- Email: [email protected]
Effects of ON and OFF subthalamic nucleus deep brain stimulation on cortical activation during finger movements tasks: a simultaneous fNIRS and EEG study
Abstracts / Brain Stimulation 8 (2015) 378e394
Continuous-wave (CW) fNIRS measures light attenuation through both the cortical and superficial (e.g., skin) tissues, while timedomain (TD) fNIRS directly measures the photon time-of flight that contains information about the depth probed by photons in the tissue, and in turn provides a possibility to separate the superficial from the cortical layer haemodynamic signals. Therefore, the aim of this study was to compare the changes in resting cortical haemodynamics measured by a CW and TD- fNIRS system during anodal tDCS. Methods: A Startstim tDCS system (Neuroelectrics) was used to deliver a constant direct current (2mA) to the left sensorimotor cortex (SMC) via an anodal 4x1 high definition (HD)-tDCS electrode montage. During 10min of anodal HD-tDCS, changes in resting oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin concentrations from the left and right SMC were monitored by a CWfNIRS system (Oxymon MK III, AMS) and in a subsequent session with a TD-fNIRS system (Politecnico di Milano). Results/Discussion: CW- and TD- fNIRS showed a similar time course (i.e. increase in O2Hb from baseline with no or only minimal decrease in HHb) in the stimulated left SMC (no or only minimal changes in right SMC) over the 10min of anodal HD-tDCS (Fig. a, b). The TD-fNIRS confirmed this time course in the cortical layer of the stimulated left SMC (Fig. d), but the changes were much smaller than the superficial layer changes (Fig. b).
393
Methods: The subject was a male (76y) with bilateral STN-DBS (unipolar stimulation at 160Hz and 3.3V). The experimental design consisted of an “OFF” followed by an “ON” stimulation condition. In both conditions, the subject performed a self-paced finger tapping (FT) task followed by a finger sequence (FS) task with his right hand in blocked design (30-s task, 30-s rest, repeated 5 times). During performance of the FT/FS task with the right hand, changes from rest in oxygenated (O2Hb) and deoxygenated haemoglobin concentrations were measured by an fNIRS system (Oxymon MkIII, AMS) from 15 channels covering the contralateral cortical sensorimotor network. EEG signals from 256 channels (GES-300MR, EGI) were collected synchronously with fNIRS signals. Results/Discussion: Concomitant with the improved FT/FS task performance, fNIRS results showed a reduction in contralateral cortical sensorimotor network activation (i.e. smaller and less variable increase in O2Hb over the 5 FT/FS task blocks) in the “ON” than “OFF” condition. The EEG results indicated that the mean power in the Beta and Gamma bands were lower in the “ON” than “OFF” condition. However, the mean power in the Delta band, which was approximately at the FT/FS movement frequency (1-3 Hz), was higher in the “ON” than “OFF” condition. Conclusion: This case study showed that STN-DBS facilitates voluntary finger movement performance by a more efficient cortical activation pattern to perform the finger movement tasks, possibly by facilitating the voluntary frequency band (Delta) and suppressing the involuntary frequency bands (Beta/Gamma).
267 Hand grasp mirror training does not increase corticospinal excitability in all healthy participants Mark van de Ruit , Chris Wright , Dr. Sarah E. Williams , Dr. Michael J. Grey School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
Conclusion: This preliminary study has shown that 10min of anodal HD-tDCS induces an increase in activation in the cortical layer of the stimulated left SMC. 266 Effects of ON and OFF subthalamic nucleus deep brain stimulation on cortical activation during finger movements tasks: a simultaneous fNIRS and EEG study M. Muthalib a,*, A.E. Taser b,c, J. Raethjen b, S. Perrey a, G. Schmidt c, G. Deuschl b, M. Muthuraman b a Movement To Health (M2H) Laboratory, EuroMov, Montpellier-1 University, France b Department of Neurology, Christian-Albrechts University, Kiel, Germany c Digital Signal Processing and System Theory, Technical Faculty, Kiel, Germany *E-mail: [email protected]. Subthalamic nucleus deep brain stimulation (STN-DBS) therapy is an effective treatment for the motor symptoms of advanced Parkinson’s disease (PD). However, the underlying neurophysiological mechanisms for the motor improvement are uncertain. We utilised a simultaneous functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) neuroimaging approach to map cortical activation changes to motor performance in a PD patient “ON” and “OFF” STN-DBS.
Mirror training (MT) has been observed to promote motor performance and in rehabilitation. The neural mechanisms of MT may be similar to that to that of motor imagery and action observation. This suggests that either motor imagery or action observation could augment the effects of MT. The objective of this study was to assess if a single session of imagery training preceding the MT could change cortical organisation compared with MT alone. Forty healthy participants were divided in two groups. One group performed paced grasping movements in a mirror box for 16 min (CONTROL), The other group performed 10 min of imagery training and then performed the same task (IMAGERY). Imagery training was performed using the layered stimulus responses training (LSRT) approach (Williams et al. 2012). Corticospinal excitability was assessed using TMS maps acquired from the extensor digitorum communis (EDC), before, immediately after and 20 min after the mirror training. Questionnaires completed after the mirror training indicated the motor imagery training was successful. Across all participants, TMS maps indicated there was no change in map area for either group. However, in the CONTROL group map area was increased in 10 participants, and in the IMAGERY group map area was increased in 7 participants. For this subset of participants map area significantly increased with the training for both groups. This study shows that mirror training does promote changes in corticospinal excitability in some healthy participants with a simple hand grasp task. However, imagery training does not seem to enhance the effect. However, the effect might be too small in healthy participants. Nonetheless, the finding that participants in the IMAGERY group did find the training easier to perform indicates imagery training in addition to MT might be beneficial for motor rehabilitation.
