Functional near-infrared spectroscopy reveals altered hemispheric laterality in relation to schizotypy during verbal fluency task

Atypical semantic cognition in schizotypal personality disorder and borderline personality disorder

Increased schizotypal traits have previously been associated with atypical semantic cognition in community samples. However, no study has yet examined whether adults diagnosed with schizotypal personality disorder (SPD) display atypical semantic fluency and memory. We hypothesized that 24 adults diagnosed with SPD would name more idiosyncratic words on the semantic fluency task and show decreased semantic recall for animal and fruit category words compared with 29 participants with borderline personality disorder (BPD) and a community sample of 96 age-matched controls. We examined whether atypical semantic cognition was specifically associated with disorganized and eccentric speech and thinking, or more broadly with pathological personality traits and personality functioning. Our main hypothesis was confirmed, as the SPD participants named more idiosyncratic words and recalled fewer semantically related words compared with controls. Surprisingly, participants with BPD likewise named more atypical words compared with controls. More idiosyncratic semantic fluency was associated with more eccentric speech and thinking. Increased idiosyncratic semantic fluency and reduced semantic recall were both coupled to increased detachment and lowered personality functioning, while reduced semantic recall further was related to increased interpersonal problems. Our findings suggest that persons with SPD, and to a lesser degree BPD, show atypical semantic cognition, which is associated with eccentric speech and thinking, and more broadly with impaired personality function, social withdrawal, and emotional flatness. The idiosyncratic semantic cognition may worsen difficulties with social reciprocity seen in SPD and BPD.

Cognitive Processes and Resting-State Functional Neuroimaging Findings in High Schizotypal Individuals and Schizotypal Personality Disorder Patients: A Systematic Review

Ample research findings indicate that there is altered brain functioning in the schizophrenia spectrum. Nevertheless, functional neuroimaging findings remain ambiguous for healthy individuals expressing high schizotypal traits and patients with schizotypal personality disorder (SPD). The purpose of this systematic review was to identify patterns of task-related and resting-state neural abnormalities across these conditions. MEDLINE-PubMed and PsycINFO were systematically searched and forty-eight studies were selected. Forty studies assessed healthy individuals with high schizotypal traits and eight studies examined SPD patients with functional neuroimaging techniques (fNIRS; fMRI; Resting-state fMRI). Functional alterations in striatal, frontal and temporal regions were found in healthy individuals with high schizotypal traits. Schizotypal personality disorder was associated with default mode network abnormalities but further research is required in order to better conceive its neural correlates. There was also evidence for functional compensatory mechanisms associated with both conditions. To conclude, the findings suggest that brain dysfunctions are evident in individuals who lie along the subclinical part of the spectrum, further supporting the continuum model for schizophrenia susceptibility. Additional research is required in order to delineate the counterbalancing processes implicated in the schizophrenia spectrum, as this approach will provide promising insights for both conversion and protection from conversion into schizophrenia.

Abnormal Prefrontal Brain Activation During a Verbal Fluency Task in Treatment-Resistant Depression Using Near-Infrared Spectroscopy

OBJECTIVE

The study investigated cognitive performance and brain function between treatment-resistant depression (TRD) and non- TRD patients to find potential neurobiological markers associated with refractoriness in depression patients.

METHODS

Fourteen TRD patients, 26 non-TRD patients and 23 healthy controls (HC) were included in the present study. The neural function of prefrontal cortex (PFC) and cognitive performance among the three group were examined using near-infrared spectroscopy (NIRS) during verbal fluency task (VFT).

RESULTS

Both TRD and non-TRD groups exhibited significantly worse VFT performance and lower activation of oxygenated hemoglobin (oxy-Hb) changes in the bilateral dorsolateral PFC (DLPFC) compared to the HC group. Within the TRD and non-TRD groups, VFT performance was no significant difference, but activation of oxy-Hb changes in dorsomedial PFC (DMPFC) in TRD patients was significantly lower than non-TRD patients. In addition, activation of oxy-Hb changes in right DLPFC were negatively correlated with the severity of depressive symptoms in depression patients.

CONCLUSION

Both TRD patients and non-TRD patients exhibited lower oxy-Hb activation in DLPFC. TRD patients exhibit lower oxy- Hb activation in DMPFC than non-TRD patients. fNIRS maybe a useful tool for predict depressive patients with or without treatment resistant.

Abnormal Cortical Activation Patterns Among Chinese-Speaking Schizophrenia Patients During Category and Letter Verbal Fluency Tasks Revealed by Multi-Channel Functional Near-Infrared Spectroscopy

Background: Functional near-infrared spectroscopy (fNIRS) has many advantages over other neuroimaging modalities for routine measurement of task-dependent cortical activation, but most fNIRS studies of schizophrenia have used letter fluency tasks (LFTs). Further, performances on category fluency tasks (CFTs) and LFTs may be distinct in Chinese patients due to the unique semantic features of Chinese written characters. To identify unique disease biomarkers measurable by fNIRS in Chinese schizophrenia patients, this study compared cortical oxygenated hemoglobin changes ([oxy-Hb]) during a Chinese LFT and CFT between patients and healthy controls. Methods: Inpatients of the Second Affiliated Hospital of Xinxiang Medical University were recruited from Match 2020 to July 2021. The Positive and Negative Symptom Scale (PANSS) was used to evaluate psychiatric symptoms. Dynamic changes in [oxy-Hb], an indicator of neural activity, were measured during CFT and LFT performance by 52-channel fNIRS. Results: Forty-seven schizophrenia inpatients and 29 healthy controls completed all tests. Schizophrenia patients showed significant cortical activation at 15 channels covering the left hemisphere and 17 channels over the right hemisphere during the CFT. During the LFT, activity was significantly increased at only six channels, all over the left hemisphere (FDR P < 0.05). In healthy controls, significant [oxy-Hb] increases were found at 24 channels over the left hemisphere and 19 channels over the right hemisphere during CFT. While during the LFT, the significant increases were found at 7 channels all over the left hemisphere (FDR P < 0.05). When years of education was included as a covariate, the schizophrenia group demonstrated no significant hypoactivation relative to healthy controls at any channel after FDR correction (FDR P < 0.05) during CFT while demonstrated significant hypoactivation at channel 11 during LFT (FDR P < 0.05). There were no significant associations between PANSS scores and [oxy-Hb] changes after FDR correction (FDR P < 0.05). Conclusions: Left lateralization during CFT was reduced among schizophrenia patients and may be related to the semantic deficit. The Chinese-CFT could be a more sensitive indicator of frontal-temporal dysfunction in schizophrenia.

