The face-responsive M170 is modulated by sensor selection: An example of circularity in the analysis of MEG-data.

BACKGROUND: Magnetoencephalography (MEG) experiments create large data sets obtained from many sensors at different locations. Therefore, a process of sensor-selection prior to hypothesis-driven data analysis is common, e.g., when studying the face-selective M170 component occurring at temporal sites around 170ms post-stimulus. However, the strategies to identify sensors of interest vary across investigations, and frequently the contrast used for sensor-selection is not independent from the contrast between experimental conditions. NEW METHOD: We re-analyzed data from a previously published MEG-experiment where participants viewed faces of either a loved person or two friends. We included different strategies for identifying face-responsive sensors based on all or each one of the face-categories before comparing M170 amplitudes across conditions. RESULTS: When sensor-selection was based on signal strength elicited by one experimental condition alone, a comparison across face-categories revealed significantly increased M170 amplitudes for the respective face category. Conducting the same analysis following sensor-selection based on averaged activity across all face-categories did not yield different M170 amplitudes. COMPARISON WITH EXISTING METHOD: Whereas this pitfall of selective analysis has been studied and discussed in detail for fMRI methods there is no comparable re-analysis of real EEG/MEG-data. CONCLUSIONS: Our results demonstrate that selection-bias is as relevant for EEG/MEG analysis as for fMRI methods. Sensor-selection must be independent from the contrast analyzed with statistical comparisons, because otherwise a distorted or 'circular' analysis might result.

A different pattern of lateralised brain activity during processing of loved faces in men and women: a MEG study.

Viewing personally familiar and loved faces evokes a distinct pattern of brain activity as demonstrated by research employing imaging and electrophysiological methods. The aim of the current investigation was to study the perception of loved faces combined with recalling past emotional experiences using whole-head magnetoencephalograpy (MEG). Twenty-eight participants (fourteen female) viewed photographs of their romantic partner as well as of two long-term friends while imagining a positive emotional encounter with the respective person. Face-stimuli evoked a slow and sustained shift of magnetic activity from 300ms post-stimulus onwards which differentiated loved from friends' faces in female participants and left-sided sensors only. This late-latency evoked magnetic field resembled (as its magnetic counterpart) ERP-modulations by affective content and memory, most notably the late positive potential (LPP). We discuss our findings in the light of studies suggesting greater responsiveness to affective cues in women as well as sex differences in autobiographical and emotional memory.

Sex-differences of face coding: evidence from larger right hemispheric M170 in men and dipole source modelling.

The processing of faces relies on a specialized neural system comprising bilateral cortical structures with a dominance of the right hemisphere. However, due to inconsistencies of earlier findings as well as more recent results such functional lateralization has become a topic of discussion. In particular, studies employing behavioural tasks and electrophysiological methods indicate a dominance of the right hemisphere during face perception only in men whereas women exhibit symmetric and bilateral face processing. The aim of this study was to further investigate such sex differences in hemispheric processing of personally familiar and opposite-sex faces using whole-head magnetoencephalography (MEG). We found a right-lateralized M170-component in occipito-temporal sensor clusters in men as opposed to a bilateral response in women. Furthermore, the same pattern was obtained in performing dipole localization and determining dipole strength in the M170-timewindow. These results suggest asymmetric involvement of face-responsive neural structures in men and allow to ascribe this asymmetry to the fusiform gyrus. This specifies findings from previous investigations employing event-related potentials (ERP) and LORETA reconstruction methods yielding rather extended bilateral activations showing left asymmetry in women and right lateralization in men. We discuss our finding of an asymmetric fusiform activation pattern in men in terms of holistic face processing during face evaluation and sex differences with regard to visual strategies in general and interest for opposite faces in special. Taken together the pattern of hemispheric specialization observed here yields new insights into sex differences in face perception and entails further questions about interactions between biological sex, psychological gender and influences that might be stimulus-driven or task dependent.

Androgen deprivation therapy of self-identifying, help-seeking pedophiles in the Dunkelfeld.

Androgen deprivation therapy (ADT) is considered an effective strategy in sexual offender treatment. However, the evidence base concerning its effects on sexual arousal control is limited. Past research has focused almost exclusively on men in forensic contexts. The present retrospective observational study provided data on ADT in a sample of self-identifying, help-seeking pedohebephilic men applying for a one-year group therapy program. Factors possibly influencing the readiness to take up or discontinue ADT were presented. Effects of a combination of ADT and group psychotherapy program on changes in paraphilic sexual behavior and associated psychological factors were examined. The proportion of men having taken up ADT was rather small (n=15). Greater awareness of potentially risky situations to commit child sexual offenses and self-rated uncontrollability of sexual urges were identified as characterizing men resorting to ADT. Additionally, these men were initially more open to include medical treatment. Examination of the effects of ADT and psychotherapy was limited to a sample of six men providing complete data sets. Descriptive data demonstrated a reduction of paraphilic sexual behaviors, an increase of risk-awareness and self-efficacy, and a decrease of offense-supportive cognitions and self-esteem. The present study underlined the importance of careful education and monitoring of self-identifying, help-seeking pedohebephilic patients interested in ADT concerning the effects and side effects of the treatment in a clinical context.

Scale for Quality of Sexual Function (QSF) as an outcome measure for both genders?

BACKGROUND: For years, there has been interest in sexual dysfunction and its impact on quality of life but usually focused on one gender. Therapeutic options that became available raised the interest to evaluate effects on the other partner but there is no standardized instrument applicable for both genders. This paper reports first data regarding the development of a new general "Quality of Sexual Function" (QSF) scale. METHODS: The raw scale was based on our own gender-specific scales and the pertinent literature. The scale was applied in over 700 persons of a cross-sectional survey in Germany. Factorial analyses were performed to describe the internal structure (domains) of the scale and for item reduction. Internal consistency reliability and some aspects of validity were analyzed with the same community sample preliminary reference values determined. RESULTS: The scale consists of 32 specific items and eight general questions. Four dimensions were identified: "psycho-somatic quality of life,""sexual activity,""sexual (dys)function-self-reflection," and "sexual (dys)function-partner's view." The internal consistency reliability coefficients of the total scale and the subscales were good as were the total-domain correlations. Content validity was promising. CONCLUSION: This self-administrable 40-item QSF scale can measure and compare quality of sexual function for both genders. The scale was well accepted by the respondents. It is easy to answer and the evaluation is simple. Only a few results of reliability and validity have been established in this early stage of the development of the new instrument. Further research is needed to complete many missing aspects of reliability and the construct validity, particular its sensitivity to treatment effects.