Assessing paedophilia based on the haemodynamic brain response to face images.

OBJECTIVES: Objective assessment of sexual preferences may be of relevance in the treatment and prognosis of child sexual offenders. Previous research has indicated that this can be achieved by pattern classification of brain responses to sexual child and adult images. Our recent research showed that human face processing is tuned to sexual age preferences. This observation prompted us to test whether paedophilia can be inferred based on the haemodynamic brain responses to adult and child faces. METHODS: Twenty-four men sexually attracted to prepubescent boys or girls (paedophiles) and 32 men sexually attracted to men or women (teleiophiles) were exposed to images of child and adult, male and female faces during a functional magnetic resonance imaging (fMRI) session. RESULTS: A cross-validated, automatic pattern classification algorithm of brain responses to facial stimuli yielded four misclassified participants (three false positives), corresponding to a specificity of 91% and a sensitivity of 95%. CONCLUSIONS: These results indicate that the functional response to facial stimuli can be reliably used for fMRI-based classification of paedophilia, bypassing the problem of showing child sexual stimuli to paedophiles.

Assessment of pedophilia using hemodynamic brain response to sexual stimuli.

CONTEXT: Accurately assessing sexual preference is important in the treatment of child sex offenders. Phallometry is the standard method to identify sexual preference; however, this measure has been criticized for its intrusiveness and limited reliability. OBJECTIVE: To evaluate whether spatial response pattern to sexual stimuli as revealed by a change in the blood oxygen level-dependent signal facilitates the identification of pedophiles. DESIGN: During functional magnetic resonance imaging, pedophilic and nonpedophilic participants were briefly exposed to same- and opposite-sex images of nude children and adults. We calculated differences in blood oxygen level-dependent signals to child and adult sexual stimuli for each participant. The corresponding contrast images were entered into a group analysis to calculate whole-brain difference maps between groups. We calculated an expression value that corresponded to the group result for each participant. These expression values were submitted to 2 different classification algorithms: Fisher linear discriminant analysis and κ -nearest neighbor analysis. This classification procedure was cross-validated using the leave-one-out method. SETTING: Section of Sexual Medicine, Medical School, Christian Albrechts University of Kiel, Kiel, Germany. PARTICIPANTS: We recruited 24 participants with pedophilia who were sexually attracted to either prepubescent girls (n = 11) or prepubescent boys (n = 13) and 32 healthy male controls who were sexually attracted to either adult women (n = 18) or adult men (n = 14). MAIN OUTCOME MEASURES: Sensitivity and specificity scores of the 2 classification algorithms. RESULTS: The highest classification accuracy was achieved by Fisher linear discriminant analysis, which showed a mean accuracy of 95% (100% specificity, 88% sensitivity). CONCLUSIONS: Functional brain response patterns to sexual stimuli contain sufficient information to identify pedophiles with high accuracy. The automatic classification of these patterns is a promising objective tool to clinically diagnose pedophilia.

Subliminal sexual stimuli facilitate genital response in women.

Visual sexual stimuli (VSS) are believed to undergo an automatic process of stimulus appraisal and (genital or subjective) response generation. Consistent with this belief, studies have found that subliminal VSS can facilitate responses to subsequent sexual stimulus presentations. We tested whether subliminal sexual stimuli facilitated a genital response in women and, furthermore, whether this genital response could be modulated by both opposite-sex stimuli and same-sex stimuli (i.e., whether the genital response to subliminal stimuli is category-specific or nonspecific). Twenty heterosexual women underwent vaginal photoplethysmography while being subliminally (20 ms) exposed to same-sex, opposite-sex, and nonsexual slides in a priming experiment. Vaginal pulse amplitude was increased when target stimuli were preceded by both opposite-sex and same-sex priming stimuli relative to nonsexual priming stimuli. This finding suggests that subliminal VSS were subjected to automatic stimulus processing, thereby facilitating nonspecific genital response preparation. Results are discussed in terms of implicit and explicit memory access and the evolutionary benefit of female nonspecific genital response.

Assessment of sexual orientation using the hemodynamic brain response to visual sexual stimuli.

