- Email: [email protected]
P171 Impact of a novel high-definition tDCS set-up on cognitive control
Abstracts / Clinical Neurophysiology 128 (2017) e1–e163
in the Eyes task (MITE) involved selecting the emotion or cognitive state represented in a set of eyes. The subjects were then asked how often they, or another (Barack Obama), felt that way. Age and gender judgements acted as a low-level social judgement control condition. After approximately 30 min, subjects were asked to recall as many chosen emotion/cognitive state words they could remember, followed by a recognition task. In between, subjects completed a task able to measure implicit, level-1 (line of sight judgment), and level-2 (location of objects relative to other’s perspective) VPT. Results: There was no effect of anodal-tDCS on MITE performance. Anodal-tDCS increased the impact of the other agent’s perspective during self-perspective judgements in level 1 and level 2 VPT, but not during implicit VPT. Specifically, during anodal-tDCS, there was a greater difference in reaction time between scenes congruent or incongruent with the perspective of the other agent. During the recognition memory task, anodal-tDCS increased memory for other-encoded emotion words with no impact on self-encoded emotion words. Conclusions: The findings demonstrate for the first time that highdefinition tDCS over the dmPFC can improve social cognition, especially concerning the salience of other encoded memories or the perspective of others. This proof of concept study paves the way for assessing the impact of HD-tDCS in clinical populations who may benefit from improved social cognition. doi:10.1016/j.clinph.2016.10.291
P171 Impact of a novel high-definition tDCS set-up on cognitive control—O. Gbadeyan a, M. Steinhauser a,b, K. McMahon a, B. Hsieh a, M. Meinzer a,* (a The University of Queensland, Brisbane, Australia, b Catholic University of Eichstaett, Eichstaett, Germany) ⇑
Corresponding author.
Question: High-definition transcranial direct current stimulation (HD-tDCS) allows for more focal current delivery than conventional-tDCS. However, very few studies have assessed potential cognitive effects and regional specificity of HD-tDCS. Objectives: This study assessed the impact and specificity of a novel HD-tDCS montage on cognitive control during a visual flanker task. Methods: 120 healthy young participants were recruited and randomly assigned to four stimulation conditions: left or right dorsolateral prefrontal cortex (DLPFC) or primary motor cortex (M1) HDtDCS (N = 30 per condition). Each group underwent both activeand sham HD-tDCS in cross-over, double-blind designs. tDCS was administered using a one-channel DC-stimulator and two concentric round rubber electrodes mimicking the frequently used ‘‘4 1” HDtDCS set-up. Our analyses focused on conflict adaptation (CA), a hallmark effect of adaptive cognitive control. Conflict adaptation in the flanker paradigm is reflected by the finding that the flanker effect (i.e., differences in response latency between incongruent and congruent trials in the flanker task) is smaller following trials with high vs. low response conflict. Results: We obtained a sizeable CA effect which was influenced by region-specific active HD-tDCS, as indicated by a significant fourway interaction between region, stimulation, current congruency and previous congruency (p < 0.05). In the DLPFC groups, a significant three-way interaction between stimulation, current congruency and previous congruency (p < 0.003) indicated larger conflict adaptation during active- vs. sham HD-tDCS. This effect was not further modulated by the laterality of the stimulation. In the M1 groups, CA was not modulated by HD-tDCS. However, we obtained trends
e101
suggesting that M1 stimulation led to activation of the contralateral hand but these effects were weak and emerged in RTs and error rates depending on whether left or right M1 was stimulated. Conclusions: Our results confirm the potential of this novel HDtDCS set-up to modulate behavioural performance in a regionally specific manner. Selectively improved conflict adaptation during DLPFC stimulation supports the theory that left and right DLPFC play a critical role in behavioral adaptation following conflict detection. doi:10.1016/j.clinph.2016.10.292
P172 Frequency modulation of reward and punishment feedback processing during frontal cathodal transcranial direct current stimulation—M. Wischnewski *, D. Schutter (Donders Institute, Donders Centre for Cognition, Nijmegen, The Netherlands) ⇑
Corresponding author.
