Friday, February 11, 2022

From 2000... Why Men Rape... Prevention efforts will founder until they are based on the understanding that rape evolved as a form of male reproductive behavior that needs a program for young men that teaches them to restrain their sexual behavior

Why Men Rape... Prevention efforts will founder until they are based on the understanding that rape evolved as a form of male reproductive behavior. Randy Thornhill, Craig T Palmer. The New York Academy of Sciences, 2000. https://www.csus.edu/indiv/m/merlinos/thornhill.html

Introduction

(1) A friend of ours once told us about her rape. The details hardly matter, but in outline her story is numbingly familiar. After a movie she returned with her date to his car, which had been left in an isolated parking lot. She was expecting him to drive her home. Instead, the man locked the car doors and physically forced her to have sex with him.

(2) Our friend was emotionally scarred by her experience: she became anxious about dating, and even about going out in public. She had trouble sleeping, eating and concentrating on her work. Indeed, like some war veterans, rape victims often suffer from post-traumatic stress disorder, in which symptoms such as anxiety, memory loss, obsessive thoughts and emotional numbness linger after a deeply disturbing experience. Yet gruesome ordeals like that of our friend are all too common: in a 1992 survey of American women aged eighteen and older, 13 percent of the respondents reported having been the victim of at least one rape, where rape was defined as unwelcome oral, anal or vaginal penetration achieved through the use or threat of force. Surely, eradicating sexual violence is an issue that modern society should make a top priority. But first a perplexing question must be confronted and answered: Why do men rape?

(3) The quest for the answer to that question has occupied the two of us collectively for more than forty years. As a purely scientific puzzle, the problem is hard enough. But it is further roiled by strong ideological currents. Many social theorists view rape not only as an ugly crime but as a symptom of an unhealthy society, in which men fear and disrespect women. In 1975 the feminist writer Susan Brownmiller asserted that rape is motivated not by lust but by the urge to control and dominate. In the twenty-five years since, Brownmiller's view has become mainstream. All men feel sexual desire, the theory goes, but not all men rape. Rape is viewed as an unnatural behavior that has nothing to do with sex, and one that has no corollary in the animal world.

(4) Undoubtedly, individual rapists may have a variety of motivations. A man may rape because, for instance, he wants to impress his friends by losing his virginity, or because he wants to avenge himself against a woman who has spurned him. But social scientists have not convincingly demonstrated that rapists are not at least partly motivated by sexual desire as well. Indeed, how could a rape take place at all without sexual motivation on the part of the rapist? Isn't sexual arousal of the rapist the one common factor in all rapes, including date rapes, rapes of children, rapes of women under anesthetic and even gang rapes committed by soldiers during war?


Sensory-Tactile Functional Mapping and Use-Associated Structural Variation of the Human Female Genital Representation Field

Sensory-Tactile Functional Mapping and Use-Associated Structural Variation of the Human Female Genital Representation Field. Andrea J. J. Knop, Stephanie Spengler, Carsten Bogler, Carina Forster, Michael Brecht, John-Dylan Haynes and Christine Heim. Journal of Neuroscience, February 9 2022, 42 (6) 1131-1140; https://doi.org/10.1523/JNEUROSCI.1081-21.2021

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.

Keywords: functional mappinggenital fieldindividual variabilityplasticitysexual behaviorsomatosensory cortex

Discussion

We present novel evidence on the precise location of the female genital representation field and its capacity for use-associated structural variation. Using functional mapping during sensory-tactile stimulation of the clitoral region, we show focal bilateral neural activations within the dorsolateral postcentral gyrus in S1. We show that the individual location of peak neural activations in response to clitoral stimulation varies considerably between women. We applied cortical surface analysis to the individually-mapped ROI to compute structural thickness of the genital field. Correlating the individually-mapped morphologic data with behavioral data on sexual contact, we provide first evidence that thickness of the genital field varies as a function of frequency of genital intercourse in the past 12 months and lifetime, in line with use-associated plasticity.

