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P19-18 Spatiotemporal dynamics of neuromagnetic oscillatory changes during observation of actions
S218 fMRI experiment showed that left frontal and middle frontal gyrus near BA 10 and BA 46 were activated. Furthermore, cingulate gyrus (BA 23) and corpus callosum (BA 29, 30), and so on were also activated. The reaction time of Yes response was a fairly shorter than that of No response about 50 ms in the MEG experiment. From the results of these experiments, it was estimated that the activation area of working memory was changing through cigulate gyrus to frontal area. It was also suggested that the difference of the reaction time (50 ms) for the judgment of Yes or No response could be affected by the priming effect. P19-15 Exploring neurovascular-neurometabolic couplings and activity-mediated water movements in the rodent cortex with an optical probe P. Marquet1,2 , E. Migacheva2,3 , S. Chamot3 , O. Seydoux3 , B. Weber4 , C. Depeursinge3 , P. Magistretti1,2 1 Centre des Neurosciences Psychiatriques, University of Lausanne; Lausanne, Switzerland, 2 Ecole Polytechnique Federale de Lausanne (EPFL), Brain Mind Institute, CH-1015 Lausanne, Switzerland, 3 Ecole Polytechnique Federale de Lausanne (EPFL), Advanced Photonics Lab., Microvision and Microdiagnosis Group CH-1015 Lausanne, Switzerland, 4 Division of Nuclear Medicine, University Hospital Zurich, Ramistrasse 100, CH-8091 Zurich, Switzerland Objective: Because the brain essentially lacks storage capacities for energy substrates, monitoring the local cerebral blood supply and energy metabolism allows the tracking of neuronal activity changes. However, currently many of the BOLD signals underlying mechanisms are only poorly understood. Furthermore, a new paradigm has emerged to look at brain activity through the observation with MRI of the molecular diffusion of water (Le Bihan Phys Med Biol 52, R57 90 (2007)). Thus, we have developed a novel optical method (optiprobe) aiming to explore the neurometabolic and neurovascular coupling mechanisms as well as activity mediated water movements in the rodent cortex. Methods: High resolution optical spectroscopy of blood oxygenation is used by several groups for investigating in vivo neuro-metabolic and neurovascular coupling mechanisms. However, significant uncertainties remain because accurate differentiation between scattering and absorption processes is not readily available with these techniques. Optiprobe allows, by recording spatially diffuse reflectance, to accurately monitor in laboratory animals the activation of discrete brain regions (~1 mm3 ) during specific tasks. Practically, based on photon migration theory in tissues, a separate measurement of the scattering and absorption spectra, corresponding to the activated brain areas can be obtained. Consequently, from absorption spectra, a direct and accurate monitoring of the local cerebral blood flow variations as well as blood oxygen level in microcirculation can be obtained. On the other hand, the scattering spectra could provide information concerning the local water diffusion, tightly related to neuronal electrical activity. Results: Preliminary results have demonstrated the optiprobe ability to record spatially diffuse reflectance variations and the dynamics of the corresponding absorption and scattering spectra during sensory tasks within the cortex of anaesthetic rats. Conclusion: Over-all, optiprobe allows an original analysis of the local intrinsic optical signals, which could provide new insights in the neurovascular-neurometabolic coupling and water movements accompanying neuronal activity. P19-16 Clinical utility of diffusion tensor imaging for evaluating patients with diffuse axonal injury and cognitive disorders K. Sugiyama1 , T. Kondo1 , Y. Oouchida1 , Y. Suzukamo1 , S.-I. Izumi1 1 Department of Physical Medicine and Rehabilitation, Tohoku University Graduate School of Medicine, Japan Objective: Although diffuse axonal injury (DAI) usually causes cognitive disorders, abnormal findings are generally undetected by conventional imaging techniques. The aim of this study was to evaluate the feasibility of using diffusion tensor imaging (DTI) to detect lesions in DAI patients and to investigate the correlation between DAI lesions and cognitive disorders. Methods: We examined 16 healthy controls and 11 patients with DAI. To assess their cognitive disorders, the DAI patients were subjected to various neuropsychological tests (MMSE, WAIS-R, TMT, PASAT, WMS-R, RBMT, WCST, and BADS). ADL and behavioral problems were evaluated
