Optimized FT-Control with FTA Sensor - Robotized Transcranial Magnetic Stimulation - page 124

• The Dorsolateral prefrontal cortex (DLPFC) is commonly targeted for treat-
ment of major depression using rTMS [ 1 , 8 ].
• The Gyrus Frontalis Medius (GFM) has been stimulated with rTMS for research
on depression [ 4 ] and we have targeted the GFM with the robotized TMS system
for a study with alcohol-addicted patients (in prep.).
Straight after the familiarization task, the users are now asked to position the TMS
coil at these targets points with the hand-assisted positioning method. To estimate
the precision of the positioning we measure the distance of the target to the actual
coil position (marked by the pen).
7.5 Performance of the FTA Sensor in Operation
7.5.1 Coil Calibration and Gravity Compensation
Subsequently to an optimized coil calibration, we have estimated the errors of the
gravity compensation for different TMS coils. For each coil tested, we have
recorded 8,000-10,000 data points in random spatial orientation.
Figure 7.7 shows the absolute errors of the gravity compensation for forces and
torques as boxplots. The coils are sorted ascendingly with respect to their weight
Fig. 7.7 Accuracy of optimized coil calibration and gravity compensation for different TMS
coils. The TMS coils are sorted by ascending weight from left to right (cf. Table 5.1 ) . The left
graph shows the absolute errors for forces and the right graph presents the absolute errors for
torques