Our results are noteworthy in several ways. To localize the female genital field, we measured neural response in a tactile-sensory stimulation paradigm that delivers a physiologically valid stimulus as opposed to a previous study using electrical stimulation of the clitoris (Michels et al., 2010). Furthermore, our tactile-sensory stimulation paradigm did not involve touching of body parts adjacent to the clitoris nor did it induce marked sexual arousal as opposed to previous studies using self-delivered or partner-delivered stimulation (Georgiadis et al., 200620092010Komisaruk et al., 2011). The sole other study that used a sensory-tactile nonarousing stimulation paradigm to localize the genital field was limited to males (Kell et al., 2005). Our stimulation paradigm induced focal targeted neural activations, without inducing neural activation in other brain regions, at comparatively (Kell et al., 2005Michels et al., 2010) high levels of statistical significance without using somatosensory template masks. Therefore, our data provide unequivocal information about the location of the female genital field and represent a significant methodological advance compared with previous studies that yielded conflicting results (Georgiadis et al., 20062009Michels et al., 2010Komisaruk et al., 2011), likely because of confounding factors inherent to stimulation paradigms used in these studies (Pratt et al., 1980Forss et al., 1994). On a group level, the mean location of the female genital field in the dorsolateral postcentral gyrus, identified in our study, corresponds with the location reported in two of the previous studies in females using electrical (Michels et al., 2010) or partner-delivered manual stimulation (Georgiadis et al., 2006) as well as with the location reported for males in the above-referenced study using sensory-tactile stimulation in males (Kell et al., 2005). Our results confirm a somatotopically-ordered representation of the female clitoris, adjacent to the representation of the hips and upper legs and commensurate with anatomic location, and disprove displaced location in the mesial wall of the precentral lobe. Our results provide independent confirmation for the revision (Kell et al., 2005) of the original homunculus (Penfield and Rasmussen, 1950) and extend the validity of the revised homunculus to women. Our results confirm a bilateral somatosensory representation of the anatomically centered clitoris, in line with histologic mapping data on the localization and bilateral representation of the rat genital cortex (Lenschow et al., 2016Lauer et al., 2017Lenschow and Brecht, 2018).

Our results suggest profound variability of the individual location of the genital field within the dorsolateral part of S1 with individual peak activations clearly deviating from the group mean. This means that any study looking at structural variation of the genital field as a function of certain conditions, such as sexual behavior, sexual abuse or sexual dysfunction, must necessarily implement individual mapping of the genital field and compute data, i.e., cortical thickness, on an individual level. Clearly, only by using individually-mapped ROIs, such studies yield precise reliable surface-based parameters for association with specific conditions.

We computed data on structural thickness of the genital field in individually-mapped ROIs, based on the 10 most activated vertices per hemisphere for each woman. We show that individual thickness of the left genital field associates with frequency of sexual intercourse. The association was stronger for genital intercourse within the past 12 months. While less pronounced, the association was significant for lifetime genital contact. Frequency of genital intercourse was not associated with thickness of the representation field of the right hand nor with thickness of the entire cortical mantle, confirming a specific association between genital touch and genital field thickness. This is compatible with the idea that the female genital field has capacity for structural plasticity depending on its use, commensurate with the general “use-it-or-lose-it” principle of experience-dependent plasticity (Hebb, 1947Elbert and Rockstroh, 2004Draganski and May, 2008). While injury-dependent or use-dependent plasticity in the human somatosensory cortex has been reported (Elbert et al., 19941995Flor et al., 1995Foell et al., 2014), our results are the first to document structural variation of genital field thickness associated with more or less frequent normative use. Our results are in line with findings from animal studies showing that genital brushing during puberty resulted in lateral expansion of the rat and mouse genital cortex (Lenschow et al., 2017Sigl-Gl√∂ckner et al., 2019). Cortical plasticity serves to enhance the efficiency of processing of behaviorally-relevant inputs and represents an adaptive response (Trachtenberg et al., 2002Markham and Greenough, 2004Feldman and Brecht, 2005May, 2011). In an earlier study, we observed decreased thickness of the genital cortex after exposure to childhood sexual abuse, suggesting that highly aversive and developmentally inappropriate sexual stimulation may limit somatosensory representation to decrease processing of detrimental input (Heim et al., 2013).

Several mechanisms might contribute to dynamic use-associated structural plasticity of the genital field. Structural thickening of the mature cortex as a function of use most likely reflects formation of new synapses by axonal sprouting, dendritic arborization, and dendritic spine growth rather than induction of new neurons through neurogenesis (Markham and Greenough, 2004Feldman and Brecht, 2005Feldman, 2009May, 2011). There is substantial evidence on the central role of glutamatergic synapses in mediating plasticity, reflecting rapid components of NMDA receptor-dependent long-term potentiation (LTP) and long-term depression (LTD; Buonomano and Merzenich, 1998Feldman, 2009). Another mechanism contributing to use-associated structural plasticity may involve alterations in glial-cell mediated myelination (Timmler and Simons, 2019). While oligodendrogenesis is rare (Yeung et al., 2019), the presence of large numbers of premyelinating oligodendrocytes in the human cortex may enable adaptive myelination to adapt conduction velocity to functional demand (Gibson et al., 2014). Future studies in humans should use novel imaging tools that allow for assessing cortical myelin density (Amunts and Zilles, 2015) to study genital field plasticity. Further, neural activation in response to somatosensory stimulation depends on axonal input from the thalamus (Feldman, 2009). When removing afferent somatosensory input from the thalamus, dendritic spine numbers of somatosensory cortical neurons attenuate (Lendvai et al., 2000). When exposing rats to genital touch or sexual contact during puberty, invading thalamo-cortical afferents promote the expansion of the female genital cortex (Lenschow et al., 2016). Future studies on genital field plasticity should therefore include assessments of thalamo-cortical connectivity and myelination.