Introduction: Evidence from electroencephalographam (EEG) studies indicates that reward and punishment-related feedback signals during decision making are associated with delta (1–3 Hz) and theta (4–7 Hz) oscillatory activity. Cathodal transcranial direct current stimulation (tDCS) to the frontal cortex has shown to impair decision making in healthy volunteers. Whether this impairment of cathodal tDCS involves the modulation of delta and theta activity to reward and punishment feedback is not known. Objective: To test the hypothesis that cathodal tDCS attenuates reward and punishment related feedback activity in the delta and theta frequency range. Methods: In a within-subjects, cross-over, double-blind, shamcontrolled design, thirty healthy adult volunteers received cathodal over the frontal cortex (cathodal position: FPz, 5 7 cm, reference position: Cz, 10 10 cm) at an intensity of 1 mA for a maximum of twelve minutes. During tDCS administration, volunteers performed a decision making task in which reward and punishment feedback was delivered in a random fashion. Event-related EEG feedback signals to reward and punishment were recorded from thirteen sensors near the stimulation electrodes. A complex Morlet wavelets analysis was performed to extract delta and theta activity following reward and punishment feedback. The study protocol was approved by the Committee on Research Involving Human Subjects of the Radboud University Medical Centre. Results: Artifact free EEG signals were analyzed in twenty-three participants from the posterior midline electrode. Cathodal compared to sham tDCS significantly decreased theta oscillatory activity between 210 and 500 ms to reward feedback. No effects were observed in the delta frequency range. Furthermore, no differences were observed during punishment-related feedback processing. Conclusion: Our findings provide evidence for frequency-specific modulatory effects of cathodal tDCS. The reduction in theta oscillations during reward-related feedback processing may indicate reduced cortical responsiveness to reward signals. doi:10.1016/j.clinph.2016.10.293
P173 Bi-frontal transcranial direct current stimulation does modulate sleep, but does not affect sleep-related memory consolidation—L. Frase a,b,*, H. Piosczyk a,b, F. Jahn a,b, S. Zittel a,b, L. Krone a,b, P. Selhausen a,b, B. Feige a,b, J.G. Maier a,b, D. Riemann b, M.A. Nitsche c,d,e,f, C. Nissen a,b (a University Medical Center Freiburg, Department of Psychiatry and Psychotherapy, Freiburg, Germany,
in the Eyes task (MITE) involved selecting the emotion or cognitive state represented in a set of eyes. The subjects were then asked how often they, or another (Barack Obama), felt that way. Age and gender judgements acted as a low-level social judgement control condition. After approximately 30 min, subjects were asked to recall as many chosen emotion/cognitive state words they could remember, followed by a recognition task. In between, subjects completed a task able to measure implicit, level-1 (line of sight judgment), and level-2 (location of objects relative to other’s perspective) VPT. Results: There was no effect of anodal-tDCS on MITE performance. Anodal-tDCS increased the impact of the other agent’s perspective during self-perspective judgements in level 1 and level 2 VPT, but not during implicit VPT. Specifically, during anodal-tDCS, there was a greater difference in reaction time between scenes congruent or incongruent with the perspective of the other agent. During the recognition memory task, anodal-tDCS increased memory for other-encoded emotion words with no impact on self-encoded emotion words. Conclusions: The findings demonstrate for the first time that highdefinition tDCS over the dmPFC can improve social cognition, especially concerning the salience of other encoded memories or the perspective of others. This proof of concept study paves the way for assessing the impact of HD-tDCS in clinical populations who may benefit from improved social cognition. doi:10.1016/j.clinph.2016.10.291
P171 Impact of a novel high-definition tDCS set-up on cognitive control—O. Gbadeyan a, M. Steinhauser a,b, K. McMahon a, B. Hsieh a, M. Meinzer a,* (a The University of Queensland, Brisbane, Australia, b Catholic University of Eichstaett, Eichstaett, Germany) ⇑
Corresponding author.
