Gender difference in premotor activity during active tactile discrimination

To investigate possible gender differences in tactile discrimination tasks, we measured cerebral blood flow of seven men and seven women using positro n emission tomography and O-15 water during tactile tasks performed with th e right index finger. A nondiscrimination, somatosensory control task activ ated the left primary sensorimotor cortex and the left parietal operculum e xtending to the posterior insula without any gender difference. Compared wi th the control task, discrimination tasks activated the superior and inferi or parietal lobules bilaterally, right dorsal premotor cortex, and dorsolat eral prefrontal cortex in both genders, consistent with the motion of right hemisphere involvement during exploratory attentional movements. In both g enders, symmetric activation of the superior and inferior parietal lobules and asymmetric activation of the right dorsolateral prefrontal cortex were confirmed. The former is consistent with the spatial representation of the tactile input and the latter with the spatial working memory. However, acti vation of the dorsal premotor cortex was asymmetric in men, whereas it was symmetric in women, the gender difference being statistically significant. This may suggest gender differences in motor programs for exploration in ma nipulospatial tasks such as tactile discrimination with active touch, possi bly by greater interhemispheric interaction through the dorsal premotor cor tices in women than in men. (C) 2000 Academic Press.