Phenomenological dimensions of sensory gating

Impaired contour object perception in psychosis

Contour integration, the process of joining spatially separated elements into a single unified line, has consistently been found to be impaired in schizophrenia. Recent work suggests that this deficit could be associated with psychotic symptomatology, rather than a specific diagnosis such as schizophrenia. Examining a transdiagnostic sample of participants with psychotic psychopathology, we obtained quantitative indices of contour perception in a psychophysical behavioral task. We found impaired contour discrimination performance among people with psychotic psychopathology (PwPP, n = 62) compared to healthy controls (n = 34) and biological relatives of PwPP (n = 44). Participants with schizophrenia (n = 31) showed impaired task performance compared to participants with bipolar disorder (n = 18). We also measured responses during an analogous task using ultra-high field (7T) functional MRI and found higher responses in the lateral occipital cortex of PwPP compared to controls. Using task-based functional connectivity analyses, we observed abnormal connectivity between visual brain areas during contour perception among PwPP. These connectivity differences only emerged when participants had to distinguish the contour object from background distractors, suggesting that a failure to suppress noise elements relative to contour elements may underlie impaired contour processing in PwPP. Our results are consistent with impaired contour integration in psychotic psychopathology, and especially schizophrenia, that is related to cognitive dysfunction, and may be linked to impaired functional connectivity across visual regions.

Faster bi-stable visual switching in psychosis

Bi-stable stimuli evoke two distinct perceptual interpretations that alternate and compete for dominance. Bi-stable perception is thought to be driven at least in part by mutual suppression between distinct neural populations that represent each percept. Abnormal visual perception has been observed among people with psychotic psychopathology (PwPP), and there is evidence to suggest that these visual deficits may depend on impaired neural suppression in the visual cortex. However, it is not yet clear whether bi-stable visual perception is abnormal among PwPP. Here, we examined bi-stable perception in a visual structure-from-motion task using a rotating cylinder illusion in a group of 65 PwPP, 44 first-degree biological relatives, and 43 healthy controls. Data from a 'real switch' task, in which physical depth cues signaled real switches in rotation direction were used to exclude individuals who did not show adequate task performance. In addition, we measured concentrations of neurochemicals, including glutamate, glutamine, and γ-amino butyric acid (GABA), involved in excitatory and inhibitory neurotransmission. These neurochemicals were measured non-invasively in the visual cortex using 7 tesla MR spectroscopy. We found that PwPP and their relatives showed faster bi-stable switch rates than healthy controls. Faster switch rates also correlated with significantly higher psychiatric symptom levels, specifically disorganization, across all participants. However, we did not observe any significant relationships across individuals between neurochemical concentrations and SFM switch rates. Our results are consistent with a reduction in suppressive neural processes during structure-from-motion perception in PwPP, and suggest that genetic liability for psychosis is associated with disrupted bi-stable perception.

Alterations in self-reported sensory gating and interoception in individuals frequently using cannabis

Background: Cannabis use is associated with altered processing of external (exteroceptive) and internal (interoceptive) sensory stimuli. However, little research exists on whether subjective experiences of these processes are altered in people who frequently use cannabis. Altered exteroception may influence externally oriented attention, whereas interoceptive differences have implications for intoxication, craving, and withdrawal states.Objectives: The goal of the current study was to investigate subjective experiences of exteroceptive sensory gating and interoception in people frequently using cannabis. We hypothesized subjective impairments in sensory gating and elevations in affect-related interoceptive awareness; furthermore, such deviations would relate to cannabis use patterns.Methods: This cross-sectional study of community adults 18-40 years old included 72 individuals (50% female) who used cannabis at least twice a week (not intoxicated during study) and 78 individuals who did not use cannabis (60% female). Participants completed the Sensory Gating Inventory and the Multidimensional Assessment of Interoceptive Awareness-2 surveys. People using cannabis completed surveys on cannabis use patterns. Analyses tested group differences and associations with cannabis use.Results: People using cannabis reported impaired sensory gating (d = 0.37-0.44; all p values < 0.05) and elevations of interoceptive awareness related to detection and affect (d = 0.21-0.61; all p values < 0.05). Problematic cannabis use was associated with increased sensory gating impairments (r = 0.37, p < .05). Interoceptive awareness was unrelated to cannabis use variables.Conclusion: These findings extend literature on subjective experiences of sensory processing in people using cannabis. Findings may inform inclusion of external attentional tendencies and internal bodily awareness in assessments of risk and novel treatment approaches.

Sleep spindle activity and psychotic experiences: Examining the mediating roles of attentional performance and perceptual distortions in a daytime nap study

Decreased sleep spindle activity in individuals with psychotic disorders is well studied, but its contribution to psychotic symptom formation is not well understood. This study explored potential underlying mechanisms explaining the association between decreased sleep spindle activity and psychotic symptoms. To this end, we analysed the links between sleep spindle activity and psychotic experiences and probed for the mediating roles of attentional performance and perceptual distortions in a community sample of young adults (N = 70; 26.33 ± 4.84 years). Polysomnography was recorded during a 90-min daytime nap and duration, amplitude, and density from slow (10-13 Hz) and fast (13-16 Hz) spindles were extracted. Attentional performance was assessed via a test battery and with an antisaccadic eye movement task. Psychotic experiences (i.e., paranoid thoughts; hallucinatory experiences) and perceptual distortions (i.e., anomalous perceptions; sensory gating deficits) were assessed via self-report questionnaires. We conducted sequential mediation analyses with spindle activity as predictor, psychotic experiences as dependent variable, and attentional performance and perceptual distortions as mediators. We found reduced right central spindle amplitude to be associated with paranoid thoughts. Increased antisaccadic error rate was associated with anomalous perceptions and perceptual distortions were associated with psychotic experiences. We did not find significant mediation effects. The findings support the notion that reduced sleep spindle activity is involved in the formation of paranoid thoughts and that decreased antisaccadic performance is indicative of perceptual distortions as potential precursors for psychotic experiences. However, further research is needed to corroborate the proposed mediation hypothesis.

