Left superior temporal blood flow increases in schizophrenic and schizophreniform patients with auditory hallucination: a longitudinal case study using 123I-IMP SPECT

Measuring imagery strength in schizophrenia: no evidence of enhanced mental imagery priming

INTRODUCTION

Recent research shows ambivalent results regarding the relationship between mental imagery and schizophrenia. The role of voluntary visual imagery in schizophrenic hallucinations remains unclear. The aim of the study was to investigate the association between visual imagery, schizophrenia, and the occurrence of schizophrenic hallucinations using an objective visual imagery task.

METHODS

The sample consisted of 16 participants with schizophrenia (59.1% female; MAge  = 45.55) and 44 participants without schizophrenia (62.5% female; MAge  = 43.94). Visual imagery was measured using the Vividness of Visual Imagery Questionnaire (VVIQ) as well as the well-validated Binocular Rivalry Task (BRT). Occurrences of hallucinations were assessed using the Launay-Slade Hallucination Scale.

RESULTS

Participants with schizophrenia showed more hallucinatory experiences but did not score higher on either the VVIQ or the BRT than participants without schizophrenia. A correlation between the VVIQ and the BRT was found, validating the measurement of visual imagery and enabling the interpretation that visual imagery vividness is not enhanced in people with schizophrenia.

CONCLUSION

The association between mental imagery vividness and schizophrenia found in previous studies may be based on other facets of mental imagery than visual imagery.

Pathological resting-state executive and language system perfusion in first-episode psychosis

BACKGROUND AND HYPOTHESIS

Cortical (e.g., Broca's area and Wernicke's area) and subcortical (e.g., putamen) language-related areas and executive control areas (e.g., inferior frontal gyrus (IFG), dorsolateral prefrontal cortex (DLPFC)) show functional and structural dysconnectivity in long-term psychosis. We examined whether resting-state basal perfusion levels revealed selective pathophysiology (likely hypo- and hyper-activation) of language-related and executive areas in first-episode psychosis (FEP).

STUDY DESIGN

Basal resting-state perfusion was measured using pseudo-continuous Arterial Spin Labeling (pcASL). Relative cerebral blood flow (rCBF) was compared between 32 FEP and 34 matched healthy comparison (HC) individuals. Structural and functional MRI scans were acquired using a 3T Prisma scanner during the same session.

STUDY RESULTS

Whole-brain comparison of resting rCBF identified 8 clusters with significant between-group differences. Reduced rCBF was found in executive control areas in left and right IFG, right DLPFC, and right parietal cortex. Increased rCBF was found in left and right temporal cortex (including Wernicke's area), and left and right putamen. A positive correlation was observed between auditory hallucination severity and rCBF in the left putamen.

CONCLUSIONS

To the degree that perfusion implies activation, language and auditory processing areas in bilateral temporal lobe and putamen showed pathological hyper-activity, and cognitive control areas (IFG, DLPFC, right parietal) showed pathological hypo-activity in FEP at rest. Pathological basal activity was present across the range of symptom severity, suggesting it may be a common underlying pathology for psychosis that may be targeted with non-invasive brain stimulation to normalize resting activity levels.

Real-Time Symptom Capture of Hallucinations in Schizophrenia with fMRI: Absence of Duration-Dependent Activity

Background

While advances in the field of functional magnetic resonance imaging (fMRI) provide new opportunities to study brain networks underlying the experience of hallucinations in psychosis, there are methodological challenges unique to symptom-capture studies.

Study Design

We extracted brain networks activated during hallucination-capture for schizophrenia patients when fMRI data collected from two sites was merged (combined N = 27). A multidimensional analysis technique was applied, which would allow separation of brain networks involved in the hallucinatory experience itself from those involved in the motor response of indicating the beginning and end of the perceived hallucinatory experience. To avoid reverse inference when attributing a function (e.g., a hallucination) to anatomical regions, it was required that longer hallucinatory experiences produce extended brain responses relative to shorter.

Study Results

For radio-speech sound files, an auditory perception brain network emerged, and displayed speech-duration-dependent hemodynamic responses (HDRs). However, in the hallucination-capture blocks, no network showed hallucination-duration-dependent HDRs, but a retrieved network that was anatomically classified as motor response emerged.

Conclusions

During symptom capture of hallucinations during fMRI, no HDR showed duration dependence, but a brain network anatomically matching the motor response network was retrieved. Previous reports on brain networks detected by fMRI during hallucination capture are reviewed in this context; namely, that the brain networks interpreted as involved in hallucinations may in fact be involved only in the motor response indicating the onset of the hallucination.

Grey matter connectome abnormalities and age-related effects in antipsychotic-naive schizophrenia

Background

Convergent evidence is increasing to indicate progressive brain abnormalities in schizophrenia. Knowing the brain network features over the illness course in schizophrenia, independent of effects of antipsychotic medications, would extend our sight on this question.

Methods

We recruited 237 antipsychotic-naive patients with schizophrenia range from 16 to 73 years old, and 254 healthy controls. High-resolution T1 weighted images were obtained with a 3.0T MR scanner. Grey matter networks were constructed individually based on the similarities of regional grey matter measurements. Network metrics were compared between patient groups and healthy controls, and regression analyses with age were conducted to determine potential differential rate of age-related changes between them.

Findings

Nodal centrality abnormalities were observed in patients with untreated schizophrenia, particularly in the central executive, default mode and salience networks. Accelerated age-related declines and illness duration-related declines were observed in global assortativity, and in nodal metrics of left superior temporal pole in schizophrenia patients. Although no significant intergroup differences in age-related regression were observed, the pattern of network metric alternation of left thalamus indicated higher nodal properties in early course patients, which decreased in long-term ill patients.

Interpretations

Global and nodal alterations in the grey matter connectome related to age and duration of illness in antipsychotic-naive patients, indicating potentially progressive network organizations mainly involving temporal regions and thalamus in schizophrenia independent from medication effects.

Funding

The National Natural Science Foundation of China, Sichuan Science and Technology Program, the Fundamental Research Funds for the Central Universities, Post-Doctor Research Project, West China Hospital, Sichuan University , the Science and Technology Project of the Health Planning Committee of Sichuan, Postdoctoral Interdisciplinary Research Project of Sichuan University and 1.3.5 Project for Disciplines of Excellence, West China Hospital, Sichuan University.

Structural and Functional Alterations of the Temporal lobe in Schizophrenia: A Literature Review

Schizophrenia is a severe chronic mental illness leading to social and occupational dysfunction. Our primary focus in this review article was to analyze further the structural and functional alterations of the temporal lobe in patients with schizophrenia, which might contribute to the associated manifestations we often see in this illness. Our goal was to see if there was any correlation between temporal lobe abnormalities, more specifically, alterations in brain volume and specific symptoms such as auditory and language processing, etc. There is a positive correlation between volume alterations and thoughts disorders in the temporal lobe in the majority of studies. However, superior temporal gyrus volume has also been correlated negatively with the severity of hallucinations and thought disorders in some studies. We utilized Medical Subject Heading (MeSH) search strategy via PubMed database in our articles search yielding 241 papers. After the application of specific inclusion and exclusion criteria, a final number of 30 was reviewed. The involvement of the temporal lobe and its gray and white matter volume alterations in schizophrenia is quite apparent from our research; however, the exact mechanism of the underlying biological process is not thoroughly studied yet. Therefore, further research on larger cohorts combining different imaging modalities including volumetry, diffusion tensor, and functional imaging is required to explain how the progressive brain changes affect the various structural, functional, and metabolic activities of the temporal lobe in schizophrenia.