Role for Positive Schizotypy and Hallucination Proneness in Semantic Processing

Semantic processing underpins the organization of verbal information for both storage and retrieval. Deficits in semantic processing are associated with both the risk for and symptoms presented in schizophrenia. However, studies are mixed and could reflect the confounding effects of medication and symptom heterogeneity. Therefore, we considered whether two risk phenotypes, positive schizotypy and hallucinatory predisposition, present in the general population were associated with differential responding profiles for a semantic processing task. One hundred and eighty-three participants completed the Schizotypal Personality Questionnaire, Launay-Slade Hallucination Scale, National Adult Reading Test, a handedness measure, and a computerized semantic relatedness judgment task. Pairs of words were related through their dominant or subordinate meanings, or unrelated. Participants were divided into four groups using a mean split on cognitive-perceptual (positive) schizotypy and hallucination proneness. Significant differences between groups were found for reaction time on the semantic relatedness task, with the high cognitive-perceptual schizotypy groups responding significantly slower to all word pairs compared to their low scoring counterparts. There was some evidence that high hallucination proneness was associated with significantly faster reaction times which may reflect disinhibitive processes, however additional support is required. The results suggest that these two components of psychosis risk are associated with different patterns of responding to semantic processing. More diffuse activation of semantic information appeared to be associated with positive schizotypy, while those predisposed to hallucinations appeared to respond quicker. These results have significant implications in the re-conceptualization of hallucination proneness as distinct from positive schizotypy. Additional research is required to investigate the association between psychotic-like experiences separate from personality variables such as positive schizotypy and semantic processing.

Resting frontal EEG asymmetry and schizotypal traits: a test-retest study

Introduction: Increase in right relative to left frontal electroencephalography (EEG) activity has been observed in patients with schizophrenia, both in cognitive tasks and during rest; and this lateralisation may be related to the severity of schizotypal traits. Methods: We used the Schizotypal Personality Questionnaire (SPQ) to assess schizotypal traits, and examined the correlation between these traits and resting EEG frontal asymmetry (left-right) in 52 college students, as well as the reliability of this correlation over a three-month interval. Results: A higher total score on the SPQ was correlated with reduced asymmetry in different frequency bands: gamma and beta2 frequency bands at baseline, and delta and alpha frequency bands three months later. Additionally, the reduced left relative to right frontal gamma and beta2 asymmetry was correlated with the participants' verbal fluency ability. However, this correlation was no longer statistically significant after the total SPQ score was controlled. Conclusions: These findings suggest that resting frontal EEG asymmetry is correlated with powers in different frequency bands, and may be an endophenotype for schizophrenia spectrum disorders.

Semantic priming and schizotypal personality: reassessing the link between thought disorder and enhanced spreading of semantic activation

The term schizotypy refers to a group of stable personality traits with attributes similar to symptoms of schizophrenia, usually classified in terms of positive, negative or cognitive disorganization symptoms. The observation of increased spreading of semantic activation in individuals with schizotypal traits has led to the hypothesis that thought disorder, one of the characteristics of cognitive disorganization, stems from semantic disturbances. Nevertheless, it is still not clear under which specific circumstances (i.e., automatic or controlled processing, direct or indirect semantic relation) schizotypy affects semantic priming or whether it does affect it at all. We conducted two semantic priming studies with volunteers varying in schizotypy, one with directly related prime-target pairs and another with indirectly related pairs. Our participants completed a lexical decision task with related and unrelated pairs presented at short (250 ms) and long (750 ms) stimulus onset asynchronies (SOAs). Then, they responded to the brief versions of the Schizotypal Personality Questionnaire and the Oxford-Liverpool Inventory of Feelings and Experiences, both of which include measures of cognitive disorganization. Bayesian mixed-effects models indicated expected effects of SOA and semantic relatedness, as well as an interaction between relatedness and directness (greater priming effects for directly related pairs). Even though our analyses demonstrated good sensitivity, we observed no influence of cognitive disorganization over semantic priming. Our study provides no compelling evidence that schizotypal symptoms, specifically those associated with the cognitive disorganization dimension, are rooted in an increased spreading of semantic activation in priming tasks.

Moderating effect of schizotypy on the relationship between smoking and neurocognition

Purpose

Smoking rates in schizotypic individuals are shown to be elevated, as in patients with schizophrenia, although findings on the association of smoking with different symptomatology of schizotypy have been mixed. Moreover, possible moderating effects of schizotypy on the relationship between smoking and cognition have not been well documented.

Subjects and methods

The Schizotypal Personality Questionnaire (SPQ) and the full version of the Wechsler Memory Scale-Revised (WMS-R) were administered to 501 healthy adults. Subjects were divided into smokers (n = 85) and non-smokers (n = 416) based on the presence/absence of current smoking.

Results

The analysis of covariance (ANCOVA) on the three factor scores as well as the total score of the SPQ, controlling for age and gender, revealed that cognitive-perceptual factor was significantly associated with an increased rate of smoking (P = 0.048). The ANCOVA on the WMS-R indices, with smoking group as a fixed factor and age, gender and total SPQ score as covariates, revealed that the schizotypy-by-smoking interaction was significant for attention/working memory (P = 0.029).

