Figure 1

Experimental protocol of fMRI experiment. The top row show the messages displayed to the subject in the scanner for each somatosensory stimulus. The stimulus was delivered after a 2-6 s delay ("Ready" message), followed by a 5 s "Wait" message before a 4 s "Rate stimulus" message was displayed, at which time the subject rated the stimulus on a five-button claw. The middle row illustrates how one stimulus (bars) is repeated 10 times, creating one run. The bottom row illustrates how each run is repeated with different stimulus modalities, making a total of 20 runs. Only stimulus intensities delivered to hairy skin (41°C and 51°C) is reported here. Intermingled were two heat stimulus intensities delivered to glabrous skin and one epidermal electrical stimulus. Results from these stimuli are reported elsewhere.