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SV1. Non-invasive electrical brain stimulation in hemianopia and visual neglect
Clinical Neurophysiology 126 (2015) e63–e170
Contents lists available at ScienceDirect
Clinical Neurophysiology journal homepage: www.elsevier.com/locate/clinph
Society Proceedings
Abstracts of the 59th Scientific Annual Meeting of the German Society for Clinical Neurophysiology and Functional Imaging, Tuebingen, Germany, 18–21 March 2015
Orals – Invited Speaker (SV) SV1. Non-invasive electrical brain stimulation in hemianopia and visual neglect—C. Gall (Universitätsklinikum Magdeburg, Magdeburg, Germany) Non-invasive electrical brain stimulation is a promising add-on approach for neurorehabiliation of visual field loss and visual neglect. Transorbital alternating current stimulation (rtACS) has been used in clinical studies to improve visual functions in patients suffering vision loss after optic nerve damage. However, in hemianopic visual field loss the effects of rtACS are less distinct than after optic nerve damage. Combining visual field training with current stimulation may enhance training effects which has been already shown for anodal transcranial direct current stimulation (tDCS) of the occipital cortex in hemianopic visual field loss after strokes. Recent observations also indicate that rebalancing the activity between the two hemispheres as a functional mechanism accompanying recovery may be induced by lateralized respectively dual-mode tDCS application. doi:10.1016/j.clinph.2015.04.076
SV2. tDCS applied over the visual cortex modifies perception—A. Antal (Universitätsmedizin Göttingen, Klinische Neurophysiologie, Göttingen, Germany) Transcranial direct current stimulation (tDCS) seems to be promising methods to induce visual cortical excitability and activity modulations. Furthermore, there are exciting prospects for the use of tDCS as a tool to promote changes of visual cortex activity paralleled by perceptual and behavioral improvements. However, compared to the motor cortex stimulation, the induced after-effects in the visual cortex are generally short-lived. Moreover, although anodal stimulation is known to increase and cathodal stimulation decreases cortical excitability, over the visual cortex they do not automatically result in better or worse perception or performance, as it was observed by stimulating the motor areas. Recently, significant efforts have been made to combine tDCS with other techniques, such as fMRI and EEG. The combination of these techniques are very important approach in learning more about localization, time course and functional specifications of a brain area involved in visual tasks. However, to make tDCS relevant not only for basic research purposes
but also for clinical use, additional studies are necessary. There have been only a few studies in which the excitability of the occipital cortex was modified in order to gain clinical reimbursement, although, in some cases (e.g. photosensitive epilepsy, stroke or migraine), the application of tDCS could be therapeutically beneficial. This talk focuses on tDCS and summarizes the latest results with regard to the application of this method over the visual areas in healthy subjects and clinical populations. doi:10.1016/j.clinph.2015.04.077
SV3. Modulation of hemifield effects in visual-spatial attention by transcranial direct current stimulation—A. Kraft a,b, S. Schmidt a, S. Kehrer a, N. Kathmann c, K. Irlbacher a, S.A. Brandt a (a Charité Universitätsmedizin Berlin, Klinik für Neurologie, Berlin, Germany, b Charité Universitätsmedizin, Berlin Institute of Health, Berlin, Germany, c Humboldt-Universität zu Berlin, Institut für Klinische Psychologie, Berlin, Germany) Introduction: A bilateral field advantage (BFA), that is enhanced visual processing when stimuli are aligned across both visual hemifields, corresponds to a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources for bilateral displays. Several studies have shown that the BFA extends beyond early stages of visual attentional processing. Visual-short-term-memory (VSTM) capacity was higher when stimuli are distributed bilaterally rather than unilaterally and repetitive transcranial magnetic stimulation (rTMS) over the right precuneus diminished the BFA (Kraft et al., 2014). Methods: Here we tested whether the BFA can be modulated by simultaneous anodal and cathodal transcranial direct current stimulation applied either over the left and right occipital cortex (O1/O2) or over the left and right parietal cortex (P3/P4). Twenty healthy subjects were tested using a whole report paradigm based on the Theory of Visual Attention (TVA; Bundesen, 1990). Results and Conclusion: This approach allowed us measuring VSTM capacity and visual processing speed variability in unilateral and bilateral displays. It is discussed how this approach can modulate the inter-hemispheric parietal and occipital balance and whether it can be used in therapeutic settings, e.g. in patients with visual deficits or spatial neglect. doi:10.1016/j.clinph.2015.04.078
