Disrupted theory of mind network processing in response to idea of reference evocation in schizophrenia

Effectiveness of accelerated intermittent theta burst stimulation for social cognition and negative symptoms among individuals with schizophrenia: A randomized controlled trial

BACKGROUND

Social cognitive and negative symptoms impairment may increase the risk of mental disability in individuals with schizophrenia. However, randomized controlled studies on the effectiveness of accelerated intermittent theta burst stimulation (iTBS) for social cognition and negative symptoms in individuals with schizophrenia are very limited.

METHODS

A total of 125 individuals with schizophrenia were recruited, 66 of whom were randomly divided into an active iTBS group (n=34) and sham iTBS group (n=32) by stratified sampling. Participants received either active iTBS or sham iTBS targeting the left dorsolateral prefrontal cortex (DLPFC) 20 sessions for 4 weeks under navigation. The Facial Emotion Recognition Test (FERT), Hinting Task (HT), and Positive and Negative Syndrome Scale (PANSS) were measured at baseline, 2 weeks, and 4 weeks. The trial protocol was registered with the Chinese Clinical Trial Registry (ChiCTR2100051984).

RESULTS

Sixty patients (90.90%) completed the intervention and the 4-week follow-up, including 29 women (43.94%) and 37 men (56.06%) with a mean (SD) age of 47.53 (10.17) years. The primary outcomes showed FERT scores (week 2; 0.27 [95% CI, 0.09 to 0.45]; P< .01; ES 0.14) (week 4; 0.63 [95% CI, 0.45 to 0.80]; P< .001; ES 0.47) and HT scores (week 2; 1.00 [95% CI, -0.02 to 1.98]; P< .05; ES 0.67) (week 4; 2.13 [95% CI, 1.21 to 3.06]; P< .001; ES 0.27) in the active iTBS group were significantly different from those in the sham iTBS group at 2 and 4 weeks of follow-up. The secondary outcome showed that the negative symptom score (-3.43 [95% CI, -4.85 to -2.01]; P< .001; ES 0.29) of the active iTBS group was significantly different from that of the sham iTBS group at the 4th week of follow-up.

CONCLUSIONS

Accelerated iTBS can effectively ameliorate the social cognition and negative symptoms of individuals with schizophrenia. These results suggest that accelerated iTBS may be a safe and effective neuromodulation technique to improve the overall functional recovery of individuals with schizophrenia, and has a good clinical application prospect.

Neural correlates of theory of mind and empathy in schizophrenia: An activation likelihood estimation meta-analysis

Social cognition impairment predicts social functioning in schizophrenia. Several studies have found abnormal brain activation in patients with schizophrenia during social cognition tasks. Nevertheless, no coordinate-based meta-analysis comparing the neural correlates of theory of mind and empathy had been done in this population. Our aim was to explore neural correlates related to theory of mind and empathy in patients with schizophrenia compared to healthy controls, in order to identify abnormal brain activation related to emotional content during mental state attribution in schizophrenia. We performed a neural-coordinate-based Activation Likelihood Estimation (ALE) meta-analysis of existing neuroimaging data in the literature to distinguish between abnormal brain maps associated with emotional attribution and those associated with intention/belief inference. We found that brain activation in patients group was significantly decreased in the right ventrolateral prefrontal cortex (VLPFC) during emotional attribution, while there was a significant decrease in the left posterior temporo-parietal junction (TPJ) during intention/belief attribution. Using a meta-analytic connectivity modeling approach (MACM), we demonstrated that both regions are coactivated with other brain regions known to play a role in social cognition, including the bilateral anterior insula, right TPJ, left amygdala and dorsolateral prefrontal cortex. In addition, abnormal activation in both the left TPJ and right VLPFC was previously reported in association with verbal-auditory hallucinations and a "jumping to conclusions" cognitive bias. Thus, these regions could be valuable targets for therapeutic interventions in schizophrenia.

