Poster No:
111
Submission Type:
Abstract Submission
Authors:
Negar Namdar1, Jukka Saari2, Sara Määttä2, Laura Säisänen3, Jelena Hyppönen2, Päivi Koskenkorva2, Elisa Kallioniemi1
Institutions:
1New Jersey Institute of Technology, Newark, NJ, 2Kuopio University Hospital, Kuopio, Northern Savonia, 3Kuopio University Hospital, University of Eastern Finland, Kuopio, Northern Savonia
First Author:
Co-Author(s):
Jukka Saari
Kuopio University Hospital
Kuopio, Northern Savonia
Sara Määttä
Kuopio University Hospital
Kuopio, Northern Savonia
Laura Säisänen
Kuopio University Hospital, University of Eastern Finland
Kuopio, Northern Savonia
Introduction:
Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique. When electroencephalography (EEG) is used concurrently with TMS, the resulting TMS-evoked EEG potentials (TEPs) offer a means to assess the excitability, connectivity, and oscillatory patterns within the targeted cortical region (Ilmoniemi et al., 1997). So far, most motor cortex studies have focused on the hand area for two main reasons: Its low stimulation intensity, which results from its proximity to the scalp, and its easily detectable hand knob structure (Yousry et al., 1997). The reason for the limited research on other motor areas, such as the leg, arises from its deeper location in the homunculus, the challenge of targeting individual muscles, and the differences in the corticospinal tract of the upper and lower limbs (Kesar et al., 2018). On the other hand, the challenges in evaluating the cortical face and tongue representations arise from directly stimulating peripheral facial nerve fibers due to the spread of the TMS-induced electric field (Dubach et al., 2004). Consequently, TEPs have been mainly studied in the hand area, with no research available evaluating the TEPs across the homunculus. In this study, we recorded and assessed TEPs in the hand, leg, and face areas to characterize them.
Methods:
Eighteen healthy volunteers (11 females, 7 males, age 46.5±17.3 years) participated in the study. First, the cortical representation areas for the right leg (tibialis anterior), hand (first dorsal interosseous), and face (mentalis) were mapped, and the resting motor threshold (rMT) of these areas was measured as the percentage of maximum stimulator output (%MSO). After that, 150 TEPs from each region were measured using single TMS pulses with a stimulation intensity of 90% rMT. TEPs were recorded with a 60-channel electrode system. The TEPs were averaged over subjects in each stimulated area in three different ROIs: left M1 (9 electrodes), right M1 (9 electrodes), and Cz (1 electrode). Artifacts in the data were removed with independent component analysis. Differences between the TEPs between different muscle groups were evaluated with a two-sample t-test (p < 0.05, uncorrected) calculated every 1ms.
Results:
In the TEPs of the right motor area there were peaks at 16, 27, 34, 54, 80, 100, 102, 112, 117, 155, 164, 168, 180, and 182ms after the TMS for the face area; at 19, 35, 51, 64, 76, 80, 88, 98, 109, 137, 147, 162, 171, and 196ms for the leg; and at 21, 31, 53, 86, 117, 126, 132, 178, 190, and 195ms for the hand area. The TEPs differed between face and leg in the time windows 15-22ms, 178-201ms, between face and hand in windows 15-23ms, 137-156ms, and between leg and hand in windows 33-41ms, 73-99ms, 179-182ms.
In the TEPs of the left motor area, there were peaks at 21, 35, 142, 145, 154, and 199ms after TMS for the face area; at 17, 31, 47, 82, 90, 107, 114, 138, 158, 162, 169, 178, and 182ms for the leg and at 34, 84, 129, and 170ms, for the hand area. The TEPs differed between face and leg in the time windows 36-53ms, 192-206ms, between face and hand in the windows 73-83ms, 198-233ms, and between leg and hand in the window 37-55ms.
Lastly, the TEP results from the Cz electrode show peaks at 31, 56, 78, 92, and 182ms for the face area; at 32, 50, 57, 76, 137, and 181ms for the leg, and at 30, 50, 63, 72, 157, and 165ms for the hand area. The TEPs differed between face and leg in the time windows 73-79ms, 115-143ms, 164-195ms, and between leg and hand in the windows 29-36ms, 67-94ms, 120-150ms.
Conclusions:
TEPs of the hand, face, and leg areas are different.
Brain Stimulation:
TMS 1
Novel Imaging Acquisition Methods:
EEG 2
Keywords:
Cortex
Electroencephaolography (EEG)
Motor
NORMAL HUMAN
Transcranial Magnetic Stimulation (TMS)
1|2Indicates the priority used for review
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Amassian, V. E., Stewart, M., Quirk, G. J., & Rosenthal, J. L. (1987), ‘Physiological basis of motor effects of a transient stimulus to cerebral cortex’, Neurosurgery, vol. 20, no.1, pp. 74–93
Ilmoniemi, R. J., Virtanen, J., Ruohonen, J., Karhu, J., Aronen, H. J., Näätänen, R., & Katila, T. (1997), ‘Neuronal responses to magnetic stimulation reveal cortical reactivity and connectivity’, Neuroreport, vol. 8, no.16, pp. 3537–3540
Ilmoniemi, R. J., Ruohonen, J., & Karhu, J. (1999), ‘Transcranial magnetic stimulation—A new tool for functional imaging of the brain’, Critical Reviews in Biomedical Engineering, vol. 27, no. 3–5, pp. 241–284
Kesar, T. M., Stinear, J. W., & Wolf, S. L. (2018), ‘The use of transcranial magnetic stimulation to evaluate cortical excitability of lower limb musculature: Challenges and opportunities’, Restorative neurology and neuroscience, vol. 36, no. 3, pp. 333–348
Yousry, T. A., Schmid, U. D., Alkadhi, H., Schmidt, D., Peraud, A., Buettner, A., & Winkler, P. (1997), ‘Localization of the motor hand area to a knob on the precentral gyrus. A new landmark’, Brain: a journal of neurology, vol. 120, pp. 141–157