Contents lists available at ScienceDirect
Clinical Neurophysiology journal homepage: www.elsevier.com/locate/clinph
Society Proceedings
Abstracts of the 59th Scientific Annual Meeting of the German Society for Clinical Neurophysiology and Functional Imaging, Tuebingen, Germany, 18–21 March 2015
Orals – Invited Speaker (SV) SV1. Non-invasive electrical brain stimulation in hemianopia and visual neglect—C. Gall (Universitätsklinikum Magdeburg, Magdeburg, Germany) Non-invasive electrical brain stimulation is a promising add-on approach for neurorehabiliation of visual field loss and visual neglect. Transorbital alternating current stimulation (rtACS) has been used in clinical studies to improve visual functions in patients suffering vision loss after optic nerve damage. However, in hemianopic visual field loss the effects of rtACS are less distinct than after optic nerve damage. Combining visual field training with current stimulation may enhance training effects which has been already shown for anodal transcranial direct current stimulation (tDCS) of the occipital cortex in hemianopic visual field loss after strokes. Recent observations also indicate that rebalancing the activity between the two hemispheres as a functional mechanism accompanying recovery may be induced by lateralized respectively dual-mode tDCS application. doi:10.1016/j.clinph.2015.04.076
SV2. tDCS applied over the visual cortex modifies perception—A. Antal (Universitätsmedizin Göttingen, Klinische Neurophysiologie, Göttingen, Germany) Transcranial direct current stimulation (tDCS) seems to be promising methods to induce visual cortical excitability and activity modulations. Furthermore, there are exciting prospects for the use of tDCS as a tool to promote changes of visual cortex activity paralleled by perceptual and behavioral improvements. However, compared to the motor cortex stimulation, the induced after-effects in the visual cortex are generally short-lived. Moreover, although anodal stimulation is known to increase and cathodal stimulation decreases cortical excitability, over the visual cortex they do not automatically result in better or worse perception or performance, as it was observed by stimulating the motor areas. Recently, significant efforts have been made to combine tDCS with other techniques, such as fMRI and EEG. The combination of these techniques are very important approach in learning more about localization, time course and functional specifications of a brain area involved in visual tasks. However, to make tDCS relevant not only for basic research purposes
but also for clinical use, additional studies are necessary. There have been only a few studies in which the excitability of the occipital cortex was modified in order to gain clinical reimbursement, although, in some cases (e.g. photosensitive epilepsy, stroke or migraine), the application of tDCS could be therapeutically beneficial. This talk focuses on tDCS and summarizes the latest results with regard to the application of this method over the visual areas in healthy subjects and clinical populations. doi:10.1016/j.clinph.2015.04.077
SV3. Modulation of hemifield effects in visual-spatial attention by transcranial direct current stimulation—A. Kraft a,b, S. Schmidt a, S. Kehrer a, N. Kathmann c, K. Irlbacher a, S.A. Brandt a (a Charité Universitätsmedizin Berlin, Klinik für Neurologie, Berlin, Germany, b Charité Universitätsmedizin, Berlin Institute of Health, Berlin, Germany, c Humboldt-Universität zu Berlin, Institut für Klinische Psychologie, Berlin, Germany) Introduction: A bilateral field advantage (BFA), that is enhanced visual processing when stimuli are aligned across both visual hemifields, corresponds to a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources for bilateral displays. Several studies have shown that the BFA extends beyond early stages of visual attentional processing. Visual-short-term-memory (VSTM) capacity was higher when stimuli are distributed bilaterally rather than unilaterally and repetitive transcranial magnetic stimulation (rTMS) over the right precuneus diminished the BFA (Kraft et al., 2014). Methods: Here we tested whether the BFA can be modulated by simultaneous anodal and cathodal transcranial direct current stimulation applied either over the left and right occipital cortex (O1/O2) or over the left and right parietal cortex (P3/P4). Twenty healthy subjects were tested using a whole report paradigm based on the Theory of Visual Attention (TVA; Bundesen, 1990). Results and Conclusion: This approach allowed us measuring VSTM capacity and visual processing speed variability in unilateral and bilateral displays. It is discussed how this approach can modulate the inter-hemispheric parietal and occipital balance and whether it can be used in therapeutic settings, e.g. in patients with visual deficits or spatial neglect. doi:10.1016/j.clinph.2015.04.078