Monika Sommer

Abnormalities in emotion processing within cortical and subcortical regions in criminal psychopaths: evidence from a functional magnetic resonance imaging study using pictures with emotional content

BACKGROUND Neurobiology of psychopathy is important for our understanding of current neuropsychiatric questions. Despite a growing interest in biological research in psychopathy, its neural underpinning remains obscure. METHODS We used functional magnetic resonance imaging to study the influence of affective contents on brain activation in psychopaths. Series containing positive and negative pictures from the International Affective Picture System were shown to six male psychopaths and six male control subjects while 100 whole-brain echo-planar-imaging measurements were acquired. Differences in brain activation were evaluated using BrainVoyager software 4.6. RESULTS In psychopaths, increased activation through negative contents was found right-sided in prefrontal regions and amygdala. Activation was reduced right-sided in the subgenual cingulate and the temporal gyrus, and left-sided in the dorsal cingulate and the parahippocampal gyrus. Increased activation through positive contents was found left-sided in the orbitofrontal regions. Activation was reduced in right medial frontal and medial temporal regions. CONCLUSIONS These findings underline the hypotheses that psychopathy is neurobiologically reflected by dysregulation and disturbed functional connectivity of emotion-related brain regions. These findings may be interpreted within a framework including prefrontal regions that provide top-down control to and regulate bottom-up signals from limbic areas. Because of the small sample size, the results of this study have to be regarded as preliminary.

Neural correlates of true and false belief reasoning

Belief reasoning plays a central role in making inferences about other peoples mental states. The ability to reason about false beliefs is considered as a critical test for having a Theory of Mind (ToM). There is some controversy as to whether it is the medial prefrontal cortex (MPFC) or the temporo-parietal junction (TPJ) that is centrally involved in belief reasoning. According to developmental studies of belief reasoning we conducted an fMRI experiment with a carefully controlled paradigm (Sally Anne scenario). We compared false belief reasoning with true belief reasoning in parallel tasks, using a series of cartoon stories depicting transfer of an object unbeknownst to the protagonist (false belief) or with the protagonist witnessing (true belief). The false belief versus true belief contrast revealed activation of the dorsal part of the anterior cingulate cortex (dACC), the right lateral rostral prefrontal cortex and the right TPJ associated with false belief. We suggest that the activation of the dACC and the lateral PFC might be associated with action monitoring and stimulus-independent cognitive processing whereas the activation of the TPJ might be related to the computation of mental representations that create perspective differences, such as a persons false belief that contrasts with reality and therefore might be centrally involved in the decoupling mechanism. Additionally we found common patterns of activation for true and false belief reasoning, including inferior parietal and precuneus activation, but we found no activation of the MPFC or the TPJ in general belief reasoning.

Common and distinct neural networks for false-belief reasoning and inhibitory control.

Ample behavioral evidence has shown that the ability to attribute false beliefs as part of a Theory of Mind (ToM) and the ability to inhibit a prepotent response are strongly correlated in both children and adults. Frequently reported areas associated with both processes are the right temporo-parietal junction (TPJ) and the medial prefrontal cortex (MPFC). Nevertheless, the exact nature of the relationship between belief-reasoning and inhibitory control at the neural level remains unclear. A functional magnetic resonance imaging (fMRI) study was conducted to investigate the neural correlates of belief-reasoning and inhibitory control in a within-subjects design using virtually identical visual stimuli. A false-belief task was used to investigate belief-attribution. The neural correlates of response inhibition were measured using a Go/No-Go task. Besides distinct activation for belief-reasoning and inhibitory control, the results also showed a substantial overlap for both processes in the right superior dorsal MPFC, the right TPJ, the dorsal part of the left TPJ, and lateral prefrontal areas. These findings suggest that the previously described behavioral link between belief attribution and inhibitory control may be explained by a common recruitment of brain areas related to domain-general cognitive processes. Also, the results indicate that neither the right TPJ nor MPFC is specific to the attribution of false beliefs.

