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P648: Transcutaneous spinal DC stimulation (tsDCS) modulates interhemispheric processing of motor and visual stimuli in a polarity-specific manner
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Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
allows a focal modification of cortical excitability in brain areas of interest and causes changes of corresponding neurophysiological functions associated with the stimulated brain areas. In our study we investigated the influences of the anodal tDCS of the prefrontal cortex on the clinical symptoms of adolescent ADHD as well as on the neuropsychological parameters: working memory, executive functions and attention. Methods: Sixteen adolescents with ADHD (12-16 years old) were treated according to the double-blind sham controlled cross-over design with anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC, 1mA, 20 min) and with the sham protocol (impedance control, no direct current, 20 min) 5 days each with a 2 weeks pause between these conditions. The first tDCS and sham stimulation were performed in the MR scanner combined with the working memory task during the fMRI (3 Tesla Siemens Trio). The influence of tDCS on the neuronal networks of attention, impulse inhibition and working memory was investigated. The clinical effects were evaluated by patients and their parents in standardized questionnaires (FBB-ADHS). The dynamik of neuropsychological parameters was studied using a computerized continuous working memory test (QbTest, QbTech, Sweden) each day during the treatment and one week after. Results: All 16 Patients tolerated the tDCS well. 5 Patients reported local sensation such as itching under the stimulation electrode, which occured during the tDCS as well as during the sham condition. A significant improvement of the reaction time variability was observed in tDCS and not in the sham condition. Corresponding activation of attention/working memory network was registered in the tDCS condition compared with sham stimulation. This activation was observed not ony in der brain area under the stimulating electrode (DLPFC) but also in brain areas remote from the stimulated region (inferior frontal gyrus, anterior cingulate). Conclusion: Anodal tDCS revealed significant clinical effects in ADHD. The neuropsychological changes in RT variability correlated with an activation of attention/working memory networks. This project expandes the perspective of a possible use of tDCS on the treatment of ADHD and other psychiatric disorders such as tics, anorexia and depression in children and adolescents.
P647 A dissociation between propriospinal facilitation and inhibition after bilateral transcranial direct current stimulation A. McCambridge 1 , W. Byblow 1,2 , J. Stinear 1,2 1 University of Auckland, Sport & Exercise Science, Auckland, New Zealand; 2 Centre for Brain Research, Auckland, New Zealand Propriospinal neurons receive bilateral input from both premotor cortex (PM) and primary motor cortex (M1) via the reticulospinal tract. In humans, the excitability of propriospinal neurons can be inferred by pairing an ascending volley from peripheral nerve stimulation and a descending volley from transcranial magnetic stimulation (TMS) to summate at the C3-C4 level. Previously conventional cathodal transcranial direct current stimulation (tDCS) was found to suppress C3-C4 propriospinal neuron excitability in the arm ipsilateral to stimulation (Bradnam et al. 2011). The effects of bilateral tDCS are unknown. The present study compared bilateral M1-M1 and PM-M1 tDCS effects on propriospinal excitability in the left arm. This was a randomised, double-blinded, sham-controlled study of 12 healthy adults (28.3 yrs, 5 males). Each participant received bilateral tDCS with the cathode over left PM or left M1, and the anode over right M1 in separate sessions (PM-M1, M1-M1 or Sham). Real tDCS stimulation was 1 mA for 15 mins. Sham stimulation was ramped down from 1 mA within 30 secs. TMS of right M1 elicited motor evoked potentials (MEPs) in left Biceps Brachii (BB) at a range of TMS intensities relative to active motor threshold (AMT). Left BB MEPs were conditioned by median nerve stimulation at an optimal interstimulus interval between 6 - 9 ms determined for each individual, and expressed as a ratio of conditioned/non-conditioned. Conditioned MEPs were facilitated (FAC, p<0.001) at TMS intensities near AMT, and inhibited (INH, p<0.001) at slightly higher intensities. After tDCS, FAC was reduced for M1-M1 tDCS compared to SHAM (p=0.039) but not after PM-M1 tDCS (p=0.67). INH was unchanged across all sessions. This pattern of results could mean that M1-M1 tDCS reduced basal facilitation of motor neurons via propriospinal neurons, while maintaining or sparing their inhibition, presumably via inhibitiory interneurons. Compared to single hemisphere stimulation, M1-M1 DCS may provide bilateral input to inhibitory interneurons allowing for more selective suppression of only facilitatory propriospinal inputs. Since propriospinal inputs can be up-
regulated in some patients after stroke (Stinear & Byblow, 2004), bilateral M1 tDCS may offer utility for promoting functional recovery of upper limb function.