Discussion and conclusion

Positive schizotypy may be associated with more smoking. Schizotypy and smoking could interact with each other to negatively affect attention/working memory.

Effects of music therapy on major depressive disorder: A study of prefrontal hemodynamic functions using fNIRS

Major depressive disorder (MDD) is a recurrent, chronic mental illness. While music therapy has been established as an effective treatment for MDD patients, the effects of this therapy on brain function remain unclear. This research employed near-infrared spectroscopy (NIRS) to explore the effects of music therapy on brain activity in mild or moderate MDD patients and to illustrate the potential mechanism of music therapy. Methods: Fifteen MDD patients and fifteen healthy controls (HC) underwent neuropsychological evaluations and NIRS measurements. All participants were treated with continuous music therapy for 10 days. Subsequently, all individuals were evaluated with neuropsychological assessments and NIRS measurements again. Results: The verbal fluency task (VFT) performances of the participants yielded significantly higher scores after music therapy in terms of vegetables, four-footed animals and fruit blocks. After the music treatment, the NIRS data showed that the mean active oxy-Hb values of channels 21, 23, 19, and 41 were significantly increased in both the MDD and HC groups. The MDD group showed significant activation in the dorsolateral prefrontal cortex (DLPFC), orbitofrontal cortex (OFC) and ventromedial prefrontal cortex (VMPFC) after music therapy. The results indicate that music therapy could improve the brain function of MDD patients.

Frontal lobe dysfunction underlies the differential word retrieval impairment in adolescents with high-functioning autism

There is substantial evidence of word retrieval impairment as indicated by poor performance on the category fluency test in autism spectrum disorder (ASD). However, little is known about the neural mechanisms underlying this impairment. Functional neuroimaging studies have shown that the lateral frontal cortex plays a key role in flexible word retrieval. Thus, we examined whether individuals with ASD exhibited altered frontal processing during the category fluency test using functional near-infrared spectroscopy (fNIRS). Twenty-two adolescents with high-functioning ASD (20 males) and 22 typically developing (TD) adolescents (16 males) aged 11-18 years were recruited. All underwent a category fluency paradigm, which required production of animal or means of transportation words for 1 min each although their frontal hemodynamic changes were recorded with fNIRS. We found that adolescents with ASD produced fewer animal but not transportation words (group-by-category interaction: P = 0.003), suggesting differential word retrieval impairment. In addition, unlike TD adolescents who exhibited activation primarily in lateral frontal regions during word production, adolescents with ASD had comparable activation across lateral and medial frontal regions. More importantly, this lack of lateral-medial distinction of activation, which was associated with poor word retrieval, differed significantly between groups only in the animal category (group-by-category interaction: P = 0.018). Thus, our findings implicate frontal lobe dysfunction in the impairment of differential word retrieval in adolescents with ASD. The relatively greater involvement of the medial frontopolar cortex might reflect the use of nonspecialized brain regions to compensate for the category-dependent difficulties with word retrieval in ASD. Autism Res 2019, 12: 600-613. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Using an optical imaging tool, we found that adolescents with autism had difficulties with producing semantically related words and exhibited frontal lobe dysfunction. Nonetheless, poor word production and altered brain processing was only seen when these adolescents were asked to produce words from a category of living things but not nonliving things (i.e., animals but not means of transportation). Category-dependent word retrieval problems and frontal lobe dysfunction might be two features of this disorder.

Schizotypal personality and semantic functioning: Revisiting category fluency effects in a subclinical sample

Semantic disturbances have been proposed as a possible cause of formal thought disorder in schizophrenia. Fluency tasks, in which volunteers are asked to produce as many exemplars as they can for a given category during one minute, are usually applied to the assessment of semantic processing. However, studies associating fluency and proneness to psychosis have provided conflicting results so it is not clear whether these disturbances can be identified at subclinical stages. We conducted two experiments. In the first one, 71 volunteers completed written category fluency tasks with four semantic categories (animals, fruits, clothing and vehicles). In the second experiment, 77 new participants completed oral category and phonological fluency tasks (words starting with f, t, p and c). In both experiments, we assessed schizotypal personality and vocabulary size. Schizotypal traits were not reliably associated with either productivity or originality of the responses in any experiment. In contrast, vocabulary size significantly predicted the participants' scores in all the tasks. Along with results of other recent studies, our data cast doubt on the reliability of previous observations pointing out an association between schizotypy and lexical-semantic disturbances, at least in relation to productivity and originality in fluency tests.

Abnormal prefrontal brain activation during a verbal fluency task in bipolar disorder patients with psychotic symptoms using multichannel NIRS

PURPOSE

Bipolar disorder (BD) patients with psychotic symptoms (BDp) worsens prognosis and decreases rates of recovery. The study investigated cognitive performance and brain function between BD patients in depressive episode with and without psychotic symptoms to find potential neurobiological markers associated with psychotic features of BD patients in depressive episode.

PATIENTS AND METHODS

Thirty-one patients without psychotic symptoms and 29 patients with psychotic symptoms diagnosed with bipolar I disorder with a current depressive episode were included in the present study. The neural function of prefrontal cortex (PFC) and cognitive performance among BDp, BD patients without psychotic symptoms, and 23 healthy controls (HC) were examined using near-infrared spectroscopy during verbal fluency task (VFT).

RESULTS

1) Both the BD groups exhibited significantly worse performance of VFT and lower activation of oxygenated hemoglobin (oxy-Hb) changes in the bilateral ventrolateral PFC compared with the HC group. 2) Within the BD group, VFT performance was not significantly different. 3) The prefrontal activation of oxy-Hb changes in the BDp patients was significantly lower than that in the BD patients without psychotic symptoms in the right dorsolateral PFC. 4) Activation of oxy-Hb changes in right dorsolateral PFC was negatively correlated with the severity of psychotic symptoms in BDp patients.

CONCLUSION

The prefrontal function differs between BD patients in depressive episode with or without psychotic symptoms measured with near-infrared spectroscopy.