Revisiting the overlap between autistic and schizotypal traits in the non-clinical population using meta-analysis and network analysis

The present study aimed to explore the relationship between autistic and schizotypal traits in the non-clinical population. We first conducted a meta-analysis to quantify the correlation between self-reported autistic traits and the three dimensions of schizotypal traits (positive, negative and disorganization). The strongest correlation was found between autistic traits and negative schizotypal traits (r = 0.536, 95% CI [0.481, 0.586]), followed by the disorganization (r = 0.355, 95% CI [0.304, 0.404]) and positive (r = 0.256, 95% CI [0.208, 0.302]) dimensions. To visualize the partial correlations between dimensional behavioural traits, we constructed a network model based on a large sample of college students (N = 2469). Negative schizotypal traits were strongly correlated with autistic social/communicative deficits, whereas positive schizotypal traits were inversely correlated with autistic-like traits, lending support to the psychosis-autism diametrical model. Disentangling the overlapping and diametrical structure of autism and schizophrenia may help to elucidate the aetiology of these two neurodevelopmental disorders.

A Functional Neuroimaging Meta-Analysis of Self-Related Processing in Schizophrenia

Background: Schizophrenia is characterized by self-disturbances, including impaired self-evaluation abilities and source monitoring. The cortical midline structures (e.g., medial prefrontal cortex, anterior and posterior cingulate cortex, and precuneus) and the temporoparietal junction are known to play a key role in self-related processing. In theory, self-disturbances in schizophrenia may arise from impaired activity in these regions. We performed a functional neuroimaging meta-analysis to verify this hypothesis. Methods: A literature search was performed with PubMed and Google Scholar to identify functional neuroimaging studies examining the neural correlates of self-processing in schizophrenia, using self-other or source monitoring paradigms. Fourteen studies were retrieved, involving 245 patients and 201 controls. Using peak coordinates to recreate an effect-size map of contrast results, a standard random-effects variance weighted meta-analysis for each voxel was performed with the Seed-based d Mapping software. Results: During self-processing, decreased activations were observed in schizophrenia patients relative to controls in the bilateral thalamus and the left dorsal anterior cingulate cortex (dACC) and dorso-medial prefrontal cortex. Importantly, results were homogeneous across studies, and no publication bias was observed. Sensitivity analyses revealed that results were replicable in 93-100% of studies. Conclusion: The current results partially support the hypothesized impaired activity of cortical midline brain regions in schizophrenia during self-processing. Decreased activations were observed in the dACC and dorsomedial prefrontal cortex, which are involved in cognitive control and/or salience attribution, as well as decision-making, respectively. These alterations may compromise patients' ability to direct their attention toward themselves and/or others and to make the decision whether a certain trait applies to one's self or to someone else. In addition, decreased activations were observed in the thalamus, which is not a core region of the default-mode network, and is involved in information integration. These thalamic alterations may compromise self-coherence in schizophrenia.

Activation of the motivation-related ventral striatum during delusional experience

Delusion is the most characteristic symptom of psychosis, occurring in almost all first-episode psychosis patients. The motivational salience hypothesis suggests delusion to originate from the experience of abnormal motivational salience. Whether the motivation-related brain circuitries are activated during the actual delusional experience remains, however, unknown. We used a forced-choice answering tree at random intervals during functional magnetic resonance imaging to capture delusional and non-delusional spontaneous experiences in patients with first-episode psychosis (n = 31) or clinical high-risk state (n = 7). The motivation-related brain regions were identified by an automated meta-analysis of 149 studies. Thirteen first-episode patients reported both delusional and non-delusional spontaneous experiences. In these patients, delusional experiences were related to stronger activation of the ventral striatum in both hemispheres. This activation overlapped with the most strongly motivation-related brain regions. These findings provide an empirical link between the actual delusional experience and the motivational salience hypothesis. Further use and development of the present methods in localizing the neurobiological basis of the most characteristic symptoms may be useful in the search for etiopathogenic pathways that result in psychotic disorders.