Abnormalities of structural covariance of insular subregions in drug-naïve OCD patients

The insula plays a significant role in the neural mechanisms of obsessive-compulsive disorder. Previous studies have identified functional and structural abnormalities in insula in obsessive-compulsive disorder patients. The predictive coding model in the context of interoception can explain the psychological and neuropathological manifestations observed in obsessive-compulsive disorder. The model is based on the degree of laminar differentiation of cerebral cortex. The interindividual differences in a local measure of brain structure often covary with interindividual differences in other brain regions. We investigated the anatomical network involving the insula in a drug-naïve obsessive-compulsive disorder sample. We recruited 58 obsessive-compulsive disorder patients and 84 matched health controls. The cortical thickness covariance maps between groups were compared at each vertex. We also evaluated the modulation of Yale-Brown Obsessive-Compulsive Scale scores and obsessive-compulsive disorder duration on thickness covariance. Our findings indicated that the thickness covariance seeded from granular and dysgranular insula are different compared with controls. The duration and severity of obsessive-compulsive disorder can modulate the thickness covariance of granular and dysgranular insula with posterior cingulate cortex and rostral anterior cingulate cortex. Our results revealed aberrant insular structural characteristics and cortical thickness covariance in obsessive-compulsive disorder patients, contributing to a better understanding of the involvement of insula in the pathological mechanisms underlying obsessive-compulsive disorder.

The Scanner as the Stimulus: Deficient Gamma-BOLD Coupling in Schizophrenia at Rest

Functional magnetic resonance imaging (fMRI) scanners are unavoidably loud and uncomfortable experimental tools that are necessary for schizophrenia (SZ) neuroscience research. The validity of fMRI paradigms might be undermined by well-known sensory processing abnormalities in SZ that could exert distinct effects on neural activity in the presence of scanner background sound. Given the ubiquity of resting-state fMRI (rs-fMRI) paradigms in SZ research, elucidating the relationship between neural, hemodynamic, and sensory processing deficits during scanning is necessary to refine the construct validity of the MR neuroimaging environment. We recorded simultaneous electroencephalography (EEG)-fMRI at rest in people with SZ (n = 57) and healthy control participants without a psychiatric diagnosis (n = 46) and identified gamma EEG activity in the same frequency range as the background sounds emitted from our scanner during a resting-state sequence. In participants with SZ, gamma coupling to the hemodynamic signal was reduced in bilateral auditory regions of the superior temporal gyri. Impaired gamma-hemodynamic coupling was associated with sensory gating deficits and worse symptom severity. Fundamental sensory-neural processing deficits in SZ are present at rest when considering scanner background sound as a "stimulus." This finding may impact the interpretation of rs-fMRI activity in studies of people with SZ. Future neuroimaging research in SZ might consider background sound as a confounding variable, potentially related to fluctuations in neural excitability and arousal.

Validation of the Dutch Sensory Gating Inventory (D-SGI): Psychometric properties and a Confirmatory factor analysis

The Sensory Gating Inventory (SGI) is an established self-report questionnaire that is used to assess the capacity for filtering redundant or irrelevant environmental stimuli. Translation and cross-cultural validation of the SGI are necessary to make this tool available to Dutch speaking populations. This study, therefore, aimed to design and validate a Dutch Sensory Gating Inventory (D-SGI). To this end, a forward-backward translation was performed and 469 native Dutch speakers filled in the questionnaire. A confirmatory factor analysis assessed the psychometric properties of the D-SGI. Additionally, test-retest reliability was measured. Results confirmed satisfactory similarity between the original English SGI and the D-SGI in terms of psychometric properties for the factor structure. Internal consistency and discriminant validity were also satisfactory. Overall test-retest reliability was excellent (ICC = 0.91, p < 0.001, 95% CI [0.87-0.93]). These findings confirm that the D-SGI is a psychometrically sound self-report measure that allows assessing the phenomenological dimensions of sensory gating in Dutch. Moreover, the D-SGI is publicly available. This establishes the D-SGI as a new tool for the assessment of sensory gating dimensions in general- and clinical Dutch speaking populations.

Slowed alpha oscillations and percept formation in psychotic psychopathology

Introduction

Psychosis is in part defined by disturbances in perception. Recent investigations have implicated the speed of alpha oscillations observed in brain electrical activity as reflective of a sampling rate of the visual environment and perception. Although both slowed alpha oscillations and aberrant percept formation are evident in disorders of psychotic psychopathology such as schizophrenia it is unclear whether slow alpha accounts for abnormal visual perception in these disorders.

Methods

To examine the role of the speed of alpha oscillations in perception in psychotic psychopathology we gathered resting-state magneto-encephalography data from probands with psychotic psychopathology (i.e., schizophrenia, schizoaffective disorder, and bipolar disorder with a history of psychosis), their biological siblings, and healthy controls. We appraised visual perceptual function without the confound of cognitive ability and effort through the use of a simple binocular rivalry task.

Results

We found a slowed pace of alpha oscillations in psychotic psychopathology that was associated with longer percept durations during binocular rivalry, consistent with the assertion that occipital alpha oscillations govern the rate of accumulation of visual information used to generate percepts. Alpha speed varied widely across individuals with psychotic psychopathology and was highly stable across several months indicating that it is likely a trait characteristic of neural function that is relevant to visual perception. Finally, a lower speed of alpha oscillation was associated with a lower IQ and greater disorder symptomatology implying that the effects of the endogenous neural oscillation on visual perception may have wider consequences for everyday functioning.

