Eleni Frangos

Women's clitoris, vagina, and cervix mapped on the sensory cortex: fMRI evidence.

INTRODUCTION The projection of vagina, uterine cervix, and nipple to the sensory cortex in humans has not been reported. AIMS The aim of this study was to map the sensory cortical fields of the clitoris, vagina, cervix, and nipple, toward an elucidation of the neural systems underlying sexual response. METHODS Using functional magnetic resonance imaging (fMRI), we mapped sensory cortical responses to clitoral, vaginal, cervical, and nipple self-stimulation. For points of reference on the homunculus, we also mapped responses to the thumb and great toe (hallux) stimulation. MAIN OUTCOME MEASURES The main outcome measures used for this study were the fMRI of brain regions activated by the various sensory stimuli. RESULTS Clitoral, vaginal, and cervical self-stimulation activated differentiable sensory cortical regions, all clustered in the medial cortex (medial paracentral lobule). Nipple self-stimulation activated the genital sensory cortex (as well as the thoracic) region of the homuncular map. CONCLUSION The genital sensory cortex, identified in the classical Penfield homunculus based on electrical stimulation of the brain only in men, was confirmed for the first time in the literature by the present study in women applying clitoral, vaginal, and cervical self-stimulation, and observing their regional brain responses using fMRI. Vaginal, clitoral, and cervical regions of activation were differentiable, consistent with innervation by different afferent nerves and different behavioral correlates. Activation of the genital sensory cortex by nipple self-stimulation was unexpected, but suggests a neurological basis for womens reports of its erotogenic quality.

Hysterectomy Improves Sexual Response? Addressing a Crucial Omission in the Literature

The prevailing view in the literature is that hysterectomy improves the quality of life. This is based on claims that hysterectomy alleviates pain (dyspareunia and abnormal bleeding) and improves sexual response. Because hysterectomy requires cutting the sensory nerves that supply the cervix and uterus, it is surprising that the reports of deleterious effects on sexual response are so limited. However, almost all articles that we encountered report that some of the women in the studies claim that hysterectomy is detrimental to their sexual response. It is likely that the degree to which a womans sexual response and pleasure are affected by hysterectomy depends not only on which nerves were severed by the surgery, but also the genital regions whose stimulation the woman enjoys for eliciting sexual response. Because clitoral sensation (via pudendal and genitofemoral nerves) should not be affected by hysterectomy, this surgery would not diminish sexual response in women who prefer clitoral stimulation. However, women whose preferred source of stimulation is vaginal or cervical would be more likely to experience a decrement in sensation and consequently sexual response after hysterectomy because the nerves that innervate those organs, that is, the pelvic, hypogastric, and vagus nerves, are more likely to be damaged or severed in the course of hysterectomy. However, all published reports of the effects of hysterectomy on sexual response that we encountered fail to specify the womens preferred sources of genital stimulation. As discussed in the present review, we believe that the critical lack of information as to womens preferred sources of genital stimulation is key to accounting for the discrepancies in the literature as to whether hysterectomy improves or attenuates sexual pleasure.

Activation of sensory cortex by imagined genital stimulation: an fMRI analysis

Background During the course of a previous study, our laboratory made a serendipitous finding that just thinking about genital stimulation resulted in brain activations that overlapped with, and differed from, those generated by physical genital stimulation. Objective This study extends our previous findings by further characterizing how the brain differentially processes physical ‘touch’ stimulation and ‘imagined’ stimulation. Design Eleven healthy women (age range 29–74) participated in an fMRI study of the brain response to imagined or actual tactile stimulation of the nipple and clitoris. Two additional conditions – imagined dildo self-stimulation and imagined speculum stimulation – were included to characterize the effects of erotic versus non-erotic imagery. Results Imagined and tactile self-stimulation of the nipple and clitoris each activated the paracentral lobule (the genital region of the primary sensory cortex) and the secondary somatosensory cortex. Imagined self-stimulation of the clitoris and nipple resulted in greater activation of the frontal pole and orbital frontal cortex compared to tactile self-stimulation of these two bodily regions. Tactile self-stimulation of the clitoris and nipple activated the cerebellum, primary somatosensory cortex (hand region), and premotor cortex more than the imagined stimulation of these body regions. Imagining dildo stimulation generated extensive brain activation in the genital sensory cortex, secondary somatosensory cortex, hippocampus, amygdala, insula, nucleus accumbens, and medial prefrontal cortex, whereas imagining speculum stimulation generated only minimal activation. Conclusion The present findings provide evidence of the potency of imagined stimulation of the genitals and that the following brain regions may participate in erogenous experience: primary and secondary sensory cortices, sensory-motor integration areas, limbic structures, and components of the ‘reward system’. In addition, these results suggest a mechanism by which some individuals may be able to generate orgasm by imagery in the absence of physical stimulation.