P648 Transcutaneous spinal DC stimulation (tsDCS) modulates interhemispheric processing of motor and visual stimuli in a polarity-specific manner T. Bocci 1,2 , B. Vannini 1 , M. Caleo 3 , E. Giorli 1,2 , A. Priori 4 , M. Vergari 4 , F. Sartucci 1,3,5 1 Unit of Neurology, Department of Clinical and Experimental Medicine, Pisa, Italy; 2 Neurology and Clinical Neurophysiology Section, Department of Neurological and Neurosensorial Sciences, Siena, Italy; 3 CNR Neuroscience Institute, Pisa, Italy; 4 Fondazione IRCCS “Cà Granda” Ospedale Maggiore di Milano, Department of Medical-Surgical Pathophysiology and Transplants Section of Neurosciences, Milano, Italy; 5 Cisanello Neurology Unit, Department Clinical and Experimental Medicine, Pisa, Italy Question: Transcutaneous spinal Direct Current Stimulation (tsDCS) is a noninvasive technique based on the application of weak electrical currents over thoracic spinal cord. Although tsDCS can influence the conduction of spinal pathways and circuits, whether this technique can modulate human brain function is unclear. Here, we studied effects of tsDCS on interhemispheric processing of motor and visual stimuli by evaluating changes in duration of ipsilateral silent period (iSP) and in hemifield Visual Evoked Potentials (hVEPs) parameters. Methods: In eight volunteers we evaluated changes in iSP and hVEPs amplitude, latency and interhemispheric delay, before (T0 ) and at a different intervals (immediately after = T1 , 60’ = T2 ) after anodal and cathodal tsDCS (T10-T12 level, 2.0 mA, 20’). Motor Evoked Potentials (MEPs) were recorded from abductor digiti minimi (ADM) and abductor hallucis (AH). VEPs were recorded by reversal (1Hz) of a horizontal square wave grating (2c/deg) with the display positioned in the right hemifield. Results: Anodal tsDCS reduced iSP (one-way ANOVA, ADM: T0 vs. T1 : p=0.0002; T0 vs. T2 : p=0.0001) and shortened the interhemispheric delay for N1 (T0 vs. T1 : p=0.0006; T0 vs. T2 : p=0.017) and P1 potentials (T0 vs. T1 : p=0.0025; T0 vs. T2 : p=0.0006), while cathodal stimulation has opposite effects both on ADM iSP (ADM: T0 vs. T1 : p=0.0001; T0 vs. T2 : p=0.0006) and hVEPs (N1: T0 vs. T1 : p=0.04; T0 vs. T2 : p=0.005; P1: T0 vs. T1 : p=0.048; T0 vs. T2 : p=0.019). Conclusion: tsDCS seems to modulate interhemispheric processing of motor and visual stimuli in a polarity-specific manner: given the well-known inhibitory effect of anodal tsDCS, opposite from that induced by anodal transcranial direct current stimulation (tDCS), it may act at supraxial level also by dampening the callosal inhibitory input, then allowing a faster interhemispheric communication. tsDCS could be a new promising therapeutic tool in managing a number of human diseases characterized by an impaired interhemispheric balance, such as stroke, parkinsonisms and schizophrenia.