Discussion

Slowed alpha oscillations in individuals with psychotic psychopathology appear to reflect altered neural functions related to percept formation.

Randomized controlled trial of the glycine transporter 1 inhibitor PF-03463275 to enhance cognitive training and neuroplasticity in schizophrenia

N-methyl-d-aspartate glutamate receptor (NMDAR) hypofunction is implicated in the impaired neuroplasticity and cognitive impairments associated with schizophrenia (CIAS). We hypothesized that enhancing NMDAR function by inhibiting the glycine transporter-1 (GLYT1) would improve neuroplasticity and thereby augment benefits of non-pharmacological cognitive training (CT) strategies. This study examined whether co-administration of a GLYT1 inhibitor and computerized CT would have synergistic effects on CIAS. Stable outpatients with schizophrenia participated in this double-blind, placebo-controlled, within-subject, crossover augmentation study. Participants received placebo or GLYT1 inhibitor (PF-03463275) for two 5-week periods separated by 2 weeks of washout. PF-03463275 doses (40 or 60 mg twice daily) were selected to produce high GLYT1 occupancy. To limit pharmacodynamic variability, only cytochrome P450 2D6 extensive metabolizers were included. Medication adherence was confirmed daily. Participants received 4 weeks of CT in each treatment period. Cognitive performance (MATRICS Consensus Cognitive Battery) and psychotic symptoms (Positive and Negative Syndrome Scale) were assessed in each period. 71 participants were randomized. PF-03463275 in combination with CT was feasible, safe, and well-tolerated at the doses prescribed but did not produce greater improvement in CIAS compared to CT alone. PF-03463275 was not associated with improved CT learning parameters. Participation in CT was associated with improvement in MCCB scores.

Faster bi-stable visual switching in psychosis

Bi-stable stimuli evoke two distinct perceptual interpretations that alternate and compete for dominance. Bi-stable perception is thought to be driven at least in part by mutual suppression between distinct neural populations that represent each percept. Abnormal visual perception is observed among people with psychotic psychopathology (PwPP), and there is evidence to suggest that these visual deficits may depend on impaired neural suppression in visual cortex. However, it is not yet clear whether bi-stable visual perception is abnormal among PwPP. Here, we examined bi-stable perception in a visual structure-from-motion task using a rotating cylinder illusion in a group of 65 PwPP, 44 first-degree biological relatives, and 43 healthy controls. Data from a 'real switch' task, in which physical depth cues signaled real switches in rotation direction were used to exclude individuals who did not show adequate task performance. In addition, we measured concentrations of neurochemicals, including glutamate, glutamine, and γ-amino butyric acid (GABA), involved in excitatory and inhibitory neurotransmission. These neurochemicals were measured non-invasively in visual cortex using 7 tesla MR spectroscopy. We found that PwPP and their relatives showed faster bi-stable switch rates than healthy controls. Faster switch rates also correlated with significantly higher psychiatric symptom levels across all participants. However, we did not observe any significant relationships across individuals between neurochemical concentrations and SFM switch rates. Our results are consistent with a reduction in suppressive neural processes during structure-from-motion perception in PwPP, and suggest that genetic liability for psychosis is associated with disrupted bi-stable perception.

The Psychosis Human Connectome Project: Design and rationale for studies of visual neurophysiology

Visual perception is abnormal in psychotic disorders such as schizophrenia. In addition to hallucinations, laboratory tests show differences in fundamental visual processes including contrast sensitivity, center-surround interactions, and perceptual organization. A number of hypotheses have been proposed to explain visual dysfunction in psychotic disorders, including an imbalance between excitation and inhibition. However, the precise neural basis of abnormal visual perception in people with psychotic psychopathology (PwPP) remains unknown. Here, we describe the behavioral and 7 tesla MRI methods we used to interrogate visual neurophysiology in PwPP as part of the Psychosis Human Connectome Project (HCP). In addition to PwPP (n = 66) and healthy controls (n = 43), we also recruited first-degree biological relatives (n = 44) in order to examine the role of genetic liability for psychosis in visual perception. Our visual tasks were designed to assess fundamental visual processes in PwPP, whereas MR spectroscopy enabled us to examine neurochemistry, including excitatory and inhibitory markers. We show that it is feasible to collect high-quality data across multiple psychophysical, functional MRI, and MR spectroscopy experiments with a sizable number of participants at a single research site. These data, in addition to those from our previously described 3 tesla experiments, will be made publicly available in order to facilitate further investigations by other research groups. By combining visual neuroscience techniques and HCP brain imaging methods, our experiments offer new opportunities to investigate the neural basis of abnormal visual perception in PwPP.

Weakened untuned gain control is associated with schizophrenia while atypical orientation-tuned suppression depends on visual acuity

Perceptual distortions are core features of psychosis. Weakened contrast surround suppression has been proposed as a neural mechanism underlying atypical perceptual experiences. Although previous work has measured suppression by asking participants to report the perceived contrast of a low-contrast target surrounded by a high-contrast surround, it is possible to modulate perceived contrast solely by manipulating the orientation of a matched-contrast center and surround. Removing the bottom-up segmentation cue of contrast difference and isolating orientation-dependent suppression may clarify the neural processes responsible for atypical surround suppression in psychosis. We examined surround suppression across a spectrum of psychotic psychopathology including people with schizophrenia (PSZ; N = 31) and people with bipolar disorder (PBD; N = 29), first-degree biological relatives of these patient groups (PBDrel, PSZrel; N = 28, N = 21, respectively), and healthy controls (N = 29). PSZ exhibited reduced surround suppression across orientations; although group differences were minimal at the condition that produced the strongest suppression. PBD and PSZrel exhibited intermediate suppression, whereas PBDrel performed most similarly to controls. Intriguingly, group differences in orientation-dependent surround suppression magnitude were moderated by visual acuity. A simulation in which visual acuity and/or focal attention interact with untuned gain control reproduces the observed pattern of results, including the lack of group differences when orientation of center and surround are the same. Our findings further elucidate perceptual mechanisms of impaired center-surround processing in psychosis and provide insights into the effects of visual acuity on orientation-dependent suppression in PSZ.

