Sensory-Tactile Functional Mapping and Use-Associated Structural Variation of the Human Female Genital Representation Field
Authors: Andrea J J Knop
Christine Heim
Carsten Bogler
Stephanie Spengler
Michael Brecht
Carina Forster
John-Dylan Haynes
Journal: Journal of Neuroscience (2022)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: functional mapping; genital field; individual variability; plasticity; sexual behavior
Affiliations: Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Psychology, 10117 Berlin, Germany., Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin Center for Advanced Neuroimaging, 10117 Berlin, Germany., Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany., Bernstein Center for Computational Neuroscience, 10115 Berlin, Germany., Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Psychology, 10117 Berlin, Germany .

Abstract:  The precise location of the human female genital representation field in the primary somatosensory cortex (S1) is controversial and its capacity for use-associated structural variation as a function of sexual behavior remains unknown. We used a functional magnetic resonance imaging (fMRI)-compatible sensory-tactile stimulation paradigm to functionally map the location of the female genital representation field in 20 adult women. Neural response to tactile stimulation of the clitoral region (vs right hand) identified individually-diverse focal bilateral activations in dorsolateral areas of S1 (BA1-BA3) in alignment with anatomic location. We next used cortical surface analyses to assess structural thickness across the 10 individually most activated vertices per hemisphere for each woman. We show that frequency of sexual intercourse within 12 months is correlated with structural thickness of the individually-mapped left genital field. Our results provide a precise functional localization of the female genital field and provide support for use-associated structural variation of the human genital cortex.SIGNIFICANCE STATEMENT We provide a precise location of the human female genital field in the somatosensory cortex and, for the first time, provide evidence in support of structural variation of the human genital field in association with frequency of genital contact. Our study represents a significant methodological advance by individually mapping genital fields for structural analyses. On a secondary level, our results suggest that any study investigating changes in the human genital field must map the field individually to achieve sufficient precision. Our results pave the way for future research into the plasticity of the human genital cortex as a function of normal or adverse experience as well as changes in pathologic conditions, i.e., sexual dysfunction, sexual deviation, or sexual risk-taking behavior. 

Retracted: No

PubPeer comments:
 This article was reviewed on the error bar podcast episode 26: https: theerrorbar.com ?e=26 story 110: https: theerrorbar.com ?s=110. The review was done in the light of newspaper headlines about the article. The slightly-edited transcript is copied here: headline: THE CLITORIS HAS BEEN FOUND tweet: the tabloids missed this story, but the error bar didn t - brain science has found the clitoris! the brain area responding to clitoral vibration is in the middle at the top of the brain, just where it should be. description: in a rare case of an open-access scientific paper about sex being missed by all the news media, the female clitoris has, at last, been found. the general anatomy of the brain is not a mystery has been known about for centuries. in the 1920s to 1950s, the specific anatomy of the brain areas that respond to touch on the body were systematically mapped. there s an area for touch on the hand - i study that one - another for the foot, another for the face. but the genitals have not been mapped precisely. well, i say genitals, but of course, following international women s day, i mean the clitoris. the penis was properly mapped - with non-arousing stroking of the penile shaft inside the brain scanner - as long ago as 2005, but the first studies of the clitoris came six years later. the new study asked 25 women to go into a brain scanner with a vibrating dome 25 minutes to themselves. with a punishing 32 repetitions of 10 seconds of the dome under their mons pubis, plus another 320 seconds vibrating their hand, science was finally able to find the clitoris in the brain. the clitoris is, aptly, underneath a fold in the uppermost part of the brain s main sensory area. no great surprises really, apart from that it s not in the place where the penis was located, way back in the 20th century. evaluation: has the clitoris been found? yes. this study its results are clear simple - in those women for whom the experiment worked, the area of the brain activated by the clitoral stimulation, as well as the area for the hand stimulation, were neat precisely-located on the brain. so, job done, right? well, no. error bar nerds wouldn t be getting their money s worth if i didn t raise a few problems, so here they are. first, 25 women were recruited for the study - presumably scanned - but no information other than it didn t work was provided for 5 of them. what happened to those 5? did they not find their own clitoris? did the brain not activate? was it a statistical problem? nothing is given, that s a problem. second, a further conclusion of the study was that the self-reported frequency of sexual activity is related to the thickness of the clitoral area on the left side of the brain, but not the right side. this relationship was found only after the analysis included several other factors in the analysis - age, years of sexual activity whole-brain thickness. it would be good if the authors had reported the analysis without these additional factors, just to be sure. it also seems that in this extra analysis two additional women s data were excluded from. but again - troublingly - no details are given about these removals. given that this weak, post-hoc relationship was found on only one side of the brain only after accounting for some other things, i think we can ignore the relationship between brain thickness sexual activity. conclusion: this clear and simple brain imaging study has indeed found the clitoris, but why shroud the results in mystery by excluding 5 then 7 of the participants in different analyses. some deeper probing is required. ,