White Matter Microstructural Abnormalities in the Broca's-Wernicke's-Putamen "Hoffman Hallucination Circuit" and Auditory Transcallosal Fibers in First-Episode Psychosis With Auditory Hallucinations

BACKGROUND

Functional connectivity abnormalities between Broca's and Wernicke's areas and the putamen revealed by functional magnetic resonance imaging (fMRI) are related to auditory hallucinations (AH). In long-term schizophrenia, reduced white matter structural integrity revealed by diffusion imaging in left arcuate fasciculus (connecting Broca's and Wernicke's areas) is likely related to AH. The structural integrity of connections with putamen and their relation to AH are unknown. Little is known about this relationship in first-episode psychosis (FEP), although auditory transcallosal connections were reported to play a role. White matter in the Broca's-Wernicke's-putamen language-related circuit and auditory transcallosal fibers was examined to investigate associations with AH in FEP.

METHODS

White matter connectivity was measured in 40 FEP and 32 matched HC using generalized fractional anisotropy (gFA) derived from diffusion spectrum imaging (DSI).

RESULTS

FEP and HC did not differ in gFA in any fiber bundle. In FEP, AH severity was significantly inversely related to gFA in auditory transcallosal fibers and left arcuate fasciculus. Although the right hemisphere arcuate fasciculus-AH association did not attain significance, the left and right arcuate fasciculus associations were not significantly different.

CONCLUSIONS

Despite overall normal gFA in FEP, AH severity was significantly related to gFA in transcallosal auditory fibers and the left hemisphere connection between Broca's and Wernicke's areas. Other bilateral tracts' gFA were weakly associated with AH. At the first psychotic episode, AH are more robustly associated with left hemisphere arcuate fasciculus and interhemispheric auditory fibers microstructural deficits, likely reflecting mistiming of information flow between language-related cortical centers.

Interhemispheric compensation: A hypothesis of TMS-induced effects on language-related areas

Repetitive transcranial magnetic stimulation (rTMS) applied over brain regions responsible for language processing is used to curtail potentially auditory hallucinations in schizophrenia patients and to investigate the functional organisation of language-related areas. Variability of effects is, however, marked across studies and between subjects. Furthermore, the mechanisms of action of rTMS are poorly understood.

Here, we reviewed different factors related to the structural and functional organisation of the brain that might influence rTMS-induced effects. Then, by analogy with aphasia studies, and the plastic-adaptive changes in both the left and right hemispheres following aphasia recovery, a hypothesis is proposed about rTMS mechanisms over language-related areas (e.g. Wernicke, Broca). We proposed that the local interference induced by rTMS in language-related areas might be analogous to aphasic stroke and might lead to a functional reorganisation in areas connected to the virtual lesion for language recovery.

Significant improvement in treatment resistant auditory verbal hallucinations after 5 days of double-blind, randomized, sham controlled, fronto-temporal, transcranial direct current stimulation (tDCS): A replication/extension study

BACKGROUND

Transcranial direct current stimulation (tDCS) is a potentially novel treatment for antipsychotic-resistant auditory verbal hallucinations (AVH) in schizophrenia. Nevertheless, results have been mixed across studies.

METHODS

89 schizophrenia/schizoaffective subjects (active: 47; Sham: 42) were randomized to five days of twice-daily 20-min active tDCS vs. sham treatments across two recruitment sites. AVH severity was assessed using the Auditory Hallucination Rating Scale (AHRS) total score. To assess target engagement, MRI was obtained in a sub sample.

RESULTS

We observed a statistically significant, moderate effect-size change in AHRS total score across one-week and one-month favoring active treatment following covariation for baseline symptoms and antipsychotic dose (p = 0.036; d = 0.48). Greatest change was observed on the AHRS loudness item (p = 0.003; d = 0.69). In exploratory analyses, greatest effects on AHRS were observed in patients with lower cognitive symptoms (d = 0.61). In target engagement analysis, suprathreshold mean field-strength (>0.2 V/m) was seen within language-sensitive regions. However, off-target field-strength, which correlated significantly with less robust clinical response, was observed in anterior regions.

CONCLUSIONS

This is the largest study of tDCS for persistent AVH conducted to date. We replicate previous reports of significant therapeutic benefit, but only if medication dosage is considered, with patients receiving lowest medication dosage showing greatest effect. Response was also greatest in patients with lowest levels of cognitive symptoms. Overall, these findings support continued development of tDCS for persistent AVH, but also suggest that response may be influenced by specific patient and treatment characteristics. CLINICALTRIALS.GOV: NCT01898299.

Understanding auditory verbal hallucinations in healthy individuals and individuals with psychiatric disorders

Auditory verbal hallucinations(AVHs) are psychiatric manifestations that are common in patients with psychiatric disorders and can occur in healthy individuals. This review summarizes the existing literature on the phenomenological features of auditory verbal hallucinations, imaging findings, and interventions, focusing on patients with schizophrenia who experience auditory verbal hallucinations, in addition to patients with borderline personality disorder, bipolar disorder, major depressive disorder, and posttraumatic stress disorder, as well as healthy individuals. The phenomenological features of AVHs vary in different psychiatric disorders, and the symptoms are associated with changes in specific brain structures and disturbances in brain function, blood flow, and metabolism. Interventions for auditory verbal hallucinations include antipsychotic drugs, neurostimulation, and cognitive behavioral therapy.

Cognitive correlates of abnormal myelination in psychosis

Psychotic illness has consistently been associated with deficits in cognitive function and reduced white matter integrity in the brain. However, the link between white matter disruptions and deficits in cognitive domains remains poorly understood. We assessed cognitive performance and white matter myelin water fraction (MWF) using multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) in recent-onset psychosis patients and age-matched healthy controls (HC). Psychosis patients showed deficits in working memory, phonological and semantic fluency, general intelligence quotient and reduced MWF in the left temporal white matter compared to HC. MWF in the left inferior fronto-occipital fasciculus and inferior longitudinal fasciculus was positively associated with intelligence quotient and verbal fluency in patients, and fully mediated group differences in performance in both phonological and semantic verbal fluency. There was no association between working memory and MWF in the left temporal white matter. Negative symptoms demonstrated a negative association with MWF within the left inferior and superior longitudinal fasciculi. These findings indicate that psychosis-related deficits in distinct cognitive domains, such as verbal fluency and working memory, are not underpinned by a single common dysfunction in white matter connectivity.

Task and resting-state fMRI studies in first-episode schizophrenia: A systematic review

In the last two decades there has been an increase on task and resting-state functional Magnetic Resonance Imaging (fMRI) studies that explore the brain's functional changes in schizophrenia. However, it remains unclear as to whether the brain's functional changes during the resting state are sensitive to the same brain regions during task fMRI. Therefore, we conducted a systematic literature search of task and resting-state fMRI studies that investigated brain pathological changes in first-episode schizophrenia (Fleischhacker et al.). Nineteen studies met the inclusion criteria; seven were resting state fMRI studies with 371 FES patients and 363 healthy controls and twelve were task fMRI studies with 235 FES patients and 291 healthy controls. We found overlapping task and resting-state fMRI abnormalities in the prefrontal regions, including the dorsal lateral prefrontal cortex, the orbital frontal cortex and the temporal lobe, especially in the left superior temporal gyrus (STG). The findings of this systematic review support the frontotemporal hypothesis of schizophrenia, and the disruption in prefrontal and STG might represent the pathophysiology of schizophrenia disorder at a relatively early stage.

