Interference inhibition in offending and non-offending pedophiles: A preliminary event-related fMRI study.

The ability to inhibit behavior is thought to be an import skill for avoiding criminal conduct, especially when combined with personal predispositions or criminogenic needs such as a pedophilic preference disorder. While previous research emphasized the relationship between impulsivity and child sexual offending, not pedophilia per se, studies on the underlying neurobiological mechanisms in subdomains of impulsivity remained scarce. Here, we focused on interference inhibition and examined event-related functional magnetic resonance imaging (fMRI) data of three groups of men performing a color-word Stroop task: (1) pedophiles with a history of CSO (P+CSO, n = 11), (2) pedophiles without a history of CSO (P-CSO, n = 8) and (3) non-pedophilic, non-offending healthy controls (HC, n = 10). On the behavioral level, P+CSO revealed increased Stroop interference as compared to P-CSO and HC. Moreover, increased Stroop interference in P+CSO was accompanied by enhanced conflict-related activity in left superior parietal cortex and precentral gyrus as compared to P-CSO. Albeit behavioral analyses of error and post-error processing revealed no significant between-group differences, P-CSO showed increased post-error-related activity in left posterior cingulate, precuneus and middle temporal gyrus as compared to P+CSO. Our preliminary data highlight inhibition deficits in offending as compared to non-offending pedophiles or healthy men and suggest that functional alterations in attention reallocation and impulse suppression/control may moderate the risk for committing CSO in men suffering from pedophilia.

An Exploratory Study on the Central Nervous Correlates of Sexual Excitation and Sexual Inhibition.

The Sexual Inhibition/Sexual Excitation Scales (SIS/SES) measure sexual excitation and sexual inhibition proneness. We used SIS and SES scores of 62 heterosexual teleiophilic men (Mage 34.3, SD = 9.9) to predict brain activation levels during the presentation of male and female visual sexual stimuli in a magnetic resonance imaging (MRI) scanner. Statistical analyses revealed significant correlations. SES and SIS1 scores were positively associated with brain activation in various brain regions during the presentation of both male and female stimuli. SIS2 turned out to be a weaker predictor of brain activation, still revealing one significant correlation in the right lateral orbitofrontal cortex. Significant regions for SES and SIS1 were, among others, primary and supplementary motor areas, the caudate nucleus, the dorsal anterior cingulate cortex, anterior insula, and prefrontal areas. Our study can be seen as an exploratory investigation of SIS and SES with means of functional brain imaging. The results provide a promising contribution to the assertion of neurophysiological systems of sexual inhibition and excitation proneness.

Approach and Avoidance Tendencies Toward Picture Stimuli of (Pre-)Pubescent Children and Adults: An Investigation in Pedophilic and Nonpedophilic Samples.

The presence of pedophilic sexual interests is considered of high importance for predicting recidivism among individuals who have committed sexual offenses. However, objective and valid assessment methods that are robust against confounding issues such as cognitive capacity and manipulation are sparse. We applied the Approach-Avoidance Task (AAT) for detecting sexual interests in 38 pedophilic men (18 primarily attracted to boys) and 27 male nonpedophilic (11 gay) participants. The AAT relies on automatic approach and avoidance tendencies, independent of cognitive abilities such as memory capacity and intelligence. Approach-avoidance tendencies toward stimuli depicting seminude prepubescent boys and girls as well as men and women are reported. The results were consistent with previous research on the utility of the AAT: Except for pedophiles attracted to girls, the mean AAT scores (approach minus avoidance reaction time for each stimulus category) were positive only for stimuli of the preferred category. A multivariate binary logistic regression approach revealed 80% overall accuracy in differentiating pedophilic from nonpedophilic participants.

Attenuated prefrontal activation during decision-making under uncertainty in schizophrenia: a multi-center fMRI study.

Decisions are called decisions under uncertainty when either prior information is incomplete or the outcomes of the decision are unclear. Alterations in these processes related to decisions under uncertainty have been linked to delusions. In patients with schizophrenia, the underlying neural networks have only rarely been studied. We aimed to disentangle the neural correlates of decision-making and relate them to neuropsychological and psychopathological parameters in a large sample of patients with schizophrenia and healthy subjects. Fifty-seven patients and fifty-seven healthy volunteers from six centers had to either indicate via button-press from which of two bottles red or blue balls were drawn (decision-making under uncertainty condition), or indicate whether eight red balls had been presented (baseline condition) while BOLD signal was measured with fMRI. Patients based their decisions on less conclusive evidence and had decreased activations in the underlying neural network, comprising of medial and lateral frontal as well as parietal areas, as compared to healthy subjects. While current psychopathology was not correlated with brain activation, positive symptoms led to longer decision latencies in patients. These results suggest that decision-making under uncertainty in schizophrenia is affected by a complex interplay of aberrant neural activation. Furthermore, reduced neuropsychological functioning in patients was related to impaired decision-making and task performance was modulated by distinct positive symptoms.

Ultrasonic properties of random media under uniaxial loading.

Acoustic properties of two types of soft tissue-like media were measured as a function of compressive strain. Samples were subjected to uniaxial strains up to 40% along the axis of the transducer beam. Measurements were analyzed to test a common assumption made when using pulse-echo waveforms to track motion in soft tissues--that local properties of wave propagation and scattering are invariant under deformation. Violations of this assumption have implications for elasticity imaging procedures and could provide new opportunities for identifying the sources of backscatter in biological media such as breast parenchyma. We measured speeds of sound, attenuation coefficients, and echo spectra in compressed phantoms containing randomly positioned scatterers either stiffer or softer than the surrounding gelatin. Only the echo spectra of gel media with soft scatterers varied significantly during compression. Centroids of the echo spectra were found to be shifted to higher frequencies in proportion to the applied strain up to 10%, and increased monotonically up to 40% at a rate depending on the scatterer size. Centroid measurements were accurately modeled by assuming incoherent scattering from oblate spheroids with an eccentricity that increases with strain. While spectral shifts can be accurately modeled, recovery of lost echo coherence does not seem possible. Consequently, spectral variance during compression may ultimately limit the amount of strain that can be applied between two data fields in heterogeneous media such as lipid-filled tissues. It also appears to partially explain why strain images often produce greater echo decorrelation in tissues than in commonly used graphite-gelatin test phantoms.