Remote, Computerised Cognitive Assessment for Breast Cancer- and Treatment-Related Cognitive Dysfunction: Psychometric Characteristics of the Cogsuite Neurocognitive Battery

OBJECTIVE

Cancer-related cognitive dysfunction (CRCD) is a significant concern for breast cancer survivors. The Cogsuite battery was developed to improve sensitivity to CRCD with the use of cognitive experimental measures, clarify specific cognitive processes impacted and to be capable of being administered either in-office or remotely.

METHODS

In sum, 357 breast cancer survivors and non-cancer controls completed the Cogsuite Battery in-office (n = 76) or remotely (n = 281). Measure validity, sensitivity to demographic factors, correlations with standard neuropsychological measures and intercorrelations of Cogsuite variables were assessed. Test-retest reliability was evaluated in-office (n = 24) and remotely (n = 80).

RESULTS

Test-retest reliability for most variables assessed was adequate to strong. Internal validity, as indicated by the confirmation of expected condition effects within each measure, was established for all measures. Assessment of external validity found age, but not education, was a significant predictor in the majority of measures. Assessment of criterion validity found that Cogsuite variables were correlated with standard measures in psychomotor speed, working memory and executive function, but not associated with self-reported cognition or mood.

CONCLUSIONS

Cogsuite is reliable and valid, and is sensitive to the effects of increasing age on cognition. The addition of the Cogsuite battery to standard assessment may improve sensitivity to CRCD and identify underlying processes that may be affected. Remote use of the Cogsuite battery in appropriate settings will lessen the burden for providers, researchers and survivors in research and clinical contexts.

People with high schizotypy experience more illusions in the Pattern Glare Test: Consistent with the hyperexcitability hypothesis

Individuals diagnosed with schizophrenia spectrum disorders (SSD) exhibit a constellation of sensory and perceptual impairments, including hyporeactivity to external input. However, individuals with SSD also report subjective experiences of sensory flooding, suggesting sensory hyperexcitability. To identify the extent to which behavioural indices of hyperexcitability are related to non-psychotic symptoms of schizophrenia, we tested a non-clinical population measured for schizophrenia-like traits (schizotypy), and a behavioural measure of sensory hyperexcitability, specifically the number of illusions seen in the Pattern Glare Test. Two samples totaling 913 individuals completed an online version of the Schizotypal Personality Questionnaire - Brief Revised (SPQ-BR) and the Pattern Glare Test. Individuals with higher schizotypy traits reported more illusions in the Pattern Glare Test. Additionally, one of the three SPQ-BR factors, the disorganized factor, significantly predicted the number of illusions reported. These data illustrate the potential for research in non-clinical samples to inform clinically relevant research.

Longitudinal Effects of Breast Cancer Treatment on Neural Correlates of Attention

OBJECTIVE

Cognitive dysfunction has been observed consistently in a subset of breast cancer survivors. Yet, the precise physiological and processing origins of dysfunction remain unknown. The current study examined the utility of methods and procedures based on cognitive neuroscience to study cognitive change associated with cancer and cancer treatment.

METHODS

We used electroencephalogram and behavioral measures in a longitudinal design to investigate pre- versus post-treatment effects on attention performance in breast cancer patients (n = 15) compared with healthy controls (n = 24), as participants completed the revised Attention Network Test, a cognitive measure of alerting, orienting, and inhibitory control of attention.

RESULTS

We found no group differences in behavioral performance from pretest to posttest, but significant event-related potential effects of cancer treatment in processing cue validity: After treatment, patients revealed decreased N1 amplitude and increased P3 amplitude, suggesting a suppressed early (N1) response and an exaggerated late (P3) response to invalid cues.

CONCLUSIONS

The results suggest that treatment-related attentional disruption begins in early sensory/perceptual processing and extends to compensatory top-down executive processes.

Cross-disorder comparison of sensory over-responsivity in chronic tic disorders and obsessive-compulsive disorder

BACKGROUND

Sensory over-responsivity (SOR) refers to excessively intense and/or prolonged behavioral responses to environmental stimuli typically perceived as non-aversive. SOR is prevalent in several neurodevelopmental disorders, including chronic tic disorders (CTDs) and obsessive-compulsive disorder (OCD). Few studies have examined the extent and clinical correlates of SOR across disorders, limiting insights into the phenomenon's transdiagnostic clinical and biological relevance. Such cross-disorder comparisons are of particular interest for CTDs and OCD given their frequent co-occurrence.

OBJECTIVE

We sought to compare the magnitude of SOR between adults with CTD and adults with OCD and to identify the clinical factors most strongly associated with SOR across these disorders.

METHODS

We enrolled 207 age- and sex-matched participants across four diagnostic categories: CTD without OCD (designated "CTD/OCD-"; n = 37), CTD with OCD ("CTD/OCD+"; n = 32), OCD without tic disorder ("OCD"; n = 69), and healthy controls (n = 69). Participants completed a self-report battery of rating scales assessing SOR (Sensory Gating Inventory, SGI), obsessive-compulsive symptoms (Dimensional Obsessive-Compulsive Scale, DOCS), inattention and hyperactivity (Adult ADHD Self-Report Screening Scale for DSM-5, ASRS-5), anxiety (Generalized Anxiety Disorder-7), and depression (Patient Health Questionnaire-9). CTD participants were also administered the Yale Global Tic Severity Scale (YGTSS). To examine between-group differences in SOR, we compared SGI score across all groups and between pairs of groups. To examine the relationship of SOR with other clinical factors, we performed multivariable linear regression.