Auditory verbal hallucinations: neuroimaging and treatment

Auditory verbal hallucinations (AVH) are a frequently occurring phenomenon in the general population and are considered a psychotic symptom when presented in the context of a psychiatric disorder. Neuroimaging literature has shown that AVH are subserved by a variety of alterations in brain structure and function, which primarily concentrate around brain regions associated with the processing of auditory verbal stimuli and with executive control functions. However, the direction of association between AVH and brain function remains equivocal in certain research areas and needs to be carefully reviewed and interpreted. When AVH have significant impact on daily functioning, several efficacious treatments can be attempted such as antipsychotic medication, brain stimulation and cognitive-behavioural therapy. Interestingly, the neural correlates of these treatments largely overlap with brain regions involved in AVH. This suggests that the efficacy of treatment corresponds to a normalization of AVH-related brain activity. In this selected review, we give a compact yet comprehensive overview of the structural and functional neuroimaging literature on AVH, with a special focus on the neural correlates of efficacious treatment.

Hallucinating Consistency

Top-down processes like heuristics and gap filling create consistency in normal perception. Sometimes top-down processes cause illusory perceptions. Top-down processes are also involved in the creation of hallucinations, experienced in phenomena like sensory deprivation and phantom limbs. Moreover, it has been argued that the left hemisphere is important in the creation of hallucinations, since it also creates consistency. The influence of the left hemisphere in creating hallucinations is evidenced by an experiment concerning anosognosia (denial of illness). In schizophrenia, top-down processes and the left hemisphere both seem to be involved in the creation of hallucinations. It is argued that hallucinations are instigated for creating consistency and thereby have a functional character.

Subcomponents of brain T2* relaxation in schizophrenia, bipolar disorder and siblings: A Gradient Echo Plural Contrast Imaging (GEPCI) study

Investigating brain tissue T2* relaxation properties in vivo can potentially guide the uncovering of neuropathology in psychiatric illness, which is traditionally examined post mortem. We use an MRI-based Gradient Echo Plural Contrast Imaging (GEPCI) technique that produces inherently co-registered images allowing quantitative assessment of tissue cellular and hemodynamic properties. Usually described as R2* (=1/T2*) relaxation rate constant, recent developments in GEPCI allow the separation of cellular-specific (R2*C) and hemodynamic (BOLD) contributions to the MRI signal decay. We characterize BOLD effect in terms of tissue concentration of deoxyhemoglobin, i.e. CDEOXY, which reflects brain activity. 17 control (CON), 17 bipolar disorder (BPD), 16 schizophrenia (SCZ), and 12 unaffected schizophrenia sibling (SIB) participants were scanned and post-processed using GEPCI protocols. A MANOVA of 38gray matter regions ROIs showed significant group effects for CDEOXY but not for R2*C. In the three non-control groups, 71-92% of brain regions had increased CDEOXY. Group effects were observed in the superior temporal cortex and the thalamus. Increased superior temporal cortex CDEOXY was found in SCZ (p=0.01), BPD (p=0.01) and SIB (p=0.02), with bilateral effects in SCZ and only left hemisphere effects in BPD and SIB. Thalamic CDEOXY abnormalities were observed in SCZ (p=0.003), BPD (p=0.03) and SIB (p=0.02). Our results suggest that increased activity in certain brain regions is part of the underlying pathophysiology of specific psychiatric disorders. High CDEOXY in the superior temporal cortex suggests abnormal activity with auditory, language and/or social cognitive processing. Larger studies are needed to clarify the clinical significance of relaxometric abnormalities.

Left-dominant temporal-frontal hypercoupling in schizophrenia patients with hallucinations during speech perception

BACKGROUND

Task-based functional neuroimaging studies of schizophrenia have not yet replicated the increased coordinated hyperactivity in speech-related brain regions that is reported with symptom-capture and resting-state studies of hallucinations. This may be due to suboptimal selection of cognitive tasks.

METHODS

In the current study, we used a task that allowed experimental manipulation of control over verbal material and compared brain activity between 23 schizophrenia patients (10 hallucinators, 13 nonhallucinators), 22 psychiatric (bipolar), and 27 healthy controls. Two conditions were presented, one involving inner verbal thought (in which control over verbal material was required) and another involving speech perception (SP; in which control verbal material was not required).

RESULTS

A functional connectivity analysis resulted in a left-dominant temporal-frontal network that included speech-related auditory and motor regions and showed hypercoupling in past-week hallucinating schizophrenia patients (relative to nonhallucinating patients) during SP only.

CONCLUSIONS

These findings replicate our previous work showing generalized speech-related functional network hypercoupling in schizophrenia during inner verbal thought and SP, but extend them by suggesting that hypercoupling is related to past-week hallucination severity scores during SP only, when control over verbal material is not required. This result opens the possibility that practicing control over inner verbal thought processes may decrease the likelihood or severity of hallucinations.

A systematic review and meta-analysis of the use of repetitive transcranial magnetic stimulation for auditory hallucinations treatment in refractory schizophrenic patients

BACKGROUND

The use of repetitive transcranial magnetic stimulation (rTMS) remains a promising therapeutic tool in the treatment of schizophrenia. Symptoms such as auditory hallucinations (AH) find contradictory results in many studies. Here we present an up-to-date systematic review and meta-analysis of rTMS in the treatment of AH in schizophrenia.

METHODS

We searched Pubmed-MEDLINE from 1999 to 2013 for double-blinded randomized sham-controlled trials that applied slow rTMS on the left temporoparietal cortex and assessed the outcome results using Hallucination Change Scale or Auditory Hallucination Rating Scale or Scale for Auditory Hallucinations (SAH). We identified 10 studies suitable for the meta-analysis.

RESULTS

We found a positive sized effect in favor of rTMS [random-effects model Hedges' g = 0.011, I-squared = 58.1%]. There was some variability between study effect sizes, but the sensitivity analysis concluded that none of them had sufficient weight to singularly alter the results of our meta-analysis.

DISCUSSION

rTMS appears to be an effective treatment for AH. The left temporoparietal cortex seems to be the area in which rTMS is effective. Although meta-analysis is a powerful analytical tool, more studies must be conducted in order to obtain a more expressive sample size to perform a more accurate analytical approach.

Bilateral Repetitive Transcranial Magnetic Stimulation for Auditory Hallucinations in Patients with Schizophrenia: A Randomized Controlled, Cross-over Study

Objective

A randomized double-blind cross-over trial was conducted in patients with persistent auditory hallucinations (AHs) to investigate whether bilateral repetitive transcranial magnetic stimulation (rTMS) at the temporoparietal area or Broca's area is more effective at high- or low-frequencies compared to a sham condition.

Methods

Twenty three patients with persistent AHs who remained stable on the same medication for 2 months were enrolled. They were randomized to one of four conditions: low-frequency (1 Hz)-rTMS to the temporoparietal area (L-TP), high-frequency (20 Hz)-rTMS to the temporoparietal area (H-TP), high-frequency (20 Hz)-rTMS to Broca's area (H-B), or sham.

Results

All the four rTMS conditions resulted in significant decrease in the scores under the auditory hallucination rating scale and hallucination change scale over time. However, there were no significant treatment effects or interaction between time and treatment, suggesting no superior effects of the new paradigms over the sham condition.

Conclusion

Our findings suggest that bilateral rTMS at the temporoparietal area or Broca's area with high- or low-frequency does not produce superior effects in reducing AHs compared to sham stimulation.

