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Hemispace Matters in Normal Individuals: Effects of Gaze and Hand Location on Corticospinal Excitability
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Abstracts / Brain Stimulation 10 (2017) e1–e19
demonstrated an increase in BOLD response within and around the US beam maxima; 33% showed no discernible BOLD activation pattern to US stimulation and 17% demonstrated a combination of increased and decreased BOLD response in the general area of the US beam axes. These results, though variable, suggest that focused ultrasound can induce detectable BOLD signature changes in humans but that optimization of signal to noise ratios is necessary and refinement of US stimulus parameters is likely needed to induce stable and detectable effect across subjects.
17 THE INFLUENCE OF TRANSCRANIAL ALTERNATING CURRENT STIMULATION AT 10 HZ ON SUSTAINED VISUAL ATTENTION
19 A RANDOMIZED CONTROLLED PILOT TRIAL SUGGESTING THAT CATHODAL BI-FRONTAL TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS) MAY SHORTEN SLEEP ONSET LATENCY, AND INCREASE SLEEP EFFICIENCY WHEN APPLIED BEFORE AN AFTERNOON NAP Gregory L. Sahlem a,b, *, Bashar W. Badran a,b , Emily Peyton a,b , Matthew T. Reeves a,b , Kimberly Leslie a,b , Jonathan J. Halford b,c , David Bachman b,c , Thomas W. Uhde a,b , Jeffery J. Borckardt a,b , Mark S. George a,b,c,d. a Departments of Psychiatry, Medical University of South Carolina, Charleston, SC, USA; b Public Health Sciences, Medical University of South Carolina, Charleston, SC, USA; c Neurology, Medical University of South Carolina, Charleston, SC, USA; d Ralph H. Johnson VA Medical Center, Charleston, SC, USA * Corresponding author.
Michael S. Clayton *, Nick Yeung, Roi Cohen Kadosh. Department of Experimental Psychology, University of Oxford, UK * Corresponding author. Alpha oscillations in sensorimotor cortex have been strongly linked with inhibition of processing. During sustained visual attention tasks, alpha power in occipito-parietal cortices correlates positively with error rates. However, this evidence is only correlational, and the causal role of posterior alpha oscillations in sustained attention remains largely undetermined. We use transcranial alternating current stimulation (tACS) to address this issue. We deliver tACS at 10 Hz to occipital cortex while subjects perform the Continuous Temporal Expectancy Task (a sustained visual attention task). We predict that this stimulation will cause an impairment in task performance.
18 HEMISPACE MATTERS IN NORMAL INDIVIDUALS: EFFECTS OF GAZE AND HAND LOCATION ON CORTICOSPINAL EXCITABILITY Matthieu M. de Wit a,*, Olufunsho K. Faseyitan b, H. Branch Coslett a,b. a Moss Rehabilitation Research Institute, Elkins Park, Pennsylvania, USA; b Department of Neurology, University of Pennsylvania School of Medicine, Pennsylvania, USA * Corresponding author. Effects of hemispace on perception and action are commonly observed in stroke survivors. In the hemispatial neglect syndrome, for example, patients fail to reliably perceive, orient to or initiate action towards stimuli in contralesional space. Stimulus location may also affect higher-level cognitive processes like language, however. Effects of hemispace on perception and action have not been extensively explored in normal individuals. Using single-pulse transcranial magnetic stimulation (TMS) over primary motor cortex, the present study examined hemispace effects on motor evoked potentials (MEPs). Normal right-handers (N = 20) placed their right hand 20 cm to the left or right of the body midline while looking either at their hand or a dot 20 cm to the right or left of the midline. There were 4 conditions generated by crossing hand location and gaze. MEPs were significantly larger when gaze was directed towards right hemispace, and when gaze and hand were dissociated (e.g., hand on right, gaze to left). The same effect was observed in a different group of righthanders (N = 17) in whom MEPs were measured in the left hand. Thus, we observed effects of the location of hand placement and gaze in the absence of any overt task. These data are consistent with accounts that postulate that egocentric location is crucial to sensorymotor processing even when location is not relevant to the task at hand. The findings also have methodological implications for the design of TMS motor studies that typically do not control for gaze or hand location relative to the body.