RESULTS

CTD/OCD-, CTD/OCD+, and OCD participants were 86.7%, 87.6%, and 89.5%, respectively, more likely to have higher SGI total scores than healthy controls. SGI total score did not differ between CTD/OCD-, CTD/OCD+, and OCD groups. In the regression model of log-transformed SGI total score, OCD diagnosis, DOCS score, and ASRS-5 score each contributed significantly to model goodness-of-fit, whereas CTD diagnosis and YGTSS total tic score did not.

CONCLUSION

SOR is prevalent in adults with CTD and in adults with OCD but does not significantly differ in magnitude between these disorders. Across CTD, OCD, and healthy control adult populations, SOR is independently associated with both obsessive-compulsive and ADHD symptoms, suggesting a transdiagnostic relationship between these sensory and psychiatric manifestations. Future cross-disorder, longitudinal, and translational research is needed to clarify the role and prognostic import of SOR in CTDs, OCD, and other neurodevelopmental disorders.

Schizophrenia, Bipolar Disorder and Pre-Attentional Inhibitory Deficits

According to recent findings schizophrenia and bipolar disorder as separate disease entities manifest similarities in neuropsychological functioning. Typical disturbances in both disorders are related to sensory gating deficits characterized by decreased inhibitory functions in responses to various insignificant perceptual signals which are experimentally tested by event related potentials (ERP) and measured P50 wave. In this context, recent findings implicate that disrupted binding and disintegration of consciousness in schizophrenia and bipolar disorder that are related to inhibitory deficits reflected in P50 response may explain similarities in psychotic disturbances in both disorders. With this aim, this review summarizes literature about P50 in both schizophrenia and bipolar disorder.

Revisiting the relationship between neural correlates of sensory gating and self-reported sensory gating inventory: An MEG investigation

BACKGROUND

Accumulated evidence has revealed that bilateral superior temporal gyrus (STG), inferior frontal gyrus (IFG), and inferior parietal lobule (IPL) are involved in the processes of sensory gating (SG). However, it remains unknown which neural correlate(s) of SG specifically reflect individuals' perceptual experiences, as measured by the Sensory Gating Inventory (SGI). Thus, this study aims to investigate the relationship of SGI with cortical SG-related regions. Furthermore, we examine whether SG hemispheric asymmetry exists, which is still an inconclusive issue.

METHODS

Twenty-two healthy young adults performed the auditory paired-stimulus paradigm during magnetoencephalographic recordings. SG of M50 and M100 was measured as ratios (S2/S1) and differences (S1-S2). They were also evaluated with SGI, which factored into three categories of Perceptual Modulation, Distractibility, and Over-Inclusion. SG in the STG, IFG, and IPL were compared between left and right hemispheres, and were used to determine the relationship with SGI.

RESULTS

Only M100 SG differences (S1-S2) of the right IFG were significantly correlated with scores of Perceptual Modulation (partial r = -0.392, p = 0.040) and total SGI scores (partial r = -0.387, p = 0.041). However, we did not find significant lateralization of M50 SG and M100 SG in any studying region.

CONCLUSIONS

The individual's perceptual experience is specifically related to electrophysiological SG function of the right IFG.

The psychosis human connectome project: An overview

Investigations within the Human Connectome Project have expanded to include studies focusing on brain disorders. This paper describes one of the investigations focused on psychotic psychopathology: The psychosis Human Connectome Project (P-HCP). The data collected as part of this project were multimodal and derived from clinical assessments of psychopathology, cognitive assessments, instrument-based motor assessments, blood specimens, and magnetic resonance imaging (MRI) data. The dataset will be made publicly available through the NIMH Data Archive. In this report we provide specific information on how the sample of participants was obtained and characterized and describe the experimental tasks and procedures used to probe neural functions involved in psychotic disorders that may also mark genetic liability for psychotic psychopathology. Our goal in this paper is to outline the data acquisition process so that researchers intending to use these publicly available data can plan their analyses. MRI data described in this paper are limited to data acquired at 3 Tesla. A companion paper describes the study's 7 Tesla image acquisition protocol in detail, which is focused on visual perceptual functions in psychotic psychopathology.

Reduced influence of perceptual context in schizophrenia: behavioral and neurophysiological evidence

BACKGROUND

Accurate perception of visual contours is essential for seeing and differentiating objects in the environment. Both the ability to detect visual contours and the influence of perceptual context created by surrounding stimuli are diminished in people with schizophrenia (SCZ). The central aim of the present study was to better understand the biological underpinnings of impaired contour integration and weakened effects of perceptual context. Additionally, we sought to determine whether visual perceptual abnormalities reflect genetic factors in SCZ and are present in other severe mental disorders.

METHODS

We examined behavioral data and event-related potentials (ERPs) collected during the perception of simple linear contours embedded in similar background stimuli in 27 patients with SCZ, 23 patients with bipolar disorder (BP), 23 first-degree relatives of SCZ, and 37 controls.

RESULTS

SCZ exhibited impaired visual contour detection while BP exhibited intermediate performance. The orientation of neighboring stimuli (i.e. flankers) relative to the contour modulated perception across all groups, but SCZ exhibited weakened suppression by the perceptual context created by flankers. Late visual (occipital P2) and cognitive (centroparietal P3) neural responses showed group differences and flanker orientation effects, unlike earlier ERPs (occipital P1 and N1). Moreover, behavioral effects of flanker context on contour perception were correlated with modulation in P2 & P3 amplitudes.

CONCLUSION

In addition to replicating and extending findings of abnormal contour integration and visual context modulation in SCZ, we provide novel evidence that the abnormal use of perceptual context is associated with higher-order sensory and cognitive processes.