Magnetic resonance imaging in studying schizophrenia, negative symptoms, and the glutamate system

Schizophrenia is characterized by positive, negative, and cognitive symptoms. While positive symptoms occur periodically during psychotic exacerbations, negative and cognitive symptoms often emerge before the first psychotic episode and persist with low functional outcome and poor prognosis. This review article outlines the importance of modern functional magnetic resonance imaging techniques for developing a stratified therapy of schizophrenic disorders. Functional neuroimaging evidence on the neural correlates of positive and particularly negative symptoms and cognitive deficits in schizophrenic disorders is briefly reviewed. Acute dysregulation of dopaminergic neurotransmission is crucially involved in the occurrence of psychotic symptoms. However, increasing evidence also implicates glutamatergic pathomechanisms, in particular N-methyl-d-aspartate (NMDA) receptor dysfunction in the pathogenesis of schizophrenia and in the appearance of negative symptoms and cognitive dysfunctions. In line with this notion, several gene variants affecting the NMDA receptor's pathway have been reported to increase susceptibility for schizophrenia, and have been investigated using the imaging genetics approach. In recent years, several attempts have been made to develop medications modulating the glutamatergic pathway with modest evidences for efficacy. The most successful approaches were those that aimed at influencing this pathway using compounds that enhance NMDA receptor function. More recently, the selective glycine reuptake inhibitor bitopertin has been shown to improve NMDA receptor hypofunction by increasing glycine concentrations in the synaptic cleft. Further research is required to test whether pharmacological agents with effects on the glutamatergic system can help to improve the treatment of negative symptoms in schizophrenic disorders.

Functional connectivity of left Heschl's gyrus in vulnerability to auditory hallucinations in schizophrenia

BACKGROUND

Schizophrenia is a heterogeneous disorder that may consist of multiple etiologies and disease processes. Auditory hallucinations (AH), which are common and often disabling, represent a narrower and more basic dimension of psychosis than schizophrenia. Previous studies suggest that abnormal primary auditory cortex activity is associated with AH pathogenesis. We thus investigated functional connectivity, using a seed in primary auditory cortex, in schizophrenia patients with and without AH and healthy controls, to examine neural circuit abnormalities associated more specifically with AH than the myriad other symptoms that comprise schizophrenia.

METHODS

Using resting-state fMRI (rsfMRI), we investigated functional connectivity of the primary auditory cortex, located on Heschl's gyrus, in schizophrenia spectrum patients with AH. Participants were patients with schizophrenia, schizoaffective disorder, or schizophreniform disorder with lifetime AH (n=27); patients with the same diagnoses but no lifetime AH (n=14); and healthy controls (n=28).

RESULTS

Patients with AH vulnerability showed increased left Heschl's gyrus functional connectivity with left frontoparietal regions and decreased functional connectivity with right hippocampal formation and mediodorsal thalamus compared to patients without lifetime AH. Furthermore, among AH patients, left Heschl's gyrus functional connectivity covaried positively with AH severity in left inferior frontal gyrus (Broca's area), left lateral STG, right pre- and postcentral gyri, cingulate cortex, and orbitofrontal cortex. There were no differences between patients with and without lifetime AH in right Heschl's gyrus seeded functional connectivity.

CONCLUSIONS

Abnormal interactions between left Heschl's gyrus and regions involved in speech/language, memory, and the monitoring of self-generated events may contribute to AH vulnerability.

Possible dysregulation of cortical plasticity in auditory verbal hallucinations-A cortical thickness study in schizophrenia

INTRODUCTION

Investigations of gray matter changes in relation with auditory verbal hallucinations (AVH) have reported conflicting results. Assuming that alterations in gray matter might be related to certain symptoms in schizophrenia this study aimed to investigate changes in cortical thickness specific to AVH. It was hypothesized that schizophrenia patients suffering from persistent AVH would show significant differences in cortical thickness in regions involved in language-production and perception when compared to schizophrenia patients which had never experienced any hallucinations.

METHODS

Using cortical thickness analysis the present study investigated ten schizophrenic patients suffering from AVH, ten non-hallucinating schizophrenic patients, and ten healthy control subjects. Anatomical data were acquired on a 3 T MRI system, transformed into standard space and cortically aligned to investigate local differences in whole brain cortical thickness between the two patient groups. Based on this comparison, brain regions with alterations specific for the patients with AVH were identified and then used as regions of interest to compare both patient groups to the healthy subjects respectively.

RESULTS

Hallucinating patients showed gray matter reductions in the dominant hemisphere predominantly in sensory language areas relevant for speech processing. Increased cortical thickness was found in regions related to self-monitoring.

CONCLUSIONS

Gray matter reductions in chronic schizophrenic patients may be the sequel of synaptic derangement or disease-related deregulation of language circuits. In order to clarify the ambiguous information processing additional demands might be put on cortical structures responsible for self-monitoring processes leading to changes in cortical thickness in the sense of neural plasticity.

Quantitative meta-analysis on state and trait aspects of auditory verbal hallucinations in schizophrenia

Auditory verbal hallucinations (AVHs) have a high prevalence in schizophrenic patients. An array of studies have explored the neural correlates of AVHs by means of functional neuroimaging and have associated AVHs with diverse brain regions, some of which have been shown to be involved in speech generation, speech perception, and auditory stimulus processing. We divided these studies into "state" studies comparing periods of presence and absence of AVHs within-subject and "trait" studies comparing patients experiencing AVHs with patients without AVHs or healthy controls during tasks with verbal material. We set out to test the internal consistency and possible dissociations of the neural correlates of AVHs. We used activation likelihood estimation to perform quantitative meta-analyses on brain regions reported in state and trait studies on AVHs to assess significant concordance across studies. State studies were associated with activation in bilateral inferior frontal gyrus, bilateral postcentral gyrus, and left parietal operculum. Trait studies on the other hand showed convergence of decreases in hallucinating subjects in left superior temporal gyrus, left middle temporal gyrus, anterior cingulate cortex, and left premotor cortex activity. Based on the clear dissociation of brain regions that show convergence across state in comparison to trait studies, we conclude that the state of experiencing AVHs is primarily related brain regions that have been implicated in speech production ie, Broca's area, whereas the general trait that makes humans prone to AVHs seems to be related to brain areas involved in auditory stimuli processing and speech perception, ie, auditory cortex.

Hearing voices: a role of interhemispheric auditory connectivity?

OBJECTIVES

Auditory verbal hallucinations (AVH) are among the most common symptoms in schizophrenia. Earlier studies suggest changes in the structural connectivity of auditory areas involved in the pathophysiology of auditory hallucinations. Combining diffusion tensor imaging (DTI) and fibre tractography provides a unique opportunity to visualize and quantify entire fibre bundles.

METHODS

Fibre tracts connecting homotopic auditory areas via the corpus callosum were identified with DTI in ten first episode paranoid schizophrenia patients and ten healthy controls. Regions of interest were drawn manually, to guide tractography, and fractional anisotropy (FA) - a measure of fibre integrity - was calculated and averaged over the entire tract for each subject.

RESULTS

There was no difference in the FA of the interhemispheric auditory fibres between schizophrenic patients and healthy controls. However, the subgroup of patients hearing conversing voices showed increased FA relative to patients without these symptoms (P = 0.047) and trendwise increased FA relative to healthy controls (P = 0.066). In addition, a trendwise correlation between FA values and AVH symptoms (P = 0.089) was found.