Masked ambiguity - Emotion identification in schizophrenia and major depressive disorder

Both patients with schizophrenia and with a major depressive disorder (MDD) display deficits in identifying facial expressions of emotion during acute phases of their illness. However, specific deficit patterns have not yet been reliably demonstrated. Tasks that employ emotionally ambiguous stimuli have recently shown distinct deficit patterns in patients with schizophrenia compared to other mental disorders as well as healthy controls. We here investigate whether a task which uses an ambiguous Japanese (Noh) mask and a corresponding human stimulus generates distinctive emotion attribution patterns in thirty-two Caucasian patients with schizophrenia, matched MDD patients and healthy controls. Results show that patients with schizophrenia displayed reaction time disadvantages compared to healthy controls while identifying sadness and anger. MDD patients were more likely to label stimuli with basic compared to subtle emotional expressions. Moreover, they showed more difficulties assigning emotions to the human stimulus than to the Noh mask. IQ, age and cognitive functioning did not modulate these results. Because overall group differences were not observed, this task is not suitable for diagnosing patients. However, the subtle differences that did emerge might give therapists handles that can be used in therapy.

An fMRI study of theory of mind in individuals with first episode psychosis

Theory of mind (ToM), the ability to infer one's own and others' mental states, is the social cognitive process shown to have the greatest impact on functional outcome in schizophrenia. It is not yet known if neural abnormalities underlying ToM present early, during the first episode of psychosis (FEP). Fourteen FEP participants and twenty-two healthy control participants, aged 15-25, were included in analyses. All participants had a 3T magnetic resonance imaging scan and completed a block-design picture-story attribution-of-intentions ToM fMRI task, and completed a battery of behavioral social cognitive measures including a ToM task. General linear model analyses were carried out. Post-hoc regression analyses were conducted to explore whether aberrant ToM-related activation in FEP participants was associated with symptomatology and global social and occupational functioning. FEP participants, when compared to healthy controls, had significantly less activity in the right temporoparietal junction, right orbitofrontal cortex and left middle prefrontal/inferior frontal cortex, when making social attributions. Aberrant ToM-related activation in the right temporoparietal junction was associated with severity of overall psychopathology, but not functional outcome. Specific regions of the social brain network, associated with ToM, are dysfunctional in young people with FEP. Future research should determine whether alteration of normal brain functioning in relation to ToM occurs before or during illness onset.

Spontaneous Activity Associated with Delusions of Schizophrenia in the Left Medial Superior Frontal Gyrus: A Resting-State fMRI Study

Delusions of schizophrenia have been found to be associated with alterations of some brain regions in structure and task-induced activation. However, the relationship between spontaneously occurring symptoms and spontaneous brain activity remains unclear. In the current study, 14 schizophrenic patients with delusions and 14 healthy controls underwent a resting-state functional magnetic resonance imaging (RS-fMRI) scan. Patients with delusions of schizophrenia patients were rated with Positive and Negative Syndrome Scale (PANSS) and Characteristics of Delusional Rating Scale (CDRS). Regional homogeneity (ReHo) was calculated to measure the local synchronization of the spontaneous activity in a voxel-wise way. A two-sample t-test showed that ReHo of the right anterior cingulate gyrus and left medial superior frontal gyrus were higher in patients, and ReHo of the left superior occipital gyrus was lower, compared to healthy controls. Further, among patients, correlation analysis showed a significant difference between delusion scores of CRDS and ReHo of brain regions. ReHo of the left medial superior frontal gyrus was negatively correlated with patients’ CDRS scores but not with delusional PANSS scores. These results suggested that altered local synchronization of spontaneous brain activity may be related to the pathophysiology of delusion in schizophrenia.