The Sensory Gating Inventory-Brief

The Sensory Gating Inventory (SGI) is a 36-item measure used to assess an individual's subjective ability to modulate, filter, over-include, discriminate, attend to, and tolerate sensory stimuli. Due to its theoretical and empirical link with sensory processing deficits, this measure has been used extensively in studies of psychosis and other psychopathology. The current work fills a need within the field for a briefer measure of sensory gating aberrations that maintains the original measure's utility. For this purpose, large samples (total n = 1552) were recruited from 2 independent sites for item reduction/selection and brief measure validation, respectively. These samples reflected subgroups of individuals with a psychosis-spectrum disorder, at high risk for a psychosis-spectrum disorder, nonpsychiatric controls, and nonpsychosis psychiatric controls. Factor analyses and item-response models were used to create the SGI-Brief (SGI-B; 10 Likert-rated items), a unidimensional self-report measure that retains the original SGI's transdiagnostic (ie, present across disorders) utility and content breadth. Findings show that the SGI-B has excellent psychometric properties (alpha = 0.92) and demonstrates external validity through strong associations with measures of psychotic symptomatology, theoretically linked measures of personality (eg, perceptual dysregulation), and modest associations with laboratory-based sensory processing tasks in the auditory and visual domains on par with the original version. Accordingly, the SGI-B will be a valuable tool for dimensional and transdiagnostic examination of sensory gating abnormalities within clinical science research, while reducing administrator and participant burden.

Sensory hypersensitivity in Tourette syndrome: A review

Tourette syndrome (TS) is a neurodevelopmental disorder defined by tics, but most patients also experience bothersome sensory phenomena, in the form of premonitory urges and/or sensory hypersensitivity. Whereas premonitory urges are temporally paired with tics, sensory hypersensitivity is a constant, heightened awareness of external and/or internal stimuli. The intensity of sensory hypersensitivity does not strongly correlate with the severity of tics or premonitory urges, suggesting it is a dissociable clinical phenomenon. At least 80% of TS patients report subjectively enhanced perception of various sensory stimuli. These same patients demonstrate normal static detection thresholds. However, individuals with TS habituate abnormally to repetitive stimuli, indicating incapacity to appropriately filter redundant sensory input, i.e. impaired sensory gating. Physiologic support for this hypothesis is provided by abnormal pre-pulse inhibition (PPI) and event-related potential (ERP) investigations. Preclinical data implicates parvalbumin-positive (PV+) interneuron dysfunction in altered sensory gating in TS and other neurodevelopment disorders. Studies probing TS sensory hypersensitivity must methodically account for comorbid psychiatric conditions, namely obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD), as these entities appear to involve pathophysiologic processes shared with TS. The presence of psychiatric comorbidities in TS is associated with even more profound sensory processing dysfunction. A deepened understanding of TS sensory hypersensitivity will afford novel insights into disease mechanisms, clinical phenotype, and therapeutic management.

Auditory sensory gating in Huffaz using an auditory brainstem response with a psychological task: A preliminary investigation

Objective

This study aims to investigate the auditory sensory gating capacity in Huffaz using an auditory brainstem response (ABR) test with and without psychological tasks.

Methods

Twenty-three participants were recruited for this study. The participants were comprised of 11 Huffaz who memorized 30 chapters of the Islamic Scripture (from the Quran) and 12 non-Huffaz as the control group. All participants had normal hearing perception and underwent an ABR test with and without psychological tasks. The ABR was elicited at 70 dB nHL using a 3000 Hz tone burst stimulus with a 2-0-2 cycle at a stimulus repetition rate of 40 Hz. The ABR wave V amplitude and latencies were measured and statistically compared. A forward digit span test was also conducted to determine participants' working memory capacity.

Results

There were no significant differences in the ABR wave V amplitudes and latencies between Huffaz and non-Huffaz in ABR with and without psychological tasks. There were also no significant differences in the ABR wave V amplitudes and latencies in both groups of ABR with and without psychological tasks. In addition, no significant differences were identified in the digit span working memory score between both groups.

Conclusions

In this study, based on the ABR findings, Huffaz showed the same auditory sensory gating capacity as the non-Huffaz group. The ABR result was consistent with the digit span working memory test score. This finding implies that both groups have similar working memory performance. However, the conclusion is limited to the specific assessment method that we used in this study.

Self-Reported Sensory Gating and Stress-Related Hypertension

BACKGROUND

Increasing evidence views hypertension as a stress-induced disorder. Stressors must be "gated" by the brain before any inflammatory or immune processes that contribute to hypertension are initiated. No studies were found that examined sensory gating in relation to hypertension.

OBJECTIVES

The aim of the study was to determine if disturbances in self-reported sensory gating could differentiate normotensive from hypertensive young adults.

METHODS

A nonmatched, case-control design was used. We administered an online survey to 163 young adult participants. Participants were predominantly female, in their mid-20s, well educated, and approximately evenly distributed by race and hypertension status. The Sensory Gating Inventory (SGI) measured gating disturbances.

RESULTS

The mean SGI scores were significantly higher among persons diagnosed with hypertension, reflecting a moderate effect size of sensory gating. After adjusting for confounders, however, the normotensive and hypertensive groups were not significantly different on their SGI scores.

DISCUSSION

With an observed moderate effect size of 0.35, but low power, more research is warranted regarding the role of gating disturbances in the development of stress-induced hypertension. Clinically, the SGI may be important for screening patients who would benefit from ambulatory blood pressure monitoring to identify persons with masked hypertension.