CONCLUSIONS

Our findings suggest that in addition to local deficits in the left auditory cortex and disturbed fronto-temporal connectivity, the interhemispheric auditory pathway might be involved in the pathogenesis of AVH.

A pilot double-blind sham-controlled trial of repetitive transcranial magnetic stimulation for patients with refractory schizophrenia treated with clozapine

Schizophrenia is a complex and heterogeneous psychiatric disorder. Auditory verbal hallucinations occur in 50-70% of patients with schizophrenia and are associated with significant distress, decreased quality of life and impaired social functioning. This study aimed to investigate the effects of active compared with sham 1-Hz repetitive transcranial magnetic stimulation (rTMS) applied to the left temporal-parietal cortex in patients with schizophrenia treated with clozapine. Symptom dimensions that were evaluated included general psychopathology, severity of auditory hallucinations, quality of life and functionality. Seventeen right-handed patients with refractory schizophrenia experiencing auditory verbal hallucinations and treated with clozapine were randomly allocated to receive either active rTMS or sham stimulation. A total of 384 min of rTMS was administered over 20 days using a double-masked, sham-controlled, parallel design. There was a significant reduction in Brief Psychiatric Rating Scale (BPRS) scores in the active group compared with the sham group. There was no significant difference between active and sham rTMS on Quality of Life Scale (QLS), Auditory Hallucinations Rating Scale (AHRS), Clinical Global Impressions (CGI) and functional assessment staging (FAST) scores. Compared with sham stimulation, active rTMS of the left temporoparietal cortex in clozapine-treated patients showed a positive effect on general psychopathology. However, there was no effect on refractory auditory hallucinations. Further studies with larger sample sizes are needed to confirm these findings.

A general neuropsychological model of delusion

INTRODUCTION

Neurocognitive accounts of delusion have traditionally highlighted perceptual misrepresentation, as the primary trigger in addition to other cognitive deficits that maintain the delusion. Here, a general neurocognitive model of delusional disorder (DSM-IV) is proposed, not so much based on perceptual or cognitive deficits after right hemisphere damage as on cognitive propensities, specifically excessive inferencing (especially jumping to conclusions) and excessive reference to the self, due to left hemisphere overactivity.

METHOD

The functional imaging, topographic EEG, and experimental imaging literatures on delusional disorder are reviewed, and 37 previously published cases of postunilateral lesion delusion (DSM-IV type, grandeur, persecution, jealousy, erotomania, or somatic), are reviewed and analysed multivariately.

RESULTS

Functional imaging and EEG topography data were slightly more indicative of left hemisphere overactivity in delusional disorder. In addition, 73% of the postunilateral lesion cases (χ(2)=7.8, p=.005) of delusional disorder (DSM-IV type) had a right hemisphere lesion, whereas only 27% had a left hemisphere lesion.

CONCLUSION

Left hemisphere release appears to be a more primary cause of delusional disorder than right hemisphere impairment, the latter merely entailing loss of inhibition of delusional beliefs. We propose that most patients with DSM-IV diagnoses of delusional disorder could be afflicted by excessive left hemisphere activity, but further research is necessary.

[Distinguishing the voice of self from others: the self-monitoring hypothesis of auditory hallucination]

Auditory hallucinations (AH), a psychopathological phenomenon where a person hears non-existent voices, commonly occur in schizophrenia. Recent cognitive and neuroscience studies suggest that AH may be the misattribution of one's own inner speech. Self-monitoring through neural feedback mechanisms allows individuals to distinguish between their own and others' actions, including speech. AH maybe the results of an individual's inability to discriminate between their own speech and that of others. The present paper tries to integrate the three theories (behavioral, brain, and model approaches) proposed to explain the self-monitoring hypothesis of AH. In addition, we investigate the lateralization of self-other representation in the brain, as suggested by recent studies, and discuss future research directions.

Functional connectivity of the temporo-parietal region in schizophrenia: effects of rTMS treatment of auditory hallucinations

Auditory-verbal hallucinations are a hallmark symptom of schizophrenia. In recent years, repetitive transcranial magnetic stimulation (rTMS) targeting speech perception areas has been advanced as a potential treatment of medication-resistant hallucinations. However, the underlying neural processes remain unclear. This study aimed to assess whether 1 Hz rTMS treatment would affect functional connectivity of the temporo-parietal junction (TPJ). Resting state fMRI scans were obtained from 18 patients with schizophrenia. Patients were assessed before and after a 6 day treatment with 1 Hz rTMS to the left TPJ, or placebo treatment with sham rTMS to the same location. We assessed functional connectivity between a priori defined regions-of-interest (ROIs) comprising the putative AVH network and the bilateral TPJ seed regions, targeted with rTMS. Symptom improvement following rTMS treatment was observed in the left rTMS group, whereas no change at occurred in the placebo group. Although no corresponding changes were observed in the functional connections previously found to be associated with AVH severity, an increase in connectivity between the left TPJ and the right insula was observed in group receiving rTMS to the left TPJ. The placebo group conversely showed a decrease in connectivity between the left TPJ and left anterior cingulate. We conclude that application of 1 Hz rTMS to the left TPJ region may affect functional connectivity of the targeted region. However, the relationship between these functional changes during the resting state and the rate of clinical improvement needs further clarification.

Auditory hallucinations in schizophrenia are associated with reduced functional connectivity of the temporo-parietal area

BACKGROUND

Schizophrenia has been conceptualized as a disorder of integration of neural activity across distributed networks. However, the relationship between specific symptom dimensions and patterns of functional connectivity remains unclear. The current study aimed to investigate the relationship between auditory-verbal hallucinations (AVH), a particularly prevalent and clinically relevant symptom in schizophrenia, and functional connectivity of the temporo-parietal junction (TPJ).

METHODS

Resting state functional magnetic resonance imaging scans were obtained from 27 schizophrenia patients with AVH and 27 matched control subjects. We calculated correlations reflecting functional connectivity between a priori defined regions-of-interest and the bilateral TPJ seed regions, comprising the neural network involved in inner speech processes and AVH.

RESULTS

Compared with healthy control subjects, schizophrenia patients showed reduced functional connectivity between left TPJ and the right homotope of Broca. Within the patient group, more severe AVH were associated with reduced neural coupling between left TPJ and bilateral anterior cingulate as well as the bilateral amygdala.

CONCLUSIONS

In schizophrenia patients with chronic hallucinations, the left TPJ-a critical node in the speech perception/AVH network-shows reduced functional connectivity with brain areas involved in the attribution of agency, self-referent processing, and attentional control.

Spatio-temporal EEG waves in first episode schizophrenia

OBJECTIVE

Schizophrenia is characterized by a deficit in context processing, with physiological correlates of hypofrontality and reduced amplitude P3b event-related potentials. We hypothesized an additional physiological correlate: differences in the spatio-temporal dynamics of cortical activity along the anterior-posterior axis of the scalp.

METHODS

This study assessed latency topographies of spatio-temporal waves under task conditions that elicit the P3b. EEG was recorded during separate auditory and visual tasks. Event-related spatio-temporal waves were quantified from scalp EEG of subjects with first episode schizophrenia (FES) and matched controls.

RESULTS

The P3b-related task conditions elicited a peak in spatio-temporal waves in the delta band at a similar latency to the P3b event-related potential. Subjects with FES had fewer episodes of anterior to posterior waves in the 2-4 Hz band compared to controls. Within the FES group, a tendency for fewer episodes of anterior to posterior waves was associated with high Psychomotor Poverty symptom factor scores.