Continuous-wave (CW) fNIRS measures light attenuation through both the cortical and superficial (e.g., skin) tissues, while timedomain (TD) fNIRS directly measures the photon time-of flight that contains information about the depth probed by photons in the tissue, and in turn provides a possibility to separate the superficial from the cortical layer haemodynamic signals. Therefore, the aim of this study was to compare the changes in resting cortical haemodynamics measured by a CW and TD- fNIRS system during anodal tDCS. Methods: A Startstim tDCS system (Neuroelectrics) was used to deliver a constant direct current (2mA) to the left sensorimotor cortex (SMC) via an anodal 4x1 high definition (HD)-tDCS electrode montage. During 10min of anodal HD-tDCS, changes in resting oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin concentrations from the left and right SMC were monitored by a CWfNIRS system (Oxymon MK III, AMS) and in a subsequent session with a TD-fNIRS system (Politecnico di Milano). Results/Discussion: CW- and TD- fNIRS showed a similar time course (i.e. increase in O2Hb from baseline with no or only minimal decrease in HHb) in the stimulated left SMC (no or only minimal changes in right SMC) over the 10min of anodal HD-tDCS (Fig. a, b). The TD-fNIRS confirmed this time course in the cortical layer of the stimulated left SMC (Fig. d), but the changes were much smaller than the superficial layer changes (Fig. b).
393
Methods: The subject was a male (76y) with bilateral STN-DBS (unipolar stimulation at 160Hz and 3.3V). The experimental design consisted of an “OFF” followed by an “ON” stimulation condition. In both conditions, the subject performed a self-paced finger tapping (FT) task followed by a finger sequence (FS) task with his right hand in blocked design (30-s task, 30-s rest, repeated 5 times). During performance of the FT/FS task with the right hand, changes from rest in oxygenated (O2Hb) and deoxygenated haemoglobin concentrations were measured by an fNIRS system (Oxymon MkIII, AMS) from 15 channels covering the contralateral cortical sensorimotor network. EEG signals from 256 channels (GES-300MR, EGI) were collected synchronously with fNIRS signals. Results/Discussion: Concomitant with the improved FT/FS task performance, fNIRS results showed a reduction in contralateral cortical sensorimotor network activation (i.e. smaller and less variable increase in O2Hb over the 5 FT/FS task blocks) in the “ON” than “OFF” condition. The EEG results indicated that the mean power in the Beta and Gamma bands were lower in the “ON” than “OFF” condition. However, the mean power in the Delta band, which was approximately at the FT/FS movement frequency (1-3 Hz), was higher in the “ON” than “OFF” condition. Conclusion: This case study showed that STN-DBS facilitates voluntary finger movement performance by a more efficient cortical activation pattern to perform the finger movement tasks, possibly by facilitating the voluntary frequency band (Delta) and suppressing the involuntary frequency bands (Beta/Gamma).
267 Hand grasp mirror training does not increase corticospinal excitability in all healthy participants Mark van de Ruit , Chris Wright , Dr. Sarah E. Williams , Dr. Michael J. Grey School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
Conclusion: This preliminary study has shown that 10min of anodal HD-tDCS induces an increase in activation in the cortical layer of the stimulated left SMC. 266 Effects of ON and OFF subthalamic nucleus deep brain stimulation on cortical activation during finger movements tasks: a simultaneous fNIRS and EEG study M. Muthalib a,*, A.E. Taser b,c, J. Raethjen b, S. Perrey a, G. Schmidt c, G. Deuschl b, M. Muthuraman b a Movement To Health (M2H) Laboratory, EuroMov, Montpellier-1 University, France b Department of Neurology, Christian-Albrechts University, Kiel, Germany c Digital Signal Processing and System Theory, Technical Faculty, Kiel, Germany *E-mail: [email protected]. Subthalamic nucleus deep brain stimulation (STN-DBS) therapy is an effective treatment for the motor symptoms of advanced Parkinson’s disease (PD). However, the underlying neurophysiological mechanisms for the motor improvement are uncertain. We utilised a simultaneous functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) neuroimaging approach to map cortical activation changes to motor performance in a PD patient “ON” and “OFF” STN-DBS.
Mirror training (MT) has been observed to promote motor performance and in rehabilitation. The neural mechanisms of MT may be similar to that to that of motor imagery and action observation. This suggests that either motor imagery or action observation could augment the effects of MT. The objective of this study was to assess if a single session of imagery training preceding the MT could change cortical organisation compared with MT alone. Forty healthy participants were divided in two groups. One group performed paced grasping movements in a mirror box for 16 min (CONTROL), The other group performed 10 min of imagery training and then performed the same task (IMAGERY). Imagery training was performed using the layered stimulus responses training (LSRT) approach (Williams et al. 2012). Corticospinal excitability was assessed using TMS maps acquired from the extensor digitorum communis (EDC), before, immediately after and 20 min after the mirror training. Questionnaires completed after the mirror training indicated the motor imagery training was successful. Across all participants, TMS maps indicated there was no change in map area for either group. However, in the CONTROL group map area was increased in 10 participants, and in the IMAGERY group map area was increased in 7 participants. For this subset of participants map area significantly increased with the training for both groups. This study shows that mirror training does promote changes in corticospinal excitability in some healthy participants with a simple hand grasp task. However, imagery training does not seem to enhance the effect. However, the effect might be too small in healthy participants. Nonetheless, the finding that participants in the IMAGERY group did find the training easier to perform indicates imagery training in addition to MT might be beneficial for motor rehabilitation.