Active touch in tactile perceptual discrimination: brain activity and behavioral responses to surface differences.

This study investigates the neural and behavioral mechanisms of tactile perceptual discrimination using fMRI and a set of wrinkled surface stimuli with varying textures. Fifteen female participants were tasked with distinguishing between different surfaces by touch alone. Behavioral results demonstrated variable discriminability across conditions, reflecting the tactile sensitivity of human fingertips. Neural analysis showed varied brain activations tied to the task's difficulty. In the easiest least fine-grained discrimination condition, widespread activations were observed across sensory and integration regions. As task difficulty increased, stronger parietal and frontal lobe involvement reflected higher cognitive demands. In the hardest most fine-grained discrimination condition, activation concentrated in the right frontal lobe, indicating reliance on executive functions. These results highlight the brain's intricate role in processing sensory information during tactile discrimination tasks of varying difficulty. As task difficulty increases, the brain adapts by engaging additional neural resources to meet higher cognitive demands. This research advances our understanding of the psychophysical and neural bases of tactile discrimination acuity, with practical implications for designing materials that enhance tactile feedback.