CONCLUSIONS

Subjects with FES had altered global EEG dynamics along the anterior-posterior axis during task conditions involving context update.

SIGNIFICANCE

The directional nature of this finding and its association with Psychomotor Poverty suggest this result is related to findings of hypofrontality in schizophrenia.

fMRI changes over time and reproducibility in unmedicated subjects at high genetic risk of schizophrenia

BACKGROUND

Functional brain abnormalities have been repeatedly demonstrated in schizophrenia but there is little data concerning their progression. For such studies to have credibility it is first important to establish the reproducibility of functional imaging techniques. The current study aimed to examine these factors in healthy controls and in unmedicated subjects at high genetic risk of the disorder: (i) to examine the reproducibility of task-related activation patterns, (ii) to determine if there were any progressive functional changes in high-risk subjects versus controls reflecting inheritance of the schizophrenic trait, and (iii) to examine changes over time in relation to fluctuating positive psychotic symptoms (i.e. state effects).

METHOD

Subjects were scanned performing the Hayling sentence completion test on two occasions 18 months apart. Changes in activation were examined in controls and high-risk subjects (n=16, n=63). Reproducibility was assessed for controls and high-risk subjects who remained asymptomatic at both time points (n=16, n=32).

RESULTS

Intra-class correlation values indicated good agreement between scanning sessions. No significant differences over time were seen between the high-risk and control group; however, comparison of high-risk subjects who developed symptoms versus those who remained asymptomatic revealed activation increases in the left middle temporal gyrus (p=0.026).

CONCLUSIONS

The current results suggest that functional changes over time occur in the lateral temporal cortex as high genetic risk subjects become symptomatic, further, they indicate the usefulness of functional imaging tools for investigating progressive changes associated with state and trait effects in schizophrenia.

Left temporal lobe structural and functional abnormality underlying auditory hallucinations in schizophrenia

In this article, we have reviewed recent findings from our laboratory, originally presented in Hugdahl et al. (2008). These findings reveal that auditory hallucinations in schizophrenia should best be conceptualized as internally generated speech mis-representations lateralized to the left superior temporal gyrus and sulcus, not cognitively suppressed due to enhanced attention to the 'voices' and failure of fronto-parietal executive control functions. An overview of diagnostic questionnaires for scoring of symptoms is presented together with a review of behavioral, structural, and functional MRI data. Functional imaging data have either shown increased or decreased activation depending on whether patients have been presented an external stimulus during scanning. Structural imaging data have shown reduction of grey matter density and volume in the same areas in the temporal lobe. We have proposed a model for the understanding of auditory hallucinations that trace the origin of auditory hallucinations to neuronal abnormality in the speech areas in the left temporal lobe, which is not suppressed by volitional cognitive control processes, due to dysfunctional fronto-parietal executive cortical networks.

Effect of augmentatory repetitive transcranial magnetic stimulation on auditory hallucinations in schizophrenia: randomized controlled study

OBJECTIVE

Auditory hallucinations are a characteristic symptom of schizophrenia and are usually resistant to treatment. The present study was conducted to further support the findings that repetitive transcranial magnetic stimulation (rTMS) reduces auditory hallucinations, and to evaluate the effect of low-frequency rTMS on auditory hallucinations in schizophrenia.

METHODS

Forty schizophrenia patients were included in the study. Patients were randomized to control or experimental group. Low-frequency rTMS (1 Hz, 90% motor threshold) was applied to the left temporoparietal cortex of patients in the experimental group for 10 days following the standard guidelines as an addition to antipsychotic treatment. The control group received only antipsychotics. The changes in the psychopathology scores for the auditory hallucinations were recorded using auditory hallucination recording scale. The rater was blind to the intervention procedure.

RESULTS

A significant improvement was found in auditory hallucinations in the experimental group as compared to the control group.

CONCLUSION

Left temporoparietal rTMS warrants further study as an intervention for auditory hallucinations. Data suggest that this intervention selectively alters neurobiological factors determining frequency of these hallucinations.

Psychotic symptoms as a continuum between normality and pathology

This paper reviews the presence of psychotic features in the nonclinical population. The results of a literature review suggest that delusional and hallucinatory experiences are more common in the general population than we may think, and that there could well be a symptomatic continuum between people who have and people who have not been diagnosed with indisputable psychotic disorders. In the nonclinical population, voices are mainly positive and nonthreatening. Conversely, in the psychiatric population, they tend to be frequent, intrusive, and distressing. We address the question of voices considered as various human experiences and describe the emergence of the nonclinical group of people who hear voices. We also review the pathophysiology of auditory hallucinations as an illustration of a neurophysiological anomaly, which is useful to understand psychosis or schizophrenia. The main obstacle in the category-specific thought is that it remains impossible to unmistakably demarcate the border around schizophrenia. It is evident that the creation of a boundary is always possible by using arbitrary criteria that improve interrater reliability but exclude a considerable number of people who share multiple common features with diagnosed people.

Nonlinear analysis of electroencephalogram in schizophrenia patients with persistent auditory hallucination

OBJECTIVE

The recent nonlinear analyses of electroencephalogram (EEG) data have shown that the correlation dimension (D2) reflects the degree of integration of information processing in the brain. There is now considerable evidence that auditory hallucination (AH) reflects dysfunctional gamma and beta frequency oscillations. Gamma oscillations are thought to reflect internally driven representations of objects, and the occurrence of subsequent beta oscillations can reflect the modification of the neuronal circuitry used to encode the sensory perception. The purpose of this study was to test whether AH in schizophrenia patients is reflected in abnormalities in D2 in their EEG, especially in the gamma and beta frequency bands.

METHODS

Twenty-five schizophrenia patients with a history of treatment-refractory AH over at least the past 2 years, and 23 schizophrenia patients with no AH (N-AH) within the past 2 years were recruited for the study. Artifact-free 30-s EEG epochs during rest were examined for D2.

RESULTS

The AH patients showed significantly increased gamma frequency D2 in Fp2 and decreased beta frequency D2 in the P3 region compared with the N-AH patients. These results imply that gamma frequency D2 in the right prefrontal cortex is more chaotic and that beta frequency D2 in the left parietal cortex is more coherent (less chaotic) in AH patients than in N-AH patients.

CONCLUSION

Our study supports the previous evidence indicating that gamma and beta oscillations are pivotal to AH, and also shows the distinctive dimensional complexity between the right prefrontal and left parietal cortexes as the underlying biological correlates of AH in schizophrenia patients.

Left hemisphere lateralisation of auditory hallucinations in schizophrenia: a dichotic listening study

INTRODUCTION

We propose that auditory hallucinations are internally generated speech misrepresentations that are lateralised to the left temporal lobe. If hallucinations are misrepresentations involving the speech perception area of the left temporal lobe, then hallucinating patients should have problems identifying a simultaneously presented external speech sound, especially when the sound is lateralised to the left hemisphere. Lateralisation of speech perception can be experimentally studied with the dichotic listening task with consonant-vowel syllables. We predicted a negative relation between frequency of auditory hallucinations and performance on the dichotic listening task.

METHOD

We studied 87 right-handed patients with schizophrenia. Hallucination scores were taken from the BPRS symptom scale. Right and left ear scores in the dichotic listening task were recorded. A right ear advantage is expected in healthy individuals, indicating left temporal lobe processing superiority. The patients were compared with 36 right-handed healthy reference subjects.