Selective Functional Disconnection of the Dorsal Subregion of the Temporal Pole in Schizophrenia

Although extensive resting-state functional connectivity (rsFC) changes have been reported in schizophrenia, rsFC changes in the temporal pole (TP) remain unknown. The TP contains several subregions with different connection patterns; however, it is not known whether TP subregions are differentially affected in schizophrenia. Sixty-six schizophrenia patients and 76 healthy comparison subjects underwent resting-state fMRI using a sensitivity-encoded spiral-in (SENSE-SPIRAL) imaging sequence to reduce susceptibility-induced signal loss and distortion. The TP was subdivided into the dorsal (TPd) and ventral (TPv) subregions. Mean fMRI time series were extracted for each TP subregion and entered into a seed-based rsFC analysis. Direct between-group comparisons revealed reduced rsFC between the right TPd and brain regions involved in language processing and multisensory integration in schizophrenia, including the left superior temporal gyrus, left mid-cingulate cortex, and right insular cortex. The rsFC changes of the right TPd in schizophrenia were independent of the grey matter reduction of this subregion. Moreover, these rsFC changes were unrelated to illness severity, duration of illness and antipsychotic medication dosage. No significant group differences were observed in the rsFC of the left TPd and bilateral TPv subregions. These findings suggest a selective (the right TPd) functional disconnection of TP subregions in schizophrenia.

Reduced default mode network connectivity in schizophrenia patients

In the present study, we explored possible alterations in the default mode network (DMN) and its functional connectivity in 41 schizophrenia patients and 42 age-matched healthy controls. Schizophrenia patients displayed reduced activation in the ventromedial prefrontal cortex, left superior temporal gyrus including auditory cortex and temporal pole. Psychophysiological interaction analysis revealed reduced connectivity between left superior temporal gyrus including auditory cortex and the left temporal pole in schizophrenia patients compared to healthy subjects.

Neural correlates of decision making after unfair treatment

Empirical evidence indicates that people are inequity averse. However, it is unclear whether and how suffering unfairness impacts subsequent behavior. We investigated the consequences of unfair treatment in subsequent interactions with new interaction partners and the associated neural mechanisms. Participants were experimentally manipulated to experience fair or unfair treatment in the ultimatum game (UG), and subsequently, they were given the opportunity to retaliate in the dictator game (DG) in their interactions with players who had not played a role in the previous fair or unfair treatment. The results showed that participants dictated less money to unrelated partners after frequently receiving unfair offers in the previous UG (vs. frequently receiving fair offers in the previous UG), but only when they were first exposed to unfair UG/DG. Stronger activation in the right dorsal anterior insula was found during receiving unfair offers and during the subsequent offer-considering phase. The regional homogeneity (ReHo), a measure of the local synchronization of neighboring voxels in resting-state brain activity, in the left ventral anterior insula and left superior temporal pole was positively correlated with the behavior change. These findings suggest that unfair treatment may encourage a spread of unfairness, and that the anterior insula may be not only engaged in signaling social norm violations, but also recruited in guiding subsequent adaptive behaviors.

Schizophrenia and autism as contrasting minds: neural evidence for the hypo-hyper-intentionality hypothesis

Both schizophrenia (SCZ) and autism spectrum disorder (ASD) are characterized by mentalizing problems and associated neural dysfunction of the social brain. However, the deficits in mental state attribution are somehow opposed: Whereas patients with SCZ tend to over-attribute intentions to agents and physical events ("hyper-intentionality"), patients with autism treat people as devoid of intentions ("hypo-intentionality"). Here we aimed to investigate whether this hypo-hyper-intentionality hypothesis can be supported by neural evidence during a mentalizing task. Using functional magnetic resonance imaging (fMRI), we investigated the neural responses and functional connectivity during reading others intention. Scanning was performed in 23 individuals with ASD, 18 with paranoid SCZ and 23 gender and IQ matched control subjects. Both clinical groups showed reduced brain activation compared to controls for the contrast intentional vs physical information processing in left posterior superior temporal sulcus (pSTS) and ventral medial prefrontal cortex (vMPFC) for SCZ, and right pSTS in ASD. As predicted, these effects were caused in a group specific way: Relative increased activation for physical information processing in SCZ that was also correlated with positive PANNS score and relative decreased activation for intentional information processing in ASD. Additionally, we could demonstrate opposed connectivity patterns between the right pSTS and vMPFC in the clinical groups, ie, increased for SCZ, decreased for ASD. These findings represent opposed neural signatures in key regions of the social brain as predicted by the hyper-hypo-intentionality hypothesis.

