Not all mammals' courtship behaviors are so obviously a product of brain-function differences between the sexes, however. In humans, these more subtle behaviors bear witness to the surprisingly abundant gender-specific differences in the central nervous system (CNS). For example, in men the auditory brainstem response has a longer latency period and smaller amplitude than in women. This may have a profound effect on men's response to auditory stimuli. Other differences in sexual behavior may be indicated by structural distinctions between male and female brains. In the areas of the brain that influence sexual behavior, women are reported to have more gray matter than men in a language-related cortical region, but not in a more visuospatially related cortical region. This indicates that the sexes have structural differences in the cerebral cortex. It also raises the question, are men inherently more responsive to visual sexual stimulation than women and are women intrinsically more responsive to sexual wooing through words?