RESULTS

A gradual decrease in the ability to process and report the right ear stimulus with increasing frequency of hallucinations was seen in the schizophrenia patients. No such relationship was found for processing and reporting of the left ear stimulus. There were no significant correlations with negative symptoms. Thus, the results were not the consequence of illness severity. There was however a significant correlation with unusual thought content symptom, pointing to a relationship also between delusions and auditory hallucinations.

CONCLUSION

The results support that auditory hallucinations may be internally generated speech misrepresentations, originating in the left temporal lobe.

The hallucinating brain: A review of structural and functional neuroimaging studies of hallucinations

Hallucinations remains one of the most intriguing phenomena in psychopathology. In the past two decades the advent of neuroimaging techniques have allowed researchers to investigate what is happening in the brain of those who experience hallucinations. In this article we review both structural and functional neuroimaging studies of patients with auditory and visual hallucinations as well as a small number of studies that have assessed cognitive processes associated with hallucinations in healthy volunteers. The current literature suggests that in addition to secondary (and occasionally primary) sensory cortices, dysfunction in prefrontal premotor, cingulate, subcortical and cerebellar regions also seem to contribute to hallucinatory experiences. Based on the findings of these studies we tentatively propose a neurocognitive model in which both bottom-up and top-down processes interact to produce these erroneous percepts. Finally, directions for future work are discussed.

Effect of low-frequency rTMS on electromagnetic tomography (LORETA) and regional brain metabolism (PET) in schizophrenia patients with auditory hallucinations

BACKGROUND

Auditory hallucinations are characteristic symptoms of schizophrenia with high clinical importance. It was repeatedly reported that low frequency (<or=1 Hz) repetitive transcranial magnetic stimulation (rTMS) diminishes treatment-resistant auditory hallucinations. A neuroimaging study elucidating the effect of rTMS in auditory hallucinations has yet to be published.

OBJECTIVE

To evaluate the distribution of neuronal electrical activity and the brain metabolism changes after low-frequency rTMS in patients with auditory hallucinations.

METHODS

Low-frequency rTMS (0.9 Hz, 100% of motor threshold, 20 min) applied to the left temporoparietal cortex was used for 10 days in the treatment of medication-resistant auditory hallucinations in schizophrenia (n = 12). The effect of rTMS on the low-resolution brain electromagnetic tomography (LORETA) and brain metabolism ((18)FDG PET) was measured before and after 2 weeks of treatment.

RESULTS

We found a significant improvement in the total and positive symptoms (PANSS), and on the hallucination scales (HCS, AHRS). The rTMS decreased the brain metabolism in the left superior temporal gyrus and in interconnected regions, and effected increases in the contralateral cortex and in the frontal lobes. We detected a decrease in current densities (LORETA) for the beta-1 and beta-3 bands in the left temporal lobe whereas an increase was found for beta-2 band contralaterally.

CONCLUSION

Our findings implicate that the effect is connected with decreased metabolism in the cortex underlying the rTMS site, while facilitation of metabolism is propagated by transcallosal and intrahemispheric connections. The LORETA indicates that the neuroplastic changes affect the functional laterality and provide the substrate for a metabolic effect.

Probing the pathophysiology of auditory/verbal hallucinations by combining functional magnetic resonance imaging and transcranial magnetic stimulation

Functional magnetic resonance imaging and repetitive transcranial magnetic stimulation (rTMS) were used to explore the pathophysiology of auditory/verbal hallucinations (AVHs). Sixteen patients with schizophrenia-spectrum disorder were studied with continuous or near continuous AVHs. For patients with intermittent hallucinations (N = 8), blood oxygenation level-dependent (BOLD) activation maps comparing hallucination and nonhallucination periods were generated. For patients with continuous hallucinations (N = 8) correlations between BOLD signal time course in Wernicke's area, and other regions were used to map functional coupling to the former. These maps were used to identify 3-6 cortical sites per patient that were probed with 1-Hz rTMS and sham stimulation. Delivering rTMS to left temporoparietal sites in Wernicke's area and the adjacent supramarginal gyrus was accompanied by a greater rate of AVH improvement compared with sham stimulation and rTMS delivered to anterior temporal sites. For intermittent hallucinators, lower levels of hallucination-related activation in Broca's area strongly predicted greater rate of response to left temporoparietal rTMS. For continuous hallucinators, reduced coupling between Wernicke's and a right homologue of Broca's area strongly predicted greater left temporoparietal rTMS rate of response. These findings suggest that dominant hemisphere temporoparietal areas are involved in expressing AVHs, with higher levels of coactivation and/or coupling involving inferior frontal regions reinforcing underlying pathophysiology.

Specific and unspecific auditory hallucinations in patients with schizophrenia: a magnetoencephalographic study

BACKGROUND/AIMS

Different neuroimaging techniques have indicated that auditory association and language cortices are active in patients with schizophrenia and auditory hallucinations. Auditory verbal hallucinations are thought to arise from a disorder of inner speech, but little is known about their origin.

METHODS

Spontaneous magnetoencephalographic (MEG) measurements were recorded with a 74-channel two-sensor system (BIOMAGNES II) in 16 patients with schizophrenia and 8 healthy subjects in frequency ranges from 2 to 6 and 12.5 to 30 Hz. Eight patients had auditory hallucinations during the MEG recordings.

RESULTS

The total group of patients with schizophrenia showed a statistically significant elevation of the number of dipoles and dipole density maxima in slow frequency ranges compared to healthy subjects (p <0.001). Significant dipole activities in the fast frequency range were only found during auditory hallucinations (p <0.001). Dipole localization was concentrated in frontal and temporal regions depending on different qualities of hallucinations. In patients with external imperative voices we found a parallel activation of the dorsolateral frontal and temporal cortex.

CONCLUSION

We conclude that various auditory hallucinations in schizophrenia are induced by different neuronal activities and may be represented by different cortical regions.

Cortical folding abnormalities in schizophrenia patients with resistant auditory hallucinations

Gray matter volume and functional abnormalities have been reported in language-related cortex in schizophrenia patients with auditory hallucinations. Such abnormalities might denote abnormal cortical folding development, which can now be investigated using gyrification measures. Anatomic magnetic resonance images (MRIs) were obtained from 30 schizophrenia patients screened for resistant auditory hallucinations and 28 control subjects. We searched for overall gyrification abnormalities in the whole cortex as well as localized abnormalities in language-related cortex, assuming that gyrification is associated with brain sulcation. A fully automated method was applied to MRIs to extract, label and measure the sulcus area in the whole cortex. Gyrification was assessed using both global and local sulcal indices, respectively the ratio between total sulcal area, or area of each labeled sulcus, and outer cortex area. For both hemispheres, the patients had a lower global sulcal index. The local sulcal index decrease was not homogeneous across the whole cortex. It was more significant in the superior temporal sulcus bilaterally, in the left middle frontal sulcus and in the diagonal branch of left sylvian fissure (Broca's area). Findings suggest abnormalities in cortical gyrification in these patients. Sulcal abnormalities in language-related cortex might underlie these patients' particular vulnerability to hallucinations.

The neurobiological underpinnings of risk and conversion in relatives of patients with schizophrenia

Schizophrenia is associated with deficits in many domains of cognitive function, along with structural and functional brain abnormalities, most notably in prefrontal and temporal lobes. In recent years, a number of research groups have turned to the study of relatives of affected individuals with the aim of determining if similar cognitive deficits and brain abnormalities are also found in those with increased genetic vulnerability to the disorder. In this article studies on such individuals are discussed. It is concluded that deficits are generally apparent in relatives, which are similar to but less marked than those seen in patients with schizophrenia. The literature on predictors of conversion in people at genetic high risk is much smaller, but suggests a combination of baseline trait severity and further change in key measures.