The relationship of categorical and phonological verbal fluency to negative schizotypy and social functioning in a non-clinical sample

INTRODUCTION

Research suggests that levels of schizotypy are related to cognitive and social functioning, with negative schizotypy being particularly related to deficits in verbal fluency (VF) and distinct social skills. Considering the possibility that different VF tasks may involve both shared and unique underlying processes, this study sought to examine the separate contributions of categorical and phonological forms of VF to social functioning in those with varying levels of negative schizotypy.

METHODS

Face-to-face interviews were conducted in which 228 college students completed VF tasks, the SPQ-BR, and a social functioning questionnaire.

RESULTS

Both phonological and categorical VF were inversely related to levels of negative schizotypy and inversely related to several social functioning domains. High and low levels of negative schizotypy groups were significantly different on elements of social engagement and interpersonal behaviour. In two instances, phonological VF appeared to moderate the relationships between negative schizotypy and specific elements of social functioning.

CONCLUSIONS

These findings support a general link between verbal processing and social functioning among those with greater negative schizotypy. Possible avenues of future research are discussed.

Reduced language lateralization in first episode schizophrenia: A near infrared spectroscopy study

BACKGROUND

Diminished functional lateralization in language-related areas is found in chronic schizophrenia (SZ). However, whether this reduced lateralization exists at the early stage of SZ remains unclear. The present study aimed to investigate language lateralization in first episode schizophrenia (FES) using near infrared spectroscopy (NIRS) during a letter version of verbal fluency test (VFT).

METHODS

A total of 28 FES patients and 33 healthy controls (HCs) underwent NIRS while performing a VFT. Six regions of interests (ROIs) were defined: the bilateral frontal-, inferior frontal gyrus (IFG), and temporal regions. Laterality index (LI) was calculated and compared between the two groups in ROIs. In addition, we investigated whether language lateralization was correlated with severity of clinical symptoms.

RESULTS

Across all ROIs, LI was significantly reduced in FES patients (p=0.037) compared to controls in the IFG region. In addition, LI was not found to be correlated with VFT performance, the PANSS positive, negative or general psychopathology subscales.

CONCLUSIONS

Our study demonstrated a diminution of leftward functional lateralization in the IFG during a VFT in FES patients. This is the first NIRS study to report reduced functional lateralization in patients at the early stage of schizophrenia.

Improvement of Orbitofrontal Cortex Function Associated with Blephrospasm Symptom Remission

OBJECTIVE

To determine whether orbitofrontal cortex (OFC) function improves with blepharospasm (BSP) symptom remission using a verbal fluency task and near-infrared spectroscopy (NIRS).

METHODS

Nineteen BSP patients and 9 healthy controls (HCs) matched by gender and education were examined using NIRS. The BSP patients were divided into 2 groups based on the onset or remission of BSP symptoms. A covariance analysis was conducted to analyze the differences among the 3 groups to avoid the influence of different ages. The least significant difference was used to process the post hoc test.

RESULTS

The hemoglobin concentration and cerebral blood flow of the bilateral orbitofrontal area (channels 27, 31, 34, 37, and 39) were not significantly different between the BSP remission and HC groups (p > 0.05); however, both groups were significantly increased compared with the BSP onset group (BSP remission group vs. BSP onset group: p = 0.003, p = 0.018, p = 0.013, p = 0.001, and p = 0.011, respectively; BSP remission group vs. BSP onset group: p = 0.037, p = 0.044, p = 0.023, p = 0.016, and p = 0.025, respectively).

CONCLUSION

This is the first investigation to control for symptom stages in BSP patients examined via NIRS. Cognitive ability and OFC function improve with BSP symptom remission. Thus, the OFC may be inter-connected with motor and cognitive symptoms in BSP.

Reduced prefrontal activation during verbal fluency task in chronic insomnia disorder: a multichannel near-infrared spectroscopy study

PURPOSE

Daytime complaints such as memory and attention deficits and failure to accomplish daily tasks are common in insomnia patients. However, objective psychological tests to detect cognitive impairment are equivocal. Neural function associated with cognitive performance may explain the discrepancy. The aim of this study was to investigate the hemodynamic response patterns of patients with chronic insomnia disorder (CID) using the noninvasive and low-cost functional neuroimaging technique of multichannel near-infrared spectroscopy (NIRS) in order to identify changes of neural function associated with cognitive performance.

PATIENTS AND METHODS

Twenty-four CID patients and twenty-five healthy controls matched for age, right-hand dominance, educational level, and gender were examined during verbal fluency tasks (VFT) using NIRS. A covariance analysis was conducted to analyze differences of oxygenated hemoglobin (oxy-Hb) changes in prefrontal cortex (PFC) between the two groups and reduce the influence of the severity of depression. Pearson correlation coeffcients were calculated to examine the relationship between the oxy-Hb changes, with the severity of insomnia and depressive symptoms assessed by the Pittsburgh Sleep Quality Index (PSQI) and the Hamilton Rating Scale for Depression (HAMD).

RESULTS

The number of words generated during the VFT in CID groups showed no statistical differences with healthy controls. CID patients showed hypoactivation in the PFC during the cognitive task. In addition, we found that the function of left orbitofrontal cortex (OFC) during the VFT was significantly negatively correlated with the PSQI scores and the function of right dorsolateral PFC (DLPFC) was significantly negatively correlated with the HAMD scores.

CONCLUSION

The present study detected dysfunctions in PFC in spite of intact performance which indicates the role of PFC in the neurophysiological underpinnings. Left OFC function is associated with insomnia symptoms and right DLPFC function is associated with depressive symptoms.

