Abstract
Recent findings indicate somesthesis can activate cortical areas in humans classically identified as visual or multisensory. To examine possible influence of tactile activation on functional organizations for orientation in visual areas, we used intrinsic-signal optical imaging to map patterns of activation in areas surrounding the posterior tip of the superior temporal sulcus (presumed MT/MST/FST) in anesthetized owl monkeys. Visual stimuli of drifting oriented gratings and random dots were used to localize MT, MST, and FST. Tactile stimuli known to elicit the percepts of pressure, flutter or vibration (sinusoidal indentations of 2, 30 or 200 Hz) were applied to the glabrous skin of an immobilized fingerpad. Imaging runs included vision alone, tactile alone, and vision plus tactile conditions.
The MT/MST complex showed greater activation to visual stimulation than for vibrotaction. The vibratory stimuli alone activated areas likely to be MST and FST. In contrast to somatosensory cortex, modular architectures for vibration were absent. Pairing vibrotactile with visual stimuli led to smaller activations when compared to visual stimulation alone. These results reveal that vibratory stimuli activate MST and FST while globally reducing the activation in MT to visual stimuli. These findings suggest a differential role of vibrotaction in MT, MST and FST.
Haidong Lu and NS44375 and NS052821.