Posters using the functional assessment measure (FAM). Fractional anisotropy (FA) was examined using voxel-based DTI analysis with statistical parametric mapping. The two-sample t-test was applied to test the differences in FA between the DAI patients and healthy controls. Next, we used regression modeling to examine the covariate effects of all neuropsychological tests scores and FA images of the DAI patients. Moreover, we investigated the correlation of the total scores on the cognitive items of FAM with the number of lesions in the DAI patients. Results: Voxel-based DTI analysis revealed that compared to healthy controls, the brains of DAI patients had significantly more regions with decreased FA (p < 0.001), whereas few lesions were detected on conventional MRI. These findings appeared to depict DAI. There was a significant relationship between the results of the WAIS-R, TMT, and some indices of the WMS-R and the decreased FA observed in various areas of the brain (p < 0.001). Furthermore, the total cognitive scores on the FAM were correlated with cluster (number of DAI lesions, p = 0.007) and voxel numbers (total size of all DAI lesions, p = 0.001). Conclusion: Our results indicate that DTI is a useful technique not only for detecting DAI lesions but also for examining cognitive disorders in DAI patients. P19-17 Functional distribution of the palm sensory area using intraoperative intrinsic optical imaging T. Maehara1 , M. Inaji1 , T. Nariai1 , K. Sato2 , K. Ohno1 1 Department of Neurosurgery, Tokyo medical and dental University, Tokyo, Japan, 2 Department of Health and Nutrition Sciences Komazawa Women’s University Faculty of Human Health, Tokyo, Japan Objective: Intraoperative intrinsic optical imaging technique is important method to detect the precise functional distribution in the sensory cortex. Although several reports demonstrated that functional representation of the finger sensory area was aligned along the central sulcus, functional distribution of the palm sensory area has not been fully analyzed. We investigated the sensory area of the palm using this method. Method: We used intrinsic optical imaging for two patients with intractable epilepsy who had epileptic focus in and around the sensory cortex and one patient with a brain tumor extending from the insula cortex. One epileptic patient suffered from intractable simple partial seizures (SPSs) started from dysesthesia of the left palm, followed by secondarily generalization. Optical recording was performed following cortical recording of SSEPs. The cortical surface was illuminated with Xenon light, and the reflected light, which passed through a 605 nm bandpass filter, was detected by optical imaging system. Individual electrical stimulation of thumb, little finger and palm induced changes in the reflected light intensities. For the purpose of visualizing the intrinsic optical responses, we constructed maps on the sensory strip. Results: (1) In all three cases, the optical response area after electrical stimulation of the palm was defined in the sensory cortex between the finger areas and the postsensory sulcus. (2) We performed multiple subpial transection on the palm area in the patient suffered from SPSs with dysesthesia of the left palm. He complained of transient dysesthesia in the left palm that disappeared in a week. Conclusion: Using intraoperative intrinsic optical imaging, we suggested that the sensory area of the palm was located in the sensory cortex between the finger areas and the postsensory sulcus. P19-18 Spatiotemporal dynamics of neuromagnetic oscillatory changes during observation of actions Y. Tamura1 , M. Hirata1,2 , T. Goto1,2 , H. Onishi3 , H. Sugata1 , M. Inui1 , T. Saori1 , S. Yorifuji1 1 Division of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Osaka, Japan, 2 Department of Neurosurgery, Osaka University Medical School, Osaka, Japan, 3 Department of Occupational Therapy, Osaka Prefecture University, Osaka, Japan Objective: Mirror neuron system (MNS) is known to be active during both observation and execution of actions, and involves inferior parietal lobule (IPL), inferior frontal gyrus (IFG) and ventral premotor cortex (vPM). However, the oscillatory changes and neural process of MNS are not fully understood. We aimed to delineate the oscillatory changes during observation of actions and the spatiotemporal profile of MNS.