P649 Transcranial direct current stimulation (tDCS) of left parietal cortex facilitates gesture processing in healthy subjects E. Achilles 1,2 , P. Weiss-Blankenhorn 1,2 , K. Moos 1 , M.D. Hesse 1 , R. Sparing 3 , G.R. Fink 1,2 1 University Hospital Cologne, Neurology, Cologne, Germany; 2 Research Center Juelich, Cognitive Neuroscience, Juelich, Germany; 3 Helios Klinik Holthausen, Hattingen, Germany Question: Gesture processing deficits constitute a key symptom of apraxia, a disorder of motor cognition frequently observed after left-hemispheric stroke. The clinical relevance of apraxia stands in stark contrast to the paucity of therapeutic options available. Transcranial direct current stimulation (tDCS) is a promising tool for modulating disturbed network function after stroke. We here investigate the effect of parietal tDCS on gesture processing in healthy human subjects. Methods: Neuropsychological and imaging studies suggest that the imitation and matching of hand gestures involves the left inferior parietal lobe (IPL). Using neuronavigation based on cytoarchitectonically defined anatomical probability maps, tDCS was applied over left IPL areas PF, PFm or PG in healthy participants (n=26). Before and after tDCS subjects performed a gesture matching task and a person discrimination task for
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
allows a focal modification of cortical excitability in brain areas of interest and causes changes of corresponding neurophysiological functions associated with the stimulated brain areas. In our study we investigated the influences of the anodal tDCS of the prefrontal cortex on the clinical symptoms of adolescent ADHD as well as on the neuropsychological parameters: working memory, executive functions and attention. Methods: Sixteen adolescents with ADHD (12-16 years old) were treated according to the double-blind sham controlled cross-over design with anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC, 1mA, 20 min) and with the sham protocol (impedance control, no direct current, 20 min) 5 days each with a 2 weeks pause between these conditions. The first tDCS and sham stimulation were performed in the MR scanner combined with the working memory task during the fMRI (3 Tesla Siemens Trio). The influence of tDCS on the neuronal networks of attention, impulse inhibition and working memory was investigated. The clinical effects were evaluated by patients and their parents in standardized questionnaires (FBB-ADHS). The dynamik of neuropsychological parameters was studied using a computerized continuous working memory test (QbTest, QbTech, Sweden) each day during the treatment and one week after. Results: All 16 Patients tolerated the tDCS well. 5 Patients reported local sensation such as itching under the stimulation electrode, which occured during the tDCS as well as during the sham condition. A significant improvement of the reaction time variability was observed in tDCS and not in the sham condition. Corresponding activation of attention/working memory network was registered in the tDCS condition compared with sham stimulation. This activation was observed not ony in der brain area under the stimulating electrode (DLPFC) but also in brain areas remote from the stimulated region (inferior frontal gyrus, anterior cingulate). Conclusion: Anodal tDCS revealed significant clinical effects in ADHD. The neuropsychological changes in RT variability correlated with an activation of attention/working memory networks. This project expandes the perspective of a possible use of tDCS on the treatment of ADHD and other psychiatric disorders such as tics, anorexia and depression in children and adolescents.
P647 A dissociation between propriospinal facilitation and inhibition after bilateral transcranial direct current stimulation A. McCambridge 1 , W. Byblow 1,2 , J. Stinear 1,2 1 University of Auckland, Sport & Exercise Science, Auckland, New Zealand; 2 Centre for Brain Research, Auckland, New Zealand Propriospinal neurons receive bilateral input from both premotor cortex (PM) and primary motor cortex (M1) via the reticulospinal tract. In humans, the excitability of propriospinal neurons can be inferred by pairing an ascending volley from peripheral nerve stimulation and a descending volley from transcranial magnetic stimulation (TMS) to summate at the C3-C4 level. Previously conventional cathodal transcranial direct current stimulation (tDCS) was found to suppress C3-C4 propriospinal neuron excitability in the arm ipsilateral to stimulation (Bradnam et al. 2011). The effects of bilateral tDCS are unknown. The present study compared bilateral M1-M1 and PM-M1 tDCS effects on propriospinal excitability in the left arm. This was a randomised, double-blinded, sham-controlled study of 12 healthy adults (28.3 yrs, 5 males). Each participant received bilateral tDCS with the cathode over left PM or left M1, and the anode over right M1 in separate sessions (PM-M1, M1-M1 or Sham). Real tDCS stimulation was 1 mA for 15 mins. Sham stimulation was ramped down from 1 mA within 30 secs. TMS of right M1 elicited motor evoked potentials (MEPs) in left Biceps Brachii (BB) at a range of TMS intensities relative to active motor threshold (AMT). Left BB MEPs were conditioned by median nerve stimulation at an optimal interstimulus interval between 6 - 9 ms determined for each individual, and expressed as a ratio of conditioned/non-conditioned. Conditioned MEPs were facilitated (FAC, p<0.001) at TMS intensities near AMT, and inhibited (INH, p<0.001) at slightly higher intensities. After tDCS, FAC was reduced for M1-M1 tDCS compared to SHAM (p=0.039) but not after PM-M1 tDCS (p=0.67). INH was unchanged across all sessions. This pattern of results could mean that M1-M1 tDCS reduced basal facilitation of motor neurons via propriospinal neurons, while maintaining or sparing their inhibition, presumably via inhibitiory interneurons. Compared to single hemisphere stimulation, M1-M1 DCS may provide bilateral input to inhibitory interneurons allowing for more selective suppression of only facilitatory propriospinal inputs. Since propriospinal inputs can be up-
regulated in some patients after stroke (Stinear & Byblow, 2004), bilateral M1 tDCS may offer utility for promoting functional recovery of upper limb function.