Positive symptoms and water diffusivity of the prefrontal and temporal cortices in schizophrenia patients: a pilot study

The development of diffusion tensor imaging (DTI) has provided information about microstructural changes in the brain. Most DTI studies have focused on white matter (WM). Few DTI studies have examined the gray matter (GM) in schizophrenia and, to date, there has been no attempt to identify the relationship between water diffusivity and symptom severity in schizophrenia. The present study aimed to examine microstructural deficits in the dorsal prefrontal cortex (DPFC) and temporal cortex in schizophrenia patients using fractional anisotropy (FA) and water diffusivity. This study also explored the relationship between DTI measurements and psychotic symptoms. Magnetic resonance imaging (MRI) and DTI were used to study 19 schizophrenia patients and 19 healthy controls. Fractional anisotropy, axial diffusivity, radial diffusivity, and regional volumes were measured in the prefrontal cortex and temporal cortex. On DTI measurements, patients showed increased axial and radial diffusivities in the prefrontal cortex and temporal cortex, but they did not demonstrate any difference in fractional anisotropy and regional volumes. Additionally, axial and radial diffusivities were significantly correlated with positive symptom scores in all regions of interest. These results indicate that water diffusivity measurements, including axial and radial diffusivities, can be used to identify microstructural changes in the gray matter in schizophrenia that may be related to symptom severity.

Further evidence for the impact of a genome-wide-supported psychosis risk variant in ZNF804A on the Theory of Mind Network

The single-nucleotide polymorphism (SNP) rs1344706 in ZNF804A is one of the best-supported risk variants for psychosis. We hypothesized that this SNP contributes to the development of schizophrenia by affecting the ability to understand other people's mental states. This skill, commonly referred to as Theory of Mind (ToM), has consistently been found to be impaired in schizophrenia. Using functional magnetic resonance imaging, we previously showed that in healthy individuals rs1344706 impacted on activity and connectivity of key areas of the ToM network, including the dorsomedial prefrontal cortex, temporo-parietal junction, and the posterior cingulate cortex, which show aberrant activity in schizophrenia patients, too. We aimed to replicate these results in an independent sample of 188 healthy German volunteers. In order to assess the reliability of brain activity elicited by the ToM task, 25 participants performed the task twice with an interval of 14 days showing excellent accordance in recruitment of key ToM areas. Confirming our previous results, we observed decreasing activity of the left temporo-parietal junction, dorsomedial prefrontal cortex, and the posterior cingulate cortex with increasing number of risk alleles during ToM. Complementing our replication sample with the discovery sample, analyzed in a previous report (total N=297), further revealed negative genotype effects in the left dorsomedial prefrontal cortex as well as in the temporal and parietal regions. In addition, as shown previously, rs1344706 risk allele dose positively predicted increased frontal-temporo-parietal connectivity. These findings confirm the effects of the psychosis risk variant in ZNF804A on the dysfunction of the ToM network.