Inner speech models of auditory verbal hallucinations: evidence from behavioural and neuroimaging studies

A range of psychological theories have been proposed to account for the experience of auditory hallucinations in patients with psychosis. Influential amongst these theories are those implicating the defective monitoring of inner speech. Furthermore, self-monitoring and inner speech models have been the most studied using functional imaging. The aim of this article is to review the behavioural and neuroimaging evidence for the impaired monitoring of inner speech in patients who experience auditory verbal hallucinations. A comprehensive literature search was conducted for research investigating inner speech and cognitive self-monitoring models of auditory hallucinations in patients with schizophrenia. The evidence is critically discussed and directions for future investigations are suggested.

Neural correlates of the misattribution of speech in schizophrenia

BACKGROUND

The neurocognitive basis of auditory verbal hallucinations is unclear.

AIMS

To investigate whether people with a history of such hallucinations would misattribute their own speech as external and show differential activation in brain areas implicated in hallucinations compared with people without such hallucinations.

METHOD

Participants underwent functional magnetic resonance imaging (fMRI) while listening to pre-recorded words. The source (self/non-self) and acoustic quality (undistorted/distorted) were varied across trials. Participants indicated whether the speech they heard was their own or that of another person. Twenty people with schizophrenia (auditory verbal hallucinations n=10, no hallucinations n=10) and healthy controls (n=11) were tested.

RESULTS

The hallucinator group made more external misattributions and showed altered activation in the superior temporal gyrus and anterior cingulate compared with both other groups.

CONCLUSIONS

The misidentification of self-generated speech in patients with auditory verbal hallucinations is associated with functional abnormalities in the anterior cingulate and left temporal cortex. This may be related to impairment in the explicit evaluation of ambiguous auditory verbal stimuli.

Left superior temporal gyrus activation during sentence perception negatively correlates with auditory hallucination severity in schizophrenia patients

The left superior temporal cortex, which supports linguistic functions, has consistently been reported to activate during auditory-verbal hallucinations in schizophrenia patients. It has been suggested that auditory hallucinations and the processing of normal external speech compete for common neurophysiological resources. We tested the hypothesis of a negative relationship between the clinical severity of hallucinations and local brain activity in posterior linguistic regions while patients were listening to external speech. Fifteen right-handed patients with schizophrenia and daily auditory hallucinations for at least 3 months were studied with event-related fMRI while listening to sentences in French or to silence. Severity of hallucinations, assessed using the auditory hallucination subscales of the Psychotic Symptom Rating Scales (PSYRATS) and of the Scale for the Assessment of Positive Symptoms (SAPS-AH), negatively correlated with activation in the left temporal superior region in the French minus silence condition. This finding supports the hypothesis that auditory hallucinations compete with normal external speech for processing sites within the temporal cortex in schizophrenia.

Therapeutic and neurophysiologic aspects of transcranial magnetic stimulation in schizophrenia

The use of repetitive transcranial magnetic stimulation (rTMS) in psychiatry provides the therapeutic field with a new tool. Since its introduction in the mid 1980s, the vast majority of studies have focussed on depression. A growing body of evidence suggests that rTMS is effective in the treatment of depression if dorsolateral prefrontal cortex is stimulated. Less is known about its efficacy in schizophrenia. Neuroimaging investigations in schizophrenia suggest abnormalities in the prefrontal and temporoparietal cortex (TPC), which are correlated with psychopathological dimensions. Based on its modulatory effect, rTMS seems to be a promising tool in exploring cortical excitability and reducing auditory hallucinations (AH) and negative symptoms. Neurophysiologic studies of patients suffering from schizophrenia using rTMS indicate high cortical excitability and a lack of transcallosal inhibition. In the therapeutic field, researches provide encouraging results, even though some studies indicate limited benefits. The most promising therapeutic effect seems to be the capability of rTMS to reduce AH if TPC is targeted using slow-frequency. The current paper aims to provide a review of the literature of the use of rTMS in schizophrenia.

Use of magnetic resonance imaging in tracking the course and treatment of schizophrenia

Confirming the early conceptualization of Bleuler (1911) and Kraepelin (1919), magnetic resonance imaging (MRI) studies have demonstrated structural and functional brain abnormalities, predominantly involving the frontal and temporal lobes, in schizophrenia. Most of the abnormalities are already present at illness onset. However, there is, growing evidence for treatment-related neural changes in schizophrenia, such as enlargement of the caudate nucleus (neurotoxic effect) with the use of typical antipsychotics and increases in cortical volumes and improved functional responses (neurotrophic effect) with the use of atypical antipsychotics. More recently, brain changes during the prodrome and transition-to-illness stages of schizophrenia have begun to be characterized. Another area of importance is the use of MRI, as a biological marker, to monitor and define partial or full resistance to medication. Understanding the trait- and state-related influences of brain abnormalities during the course of the illness is critical for developing effective treatment and possibly prevention strategies in schizophrenia.

Positive symptoms and duration of illness predict functional laterality and attention modulation in schizophrenia

OBJECTIVE

Dichotic listening (DL) performance in schizophrenia, reflecting hemispheric asymmetry and the functional integrity of the left temporal lobe, can vary with clinical characteristics. Previous studies have not taken the co-linearity of clinical variables into account. The aim of the present study was to evaluate the roles of positive symptoms and duration of illness in DL through Structural Equation Modeling (SEM), thus allowing for complex relationships between the variables.

METHOD

We pooled patients from four previous DL studies to create a heterogeneous group of 129 schizophrenic patients, all tested with a consonant-vowel syllables DL procedure that included attentional instructions.

RESULTS

A model where positive symptoms predicted a laterality component and duration of illness predicted an attention component in DL was confirmed.

CONCLUSION

Positive symptoms predicted reduced functional laterality, suggesting involvement of left temporal lobe language processing. Duration of illness predicted impaired attention modulation, possibly reflecting the involvement of frontotemporal networks.

Morphologic alterations of the parcellated superior temporal gyrus in schizophrenia spectrum

Morphologic abnormalities of the superior temporal gyrus (STG) as well as its sub-regions such as Heschl's gyrus (HG) or planum temporale (PT) have been reported in schizophrenia patients, but have not been extensively studied in schizotypal subjects. In the present study, magnetic resonance images were acquired from 65 schizophrenia patients, 39 schizotypal disorder patients, and 72 healthy controls. Volumetric analyses were performed using consecutive 1-mm coronal slices on the temporal pole (TP) and superior temporal sub-regions [planum polare (PP), HG, PT, rostral STG, and caudal STG]. The HG was significantly smaller in schizophrenia patients compared with controls but not in schizotypal patients, while volume reductions of the left PT and bilateral caudal STG were common to both disorders. The TP gray matter was larger in female schizotypal patients compared with female schizophrenia patients. There were no significant group differences in the PP and rostral STG volume. In the subgroup of early phase schizophrenia patients (illness duration <1.0 year), smaller volumes for the left PP and rostral STG were correlated with hallucinations and delusions. Our findings suggest that morphologic changes in the posterior regions of the STG are common to the schizophrenia spectrum, whereas less involvement of the HG, and possibly the PP and rostral STG might be related to the sparing of schizotypal patients from developing overt psychosis.