Visuo-Motor Interactions in the Human Brain: A Transcranial Magnetic Stimulation study


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A Master's thesis.
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Master (thesis) (master)
Visuo-Motor Interactions in the Human Brain: A Transcranial Magnetic Stimulation study
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Université de Lausanne, Faculté de biologie et médecine
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The interaction between the visual and the motor cortex is of primary importance in the daily life of people. Almost every muscle movement is ordered according to what appears in our field of vision. Studies have shown that damages of the primary visual cortex of monkeys have been linked with impaired motor functions and with structural lesions of the motor cortex. Such link between those two regions in the human brain has already been found but remains unclear. In this project, we aim to measure the impact of a virtual lesion of the primary visual cortex (V1) on the primary motor cortex (M1) of the contralateral hemisphere compared with a control stimulation (sham). In order to do this, we use the transcranial magnetic stimulation (TMS) as a non-invasive brain stimulation. Firstly, we use single pulse TMS on M1 to assess three parameters of the muscle response (the motor evoked potential – MEP) as the amplitude (AMP), the cortical silent period (CSP) and the area under the curve (Area). Then, we apply a repetitive stimulation of TMS on V1 to inhibit locally the activity and finally, we measure again the M1 activity with the MEPS. Our results show a decrease of AMP without reaching significance (p = 0.14), a significant decrease of Area (p = 0.037) and a significant increase of the CSP (p < 4.2e-11). These results show that there is a tight connection between the visual and motor cortices and that in case of aberrancies of V1, it will have an impact not only in the local region but also at distance in the motor cortex of the contralateral hemisphere. The exact pathway of the information’s integration is not fully understood but we assume that the changes of excitability is transmitted to the contralateral hemisphere through the corpus callosum. This discovery allows us to understand better this connection and maybe use this protocol in further application such as a clinical therapy for diseases that imply aberrant connection between both brain regions.
repetitive TMS, rTMS, phosphene threshold (PT), contralateral hemisphere, visual deafferentation, visuo-motor integration
Create date
07/09/2020 13:37
Last modification date
04/02/2021 7:26
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