Perceptual Mechanisms of Visual Hallucinations and Illusions in Psychosis

Psychosis has been associated with neural anomalies across a number of brain regions and cortical networks. Nevertheless, the exact pathophysiology of the disorder remains unclear. Aberrant visual perceptions such as hallucinations are evident in psychosis, while the occurrence of visual distortions is elevated in individuals with genetic liability for psychosis. The overall goals of this project are to: (1) use psychophysical tasks and neuroimaging to characterize deficits in visual perception; (2) acquire a mechanistic understanding of these deficits through development and validation of a computational model; and (3) determine if said mechanisms mark genetic liability for psychosis. Visual tasks tapping both low- and high-level visual processing are being completed as individuals with psychotic disorders (IPD), first-degree biological siblings of IPDs (SibIPDs) and healthy controls (HCs) undergo 248-channel magneto-encephalography (MEG) recordings followed by 7 Tesla functional magnetic resonance imaging (MRI). By deriving cortical source signals from MEG and MRI data, we will characterize the timing, location and coordination of neural processes. We hypothesize that IPDs prone to visual hallucinations will exhibit deviant functions within early visual cortex, and that aberrant contextual influences on visual perception will involve higher-level visual cortical regions and be associated with visual hallucinations. SibIPDs who experience visual distortions-but not hallucinations-are hypothesized to exhibit deficits in higher-order visual processing reflected in abnormal inter-regional neural synchronization. We hope the results lead to the development of targeted interventions for psychotic disorders, as well as identify useful biomarkers for aberrant neural functions that give rise to psychosis.

Abnormal beta and gamma frequency neural oscillations mediate auditory sensory gating deficit in schizophrenia

BACKGROUND

Sensory gating is a process in which the brain's response to irrelevant and repetitive stimuli is inhibited. The sensory gating deficit in schizophrenia (SZ) is typically measured by the ratio or difference score of the P50 event-related potential (ERP) amplitudes in response to a paired click paradigm. While the P50 gating effect has usually been measured in relation to the peak amplitude of the S1 and S2 P50 ERPs, there is increasing evidence that inhibitory processes may be reflected by evoked or induced oscillatory activity during the inter-click interval in the beta (20-30 Hz) and gamma (30-50 Hz) frequency bands. We therefore examined the relationship between frequency specific activity in the inter-click interval with gating effects in the time and frequency domains.

METHOD

Paired-auditory stimuli were presented to 131 participants with schizophrenia and 196 healthy controls (HC). P50 ERP amplitudes to S1 and S2as well as averaged- and single-trial beta (20-30 Hz) and gamma (30-50 Hz) frequency power during the inter-click interval were measured from the CZ electrode site.

RESULTS

In the time domain, P50 gating deficits were apparent in both ratio and difference scores. This effect was mainly due to smaller S1 amplitudes in the patient group. SZ patients exhibited less evoked beta and gamma power, particularly at the 0-100 ms time point, in response to S1. Early (0-100 ms) evoked beta and gamma responses were critical in determining the S1 amplitude and extent of P50 gating across the delay interval for both HC and SZ.

CONCLUSION

Our findings support a disruption in initial sensory registration in those with SZ, and do not support an active mechanism throughout the delay interval. The degree of response to S1 and early beta and gamma frequency oscillations in the delay interval provides information about the mechanisms supporting auditory sensory gating, and may provide a framework for studying the mechanisms that support sensory inhibition.

Striatal and Thalamic Auditory Response During Deep Brain Stimulation for Essential Tremor: Implications for Psychosis

INTRODUCTION

The P50, a positive auditory-evoked potential occurring 50 msec after an auditory click, has been characterized extensively with electroencephalography (EEG) to detect aberrant auditory electrophysiology in disorders like schizophrenia (SZ) where 61-74% have an auditory gating deficit. The P50 response occurs in primary auditory cortex and several thalamocortical regions. In rodents, the gated P50 response has been identified in the reticular thalamic nucleus (RT)-a deep brain structure traversed during deep brain stimulation (DBS) targeting of the ventral intermediate nucleus (VIM) of the thalamus to treat essential tremor (ET) allowing for interspecies comparison. The goal was to utilize the unique opportunity provided by DBS surgery for ET to map the P50 response in multiple deep brain structures in order to determine the utility of intraoperative P50 detection for facilitating DBS targeting of auditory responsive subterritories.

MATERIALS AND METHODS

We developed a method to assess P50 response intraoperatively with local field potentials (LFP) using microelectrode recording during routine clinical electrophysiologic mapping for awake DBS surgery in seven ET patients. Recording sites were mapped into a common stereotactic space.

RESULTS

Forty significant P50 responses of 155 recordings mapped to the ventral thalamus, RT and CN head/body interface at similar rates of 22.7-26.7%. P50 response exhibited anatomic specificity based on distinct positions of centroids of positive and negative responses within brain regions and the fact that P50 response was not identified in the recordings from either the internal capsule or the dorsal thalamus.

CONCLUSIONS

Detection of P50 response intraoperatively may guide DBS targeting RT and subterritories within CN head/body interface-DBS targets with the potential to treat psychosis and shown to modulate schizophrenia-like aberrancies in mouse models.

Sensory Hypersensitivity Severity and Association with Obsessive-Compulsive Symptoms in Adults with Tic Disorder

BACKGROUND

Sensory hypersensitivity, defined as heightened awareness of and reactivity to external stimuli, is a bothersome symptom that affects up to 80% of adults with Tourette syndrome (TS). Such widespread prevalence suggests sensory hypersensitivity is a core feature of the disorder, but its severity and association with other clinical features of TS remain largely unexplored. Complicating matters, sensory hypersensitivity has been observed in two neurodevelopmental disorders commonly comorbid with TS: obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD).

OBJECTIVE

We sought to measure sensory hypersensitivity in TS patients relative to healthy controls and to investigate the relationship of sensory hypersensitivity with OCD and ADHD symptoms in the context of TS.

