Albanese Et Al., Cognitive Modulation of Vibrotactile Cortical Processing

24 This event-related fMRI study examines the neural correlates of vibrotactile 25 sensation within the context of different psychophysical demands. Nine subjects 26 received vibrotactile stimuli on the right volar forearm during detection, localization and 27 passive tasks. In the detection task, subjects indicated the offset (end) of each stimulus 28 by pressing a response key with their left hand. In the localization task, subjects 29 identified the location of the stimulus ('distal?' or 'proximal?') by pressing the appropriate 30 response key 4s after the end of the stimulus. In the passive task, subjects received the 31 same vibrotactile stimuli, but no response was required. Analysis of stimulus-evoked 32 activity compared to the resting baseline period revealed significant bilateral secondary 33 somatosensory cortex (SII) activation for all three tasks. However, only in the offset34 detection and localization tasks was stimulus-evoked activation observed in other 35 expected areas of tactile processing, such as contralateral primary somatosensory 36 cortex neighboring the posterior parietal cortex (SI/PPC) and in bilateral anterior insular 37 cortex (aIC). During the localization task, we identified vibrotactile-evoked activation in 38 right aIC, which was maintained after the termination of the stimulus. Results suggest 39 that vibrotactile-related activation within SI/PPC and aIC is enhanced by the increased 40 levels of attention and cognitive demands required by the detection and localization 41 tasks. Activation of aIC during vibrotactile stimulation, as well as during the post42 stimulus delay in the localization trials, is consistent with the growing literature linking 43 this area with the perception and short-term memory of tactile information. 44 45