Disturbed Prefrontal and Temporal Brain Function During Emotion and Cognition Interaction in Criminal Psychopathy

Impaired emotional responsiveness has been revealed as a hallmark of psychopathy. In spite of an increasing database on emotion processing, studies on cognitive function and in particular on the impact of emotion on cognition in psychopathy are rare. We used pictures from the International Affective Picture Set (IAPS) and a Simon Paradigm to address emotion-cognition interaction while functional and structural imaging data were obtained in 12 healthy controls and 10 psychopaths. We found an impaired emotion-cognition interaction in psychopaths that correlated with a changed prefrontal and temporal brain activation. With regard to the temporal cortex, it is shown that structure and function of the right superior temporal gyrus is disturbed in psychopathy, supporting a neurobiological approach to psychopathy, in which structure and function of the right STG may be important.

Neural correlates of emotional working memory in patients with mild cognitive impairment

Emotional stimuli can have beneficial effects on memory in healthy aged subjects and partly on patients with dementia. So far, no experimental study has explored the effects of memory for emotional stimuli in patients with mild cognitive impairment (MCI), a concept that describes a transitional state between normal aging and dementia. The present fMRI study explored working memory for emotional stimuli in 16 patients with amnestic MCI (aMCI) and 16 healthy aged participants. Subjects performed an n-back task (2-back) with neutral, positive, and negative emotional pictures. The analysis focused on target processing. Results showed that groups did not differ in working memory performance. In healthy aged participants emotional targets had no significant impact on working memory. In patients with aMCI a negativity bias was observed, indicating that negative targets were better remembered compared to neutral and positive targets. Regarding fMRI results, both groups showed an increase in functional activity in prefrontal and lateral parietal brain regions associated with target processing. As a key result, we observed significant group by emotion interaction effects in the precuneus. Healthy aged participants showed a signal decrease in the left precuneus for positive compared to neutral targets. The precuneus deactivation in healthy aged participants may indicate a disengagement of self-referential processes towards task-related processes. Patients with aMCI revealed a signal increase in the right precuneus for negative compared to neutral targets. This increase in precuneus activity, combined with a behavioural facilitation effect, may indicate a mechanism to compensate disease related processes in aMCI.

How should I decide? The neural correlates of everyday moral reasoning

The present fMRI study is the first that investigates everyday moral conflict situations in which a moral standard clashes with a personal desire. In such situations people have to decide between a morally guided and a hedonistic behaviour. Twelve healthy subjects were presented with verbal stories describing conflicts with either moral or neutral content. The moral stories described conflicts requiring a decision between a personal desire and a conflicting moral standard, whereas the neutral conflicts required a decision between two conflicting personal desires. When compared to neutral conflicts, moral conflicts elicited higher activity in a wide spread neural network including the medial frontal cortex, the temporal cortex and the temporo-parietal junction and the posterior cingulate cortex. Further analyses of the moral conflicts revealed that hedonistic decisions in contrast to morally guided decisions were associated with significantly higher rankings of uncertainty and unpleasant emotions and induced significant more activation in the amygdala/parahippocampal region. The present results generalise findings on the neuroscience of moral understanding by extending it to everyday moral decisions. Furthermore, the results show that the amydala region plays a central role in the processing of negative emotional consequences associated with immoral decisions.

Functional activity of the right temporo-parietal junction and of the medial prefrontal cortex associated with true and false belief reasoning

Since false belief reasoning requires mental state representation independently of the state of reality, it is seen as a key ability in Theory of Mind (ToM). Although true beliefs do not have to be processed independently of the state of reality, growing behavioural evidence indicates that true belief reasoning is different from just reasoning about the state of reality. So far, neural studies on true and false belief reasoning revealed inconsistent findings in the medial prefrontal cortex (MPFC) and in the right temporo-parietal junction (R-TPJ), brain regions that are hypothesized to play an important role in ToM. To further explore true and false belief reasoning, the present functional magnetic resonance imaging (fMRI) study in eighteen adult subjects used methodological refinements such as ensuring that the true belief trials did not elicit false belief reasoning, as well as including paralleled control conditions requiring reasoning about the state of reality. When compared to its control condition, common R-TPJ activity was observed for true and false belief reasoning, supporting its role in belief reasoning in general, and indicating that, at least in adults, also true belief reasoning appears to be different from reasoning about the state of reality. Differential activity was observed in a broad network of brain regions such as the MPFC, the inferior frontal cortex, and the precuneus. False over true belief reasoning induced activation in the posterior MPFC (pMPFC), supporting its role in the decoupling mechanisms, which is defined as processing a mental state independently of the state of reality.