29th International Congress of Clinical Neurophysiology Methods: Neuromagnetic activities were measured in twelve healthy right-handed subjects. The subjects observed a movie of other’s tapping his right index or middle fingers and executed the same actions 500 ms after the observation. As a control stimulus, we used a static image that either index or middle fingers were marked with a cross marker. As a control task, just the observation of the fingers without execution of the actions was used. These four (2 stimuli × 2 tasks) tasks were randomly presented. Oscillatory changes during observation of actions were investigated over the theta to high gamma bands using a beamforming technique with sliding time windows and a statistical group analysis. Result: Event-related desynchronizations (ERDs) in the low gamma band were observed in left vPM and right IFG at 300 ms after the visual stimulus, and alpha ERD in bilateral IPL at 400 ms. Left vPM was desynchronized during observation of actions, whereas Right IFG was desynchronized in the tasks that the subjects tapped their fingers despite they observed actions or static fingers. On the other hand, bilateral IPLs were desynchronized in all tasks. Conclusion: The oscillatory changes related to observation of actions were delineated over the alpha to low gamma bands, which reflect neural process of MNS. Our results suggest that left vPM is related to perception of finger actions and to forming inner representation of the actions, and that right IFG related to imaging of actions. P19-19 Multimodal neuroimaging for characterizing cortical dynamics while perceiving 3-D object from optic flow S. Iwaki1,2 , J.W. Belliveau2 National Institute of Advanced Industrial Science and Technology (AIST), Japan, 2 Massachusetts General Hospital, Boston, MA, USA 1
Two-dimensional optic flow is an important cue to perceive 3D structure of objects. Recent neuroimaging studies suggest the involvement of both the ventral and the dorsal visual pathways in the perception of 3D structure from motion (3D-SFM), though the neural dynamics underlying the 3DSFM is not fully understood. Here, we combine magnetoencephalography (MEG) and fMRI to detect the dynamic brain responses to 3D-SFM. We manipulated the coherence of randomly moving dots to create different levels of 3D perception and investigated the associated changes in brain activity. Results of the fMRI analysis were used to impose plausible constraints on the MEG inverse calculation to improve spatial resolution of the spatiotemporal activity estimates. The infero-temporal (IT), parietooccipital (PO), and intraparietal (IP) regions showed increased neural activity at different latencies during highly coherent motion conditions in which subjects perceived a robust 3D object. Causality analysis between the estimated neural activities in these regions indicated a significant causal influence from IP to IT and from IT to PO only in conditions where subjects perceived a robust 3D object. Current results suggest that the interactions between the dorsal and ventral visual subsystems are crucial for the perception of 3D object from 2D optic flow. P20. TMS (2) P20-1 Investigation of the contribution of motor cortex to mastication using transcranial magnetic stimulation A.P. Lavender1,2 , E.S. Atis3 , K.S. Turker3 1 The Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan, 2 Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Namiki, Tokorozawa, Japan, 3 Gender Reflex Laboratories, Center for Brain Research, Department of Physiology, Ege University, Bornova, Izmir, Turkey Objective: To use transcranial magnetic brain stimulation (TMS) to assess the contribution of masticatory centre of motor cortex (M1) to mastication. Methods: M1 area innervating the jaw muscles was stimulated using TMS in twelve healthy volunteers with no history of neurological or dental disorders. TMS was applied to the left masticatory M1 during two active tasks. Static, where subjects bit down on a specially designed chewing device which provided immediate feedback and recorded force and gape, and dynamic during which subjects were required to move the mandible through its entire range of motion, again on the chewing device. For dynamic, stimuli were given when the mandible crossed the