P648 Transcutaneous spinal DC stimulation (tsDCS) modulates interhemispheric processing of motor and visual stimuli in a polarity-specific manner T. Bocci 1,2 , B. Vannini 1 , M. Caleo 3 , E. Giorli 1,2 , A. Priori 4 , M. Vergari 4 , F. Sartucci 1,3,5 1 Unit of Neurology, Department of Clinical and Experimental Medicine, Pisa, Italy; 2 Neurology and Clinical Neurophysiology Section, Department of Neurological and Neurosensorial Sciences, Siena, Italy; 3 CNR Neuroscience Institute, Pisa, Italy; 4 Fondazione IRCCS “Cà Granda” Ospedale Maggiore di Milano, Department of Medical-Surgical Pathophysiology and Transplants Section of Neurosciences, Milano, Italy; 5 Cisanello Neurology Unit, Department Clinical and Experimental Medicine, Pisa, Italy Question: Transcutaneous spinal Direct Current Stimulation (tsDCS) is a noninvasive technique based on the application of weak electrical currents over thoracic spinal cord. Although tsDCS can influence the conduction of spinal pathways and circuits, whether this technique can modulate human brain function is unclear. Here, we studied effects of tsDCS on interhemispheric processing of motor and visual stimuli by evaluating changes in duration of ipsilateral silent period (iSP) and in hemifield Visual Evoked Potentials (hVEPs) parameters. Methods: In eight volunteers we evaluated changes in iSP and hVEPs amplitude, latency and interhemispheric delay, before (T0 ) and at a different intervals (immediately after = T1 , 60’ = T2 ) after anodal and cathodal tsDCS (T10-T12 level, 2.0 mA, 20’). Motor Evoked Potentials (MEPs) were recorded from abductor digiti minimi (ADM) and abductor hallucis (AH). VEPs were recorded by reversal (1Hz) of a horizontal square wave grating (2c/deg) with the display positioned in the right hemifield. Results: Anodal tsDCS reduced iSP (one-way ANOVA, ADM: T0 vs. T1 : p=0.0002; T0 vs. T2 : p=0.0001) and shortened the interhemispheric delay for N1 (T0 vs. T1 : p=0.0006; T0 vs. T2 : p=0.017) and P1 potentials (T0 vs. T1 : p=0.0025; T0 vs. T2 : p=0.0006), while cathodal stimulation has opposite effects both on ADM iSP (ADM: T0 vs. T1 : p=0.0001; T0 vs. T2 : p=0.0006) and hVEPs (N1: T0 vs. T1 : p=0.04; T0 vs. T2 : p=0.005; P1: T0 vs. T1 : p=0.048; T0 vs. T2 : p=0.019). Conclusion: tsDCS seems to modulate interhemispheric processing of motor and visual stimuli in a polarity-specific manner: given the well-known inhibitory effect of anodal tsDCS, opposite from that induced by anodal transcranial direct current stimulation (tDCS), it may act at supraxial level also by dampening the callosal inhibitory input, then allowing a faster interhemispheric communication. tsDCS could be a new promising therapeutic tool in managing a number of human diseases characterized by an impaired interhemispheric balance, such as stroke, parkinsonisms and schizophrenia.
P649 Transcranial direct current stimulation (tDCS) of left parietal cortex facilitates gesture processing in healthy subjects E. Achilles 1,2 , P. Weiss-Blankenhorn 1,2 , K. Moos 1 , M.D. Hesse 1 , R. Sparing 3 , G.R. Fink 1,2 1 University Hospital Cologne, Neurology, Cologne, Germany; 2 Research Center Juelich, Cognitive Neuroscience, Juelich, Germany; 3 Helios Klinik Holthausen, Hattingen, Germany Question: Gesture processing deficits constitute a key symptom of apraxia, a disorder of motor cognition frequently observed after left-hemispheric stroke. The clinical relevance of apraxia stands in stark contrast to the paucity of therapeutic options available. Transcranial direct current stimulation (tDCS) is a promising tool for modulating disturbed network function after stroke. We here investigate the effect of parietal tDCS on gesture processing in healthy human subjects. Methods: Neuropsychological and imaging studies suggest that the imitation and matching of hand gestures involves the left inferior parietal lobe (IPL). Using neuronavigation based on cytoarchitectonically defined anatomical probability maps, tDCS was applied over left IPL areas PF, PFm or PG in healthy participants (n=26). Before and after tDCS subjects performed a gesture matching task and a person discrimination task for