The name is absent

123

Figure 8 Time series of the same voxel under the same conditions, but here the new coil control box is
being used. Since the coil is now physically disconnected from the TMS when it is not being triggered,
there is now no induced current caused by the charging snubbing capacitors.

To test whether the system is now usable in an fMRI scanner we performed a simple
experiment in which we had a subject alternate between tapping her for ten trials and
keeping them still for another ten. In every trial that she tapped her fingers we delivered a
TMS pulse. Figure 9 shows a time series of a voxel in primary motor cortex, the vertical
lines separate each block of 20 trials. As you can see we were able to record a strong signal
in response to her motor activity. The scale is this figure is the same as figures 6 and 8.
Notice that the signal is significantly smaller than the noise shown in figure 6; this signal
would be completely obscured if the capacitor charging noise was still present. Figure 10
shows an axial cross section of her brain with activation overlaid.

<<   131   132   133   134   135   136   137   >>

More intriguing information