Me, myself and I: temporal dysfunctions during self-evaluation in patients with schizophrenia

Self-concept is deeply affected in schizophrenia. Positive symptoms in particular are related to disturbed self/other distinctions. The neural networks underlying self-evaluation in schizophrenia have barely been investigated. The study reported here involved 13 patients with schizophrenia and 13 matched controls. During functional MRI, participants decided in three conditions whether the presented positive and negative personality traits characterized themselves, an intimate person, or included a certain letter. Based on the responses, each experimental condition was designed using a flexible factorial model. Controls and patients showed a similar behavioral pattern during self-evaluation, with group comparison revealing decreased activation in patients in the left inferior temporal gyrus and both temporal poles during self-ascription of traits, and in the anterior medial prefrontal cortex during evaluation of an intimate person. In patients, positive symptoms correlated positively with brain activation in the left parahippocampus during trait self-ascription. Hence, while evaluating themselves, schizophrenia patients revealed decreased activation in areas related to self-awareness overlapping with networks involved in theory of mind, empathy and social knowledge. Moreover, patients' brain activation during self-reflection was affected by the current positive symptomatology. The close interaction between self and other highlights the clinical and social relevance of self-processing deficits in schizophrenia.

Hyperintentionality during automatic perception of naturalistic cooperative behavior in patients with schizophrenia

Social cognition and the corresponding functionality of involved brain networks are essential for effortless social interaction. Patients with schizophrenia exhibit impaired social functioning. In this study, we focused on the neural networks involved in the automatic perception of cooperative behavior and their alterations in schizophrenia. We performed a functional magnetic resonance imaging study of 19 schizophrenia patients and 19 healthy matched controls. Participants watched a set of short videos with two actors manipulating objects, either with (C+) or without cooperation (C-). Additionally, we assessed delusional symptoms in patients using the Scales for the Assessment of Positive Symptoms and psychosis proneness in healthy controls using the brief schizotypal personality questionnaire. The observed group-by-condition interaction revealed a contrasting activation pattern for patients versus healthy controls in the medial and lateral prefrontal cortex, the middle cingulate cortex, and the left angular gyrus. Furthermore, increased activation of the middle prefrontal areas, left angular gyrus, and the posterior sulcus temporalis superior in response to the noncooperative condition (C-) was positively correlated with delusional symptoms in patients. Our findings suggest an overactivated "theory of mind" network in patients for the processing of noncooperative behavior. Thus, "overmentalizing" might be based on delusions and altered processing of cooperative behavior in patients with schizophrenia.

A possible brain network for representation of cooperative behavior and its implications for the psychopathology of schizophrenia

It has been shown that social deficits contribute to psychopathology in schizophrenia, such as the bleulerian autism. A possible dysfunction in the mirror neuron system may be the reason for these deficits in the disorder. We wanted to better characterize the neural networks involved in the perception of social behavior. Fifteen healthy participants were presented with video clips of 8 seconds' duration depicting either (1) one actor manipulating an object, (2) two actors with only one manipulating an object or (3) two actors cooperating in manipulating an object and 2 other control conditions. Functional magnetic resonance imaging data were acquired during watching these videos. We found the perception of social cooperation is supported by a neural network comprising the precuneus, the temporoparietal junction (supramarginal gyrus, angular gyrus, BA 39/40), the middle temporal gyrus (including superior temporal sulcus) and frontal regions (medial frontal gyrus, inferior frontal gyrus). These areas form a complex network also being activated during theory of mind and cooperative behavior tasks. Its nodes overlap with those of the mirror neuron system. Consequently, both theory of mind abilities and mirror mechanisms are relevant in the perception and understanding of social cooperative behavior. We outline the consequences of these results for a further understanding of schizophrenic psychopathology with respect to social deficits and ego disturbances.

Linguistic production and syntactic comprehension in schizophrenia and bipolar disorder

OBJECTIVE

To explore linguistic abilities in schizophrenia and bipolar disorder. Specifically, the aims of this study were to: i) investigate microlinguistic (lexicon, morphology, syntax) and macrolinguistic (discourse coherence, pragmatics) dimensions of speech production and ii) evaluate syntactic comprehension skills in both schizophrenia and bipolar disorder.

METHOD

Linguistic performance of 30 Italian-speaking patients with schizophrenia, 30 participants with bipolar disorder and 30 healthy controls comparable for age and educational level has been assessed using a story-telling task and a computer-based test of syntactic comprehension.