Altered Frontal Lateralization Underlies the Category Fluency Deficits in Older Adults with Mild Cognitive Impairment: A Near-Infrared Spectroscopy Study

Individuals with mild cognitive impairment (MCI) have been consistently found to have category fluency deficits. However, little is known about the neural basis of these deficits. A diversity of neuroimaging studies has revealed left-lateralized prefrontal activations due to verbal processing and control functions during the performance of category fluency tasks. Given the reports of structural and functional abnormalities in the prefrontal cortices in individuals with MCI, it is conceivable that these individuals would also exhibit altered prefrontal activation patterns during a category fluency task. The present study aimed to investigate the prefrontal dynamics during the category fluency task in older adults with MCI by using near-infrared spectroscopy (NIRS). Twenty-six older adults with MCI were compared with 26 older adults with normal cognition (NC) who were matched in age, gender, handedness, and educational level. All participants performed a category fluency task while the prefrontal dynamics were recorded. The results showed that the MCI group generated fewer unique words, made fewer switches between subcategories, and generated fewer new subcategories than did the NC group. Importantly, the NIRS results showed that the NC group exhibited a left lateralization of frontal activations during the category fluency task, while the MCI group did not exhibit such a lateralization. Furthermore, there was a significant positive correlation between the category fluency performance and the extent of lateralization, suggesting that the category fluency deficits in the MCI group could be related to frontal dysfunction. That is, the rightward shift of frontal activations in the MCI group may reflect the presence of cortical reorganization in which the contralateral regions (i.e., the right hemisphere) are recruited to take over the function that is declining in the specialized regions (i.e., the left hemisphere). Our lateralization finding may serve as an objective neural marker for distinguishing between normal aging and MCI. Our study highlights that an alteration of neural functioning is already present at the prodromal stage of dementia.

Associations between schizotypy and cerebral laterality

Atypical lateralization for language has been found in schizophrenia, suggesting that language and thought disorders on the schizophrenia spectrum may be due to left hemispheric dysfunction. However, research with those with non-clinical schizotypy has been inconsistent, with some studies finding reduced or reversed language laterality (particularly with positive schizotypal traits), and others finding typical left hemispheric specialization. The aim of the current study was to use both a behavioural (dual reading-finger tapping) task and an functional magnetic resonance imaging lexical decision task to investigate language laterality in a university sample of high- and low-schizotypal adults. Findings revealed no evidence for atypical lateralization in our sample for both overall schizotypy (measured by the Oxford-Liverpool Inventory of Feelings and Experiences) and positive schizotypy (measured by the Unusual Experiences subscale) groups. Our findings provide further evidence that non-clinical schizotypy is not associated with atypical language laterality.

Prefrontal Hemodynamic Functions during a Verbal Fluency Task in Blepharospasm Using Multi-Channel NIRS

Blepharospasm (BSP) has a morbidity of 16 to 133 per million and is characterized by orbicularis oculi spasms. BSP can severely impact daily life. However, to date, its pathophysiology has not been clearly demonstrated. Near-infrared spectroscopy (NIRS) is a portable, non-invasive, and high time resolution apparatus used to measure cerebral blood flow. This study aimed to investigate the hemodynamic response patterns of BSP patients and determine whether BSP alone can be an attributional factor to influence the function of the prefrontal area using a verbal fluency task (VFT) and NIRS. Twenty-three BSP patients (10 males and 13 females) and 13 healthy controls (HC; five males and eight females) matched by gender and education were examined using NIRS. BSP patients were divided into two groups based on the presence or absence of depression and anxiety symptoms. A covariance analysis was conducted to analyze differences between the three groups and reduce the influence of different ages and educational levels. Bonferroni was used to process the post hoc test. The bilateral orbitofrontal area (ch36, 39, and 41; P<0.01) exhibited a lower activation in BSP patients without psychiatric symptoms compared with HC. This study is the first report to identify the prefrontal function in BSP using NIRS. Our findings indicate that BSP alone may cause a hypoactive hemodynamic performance in the prefrontal cortex in the absence of psychiatric symptoms. These findings provide evidence to support novel pathophysiological mechanisms of BSP.

Neural correlates of creative thinking and schizotypy

Empirical studies indicate a link between creativity and schizotypal personality traits, where individuals who score highly on schizotypy measures also display greater levels of creative behaviour. However, the exact nature of this relationship is not yet clear, with only a few studies examining this association using neuroimaging methods. In the present study, the neural substrates of creative thinking were assessed with a drawing task paradigm in healthy individuals using fMRI. These regions were then statistically correlated with the participants' level of schizotypy as measured by the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE), which is a questionnaire consisting of four dimensions. Neural activations associated with the creativity task were observed in bilateral inferior temporal gyri, left insula, left parietal lobule, right angular gyrus, as well as regions in the prefrontal cortex. This widespread pattern of activation suggests that creative thinking utilises multiple neurocognitive networks, with creative production being the result of collaboration between these regions. Furthermore, the correlational analyses found the Unusual Experiences factor of the O-LIFE to be the most common dimension associated with these areas, followed by the Impulsive Nonconformity dimension. These correlations were negative, indicating that individuals who scored the highest in these factors displayed the least amount of activation when performing the creative task. This is in line with the idea that 'less is more' for creativity, where the deactivation of specific cortical areas may facilitate creativity. Thus, these findings contribute to the evidence of a common neural basis between creativity and schizotypy.