S219 mid-point between open and closed at 0.7, 0.8, 0.9, 1.0, 1.1 and 1.2 × threshold (T). Surface EMG was recorded from the contralateral masseter. Recordings were filtered and full wave rectified before averaging around the time of the stimulus. Conditions were compared using the cumulative summation (CUSUM) method. Results: MEP of the right masseter were observed at a latency of ~7.5 ms at stimulus levels above T for static condition and increased in size with increasing stimulus intensity. This was not evident at any stimulus intensity for the dynamic condition. No inhibition was evident in either EMG recordings or CUSUM analyses for subthreshold stimulus intensities. Conclusions: This study shows that M1 excitability is less during dynamic jaw activation than static clenching. During static jaw clenching MEP responses increased with stimulus intensity, but there were negligible changes at suprathreshold stimulus intensities for the dynamic condition. Significance: M1 contribution to chewing appears to be low. Further studies are required to assess the mechanisms for controlling jaw movement. It is likely the central pattern generator controls movement of the jaw and adjusts to reduce chances of injury to the tongue and cheeks. P20-2 Navigated TMS mapping of bulbar muscles L. Saisanen1,2 , S. Kemppainen1 , P. Julkunen1 , H. Siintamo2 , E. Mervaala2 , M. Kononen1,3 1 Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland, 2 University of Eastern Finland, Kuopio, Finland, 3 Department of Radiology, Kuopio University Hospital, Kuopio, Finland Objective: We evaluated the cortical representation areas of bulbar muscles of the right cerebral hemisphere in 8 healthy subjects (6 female, 2 male, mean age: 33.8 years) by applying neuronavigated transcranial magnetic stimulation (nTMS). The aim was to find out which muscles motor evoked potentials (MEPs) can be detected from relaxed bulbar muscles using EMG recording with superficial EMG electrodes. Methods: Motor threshold (MT) for thenar muscles was first determined. Thereafter, we defined the MT for mentalis muscle and determined latency and amplitude using 20 MEPs at stimulation intensity of 120%MT. Finally, a mapping of large area in the lateral motor strip was performed at the intensity of 110% of the mentalis MT. MEPs were recorded from several muscles: frontalis, orbicularis oculi, nasalis, mentalis, orbicularis oris, masseter, sternocleidomastoideus and trapezius. Coil orientations 45 degrees towards midline and posterior-anterior direction were used. Results: Mean MT was higher in mentalis (mean 53.9±11.6% stimulator output) than in thenar muscles (mean 43.5±14.7% stimulator output). The mean MEP latency for mentalis was 12.8±2.9 ms and amplitude 167±73 mV. Clear muscle responses were achieved in mentalis, orbicularis oris and masseter muscles. Responses that were more diffuse to define were elicited in nasalis, sternocleidomastoideus and trapezius. Responses could not be elicited in frontalis, orbicularis oculi. Maps of mentalis, orbicularis oris and masseter were partly overlapping, but still distinguishable. Motor representation area was larger than expected in anterior-posterior orientation compared to standard anatomic atlas. The posterior-anterior coil orientation seemed to be more effective in activating cortical representation of bulbar muscles. Conclusions: Muscles appropriate and most favourable for the preoperative evaluation of motor cortical areas were mentalis, orbicularis oris and masseter. Hence, bulbar muscles can be used with nTMS in preoperative evaluation of cortical motor function. P20-3 Excitability changes in the human primary motor cortex by Dual motor Task are dependent on task properties K. Uehara1,3 , T. Higashi1 , S. Tanabe2 , T. Morishita3 , M. Ninomiya3 , K. Funase3 , K. Sugawara1 1 Rehabilitation Science, Division of Health & Social Work, Kanagawa University of Human Services Graduate School of Health & Social Work Sciences, Yokosuka, Japan, 2 Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan, 3 Division of Human Sciences, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashihiroshima, Japan Objective: The aim of this study was to investigate whether the effects of changes in primary motor cortex (M1) with the upper limb movement during gait, which is referred to as Dual motor Task. To further investigate how Dual motor Task are dependent on task properties measured using transcranial magnetic stimulation (TMS).
