by means of cathodal tDCS and studied the effects of this inhibition on ERP components elicited during a Go/NoGo task in healthy subjects. Sixteen healthy subjects underwent a Go/NoGo task prior to and after cathodal and sham cerebellar tDCS in separate sessions. A reduction in N2-NoGo amplitude and a prolongation in N2-NoGo latency emerged after cathodal tDCS whereas no differences were detected after sham stimulation. Moreover, commission errors in NoGo trials were significantly higher after cathodal tDCS than at the basal evaluation. No differences emerged between performances in Go trials and those after sham stimulation. These data indicate that cerebellar inhibition following cathodal stimulation alters the ability to allocate attentional resources to stimuli containing conflict information and the inhibitory control. The cerebellum may regulate the attentional mechanisms of stimulus orientation and inhibitory control both directly, by making predictions of errors or behaviors related to errors, and indirectly, by controlling the functioning of the cerebral cortical areas involved in the perception of conflict signals and of the basal ganglia involved in the inhibitory control of movement.

Prefrontal but not cerebellar tDCS attenuates renewal of extinguished conditioned eyeblink responses.

An extended neural network is known to underlie extinction learning. As yet, comparatively little is known about the possible contribution of the cerebellum and the dorsolateral prefrontal cortex (dlPFC). In the present study, transcranial direct current stimulation (tDCS) was used to provide further evidence that the dlPFC and the cerebellum are involved in extinction-related processes. A total of 100 young and healthy human participants were randomly assigned to one of five stimulation groups: (1) anodal tDCS of the cerebellum, (2) cathodal tDCS of the cerebellum, (3) anodal tDCS of the dlPFC, (4) cathodal tDCS of the dlPFC, and (5) sham stimulation. Participants underwent delay eyeblink conditioning using an A-B-A/B renewal paradigm. Two different colors of background light (orange and blue) were used as contexts. On day 1, acquisition of conditioned eyeblink responses was performed in context A, followed by extinction in context B. tDCS was applied during extinction. On day 2, extinction recall was tested in contexts A and B with higher incidence of conditioned responses in acquisition context A compared to extinction context B indicating renewal effects. All groups showed significant effects of acquisition of conditioned eyeblink responses and significant effects of extinction. There was no significant difference in extinction between stimulation groups. During extinction recall, renewal effects were present in all groups, except the group which had received anodal tDCS of the dlPFC during extinction. In the present study, no direct effects of dlPFC or cerebellar tDCS were demonstrated on extinction. Anodal tDCS of the dlPFC, but not the cerebellum, resulted in delayed effects on context-related processes of extinction, possibly explained by shifting attention away from the context and towards the conditioned stimulus during extinction learning. Anodal tDCS of the dlPFC attenuated context-related recall of learned aversive responses. Effects of tDCS, however, were weak and need to be confirmed in future studies. Lack of cerebellar tDCS effects do not exclude a possible role of the cerebellum in extinction-related processes, and are likely explained by methodological limitations of cerebellar tDCS.

The Effect of Cerebellar tDCS on Sequential Motor Response Selection

Transcranial direct current stimulation (tDCS) transiently alters cortical excitability and synaptic plasticity. So far, few studies have investigated the behavioral effects of applying tDCS to the cerebellum. Given the cerebellum’s inhibitory effects on cortical motor areas as well as its role in fine motor control and motor coordination, we investigated whether cerebellar tDCS can modulate response selection processes and motor sequence learning. Seventy-two participants received either cerebellar anodal (excitatory), cathodal (inhibitory), or sham (placebo) tDCS while performing a serial reaction time task (SRTT). To compare acute and long-term effects of stimulation on behavioral performance, participants came back for follow-up testing at 24 h after stimulation. Results indicated no group differences in performance prior to tDCS. During stimulation, tDCS did not affect sequence-specific learning, but anodal as compared to cathodal and sham stimulations did modulate response selection processes. Specifically, anodal tDCS increased response latencies independent of whether a trained or transfer sequence was being performed, although this effect became smaller throughout training. At the 24-h follow-up, the group that previously received anodal tDCS again demonstrated increased response latencies, but only when the previously trained sequence and a transfer sequence had to be performed in the same experimental block. This increased behavioral interference tentatively points to a detrimental effect of anodal cerebellar tDCS on sequence consolidation/retention. These results are consistent with the notion that the cerebellum exerts an inhibitory effect on cortical motor areas, which can impair sequential response selection when this inhibition is strengthened by tDCS.

No effects of cerebellar transcranial direct current stimulation on force field and visuomotor reach adaptation in young and healthy subjects.

Previous studies have shown that cerebellar transcranial direct current stimulation (tDCS) leads to faster adaptation of arm reaching movements to visuomotor rotation and force field perturbations in healthy subjects. The first aim of the present study was to confirm a stimulation-dependent effect on motor adaptation. Second, we investigated whether tDCS effects differ depending on onset, that is, before or at the beginning of the adaptation phase. A total of 120 healthy and right-handed subjects (60 women, mean age 23.2 ± SD 2.7 yr, range 18-31 yr) were tested. Subjects moved a cursor with a manipulandum to one of eight targets presented on a vertically orientated screen. Three baseline blocks were followed by one adaptation block and three washout blocks. Sixty subjects did a force field adaptation task (FF), and 60 subjects did a visuomotor adaptation task (VM). Equal numbers of subjects received anodal, cathodal, or sham cerebellar tDCS beginning either in the third baseline block or at the start of the adaptation block. In FF and VM, tDCS and the onset of tDCS did not show a significant effect on motor adaptation (all P values >0.05). We were unable to support previous findings of modulatory cerebellar tDCS effects in reaching adaptation tasks in healthy subjects. Prior to possible application in patients with cerebellar disease, future experiments are needed to determine which tDCS and task parameters lead to robust tDCS effects. NEW & NOTEWORTHY Transcranial direct current stimulation (tDCS) is a promising tool to improve motor learning. We investigated whether cerebellar tDCS improves motor learning in force field and visuomotor tasks in healthy subjects and what influence the onset of stimulation has. We did not find stimulation effects of tDCS or an effect of onset of stimulation. A reevaluation of cerebellar tDCS in healthy subjects and at the end of the clinical potential in cerebellar patients is demanded.