RESULTS

In narrative production, compared with healthy participants, those with schizophrenia had slight problems in speech rate and deficits at both local and global discourse coherence, whereas patients with bipolar disorder showed reduced mean length of utterance. As regards syntactic comprehension, both groups of patients collected more grammatical errors than controls, but they differed with regard to the number and kind of grammatical construction they missed.

CONCLUSION

Linguistic deficits have been detected in both groups of patients, being, however, more severe and generalized in schizophrenia than in bipolar disorder. Such results help us in improving our understanding of the potential psychopathological overlapping between these disorders.

Theory of mind in patients with schizophrenia: is mentalizing delayed?

OBJECTIVE

Functional imaging studies have used numerous neurocognitive designs to investigate brain activation during theory of mind (ToM) tasks in patients with schizophrenia. The majority of studies asks participants to retrospectively attribute mental states to others. We used a novel animated task to investigate implicit mentalizing online. Because behavioral studies have revealed slower ToM performance reaction times in patients with schizophrenia, we hypothesized that time would influence functional MRI (fMRI) activation patterns also.

METHODS

We applied the "Moving Shapes" paradigm, which involves two interacting triangles, to a functional MRI block design and investigated the neural activation patterns of 15 patients with schizophrenia and 14 healthy controls. We additionally analyzed the first and second halves of each video separately to assess time-related differences.

RESULTS

Overall, patients with schizophrenia showed increased activation in the inferior and middle frontal gyri, the superior temporal gyrus, the precuneus and the cerebellum compared with controls during ToM versus non-ToM videos. Most importantly, patients with schizophrenia had predominantly increased activation in ToM-related brain areas during the second half of the ToM paradigm, whereas the activation in areas of the ToM-network in healthy controls occurred during the first half of the presentation.

CONCLUSIONS

Our results confirm recent findings of significantly stronger neural activations that encompass the fronto-temporo-parietal cerebral areas in patients with schizophrenia compared with controls during ToM tasks. The observation of slower cognitive processing in patients with schizophrenia during mentalizing might explain some of the contradictory imaging findings in these patients and have implications for cognitive remediation.

Mirror neuron function, psychosis, and empathy in schizophrenia

Processing of social and emotional information has been shown to be disturbed in schizophrenia. The biological underpinnings of these abnormalities may be explained by an abnormally functioning mirror neuron system. Yet the relationship between mirror neuron system activity in schizophrenia, as measured using an electroencephalography (EEG) paradigm, and socio-emotional functioning has not been assessed. The present research measured empathy and mirror neuron activity using an established EEG paradigm assessing the integrity of the Mu rhythm (8-13Hz) suppression over the sensorimotor cortex during observed and actual hand movement in 16 schizophrenia-spectrum disorder (SSD) participants (n=8 actively psychotic and n=8 in residual illness phase) and 16 age- and gender-matched healthy comparison participants. Actively psychotic SSD participants showed significantly greater mu suppression over the sensorimotor cortex of the left hemisphere than residual phase SSD and healthy comparison individuals. The latter two groups showed similar levels of mu suppression. Greater left-sided mu suppression was positively correlated with psychotic symptoms (i.e., greater mu suppression/mirror neuron activity was highest among subjects with the greater severity of psychotic symptoms). SSD subjects tended to have significantly higher levels of Personal Distress (as measured by the Interpersonal Reactivity Index) than healthy participants. The present study suggests that abnormal mirror neuron activity may exist among patients with schizophrenia during the active (psychotic) phase of the illness, and correlates with severity of psychosis.

Theory of mind and its relevance in schizophrenia

PURPOSE OF REVIEW

Social cognitive impairments are considered to be core features of schizophrenia and have been hypothesized to play a mediator role between basic neurocognition and patients' outcomes. In this context, theory of mind (ToM) abilities are of special relevance, and deficits in this area may represent trait markers of schizophrenia.