Relationship between the prefrontal function and the severity of the emotional symptoms during a verbal fluency task in patients with major depressive disorder: a multi-channel NIRS study

Multi-channel near-infrared spectroscopy (NIRS) is a noninvasive and low-cost functional neuroimaging technique in psychiatric research, and it has been wildly used for detecting the spatiotemporal characteristics of brain activity. In order to evaluate the clinical value of NIRS data in the assistant diagnosis of major depressive disorder (MDD), prefrontal cortex (PFC) hemoglobin concentration exchange of 30 MDD patients combined with anxious and obsessive-compulsive symptom was detected by NIRS under voice fluency task (VFT), then the relationship between the severity of depressive, anxious and obsessive-compulsive symptom assessed by Hamilton Rating Scale for Depression (HAMD), Hamilton Anxiety Rating Scale (HAMA) and Yale-Brown Obsessive Compulsive Scale (Y-BOCS) with NIRS data in PFC was analyzed. Hypoactivation in lateral and lower PFC of MDD patients was confirmed in this study. Furthermore, Spearman correlation found that oxy-hemoglobin concentration ([oxy-Hb]) exchange in right-lateral PFC was associated with the severity of anxiety, while bilateral PFC and antero-medial PFC were associated with severity of depression. Meanwhile, no statistical correlation was observed on the severity of obsessive-compulsive symptom. The results prompted that MDD patients with anxiety and obsession-compulsion symptom showed a PFC hypoactivation state in NIRS. Furthermore, the function of right-lateral PFC was associated with anxiety symptom, while bilateral PFC and antero-medial PFC were associated with depression symptom. Different from depression and anxiety, obsession-compulsion may have a different biological character in PFC function.

How semantic deficits in schizotypy help understand language and thought disorders in schizophrenia: a systematic and integrative review

Introduction: Disorders of thought are psychopathological phenomena commonly present in schizophrenia and seem to result from deficits of semantic processing. Schizotypal personality traits consist of tendencies to think and behave that are qualitatively similar to schizophrenia, with greater vulnerability to such disorder. This study reviewed the literature about semantic processing deficits in samples of individuals with schizotypal traits and discussed the impact of current knowledge upon the comprehension of schizophrenic thought disorders. Studies about the cognitive performance of healthy individuals with schizotypal traits help understand the semantic deficits underlying psychotic thought disorders with the advantage of avoiding confounding factors usually found in samples of individuals with schizophrenia, such as the use of antipsychotics and hospitalizations. Methods: A search for articles published in Portuguese or English within the last 10 years on the databases MEDLINE, Web of Science, PsycInfo, LILACS and Biological Abstracts was conducted, using the keywords semantic processing, schizotypy and schizotypal personality disorder. Results: The search retrieved 44 manuscripts, out of which 11 were firstly chosen. Seven manuscripts were additionally included after reading these papers. Conclusion: The great majority of the included studies showed that schizotypal subjects might exhibit semantic processing deficits. They help clarify about the interfaces between cognitive, neurophysiological and neurochemical mechanisms underlying not only thought disorders, but also healthy human mind's creativity.

Genetics, cognition, and neurobiology of schizotypal personality: a review of the overlap with schizophrenia

Schizotypy refers to a set of temporally stable traits that are observed in the general population and that resemble the signs and symptoms of schizophrenia. Here, we review evidence from studies on genetics, cognition, perception, motor and oculomotor control, brain structure, brain function, and psychopharmacology in schizotypy. We specifically focused on identifying areas of overlap between schizotypy and schizophrenia. Evidence was corroborated that significant overlap exists between the two, covering the behavioral brain structural and functional as well molecular levels. In particular, several studies showed that individuals with high levels of schizotypal traits exhibit alterations in neurocognitive task performance and underlying brain function similar to the deficits seen in patients with schizophrenia. Studies of brain structure have shown both volume reductions and increase in schizotypy, pointing to schizophrenia-like deficits as well as possible protective or compensatory mechanisms. Experimental pharmacological studies have shown that high levels of schizotypy are associated with (i) enhanced dopaminergic response in striatum following administration of amphetamine and (ii) improvement of cognitive performance following administration of antipsychotic compounds. Together, this body of work suggests that schizotypy shows overlap with schizophrenia across multiple behavioral and neurobiological domains, suggesting that the study of schizotypal traits may be useful in improving our understanding of the etiology of schizophrenia.

A latent profile analysis of schizotypy, temperament and character in a nonclinical population: association with neurocognition

Schizotypy is conceptualized as a latent personality construct that confers liability for schizophrenia, while it is also suggested that schizotypy can relate to certain favorable aspects. Investigating individual-level interactions between schizotypy and broader personality characteristics might give a clue to this question. We aimed to identify homogeneous classes of individuals based on schizotypy, temperament and character and to validate this classification using comprehensive neurocognitive data. We studied 455 nonclinical adults using the Schizotypal Personality Questionnaire, the Temperament and Character Inventory, and an array of neuropsychological tests. A latent profile analysis (LPA) of schizotypy, temperament and character was conducted, and cognitive performance was compared as a function of latent class membership. LPA provided a 3-class solution. Of the sample, 15% was classified into a "high-positive-schizotypy/adaptive" group characterized by high cognitive-perceptual but low interpersonal schizotypy, together with low harm avoidance and high self-directedness, cooperativeness and self-transcendence; 18% was classified into a "high-schizotypy/maladaptive" group characterized by overall high schizotypy, together with high harm avoidance and low self-directedness and cooperativeness; and 67% was classified into a "low-schizotypy/adaptive" group characterized by overall low schizotypy, together with intermediate-to-low harm avoidance, high self-directedness and intermediate-to-high cooperativeness. Overall cognitive performance of the high-positive-schizotypy/adaptive group was comparable to that of the low-schizotypy/adaptive group and superior to that of the high-schizotypy/maladaptive group. The present LPA clearly defines a group of individuals who have adaptive personality traits and intact neuropsychological functions despite high positive schizotypy, suggesting that there may be complex, nonlinear relationships between schizotypal traits and psychopathology.

Schizotypal trait in healthy women is associated with a shift away from dextrality on a spatial motor control task, but not on a force control task

It is generally acknowledged that schizophrenia and schizotypy lie on the same continuum, while there is an ongoing debate as to whether schizotypy represents true dimension or quasi-dimension. Evidence suggests that reduced hemispheric lateralization and mixed handedness are associated with both schizophrenia and schizotypy. However, the possible relationship of schizotypy with laterality as assessed with motor function tasks has not been well documented. A few studies using fine motor control tasks have demonstrated the relationship between schizotypy and reduced laterality among student populations, yet little has been done in community samples. Here we employed 249 healthy women and examined the association between schizotypal traits assessed with the Schizotypal Personality Questionnaire and motor functions assessed with the Purdue Pegboard test (as a measure of spatial motor control) and a handgrip force test. Correlational and categorical analyses both showed that schizotypal traits were significantly associated with leftward and bilateral bias in the fine motor control task, but not in the handgrip force test. Schizotypy did not significantly affect the performance level on either of these tasks. These results indicate that schizotypal traits in healthy women are associated with a shift away from dextrality, supporting the fully dimensional model of schizotypy.

