Motor mapping is a common procedure in TMS to determine the site and size of motor cortex representations. In addition, motor threshold measurements are often used as a basis for TMS sessions.

Visor combines all this in one system. Motor-evoked Potential (MEP) can be recorded for each stimulated site and is projected in real-time to the brain surface in order to create a map with corresponding EMG amplitudes.

Motor evoked potential is recorded for each stimulated point and projected in real-time onto the brain in order to create corresponding EMG amplitude maps.

Motor threshold measurements can be done quickly with Visor and used as a basis for the TMS session. Visor records all parameters of the TMS stimulation session so that is can be reproduced easily .

The protocol for motor cortex mapping consists of positioning the coil at a number of different sites, single pulse TMS at the sites, and successive recording of the evoked motor potential (MEP) of a selected muscle. The position of the coil, its electrical properties, and the evoked responses are then used to calculate the cortical representation site of the selected muscle.

When the stimulation responses for stimulation at all planned sites have been recorded, the data is used to calculate the most likely statistical representation point of the muscle on the cortex. This approach is based on a calculation of a likelihood map, evaluating the correspondence between the electric field strength at points on the cortex and the motor responses using Kendalls statistics.

Matthaus L, Trillenberg P, Fadini T, Finke M, Schweikard A. Brain mapping with transcranial magnetic stimulation using a refined correlation ratio and Kendalls tau. Stat Med. 2008 Nov 10;27(25):5252-70.