INTRODUCTION: The assessment of sexual orientation is of importance to the diagnosis and treatment of sex offenders and paraphilic disorders. Phallometry is considered gold standard in objectifying sexual orientation, yet this measurement has been criticized because of its intrusiveness and limited reliability. AIM: To evaluate whether the spatial response pattern to sexual stimuli as revealed by a change in blood oxygen level-dependent (BOLD) signal can be used for individual classification of sexual orientation. METHODS: We used a preexisting functional MRI (fMRI) data set that had been acquired in a nonclinical sample of 12 heterosexual men and 14 homosexual men. During fMRI, participants were briefly exposed to pictures of same-sex and opposite-sex genitals. Data analysis involved four steps: (i) differences in the BOLD response to female and male sexual stimuli were calculated for each subject; (ii) these contrast images were entered into a group analysis to calculate whole-brain difference maps between homosexual and heterosexual participants; (iii) a single expression value was computed for each subject expressing its correspondence to the group result; and (iv) based on these expression values, Fisher's linear discriminant analysis and the kappa-nearest neighbor classification method were used to predict the sexual orientation of each subject. MEAN OUTCOME MEASURE: Sensitivity and specificity of the two classification methods in predicting individual sexual orientation. RESULTS: Both classification methods performed well in predicting individual sexual orientation with a mean accuracy of >85% (Fisher's linear discriminant analysis: 92% sensitivity, 85% specificity; kappa-nearest neighbor classification: 88% sensitivity, 92% specificity). CONCLUSION: Despite the small sample size, the functional response patterns of the brain to sexual stimuli contained sufficient information to predict individual sexual orientation with high accuracy. These results suggest that fMRI-based classification methods hold promise for the diagnosis of paraphilic disorders (e.g., pedophilia).

Male sexual dysfunction: diagnosis and treatment from a sexological and interdisciplinary perspective.

BACKGROUND: Among all types of sexual disturbance in men, disturbances of sexual function are the most important in clinical practice. These are classified by the segment of the sexual reaction cycle in which they arise (appetence, arousal, orgasm, and resolution). Partial functional impairment must be distinguished from dysfunction causing significant suffering and requiring treatment. METHODS: The authors' clinical experience is supplemented with a selective review of the literature on sexual dysfunction, its association with underlying diseases, and its impact on sexual and relational satisfaction. RESULTS: The sexual history (including the partner's sexual history, as far as this can be obtained) is of prime importance in the diagnostic evaluation of sexual disturbances. This evaluation must take the multidimensionality and multiple functions of human sexuality into account. Chronic frustration of the fundamental psychosocial needs for acceptance, closeness, and security is a very important factor that has been neglected until now by the prevailing conceptions of the etiology and pathogenesis of sexual disturbances. Their treatment involves a combination of elements from sexual medicine and psychotherapy, along with somatic medical and pharmacotherapeutic intervention, if needed. The goal of syndyastic sex therapy, a further development of the previous therapies, is to fulfill these fundamental needs and thereby to improve the patient's sexual function and deepen his satisfaction with the relationship in its entirety. CONCLUSIONS: It is essential to understand the different types of sexual disturbance in their biopsychosocial context as well as the significance of sexuality for the individual, and for the couple, with respect to reproduction, sexual pleasure, and bonding. Sexual disturbances are common, and patients therefore expect their physicians to be proficient in sexual medicine. The coverage of this subject in both undergraduate and postgraduate medical education in Germany needs to be improved.

Gender identity disorders: diagnostic and surgical aspects.