Functional near-infrared spectroscopy for the assessment of speech related tasks

Over the past years functional near-infrared spectroscopy (fNIRS) has substantially contributed to the understanding of language and its neural correlates. In contrast to other imaging techniques, fNIRS is well suited to study language function in healthy and psychiatric populations due to its cheap and easy application in a quiet and natural measurement setting. Its relative insensitivity for motion artifacts allows the use of overt speech tasks and the investigation of verbal conversation. The present review focuses on the numerous contributions of fNIRS to the field of language, its development, and related psychiatric disorders but also on its limitations and chances for the future.

Relationships between season of birth, schizotypy, temperament, character and neurocognition in a non-clinical population

While schizophrenia has been associated with a slight excess of winter/early spring birth, it is unclear whether there is such an association in relation to schizotypal personality traits. Season of birth has also been reported to relate to temperament and character personality dimensions and cognitive functioning. Moreover, non-clinical schizotypy has been shown to be associated with mild cognitive impairment, although its precise nature is yet to be elucidated. Here we examined the relationships between season of birth, schizotypal traits, temperament and character, and cognitive function. Four hundred and fifty-one healthy adults completed the Schizotypal Personality Questionnaire (SPQ). The Temperament and Character Inventory (TCI) and a neuropsychological test battery consisting of full versions of the Wechsler Memory Scale-Revised and the Wechsler Adult Intelligence Scale-Revised, and the Wisconsin Card Sorting Test, were also administered to most of the participants. The total SPQ score of those born in winter was significantly higher than that of the remaining participants. Season of birth was not significantly associated with any of the TCI dimensions or cognitive test results. Significant but mild relationships between higher SPQ scores and lower scores on some aspects of IQ were observed. These results support the notion that schizotypy and schizophrenia are neurodevelopmental conditions on the same continuum.

Lateralisation of language and emotion in schizotypal personality: Evidence from dichotic listening

Striking disturbances have been reported in language and emotional prosody processing by patients diagnosed with schizophrenia. In view of this and of research suggesting that schizotypal personality traits can also be expressed sub-clinically, the present study aimed to discover whether similar disturbances would be reflected in cognitive laterality patterns when symptoms of schizotypy are present yet at a non-clinical level. A dichotic listening task was used to examine the sensitivity and speed with which 132 right-handed participants (85 females and 47 males, mean age = 32.44, SD = 12.29) detected both words and emotional prosody, all of whom also completed the Schizotypal Personality Questionnaire. Findings indicated that both high (n = 64) and low (n = 68) schizotypy groups demonstrated the typical right ear advantage for the detection of words and left ear advantage for the detection of emotional prosody. Individuals with higher schizotypal personality scores also demonstrated poorer sensitivity in detecting emotional prosody. These results reveal that within the healthy population, higher levels of schizotypy are not associated with the atypical lateralisation of language and emotion. Nevertheless, the existence of these symptoms does signal the presence of shared characteristics with the clinical sphere, namely poorer emotion recognition performance.

Schizotypal personality in healthy adults is related to blunted cortisol responses to the combined dexamethasone/ corticotropin-releasing hormone test

BACKGROUND/AIMS

Schizotypy is viewed as a dimensional trait ranging from healthy people to schizophrenic spectrum patients. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, and accumulated evidence suggests that schizophrenia is associated with altered HPA axis function; however, HPA axis function in relation to schizotypal personality has not been well documented.

METHODS

We examined the relationship between schizotypal traits as assessed with the Schizotypal Personality Questionnaire (SPQ) and cortisol responses to the combined dexamethasone/corticotropin- releasing hormone test in 141 healthy volunteers. Subjects were divided into three groups based on their cortisol responses to the dexamethasone/corticotropin-releasing hormone test: incomplete suppressors, moderate suppressors, and enhanced suppressors. SPQ scores were compared between these three groups using the analysis of covariance, controlling for age and sex.

RESULTS

The analysis of covariance showed significant main effects of the suppressor status on the ideas of reference and suspiciousness/paranoid ideation subscales and cognitive-perceptual factor. Post-hoc analyses with Bonferroni correction revealed that the enhanced suppressors scored significantly higher than the moderate suppressors on these SPQ indices.

CONCLUSION

These results indicate that nonclinical schizotypal traits in healthy adults are associated with blunted cortisol reactivity, potentially suggesting a shared neuroendocrinological mechanism across schizophrenia spectrum pathology.

A functional promoter polymorphism of neuronal nitric oxide synthase moderates prefrontal functioning in schizophrenia

Cognitive deficits in tasks involving the prefrontal cortex such as working memory or verbal fluency are a key component of schizophrenia. This led to the hypofrontality hypothesis of schizophrenia, which is widely accepted even though molecular underpinnings are elusive. While disturbances of glutamatergic neurotransmission might play a role, other components have rarely been investigated. Recently, the promoter region of nitric oxide (NO) synthase-I (NOS-I, encoded by the gene NOS1), impacting on prefrontal glutamate transmission, has repeatedly been associated with schizophrenia. We thus tested whether an associated schizophrenia risk variant (rs41279104), leading to reduced expression of the transcript, influences prefrontal brain functioning. Forty-three patients suffering from chronic schizophrenia and 44 controls were genotyped for NOS1 rs41279104 and investigated by means of functional near-infrared spectroscopy (fNIRS), while completing a working-memory task (2-back test) and a verbal fluency test (VFT). After matching for genotype, behavioural and brain activation data of 26 patients and 28 comparable controls were correlated to rs41279104. Healthy controls showed significant activation of large parts of the lateral prefrontal cortex during both tasks, whereas task-related changes in oxygenation were significantly reduced in patients. Schizophrenia patients also performed worse in both tasks. The NOS1 schizophrenia risk genotype rs41279104 AA/AG was associated with slower reaction time in the 2-back task, as well as with reduced right-hemispheric activation of the frontal cortex for VFT in patients only. Our fNIRS data extend previous studies suggesting disturbed prefrontal functioning in schizophrenia and suggest that genetic variation of NOS1 has a role in cognitive dysfunction, probably by mediating glutamatergic tone.