Background: Previous studies have demonstrated that a BiFrontal (F3/F4) negative direct current (DC) potential shift precedes sleep onset. Transcranial Direct Current Stimulation (tDCS) is a noninvasive form of brain stimulation capable of inducing DC potential shifts. We explored the effect of applying Anodal, Cathodal, or Sham tDCS prior to afternoon nap opportunities. Methods: Ten healthy participants (Age 32.1 ± 9.7SD, 7 women) each underwent three 30-minute afternoon naps with at least 48 hours between each nap opportunity. Immediately before each nap they received 10 minutes of (Anodal, Cathodal, or Sham) Bi-Frontal (F3/ F4) tDCS at 2 mA with return lead at the arm, delivered through saline soaked sponges (current density 0.057 mA/cm2). Primary outcome measures included Sleep Onset Latency (SOL), and Sleep Efficiency (SE) as measured by Polysomnography (PSG). Results: As we hypothesized, participants receiving Cathodal stimulation prior to a nap opportunity had a mathematical but not statistically significant reduction in SOL, and an increase in SE. SOL(Cathodal 9.6 ± 8.2SD Mins; Anodal 11.8 ± 11.3SD Mins; Sham 12.5 ± 10.3SD Mins), SE (Cathodal 61.2% ± 27.8SD; Anodal 51.8% ± 34.1SD; Sham 46.8% ± 31.8SD). The results were confounded by a clear order effect (Participants had reduced SOL and increased SE on the third nap opportunity compared to the first or second.). Conclusions: This preliminary evidence suggests that the use of Cathodal Bi-Frontal tDCS is feasible and safe and may increase sleep propensity in healthy participants during an afternoon nap, however further study with a larger sample is needed to definitively prove or disprove this hypothesis. Acknowledgments: NIDA R25 DA020537-06 (PI’s Back and Brady), MUSC Department of Psychiatry Chairs Research Development Fund, MUSC Sleep and Anxiety Treatment and Research Program. Clinicaltrials.gov registry #:NCT02176785 20 EFFECTS ON EEG DYNAMICS BY WEAK ELECTRIC FIELDS FROM SHAM TMS Jerel Mueller a,*, Alexander Opitz b,c,d, Wynn Legon e, Walter Paulus b, William Tyler f. a School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA, 24061, USA; b Department of Clinical Neurophysiology, Georg-August-University, Göttingen, 37075, Germany; c Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA; d Center for the Developing Brain, Child Mind Institute, New York, NY 10022, USA; e Department of Physical Medicine and Rehabilitation, University of Minnesota, Minneapolis, MN 55455, USA; f School of Biological and Health Systems Engineering, Arizona State University, Phoenix, AZ, 85287, USA * Corresponding author. Weak electric fields from both transcranial DC and AC stimulation have been shown to transiently alter cortical excitability. Despite this,
Abstracts / Brain Stimulation 10 (2017) e1–e19
demonstrated an increase in BOLD response within and around the US beam maxima; 33% showed no discernible BOLD activation pattern to US stimulation and 17% demonstrated a combination of increased and decreased BOLD response in the general area of the US beam axes. These results, though variable, suggest that focused ultrasound can induce detectable BOLD signature changes in humans but that optimization of signal to noise ratios is necessary and refinement of US stimulus parameters is likely needed to induce stable and detectable effect across subjects.
17 THE INFLUENCE OF TRANSCRANIAL ALTERNATING CURRENT STIMULATION AT 10 HZ ON SUSTAINED VISUAL ATTENTION
19 A RANDOMIZED CONTROLLED PILOT TRIAL SUGGESTING THAT CATHODAL BI-FRONTAL TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS) MAY SHORTEN SLEEP ONSET LATENCY, AND INCREASE SLEEP EFFICIENCY WHEN APPLIED BEFORE AN AFTERNOON NAP Gregory L. Sahlem a,b, *, Bashar W. Badran a,b , Emily Peyton a,b , Matthew T. Reeves a,b , Kimberly Leslie a,b , Jonathan J. Halford b,c , David Bachman b,c , Thomas W. Uhde a,b , Jeffery J. Borckardt a,b , Mark S. George a,b,c,d. a Departments of Psychiatry, Medical University of South Carolina, Charleston, SC, USA; b Public Health Sciences, Medical University of South Carolina, Charleston, SC, USA; c Neurology, Medical University of South Carolina, Charleston, SC, USA; d Ralph H. Johnson VA Medical Center, Charleston, SC, USA * Corresponding author.
Michael S. Clayton *, Nick Yeung, Roi Cohen Kadosh. Department of Experimental Psychology, University of Oxford, UK * Corresponding author. Alpha oscillations in sensorimotor cortex have been strongly linked with inhibition of processing. During sustained visual attention tasks, alpha power in occipito-parietal cortices correlates positively with error rates. However, this evidence is only correlational, and the causal role of posterior alpha oscillations in sustained attention remains largely undetermined. We use transcranial alternating current stimulation (tACS) to address this issue. We deliver tACS at 10 Hz to occipital cortex while subjects perform the Continuous Temporal Expectancy Task (a sustained visual attention task). We predict that this stimulation will cause an impairment in task performance.