Posters using the functional assessment measure (FAM). Fractional anisotropy (FA) was examined using voxel-based DTI analysis with statistical parametric mapping. The two-sample t-test was applied to test the differences in FA between the DAI patients and healthy controls. Next, we used regression modeling to examine the covariate effects of all neuropsychological tests scores and FA images of the DAI patients. Moreover, we investigated the correlation of the total scores on the cognitive items of FAM with the number of lesions in the DAI patients. Results: Voxel-based DTI analysis revealed that compared to healthy controls, the brains of DAI patients had significantly more regions with decreased FA (p < 0.001), whereas few lesions were detected on conventional MRI. These findings appeared to depict DAI. There was a significant relationship between the results of the WAIS-R, TMT, and some indices of the WMS-R and the decreased FA observed in various areas of the brain (p < 0.001). Furthermore, the total cognitive scores on the FAM were correlated with cluster (number of DAI lesions, p = 0.007) and voxel numbers (total size of all DAI lesions, p = 0.001). Conclusion: Our results indicate that DTI is a useful technique not only for detecting DAI lesions but also for examining cognitive disorders in DAI patients. P19-17 Functional distribution of the palm sensory area using intraoperative intrinsic optical imaging T. Maehara1 , M. Inaji1 , T. Nariai1 , K. Sato2 , K. Ohno1 1 Department of Neurosurgery, Tokyo medical and dental University, Tokyo, Japan, 2 Department of Health and Nutrition Sciences Komazawa Women’s University Faculty of Human Health, Tokyo, Japan Objective: Intraoperative intrinsic optical imaging technique is important method to detect the precise functional distribution in the sensory cortex. Although several reports demonstrated that functional representation of the finger sensory area was aligned along the central sulcus, functional distribution of the palm sensory area has not been fully analyzed. We investigated the sensory area of the palm using this method. Method: We used intrinsic optical imaging for two patients with intractable epilepsy who had epileptic focus in and around the sensory cortex and one patient with a brain tumor extending from the insula cortex. One epileptic patient suffered from intractable simple partial seizures (SPSs) started from dysesthesia of the left palm, followed by secondarily generalization. Optical recording was performed following cortical recording of SSEPs. The cortical surface was illuminated with Xenon light, and the reflected light, which passed through a 605 nm bandpass filter, was detected by optical imaging system. Individual electrical stimulation of thumb, little finger and palm induced changes in the reflected light intensities. For the purpose of visualizing the intrinsic optical responses, we constructed maps on the sensory strip. Results: (1) In all three cases, the optical response area after electrical stimulation of the palm was defined in the sensory cortex between the finger areas and the postsensory sulcus. (2) We performed multiple subpial transection on the palm area in the patient suffered from SPSs with dysesthesia of the left palm. He complained of transient dysesthesia in the left palm that disappeared in a week. Conclusion: Using intraoperative intrinsic optical imaging, we suggested that the sensory area of the palm was located in the sensory cortex between the finger areas and the postsensory sulcus. P19-18 Spatiotemporal dynamics of neuromagnetic oscillatory changes during observation of actions Y. Tamura1 , M. Hirata1,2 , T. Goto1,2 , H. Onishi3 , H. Sugata1 , M. Inui1 , T. Saori1 , S. Yorifuji1 1 Division of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Osaka, Japan, 2 Department of Neurosurgery, Osaka University Medical School, Osaka, Japan, 3 Department of Occupational Therapy, Osaka Prefecture University, Osaka, Japan Objective: Mirror neuron system (MNS) is known to be active during both observation and execution of actions, and involves inferior parietal lobule (IPL), inferior frontal gyrus (IFG) and ventral premotor cortex (vPM). However, the oscillatory changes and neural process of MNS are not fully understood. We aimed to delineate the oscillatory changes during observation of actions and the spatiotemporal profile of MNS.