P104. The impact of timing of cerebellar anodal transcranial direct current stimulation on motor performance in a sequential finger tapping task

Background Transcranial direct current stimulation (tDCS) of the cerebellum could constitute an innovative approach in understanding the role of cerebellar function in healthy and pathological conditions. Recently, attention has grown toward cerebellar neuromodulation in motor learning using tDCS. An important point of discussion regarding this modulation is the optimal timing of tDCS. As this parameter could significantly influence the outcome, we aimed to compare the effect of anodal cerebellar tDCS applied at different times on the motor performance and retention using a sequential finger tapping task (FTT). Methods Fifty-six healthy young, right-handed subjects performed two days of FTT on a custom keyboard. The task was presented with OpenSesame software and lasted 40 s followed by 20 s rest forming one trial. Each participant performed 20 trials on the first day (20 min) and 10 trials on the following one (10 min). tDCS (2 mA, sponge electrodes of 25 cm2, duration 20 min) was applied to the ipsilateral cerebellar hemisphere on day 1 at the following times: (1) before ‘tDCS-before’, (2) sham during ‘tDCS-sham’, (3) active during ‘tDCS-active’ or (4) after the training ‘tDCS-after’. Motor skill performance and retention were assessed. Results All participants showed significant effects of learning ( p 0.0001 ). The mean performance on day 1 was significantly different ( p 0.0001 ): The tDCS-after group performed better than all the other groups, whereas the tDCS-active group performed worse than the tDCS-before group. Similarly, there was a significant difference in the mean performance on day 2 ( p 0.0001 ): tDCS-after was associated with a better performance on day 2, compared to tDCS-sham and tDCS-active. The tDCS-before group also performed better than the tDCS-sham or the tDCS-active groups. Motor skill retention was not different between the groups (p = 0.15). Discussion Cerebellar tDCS applied during the FTT (‘on-line’) interfered with task execution, resulting in an impaired performance on days 1 and 2 compared to the other groups. This inhibitory effect of anodal tDCS may caution against a simple transfer of tDCS’ effects on the motor cortex to regions with a different architecture like the cerebellum. It calls for a careful attention to the timing of stimulation when designing experiments with tDCS. Cerebellar tDCS did not facilitate the retention of the motor skill in the FTT – however, it cannot be excluded that young healthy subjects already performed at a near optimal level with little room for further improvement. Future work will evaluate the effect of cerebellar tDCS in a population where motor learning and cerebellar volume are known to decline.

Short-Term Effects of Cerebellar tDCS on Standing Balance Performance in Patients with Chronic Stroke and Healthy Age-Matched Elderly

Transcranial direct current stimulation (tDCS) may serve as an adjunct approach in stroke rehabilitation. The cerebellum could be a target during standing balance training due to its role in motor adaptation. We tested whether cerebellar tDCS can lead to short-term effects on standing balance performance in patients with chronic stroke. Fifteen patients with a chronic stroke were stimulated with anodal stimulation on the contra-lesional cerebellar hemisphere, ipsi-lesional cerebellar hemisphere, or sham stimulation, for 20 min with 1.5 mA in three sessions in randomized order. Ten healthy controls participated in two sessions with cerebellar stimulation ipsi-lateral to their dominant leg or sham stimulation. During stimulation, subjects performed a medio-lateral postural tracking task on a force platform. Standing balance performance was measured directly before and after each training session in several standing positions. Outcomes were center of pressure (CoP) amplitude and its standard deviation, and velocity and its standard deviation and range, subsequently combined into a CoP composite score (comp-score) as a qualitative outcome parameter. In the patient group, a decrease in comp-score in the tandem position was found after contra-lesional tDCS: β = − 0.25, CI = − 0.48 to − 0.03, p = 0.03. No significant differences in demographics and clinical characteristics were found between patients who responded (N = 10) and patients who did not respond (N = 5) to the stimulation. Contra-lesional cerebellar tDCS shows promise for improving standing balance performance. Exploration of optimal timing, dose, and the relation between qualitative parameters and clinical improvements are needed to establish whether tDCS can augment standing balance performance after stroke.

S206. Cerebellar Transcranial Direct Current Stimulation (tDCS) Improves Procedural Learning in Non-Clinical Psychosis

Literature suggests that cerebellar dysfunction may contribute to motor learning deficits characteristic of psychosis. Transcranial direct current stimulation (tDCS) may provide a non-invasive way of normalizing cerebellar function. While studies targeting other brain regions with tDCS (e.g. dorsal lateral prefrontal cortex) have observed improvements in both symptomatology and cognition among patients with schizophrenia, to date there have been no investigations examining cerebellar stimulation or procedural learning in a psychosis or psychosis risk population. The present double-blind crossover study examines the effects of cerebellar tDCS in controls and in an analogue population to psychosis: individuals reporting elevated symptoms of non-clinical psychosis (NCP).