Intelligent behavior depends on the ability to suppress inappropriate actions and resolve interference between competing responses. Recent clinical and neuroimaging evidence has demonstrated the involvement of prefrontal, parietal, and premotor areas during behaviors that emphasize conflict and inhibition. It remains unclear, however, whether discrete subregions within this network are crucial for overseeing more specific inhibitory demands. Here we probed the functional specialization of human prefrontal cortex by combining repetitive transcranial magnetic stimulation (rTMS) with integrated behavioral measures of response inhibition (stop-signal task) and response competition (flanker task). Participants undertook a combined stop-signal/flanker task after rTMS of the inferior frontal gyrus (IFG) or dorsal premotor cortex (dPM) in each hemisphere. Stimulation of the right IFG impaired stop-signal inhibition under conditions of heightened response competition but did not influence the ability to suppress a competing response. In contrast, stimulation of the right dPM facilitated execution but had no effect on inhibition. Neither of these results was observed during rTMS of corresponding left-hemisphere regions. Overall, our findings are consistent with existing evidence that the right IFG is crucial for inhibitory control. The observed double dissociation of neurodisruptive effects between the right IFG and right dPM further implies that response inhibition and execution rely on distinct neural processes despite activating a common cortical network. I N T R O D U C T I O NNeural mechanisms of cognitive control are essential to coordinate, execute and update behavior. A crucial feature of successful updating is the ability to inhibit thoughts and actions that are no longer appropriate or relevant. A large body of neuropsychological evidence has identified the human prefrontal cortex (PFC) and basal ganglia as especially crucial for response inhibition (see Aron et al. 2004 ;Hodgson et al. 2007 for recent reviews). Recent studies, for instance, have demonstrated that lesions to the inferior frontal gyrus (IFG) can cause a deficit of response inhibition, as measured using tasks that require the cancellation of an initiated manual response (Aron et al. 2003) or the suppression of a reflexive saccade (Hodgson et al. 2007). Importantly, Aron et al. further showed that the magnitude of this deficit in the stop-signal paradigm can be predicted uniquely by the extent of damage to the right IFG but not the nearby middle frontal gyrus (MFG) or superior frontal gyrus (SFG).Despite the general agreement in the neuropsychological literature that the PFC is crucial for response inhibition, key questions remain concerning the specificity of the underlying control mechanism. In particular, some patient studies have shown that impairments of inhibition are more likely after lesions of the right medial SFG (Floden and Stuss 2006) or left supplementary motor/dorsal premotor cortex (dPM) (Picton et al. 2007), whereas other evidence s...

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Primary objective: Social cognition underlies social skills and can be disrupted in numerous developmental and acquired brain disorders during childhood and adolescence. Despite this, there are few tools to assess social cognition clinically in this age group. This study examined adolescent performance on The Awareness of Social Inference Test (TASIT), a valid measure of social cognition in adults. Design: Cross-sectional design examining performance on Parts 1, 2 and 3 of TASIT (and alternate forms) in Australian girls and boys with varying levels of English familiarity. Methods: 665 schoolchildren from private and government schools were administered TASIT subtests. Of these, 464 students aged 13-15 were selected to provide normative data. Scores from a further 97 provided information about the effects of lack of English familiarity. Results: The two Forms of TASIT were statistically equivalent for two of the three parts. Adolescents performed lower than adults, although the differences were not large. Some incremental effects were seen for chronological age. Gender effects were apparent on all subtests. Lack of English familiarity (i.e., English not spoken at home) reduced scores a further 6-13% relative to high English proficiency. Conclusions: TASIT appears to be suitable for adolescents. Norms are best aggregated across ages in adolescence and stratified according to gender.

Background: High levels of callous-unemotional (CU) traits are associated with reduced effectiveness of parenting programmes for children with conduct problems. This may be due to low levels of emotional engagement (EE) by these children with their parents. We evaluate a theoretically driven strategy for improving emotional engagement in high CU traits children undergoing a parenting intervention (parent management training; PMT) for child conduct problems. Methods: N = 40, 3-to 8-year-old children referred for conduct problems and showing stable, high levels of CU traits, were randomised to receive PMT+Emotional Engagement (EE), or the control condition PMT+Child Centred Play (CCP). A benchmarking sample of N = 70 children who received PMT only was also included. Observational coding of the parent-child interactions targeted by EE and CCP respectively was repeated throughout treatment and follow-up. Results: Emotional engagement produced unique improvements in parent-child emotional engagement (shared eye gaze); however, these reverted to baseline levels after treatment. CCP produced unique improvements in parents' child centeredness and child positive play, but by post-treatment, all children had improved on these factors. Both interventions produced similar improvements in general parental warmth. Reductions in severity of conduct problems at post-treatment and follow-up were large in size and did not differ between conditions or from the benchmarking group. Levels of CU traits reduced significantly but again did not differ between groups. Conclusions: The putative mechanism of emotional engagement through reciprocated eye gaze proved to be impervious to sustained change, and thus failed to have a specific impact of conduct problems or levels of CU traits. The development of novel treatment approaches to children with high levels of CU is a challenging endeavour, and these results indicate that focussing on children with stable levels at pretreatment should be a priority.

Traumatic brain injuries (TBI) in children and adolescents can impair social cognition and communication skills but there are few assessment tools suitable for adolescents. The Awareness of Social Inference Test (TASIT) uses professionally enacted audiovisual vignettes of everyday conversational exchanges and is a valid measure of social perception disorders in adults. This study examined its utility for assessing impairments in social cognition in a group of 16 adolescents with TBI, compared to a group of 16 typically developing (TD) adolescents. Adolescents with TBI were, on average, no different to their TD peers on TASIT 1 (emotion recognition) and TASIT 3 (recognizing lies and sarcasm when provided with additional cues) but performed more poorly on TASIT 2 which required them to interpret sarcastic and sincere conversational exchanges with few cues other than the demeanor of the speakers. Within the TBI group, poor performance on TASIT correlated to both relative and self-reported communication difficulties at home. It also correlated with IQ, face recognition and severity of injury as indexed by duration of post-traumatic amnesia. Overall, this study suggests TASIT is a valid measure for adolescents although it raised questions as to how effective normative data is for comparing performance in social cognition during childhood and adolescence.