18 HEMISPACE MATTERS IN NORMAL INDIVIDUALS: EFFECTS OF GAZE AND HAND LOCATION ON CORTICOSPINAL EXCITABILITY Matthieu M. de Wit a,*, Olufunsho K. Faseyitan b, H. Branch Coslett a,b. a Moss Rehabilitation Research Institute, Elkins Park, Pennsylvania, USA; b Department of Neurology, University of Pennsylvania School of Medicine, Pennsylvania, USA * Corresponding author. Effects of hemispace on perception and action are commonly observed in stroke survivors. In the hemispatial neglect syndrome, for example, patients fail to reliably perceive, orient to or initiate action towards stimuli in contralesional space. Stimulus location may also affect higher-level cognitive processes like language, however. Effects of hemispace on perception and action have not been extensively explored in normal individuals. Using single-pulse transcranial magnetic stimulation (TMS) over primary motor cortex, the present study examined hemispace effects on motor evoked potentials (MEPs). Normal right-handers (N = 20) placed their right hand 20 cm to the left or right of the body midline while looking either at their hand or a dot 20 cm to the right or left of the midline. There were 4 conditions generated by crossing hand location and gaze. MEPs were significantly larger when gaze was directed towards right hemispace, and when gaze and hand were dissociated (e.g., hand on right, gaze to left). The same effect was observed in a different group of righthanders (N = 17) in whom MEPs were measured in the left hand. Thus, we observed effects of the location of hand placement and gaze in the absence of any overt task. These data are consistent with accounts that postulate that egocentric location is crucial to sensorymotor processing even when location is not relevant to the task at hand. The findings also have methodological implications for the design of TMS motor studies that typically do not control for gaze or hand location relative to the body.
Background: Previous studies have demonstrated that a BiFrontal (F3/F4) negative direct current (DC) potential shift precedes sleep onset. Transcranial Direct Current Stimulation (tDCS) is a noninvasive form of brain stimulation capable of inducing DC potential shifts. We explored the effect of applying Anodal, Cathodal, or Sham tDCS prior to afternoon nap opportunities. Methods: Ten healthy participants (Age 32.1 ± 9.7SD, 7 women) each underwent three 30-minute afternoon naps with at least 48 hours between each nap opportunity. Immediately before each nap they received 10 minutes of (Anodal, Cathodal, or Sham) Bi-Frontal (F3/ F4) tDCS at 2 mA with return lead at the arm, delivered through saline soaked sponges (current density 0.057 mA/cm2). Primary outcome measures included Sleep Onset Latency (SOL), and Sleep Efficiency (SE) as measured by Polysomnography (PSG). Results: As we hypothesized, participants receiving Cathodal stimulation prior to a nap opportunity had a mathematical but not statistically significant reduction in SOL, and an increase in SE. SOL(Cathodal 9.6 ± 8.2SD Mins; Anodal 11.8 ± 11.3SD Mins; Sham 12.5 ± 10.3SD Mins), SE (Cathodal 61.2% ± 27.8SD; Anodal 51.8% ± 34.1SD; Sham 46.8% ± 31.8SD). The results were confounded by a clear order effect (Participants had reduced SOL and increased SE on the third nap opportunity compared to the first or second.). Conclusions: This preliminary evidence suggests that the use of Cathodal Bi-Frontal tDCS is feasible and safe and may increase sleep propensity in healthy participants during an afternoon nap, however further study with a larger sample is needed to definitively prove or disprove this hypothesis. Acknowledgments: NIDA R25 DA020537-06 (PI’s Back and Brady), MUSC Department of Psychiatry Chairs Research Development Fund, MUSC Sleep and Anxiety Treatment and Research Program. Clinicaltrials.gov registry #:NCT02176785 20 EFFECTS ON EEG DYNAMICS BY WEAK ELECTRIC FIELDS FROM SHAM TMS Jerel Mueller a,*, Alexander Opitz b,c,d, Wynn Legon e, Walter Paulus b, William Tyler f. a School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA, 24061, USA; b Department of Clinical Neurophysiology, Georg-August-University, Göttingen, 37075, Germany; c Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA; d Center for the Developing Brain, Child Mind Institute, New York, NY 10022, USA; e Department of Physical Medicine and Rehabilitation, University of Minnesota, Minneapolis, MN 55455, USA; f School of Biological and Health Systems Engineering, Arizona State University, Phoenix, AZ, 85287, USA * Corresponding author. Weak electric fields from both transcranial DC and AC stimulation have been shown to transiently alter cortical excitability. Despite this,