Question: High-definition transcranial direct current stimulation (HD-tDCS) allows for more focal current delivery than conventional-tDCS. However, very few studies have assessed potential cognitive effects and regional specificity of HD-tDCS. Objectives: This study assessed the impact and specificity of a novel HD-tDCS montage on cognitive control during a visual flanker task. Methods: 120 healthy young participants were recruited and randomly assigned to four stimulation conditions: left or right dorsolateral prefrontal cortex (DLPFC) or primary motor cortex (M1) HDtDCS (N = 30 per condition). Each group underwent both activeand sham HD-tDCS in cross-over, double-blind designs. tDCS was administered using a one-channel DC-stimulator and two concentric round rubber electrodes mimicking the frequently used ‘‘4 1” HDtDCS set-up. Our analyses focused on conflict adaptation (CA), a hallmark effect of adaptive cognitive control. Conflict adaptation in the flanker paradigm is reflected by the finding that the flanker effect (i.e., differences in response latency between incongruent and congruent trials in the flanker task) is smaller following trials with high vs. low response conflict. Results: We obtained a sizeable CA effect which was influenced by region-specific active HD-tDCS, as indicated by a significant fourway interaction between region, stimulation, current congruency and previous congruency (p < 0.05). In the DLPFC groups, a significant three-way interaction between stimulation, current congruency and previous congruency (p < 0.003) indicated larger conflict adaptation during active- vs. sham HD-tDCS. This effect was not further modulated by the laterality of the stimulation. In the M1 groups, CA was not modulated by HD-tDCS. However, we obtained trends
e101
suggesting that M1 stimulation led to activation of the contralateral hand but these effects were weak and emerged in RTs and error rates depending on whether left or right M1 was stimulated. Conclusions: Our results confirm the potential of this novel HDtDCS set-up to modulate behavioural performance in a regionally specific manner. Selectively improved conflict adaptation during DLPFC stimulation supports the theory that left and right DLPFC play a critical role in behavioral adaptation following conflict detection. doi:10.1016/j.clinph.2016.10.292
P172 Frequency modulation of reward and punishment feedback processing during frontal cathodal transcranial direct current stimulation—M. Wischnewski *, D. Schutter (Donders Institute, Donders Centre for Cognition, Nijmegen, The Netherlands) ⇑
Corresponding author.
Introduction: Evidence from electroencephalographam (EEG) studies indicates that reward and punishment-related feedback signals during decision making are associated with delta (1–3 Hz) and theta (4–7 Hz) oscillatory activity. Cathodal transcranial direct current stimulation (tDCS) to the frontal cortex has shown to impair decision making in healthy volunteers. Whether this impairment of cathodal tDCS involves the modulation of delta and theta activity to reward and punishment feedback is not known. Objective: To test the hypothesis that cathodal tDCS attenuates reward and punishment related feedback activity in the delta and theta frequency range. Methods: In a within-subjects, cross-over, double-blind, shamcontrolled design, thirty healthy adult volunteers received cathodal over the frontal cortex (cathodal position: FPz, 5 7 cm, reference position: Cz, 10 10 cm) at an intensity of 1 mA for a maximum of twelve minutes. During tDCS administration, volunteers performed a decision making task in which reward and punishment feedback was delivered in a random fashion. Event-related EEG feedback signals to reward and punishment were recorded from thirteen sensors near the stimulation electrodes. A complex Morlet wavelets analysis was performed to extract delta and theta activity following reward and punishment feedback. The study protocol was approved by the Committee on Research Involving Human Subjects of the Radboud University Medical Centre. Results: Artifact free EEG signals were analyzed in twenty-three participants from the posterior midline electrode. Cathodal compared to sham tDCS significantly decreased theta oscillatory activity between 210 and 500 ms to reward feedback. No effects were observed in the delta frequency range. Furthermore, no differences were observed during punishment-related feedback processing. Conclusion: Our findings provide evidence for frequency-specific modulatory effects of cathodal tDCS. The reduction in theta oscillations during reward-related feedback processing may indicate reduced cortical responsiveness to reward signals. doi:10.1016/j.clinph.2016.10.293
P173 Bi-frontal transcranial direct current stimulation does modulate sleep, but does not affect sleep-related memory consolidation—L. Frase a,b,*, H. Piosczyk a,b, F. Jahn a,b, S. Zittel a,b, L. Krone a,b, P. Selhausen a,b, B. Feige a,b, J.G. Maier a,b, D. Riemann b, M.A. Nitsche c,d,e,f, C. Nissen a,b (a University Medical Center Freiburg, Department of Psychiatry and Psychotherapy, Freiburg, Germany,