29th International Congress of Clinical Neurophysiology Methods: Neuromagnetic activities were measured in twelve healthy right-handed subjects. The subjects observed a movie of other’s tapping his right index or middle fingers and executed the same actions 500 ms after the observation. As a control stimulus, we used a static image that either index or middle fingers were marked with a cross marker. As a control task, just the observation of the fingers without execution of the actions was used. These four (2 stimuli × 2 tasks) tasks were randomly presented. Oscillatory changes during observation of actions were investigated over the theta to high gamma bands using a beamforming technique with sliding time windows and a statistical group analysis. Result: Event-related desynchronizations (ERDs) in the low gamma band were observed in left vPM and right IFG at 300 ms after the visual stimulus, and alpha ERD in bilateral IPL at 400 ms. Left vPM was desynchronized during observation of actions, whereas Right IFG was desynchronized in the tasks that the subjects tapped their fingers despite they observed actions or static fingers. On the other hand, bilateral IPLs were desynchronized in all tasks. Conclusion: The oscillatory changes related to observation of actions were delineated over the alpha to low gamma bands, which reflect neural process of MNS. Our results suggest that left vPM is related to perception of finger actions and to forming inner representation of the actions, and that right IFG related to imaging of actions. P19-19 Multimodal neuroimaging for characterizing cortical dynamics while perceiving 3-D object from optic flow S. Iwaki1,2 , J.W. Belliveau2 National Institute of Advanced Industrial Science and Technology (AIST), Japan, 2 Massachusetts General Hospital, Boston, MA, USA 1
Two-dimensional optic flow is an important cue to perceive 3D structure of objects. Recent neuroimaging studies suggest the involvement of both the ventral and the dorsal visual pathways in the perception of 3D structure from motion (3D-SFM), though the neural dynamics underlying the 3DSFM is not fully understood. Here, we combine magnetoencephalography (MEG) and fMRI to detect the dynamic brain responses to 3D-SFM. We manipulated the coherence of randomly moving dots to create different levels of 3D perception and investigated the associated changes in brain activity. Results of the fMRI analysis were used to impose plausible constraints on the MEG inverse calculation to improve spatial resolution of the spatiotemporal activity estimates. The infero-temporal (IT), parietooccipital (PO), and intraparietal (IP) regions showed increased neural activity at different latencies during highly coherent motion conditions in which subjects perceived a robust 3D object. Causality analysis between the estimated neural activities in these regions indicated a significant causal influence from IP to IT and from IT to PO only in conditions where subjects perceived a robust 3D object. Current results suggest that the interactions between the dorsal and ventral visual subsystems are crucial for the perception of 3D object from 2D optic flow. P20. TMS (2) P20-1 Investigation of the contribution of motor cortex to mastication using transcranial magnetic stimulation A.P. Lavender1,2 , E.S. Atis3 , K.S. Turker3 1 The Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan, 2 Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Namiki, Tokorozawa, Japan, 3 Gender Reflex Laboratories, Center for Brain Research, Department of Physiology, Ege University, Bornova, Izmir, Turkey Objective: To use transcranial magnetic brain stimulation (TMS) to assess the contribution of masticatory centre of motor cortex (M1) to mastication. Methods: M1 area innervating the jaw muscles was stimulated using TMS in twelve healthy volunteers with no history of neurological or dental disorders. TMS was applied to the left masticatory M1 during two active tasks. Static, where subjects bit down on a specially designed chewing device which provided immediate feedback and recorded force and gape, and dynamic during which subjects were required to move the mandible through its entire range of motion, again on the chewing device. For dynamic, stimuli were given when the mandible crossed the