Transsexualism is defined as a strong and persistent cross-gender identification with the patient's persistent discomfort with his or her sex and a sense of inappropriateness in the gender role of that sex (Diagnostic and Statistical Manual of Mental Disorders, fourth revision, text revision [DSM-IV-TR]). The disturbance is not concurrent with a physical intersex condition and causes clinical distress or impairment in social, occupational, or other important areas of functioning. The trained mental health professional is obliged to find out if the patient fulfills the criteria of an irreversible gender transposition and if he or she will benefit from medical (hormonal and surgical) sex-reassignment treatment. If a patient has absolved 12 months of real-life experience and at least 6 months of continuous hormonal treatment, the indication for surgical sex reassignment may be given. Genital sex-reassignment in male-to-female transsexuals includes vaginoplasty, preferably by inversion of penoscrotal skin flaps, clitoroplasty, and vulvoplasty. The operation may be performed in one or two sessions. In contrast to genital reassignment in male-to-female patients, no operative standards are available in female-to-male subjects. Recently, neophallus creation from sensate free forearm flaps has emerged as the most promising approach for those patients who want to have a neophallus. Other alternatives such as metoidoioplasty or neophallus reconstruction from regional flaps exist, but are also accompanied by multiple possible complications and re-interventions. Best results are to be expected when using multidisciplinary teams of plastic surgeons, urologists, gynecologists, and experts in sexual medicine in large volume centers.

Homosexual women have less grey matter in perirhinal cortex than heterosexual women.

Is sexual orientation associated with structural differences in the brain? To address this question, 80 homosexual and heterosexual men and women (16 homosexual men and 15 homosexual women) underwent structural MRI. We used voxel-based morphometry to test for differences in grey matter concentration associated with gender and sexual orientation. Compared with heterosexual women, homosexual women displayed less grey matter bilaterally in the temporo-basal cortex, ventral cerebellum, and left ventral premotor cortex. The relative decrease in grey matter was most prominent in the left perirhinal cortex. The left perirhinal area also showed less grey matter in heterosexual men than in heterosexual women. Thus, in homosexual women, the perirhinal cortex grey matter displayed a more male-like structural pattern. This is in accordance with previous research that revealed signs of sex-atypical prenatal androgenization in homosexual women, but not in homosexual men. The relevance of the perirhinal area for high order multimodal (olfactory and visual) object, social, and sexual processing is discussed.

What do the X and Y chromosomes tell us about sex and gender in forensic case analysis?

Sex determination can be particularly crucial in forensic casework such as rape cases or cases of missing persons. Biological traces have to be genetically typed and the classification of the sex is of great importance for further investigations. Lately, several papers were published on reliability of sex determination by genetic typing of amelogenin gene-specific fragments. Problems may arise not only from false detection (or non-detection) of amelogenin-specific fragments, but also in cases of chimerism (bone marrow transplants) or micro chimerism (pregnant women carrying male fetuses), and from the possible discrepancies between the biological gender and the (forensic relevant) legal gender in the personal identity documents. The phenotype based classification of the legal gender may contradict the genetic sex under several conditions as there are genetic diversity, intersex conditions and transsexualism. The forensic relevance of the possible misinterpretation (sex is not necessarily legal gender) should not be underestimated.

A functional endophenotype for sexual orientation in humans.

Sexually arousing visual stimuli activate the human reward system and trigger sexual behavior. Here we performed event-related fMRI during visual processing of sexual core stimuli to pinpoint a neuronal correlate of sexual preference in humans. To dissociate gender of the stimulus from sexual preference, we studied male and female heterosexual and homosexual volunteers while they viewed sexual and nonsexual control stimuli. In contrast to previous work, we used core single-sex stimuli displaying male and female sexually aroused genitals. Since stimuli lacked any additional contextual information, they evoked no activity related to neuronal processing of faces, gestures or social interactions. Our prediction was that the sexual preference of the observer determines the neuronal responsiveness to pure male or female sexual stimuli in the human reward and motor system. Consistent with our prediction, the ventral striatum and the centromedian thalamus, showed a stronger neuronal response to preferred relative to non-preferred stimuli. Likewise, the ventral premotor cortex which is a key structure for imitative (mirror neurons) and tool-related (canonical neurons) actions showed a bilateral sexual preference-specific activation, suggesting that viewing sexually aroused genitals of the preferred sex triggers action representations of sexual behavior. The neuronal response of the ventral striatum, centromedian thalamus and ventral premotor cortex to preferred sexual stimuli was consistent across all groups. We propose that this invariant response pattern in core regions of the human reward and motor system represents a functional endophenotype for sexual orientation independent of the gender of the observer and gender of the stimulus.