7.3 Results

Figure 7.7 shows the activation at 0 s, 3 s, 6 s and 9 s following the stimulus, for one subject in the 'go, no-go' experiment. Maximum activation occurs at 3-6 seconds from the delivery of the stimulus. During the 'no-go' task, activation was seen in the medial premotor cortex for all the subjects. This region was rostral to the anterior commissural (AC) line. Activity was observed in these regions during the 'go' task as well (see Figure 7.8). During the 'go' task activation was also seen in a region of the premotor cortex caudal to the AC line.

Figure 7.7 Volume images acquires between 0 and 12 seconds after the presentation of either a 'go' or 'no-go' stimulus

Go	No-Go

Figure 7.8 View of the medial surface of the left hemisphere, three seconds after the stimulus in a go, no-go paradigm.

The mean value of the percentage change upon activation of the areas involved in the motor task are shown in Figure 7.9. This shows the rostral part of the premotor cortex (labelled pre-SMA) to be active in both 'go' and 'no-go' tasks, with the caudal part (labelled SMA) being only active in the 'go' task. This suggests that the pre-SMA is involved in the movement decision making aspect of the task, whereas the SMA proper is more intimately involved in the movement itself.

Figure 7.9 Plots of the percentage signal change in the Pre-SMA, SMA and primary motor cortex, for the 'go' and the 'no-go' task.

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