True- and false-belief reasoning in children and adults: An event-related potential study of theory of mind

The understanding that another persons belief can differ from reality and that behaviour is guided by beliefs and not by reality reflects an important cornerstone in the development of a Theory of Mind. The present event-related potential (ERP) study had two aims: first, to reveal ERPs that distinguish between false- and true-belief reasoning and second, to investigate the neural changes in the development of false- and true-belief reasoning from childhood to adulthood. True- and false-belief cartoon stories were presented to adults and 6-8-year-old children. Results revealed two waveforms that differentiated between the two conditions: a late positive complex (LPC) associated with the reorientation from external stimuli to internal mental representations and a late anterior slow wave (LSW) associated with stimulus-independent processing of internal mental representations, a process that might be centrally involved in the decoupling mechanism. Additionally, we found developmental effects at an ERP level. Children showed a more posterior localization of the LPC and a broader frontal distribution of the LSW. The results may reflect developmental progress in conceptualizing the mental domain and support the idea that the cortical mentalizing network continues to develop even after children are able to master false beliefs.

Integration of emotion and cognition in patients with psychopathy.

Psychopathy is a personality disorder associated with emotional characteristics like impulsivity, manipulativeness, affective shallowness, and absence of remorse or empathy. The impaired emotional responsiveness is considered to be the hallmark of the disorder. There are two theories that attempt to explain the emotional dysfunction and the poor socialization in psychopathy: (1) the low-fear model and (2) the inhibition of violence model. Both approaches are supported by several studies. Studies using aversive conditioning or the startle modulation underline the severe difficulties in processing negative stimuli in psychopaths. Studies that explore the processing of emotional expressions show a deficit of psychopathic individuals for processing sad or fearful facial expressions or vocal affect. In the cognitive domain, psychopaths show performance deficits in the interpretation of the motivational significance of stimuli. Studies investigating the impact of emotions on cognitive processes show that in psychopaths in contrast to healthy controls negative emotions drain no resources from a cognitive task. It is suggested that dysfunctions in the frontal cortex, especially the orbitofrontal cortex, the cingulate cortex and the amygdala are associated with the emotional and cognitive impairments.

Distinct neural correlates underlying pretense and false belief reasoning: evidence from ERPs.

Two important milestones characterize the development of a theory of mind (ToM): The emergence of pretend play (PT) in which infants as young as 18 months separate the real world from fictional or imagined worlds. And the explicit understanding of false beliefs (FB) which develops around the age of about 4 years and demands a differentiation between mental states and reality. Although there is an outstanding debate about whether or not PT play involves metarepresentation understanding, to date, the neural correlates of FB and PT reasoning have not been investigated within one paradigm. The present study investigated PT and FB in comparison to reality understanding (RE) in an ERP paradigm presenting cartoon stories to 24 healthy adults. Results revealed a sequence of ERP components that distinguished between the conditions. PT compared to FB and RE was associated with a higher P2-amplitude at parieto-occipital sites and a late slow wave divergence (270-600 ms) at left frontal and left posterior positions. These components may indicate the processing of incongruity between the protagonists knowledge and behavior and the identifying of the intentional character of the pretended action. In accordance with previous ERP studies on FB reasoning, we found late anterior activation (600-900 ms) for FB reasoning, probably indicating the decoupling mechanism involved in metarepresentation. These temporal and topographic differences indicate distinct underlying neural substrates for FB and PT processing, and do not support metarepresentational interpretations of PT.