RECENT FINDINGS

In this review, studies published since September 2010 have been summarized with a particular focus on the relationships between ToM and psychopathology, neurocognition, and psychosocial outcomes in patients with schizophrenia, as well as on ToM abilities in high-risk individuals. In addition, recent neuroimaging data as well as treatment interventions have been described.

SUMMARY

The reviewed literature strengthens the hypothesis that ToM deficits have the potential to be valid markers for schizophrenia.

Exploring the neural correlates of delusions of reference

BACKGROUND

Referential delusions are the most common symptom of schizophrenia and offer an opportunity to examine the neural correlates of delusions because they occur in discrete episodes that can be studied in the scanner. The cortical midline structures (CMS) and subcortical regions, including the amygdala and striatum, are linked with self-reference in healthy adults. Less is known about the neural substrates of altered self-reference in schizophrenia.

METHODS

In this study, patients with schizophrenia experiencing prominent referential delusions (n = 18) and healthy control subjects (n = 17) were presented with ambiguous sentences while in the magnetic resonance imaging scanner and asked to rate whether they felt the sentences had been written specifically about them. The sentences were either generic (nonpersonalized) or individually tailored personalized sentences, designed to induce referential ideation. We hypothesized that both groups would show activity in the CMS, limbic, and striatal regions and that induced referential ideation would be associated with greater activity in striatal areas in patients with schizophrenia.

RESULTS

A robust main effect of endorsement (endorsed vs. nonendorsed) was observed in the CMS, as well as subcortical regions, including the nucleus accumbens/ventral striatum, amygdala, insula, and midbrain dopamine regions. A group-by-endorsement interaction was seen in the medial prefrontal cortex, insula and nucleus accumbens/ventral striatum. Activity in insula and ventral striatum also correlated with the strength of the delusions of reference.

CONCLUSIONS

Referential ideation in persons with delusions is associated with heightened CMS, limbic and striatal activity and reduced differentiation between self- and non-self-relevant information.

Autism spectrum disorders and schizophrenia: meta-analysis of the neural correlates of social cognition

Context

Impaired social cognition is a cardinal feature of Autism Spectrum Disorders (ASD) and Schizophrenia (SZ). However, the functional neuroanatomy of social cognition in either disorder remains unclear due to variability in primary literature. Additionally, it is not known whether deficits in ASD and SZ arise from similar or disease-specific disruption of the social cognition network.

Objective

To identify regions most robustly implicated in social cognition processing in SZ and ASD.

Data Sources

Systematic review of English language articles using MEDLINE (1995–2010) and reference lists.

Study Selection

Studies were required to use fMRI to compare ASD or SZ subjects to a matched healthy control group, provide coordinates in standard stereotactic space, and employ standardized facial emotion recognition (FER) or theory of mind (TOM) paradigms.

Data Extraction

Activation foci from studies meeting inclusion criteria (n = 33) were subjected to a quantitative voxel-based meta-analysis using activation likelihood estimation, and encompassed 146 subjects with ASD, 336 SZ patients and 492 healthy controls.

Results

Both SZ and ASD showed medial prefrontal hypoactivation, which was more pronounced in ASD, while ventrolateral prefrontal dysfunction was associated mostly with SZ. Amygdala hypoactivation was observed in SZ patients during FER and in ASD during more complex ToM tasks. Both disorders were associated with hypoactivation within the Superior Temporal Sulcus (STS) during ToM tasks, but activation in these regions was increased in ASD during affect processing. Disease-specific differences were noted in somatosensory engagement, which was increased in SZ and decreased in ASD. Reduced thalamic activation was uniquely seen in SZ.

Conclusions

Reduced frontolimbic and STS engagement emerged as a shared feature of social cognition deficits in SZ and ASD. However, there were disease- and stimulus-specific differences. These findings may aid future studies on SZ and ASD and facilitate the formulation of new hypotheses regarding their pathophysiology.