It must be noted that use-associated variation of structural thickness of the female genital field in our study was limited to the left hemisphere. This lateralized effect is puzzling given that the neural representation of the clitoris is bilateral. Left-hemispheric dominance of neural plasticity has been reported for learning-dependent structural change after coordination and motor skill training (Draganski et al., 2004Taubert et al., 2010Rogge et al., 2018). Such lateralized plasticity may reflect hemispheric specialization (Serrien et al., 2006). In the above referenced study (Heim et al., 2013), thinning of the genital field after sexual abuse was limited to the left hemisphere. While we cannot comprehensively explain these findings, one plausible mechanism may involve lateralized limbic-cortical modulation of sensory afferent inputs into the genital field, leading to unilateral associations of sexual behavior with genital field morphology.

While our localization of the female genital field was experimental in nature, our investigation of the capacity of the genital field for structural variation as a function of genital contact was cross-sectional and relied on retrospective self-report of genital intercourse. Our results align with the general principle of an association between frequency of genital intercourse and structural variation, albeit the direction of effect is a matter of discussion. It is conceivable that thickness of the genital field may drive frequency of sexual intercourse. Results from animal models provide causal that clitoral stimulation drives genital field thickness (Lenschow et al., 2016Lenschow and Brecht, 2018). Future prospective studies or studies exploiting quasi-experimental conditions, such as induction of behavior change during sexual therapy, are needed to establish causality.

In conclusion, we provide an unequivocal localization of the female genital field in S1 and support for use-associated plasticity of the human genital field. On a secondary level, our findings support the notion that studies investigating change of the human genital field must map the field individually. Our results pave the way for future research into the plasticity of the human genital field as a function of normal or adverse experience as well as genital field structure, function and plasticity in pathologic conditions, such sexual dysfunction, sexual deviation, or sexual risk-taking behavior.

Those from low control environments will invest less in pathogen-avoidance strategies (disgust) vs pathogen management (prophylactic immunological activity

Control over pathogen exposure and basal immunological activity influence disgust and pathogen-avoidance motivation. Hannah Bradshaw, Jeff Gassen, Marjorie Prokosch, Gary Boehm & Sarah Hill. Cognition and Emotion, Feb 9 2022. https://doi.org/10.1080/02699931.2022.2031905

Abstract: Disgust is reasoned to operate in conjunction with the immune system to help protect the body from illness. However, less is known about the factors that impact the degree to which individuals invest in pathogen avoidance (disgust) versus pathogen management (prophylactic immunological activity). Here, we examine the role that one’s control over pathogen contact plays in resolving such investment trade-offs, predicting that (a) those from low control environments will invest less in pathogen-avoidance strategies and (b) investment in each of these two strategies will occur in a compensatory fashion (i.e. they will be traded off with one other). Across four studies, we found support for these predictions, using a variety of manipulations and measures. By providing novel insights into how one’s control over pathogen exposure influences disgust sensitivity and immune system activity, the current research poses an important contribution to the literature on disgust, pathogen avoidance, and the immune system.

Keywords: disgustcontrolpathogen avoidanceimmune systemfunctional flexibility


Universals & preferential reactions to Western music in 53 countries: trait Extraversion was correlated with stronger reactions to contemporary music, whereas trait Openness was correlated with stronger reactions to sophisticated music

Universals and variations in musical preferences: A study of preferential reactions to Western music in 53 countries. Greenberg, D. M., Wride, S. J., Snowden, D. A., Spathis, D., Potter, J., & Rentfrow, P. J. (2022). Universals and variations in musical preferences: A study of preferential reactions to Western music in 53 countries. Journal of Personality and Social Psychology, 122(2), 286–309. Feb 2022. https://doi.org/10.1037/pspp0000397

Are there universal patterns in musical preferences? To address this question, we built on theory and research in personality, cultural, and music psychology to map the terrain of preferences for Western music using data from 356,649 people across six continents. In Study 1 (N = 284,935), participants in 53 countries completed a genre favorability measure, and in Study 2 (N = 71,714), participants in 36 countries completed an audio-based measure of preferential reactions to music. Both studies included self-report measures of the Big Five personality traits and demographics. Results converged to show that individual differences in preferences for Western music can be organized in terms of five latent factors that are invariant (i.e., universal) across countries and that generalize across assessment methods. Furthermore, the patterns of correlations between personality traits and musical preferences were largely consistent across countries and assessment methods. For example, trait Extraversion was correlated with stronger reactions to Contemporary musical styles (which feature rhythmic, upbeat, and electronic attributes), whereas trait Openness was correlated with stronger reactions to Sophisticated musical styles (which feature complex and cerebral attributes often heard in improvisational and instrumental music). The patterns of correlations between musical preferences and gender differences, ethnicity, and other sociodemographic metrics were also largely invariant across countries. Together, these findings strongly suggest that there are universal patterns in preferences for Western music, providing a foundation on which to develop and test hypotheses about the interactions between music, psychology, biology, and culture.