S219 mid-point between open and closed at 0.7, 0.8, 0.9, 1.0, 1.1 and 1.2 × threshold (T). Surface EMG was recorded from the contralateral masseter. Recordings were filtered and full wave rectified before averaging around the time of the stimulus. Conditions were compared using the cumulative summation (CUSUM) method. Results: MEP of the right masseter were observed at a latency of ~7.5 ms at stimulus levels above T for static condition and increased in size with increasing stimulus intensity. This was not evident at any stimulus intensity for the dynamic condition. No inhibition was evident in either EMG recordings or CUSUM analyses for subthreshold stimulus intensities. Conclusions: This study shows that M1 excitability is less during dynamic jaw activation than static clenching. During static jaw clenching MEP responses increased with stimulus intensity, but there were negligible changes at suprathreshold stimulus intensities for the dynamic condition. Significance: M1 contribution to chewing appears to be low. Further studies are required to assess the mechanisms for controlling jaw movement. It is likely the central pattern generator controls movement of the jaw and adjusts to reduce chances of injury to the tongue and cheeks. P20-2 Navigated TMS mapping of bulbar muscles L. Saisanen1,2 , S. Kemppainen1 , P. Julkunen1 , H. Siintamo2 , E. Mervaala2 , M. Kononen1,3 1 Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland, 2 University of Eastern Finland, Kuopio, Finland, 3 Department of Radiology, Kuopio University Hospital, Kuopio, Finland Objective: We evaluated the cortical representation areas of bulbar muscles of the right cerebral hemisphere in 8 healthy subjects (6 female, 2 male, mean age: 33.8 years) by applying neuronavigated transcranial magnetic stimulation (nTMS). The aim was to find out which muscles motor evoked potentials (MEPs) can be detected from relaxed bulbar muscles using EMG recording with superficial EMG electrodes. Methods: Motor threshold (MT) for thenar muscles was first determined. Thereafter, we defined the MT for mentalis muscle and determined latency and amplitude using 20 MEPs at stimulation intensity of 120%MT. Finally, a mapping of large area in the lateral motor strip was performed at the intensity of 110% of the mentalis MT. MEPs were recorded from several muscles: frontalis, orbicularis oculi, nasalis, mentalis, orbicularis oris, masseter, sternocleidomastoideus and trapezius. Coil orientations 45 degrees towards midline and posterior-anterior direction were used. Results: Mean MT was higher in mentalis (mean 53.9±11.6% stimulator output) than in thenar muscles (mean 43.5±14.7% stimulator output). The mean MEP latency for mentalis was 12.8±2.9 ms and amplitude 167±73 mV. Clear muscle responses were achieved in mentalis, orbicularis oris and masseter muscles. Responses that were more diffuse to define were elicited in nasalis, sternocleidomastoideus and trapezius. Responses could not be elicited in frontalis, orbicularis oculi. Maps of mentalis, orbicularis oris and masseter were partly overlapping, but still distinguishable. Motor representation area was larger than expected in anterior-posterior orientation compared to standard anatomic atlas. The posterior-anterior coil orientation seemed to be more effective in activating cortical representation of bulbar muscles. Conclusions: Muscles appropriate and most favourable for the preoperative evaluation of motor cortical areas were mentalis, orbicularis oris and masseter. Hence, bulbar muscles can be used with nTMS in preoperative evaluation of cortical motor function. P20-3 Excitability changes in the human primary motor cortex by Dual motor Task are dependent on task properties K. Uehara1,3 , T. Higashi1 , S. Tanabe2 , T. Morishita3 , M. Ninomiya3 , K. Funase3 , K. Sugawara1 1 Rehabilitation Science, Division of Health & Social Work, Kanagawa University of Human Services Graduate School of Health & Social Work Sciences, Yokosuka, Japan, 2 Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan, 3 Division of Human Sciences, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashihiroshima, Japan Objective: The aim of this study was to investigate whether the effects of changes in primary motor cortex (M1) with the upper limb movement during gait, which is referred to as Dual motor Task. To further investigate how Dual motor Task are dependent on task properties measured using transcranial magnetic stimulation (TMS).