Cerebral asymmetry in schizophrenia

The hemispheres of the human brain are anatomically and functionally asymmetric, and many cognitive and motor functions such as language and handedness are lateralized. This review examines anatomical, psychological, and physiological approaches to the understanding of separate hemispheric functions and their integration. The concept of hemispheric laterality plays a central role in current neuropsychological and pathophysiological models of schizophrenia. Reduced hemispheric asymmetry has also been reported for other mental disorders, for example, bipolar disorder. Recent research reflects an increasing interest in the molecular and population genetics of laterality and its potential link with animal models of schizophrenia. The authors review the principles of laterality and brain asymmetry and discuss the evidence for changes in asymmetry in schizophrenia and other mental disorders.

Habituation in prepulse inhibition is affected by a polymorphism on the NMDA receptor 2B subunit gene (GRIN2B)

OBJECTIVES

To identify the reliable connectivity between causal genes or variants with an abnormality expressed in a certain endophenotype has been viewed as a crucial step in unraveling the etiology of schizophrenia because of the considerable heterogeneity in this disorder.

METHODS

According to this practical and scientific demand, we aimed to investigate the relationship between seven top-ranked variants in the SZgene database [120-bpTR in DRD4, rs1801028 and rs6277 in DRD2, rs1019385 (T200G) in GRIN2B, rs1800532 in TPH1, rs1801133 (C677T) in MTHFR, rs2619528 (P1765) in DTNBP1] and prepulse inhibition (PPI) and habituation after acoustic stimulus (HAB).

RESULTS

Both PPI and HAB were decreased significantly in patients with schizophrenia. In addition, we observed a significant effect of GRIN2B (human NMDA receptor 2B subunit gene, NR2B) genotype on HAB (P<0.05, not corrected).

CONCLUSION

Although these findings need to be replicated in other samples, an underlying mechanism of impaired biological reaction may be influenced by NMDA hypofunctioning in schizophrenia.

Atypical EEG beta asymmetry in adults with ADHD

BACKGROUND

Abnormal brain laterality (ABL) is well established in ADHD. However, its clinical specificity and association to cognitive and clinical symptoms is not yet understood. Previous studies indicate increased right hemisphere (RH) contribution in both ADHD and reading impaired samples. The current study investigates whether this ABL characteristic occurs in adults with ADHD absent comorbid language impairment.

METHODS

EEG beta asymmetry was compared in 35 adult ADHD subjects and 104 controls during rest and active cognition. Group differences in beta asymmetry were then further evaluated for association to linguistic and attentional abilities, as well as association to beta asymmetry measures across different brain regions.

RESULTS

Adults with ADHD showed pronounced rightward beta asymmetry (p=.00001) in inferior parietal regions (P8-P7) during a continuous performance task (CPT) that could not be attributed to linguistic ability. Among ADHD subjects only, greater rightward beta asymmetry at this measure was correlated with better CPT performance. Furthermore, this measure showed a lack of normal association (i.e., observed in controls) to left-biased processing in temporal-parietal (TP8-TP7) brain regions important for higher order language functions.

CONCLUSION

Adult ADHD involves abnormally increased right-biased contribution to CPT processing that could not be attributed to poor language ability. This appears to also involve abnormal recruitment of LH linguistic processing regions and represents an alternative, albeit less effective, CPT processing strategy. These findings suggest different pathophysiologic mechanisms likely underlie RH biased processing in ADHD and reading impaired samples.

Metaphor processing in high and low schizotypal individuals

Two hypotheses were considered regarding the relationship between positive schizotypy and metaphor processing. On the basis of continuity between schizophrenia and schizotypy, high schizotypal individuals would be expected to be impaired at metaphor processing. However, given the right hemisphere processing bias that has been associated with positive schizotypy, they would be expected to be superior at metaphor processing. A story completion task in which participants judged the appropriateness of literal and metaphoric statements was administered to 30 high and 29 low schizotypal individuals. Contrary to both hypotheses, groups did not differ in their ability to discriminate between appropriate and inappropriate statements, whether literal or metaphoric. However, the high schizotypal group demonstrated a less conservative response bias; they were more likely than the low schizotypal group to identify a statement as appropriate, whether it was or was not. Implications of these results for our understanding of language processing in schizophrenia and schizotypy are discussed.

Relationship between prepulse inhibition of acoustic startle response and schizotypy in healthy Japanese subjects

Prepulse inhibition (PPI) of the acoustic startle reflex (ASR) is the most common psychophysiological index of sensorimotor gating. Several studies have investigated the relationship of PPI of ASR to schizotypy in Caucasians. However, little has been reported on this relationship in Asians. We investigated a possible relationship between PPI of ASR and schizotypy in 79 healthy Japanese subjects. Schizotypy was assessed by the Schizotypal personality Questionnaire (SPQ). PPI was evaluated at signal-to-noise ratios (SnRs: difference between background noise intensity and prepulse intensity) of +12, +16, and +20 dB. The total SPQ score, cognitive/perceptual score, and interpersonal score correlated negatively with PPI at SnR of +16 and +20 dB. We conclude that PPI is associated with the trait of schizotypy in healthy Asian subjects.