METHODS

We recruited 34 adults with TS or chronic tic disorder to undergo evaluation with the Yale Global Tic Severity Scale (YGTSS) and a battery of validated self-report instruments assessing sensory hypersensitivity (Sensory Gating Inventory, SGI; Sensory Perception Quotient, SPQ), premonitory urge (Premonitory Urge to Tic Scale, PUTS), OCD (Dimensional Obsessive-Compulsive Scale, DOCS), and ADHD (Adult ADHD Self-Report Screening Scale for DSM-5, ASRS-V). Age- and sex-matched healthy controls were recruited to complete SGI and psychiatric measures.

RESULTS

SGI and SPQ scores strongly correlated (r _s = -0.73, p < 0.0001) within patients. SGI total score was significantly higher in patients versus controls (119.0 vs 67.6, U =-5.3, p < 0.0001), indicating greater sensory hypersensitivity in the tic disorder group. SGI score correlated modestly with PUTS, DOCS, and ASRS-V scores but not with YGTSS total tic score. Hierarchical linear regression analysis revealed that, of the tested variables, only DOCS score contributed significantly to mean SGI score, with β ranging from 1.03 (p = 0.044) to 1.41 (p = 0.001). A simple linear regression model with DOCS as the independent variable accounted for 31.9% of SGI score variance.

CONCLUSION

Sensory hypersensitivity is prominent in adults with tic disorder and is independently associated with obsessive-compulsive symptom severity.

Auditory Sensory Gating and the Big Five Personality Factors

Abstract. Sensory gating allows an individual to filter out irrelevant sensory information from the environment, potentially freeing attentional resources for more complex tasks. Some work has demonstrated a relationship between auditory sensory gating and cognitive skills such as executive function, although the functional significance is not well understood. The relationship between sensory gating and personality dimensions has not been adequately explored. Participants completed a paired-tone sensory gating event-related potential (ERP) paradigm and the Big Five Inventory to assess personality characteristics. Participants with more robust P50 sensory gating reported a significantly greater degree of conscientiousness; conscientiousness (but not the other Big Five factors) predicted sensory gating ability. Longer ERP latencies were associated with participants being more conscientious (P50 component), more agreeable, and less neurotic (N100 component). A better understanding of the behavioral correlates of sensory gating will help elucidate the functional consequences of reduced sensory gating both in typical adults and clinical groups.

Developing the Persian Version of Sensory Gating Inventory and Assessing Its Validity and Reliability

Introduction:

Sensory Gating Inventory (SGI) measures behavioral aspects of Sensory Gating (SG), which filters irrelevant sensory inputs into the higher cortex. It modifies sensitivity to sensory stimuli. Abnormal SG leads to overloading of information in the brain and its subsequent dysfunction. Electrophysiological techniques cannot assess the behavioral aspects of SG. We aimed to design the Persian version of SGI with high validity and reliability.

Methods:

After a forward and then backward translation of the original SGI, we assessed the content validity and construct validity of the Persian version. A total of 405 participants filled the Persian version of SGI. To assess test-retest reliability, 100 participants filled the inventory again 7–10 days later. The content validity ratio and index, as well as confirmatory factor analysis, were computed, too. Finally, the Cronbach’s alpha, Cohen’s kappa, and intraclass correlation coefficients were calculated.

Results:

The content validity ratios of all items of the inventory were more than 60%, which means that they were necessary according to the experts’ opinions. Confirmatory factor analysis confirmed the fitness of the 4-factor structure of the original Inventory. The test-retest reliability using the intraclass correlation coefficient and Cronbach’s alpha coefficients were also high for the four subscales. The Cohen’s kappa coefficients revealed moderate to substantial level of agreement between the first and second scores for all items.

Conclusion:

The Persian version of SGI has good and acceptable psychometric properties. It can be used as a valid and reliable tool for studying behavioral aspects of SG in Persian speaking population.

Sensory Gating Capacity and Attentional Function in Adults With ADHD: A Preliminary Neurophysiological and Neuropsychological Study

Objective: The inability to filter sensory input correctly may impair higher cognitive function in ADHD. However, this relationship remains largely elusive. The objectives of the present study is to investigate the relationship between sensory input processing and cognitive function in adult patients with ADHD. Method: This study investigated the relationship between deficit in sensory gating capacity (P50 amplitude changes in a double-click conditioning-testing paradigm and perceptual abnormalities related to sensory gating deficit with the Sensory Gating Inventory [SGI]) and attentional and executive function (P300 amplitude in an oddball paradigm and attentional and executive performances with a neuropsychological test) in 24 adult patients with ADHD. Results: The lower the sensory gating capacity of the brain and the higher the distractibility related to sensory gating inability that the patients reported, the lower the P300 amplitude. Conclusion: The capacity of the brain to gate the response to irrelevant incoming sensory input may be a fundamental protective mechanism that prevents the flooding of higher brain structures with irrelevant information in adult patients with ADHD.

Abnormal frontal generator during auditory sensory gating in panic disorder: An MEG study

Patients with panic disorder (PD) exhibit abnormalities in early-stage information processing, even for the nonthreatening stimuli. A previous event-related potential study reported that PD patients show a deficit in sensory gating (SG), a protective mechanism of the brain to filter out irrelevant sensory inputs. However, there is no clear understanding about the neural correlates of SG deficits in PD. Moreover, whether SG deficits, if any, are associated with clinical manifestations remain unknown. In this study, 18 patients with PD and 20 age- and gender-matched healthy controls were recruited to perform auditory paired-stimulus paradigm using magnetoencephalographic (MEG) recordings. Results showed that PD patients demonstrated significantly higher M50 SG ratios in the right inferior frontal gyrus (RIFG) and higher M100 SG ratios in both RIFG and right superior temporal gyrus (RSTG) than those of the control group. It was important to note that in the RIFG, the M50 SG ratios correlated significantly with the scores of Body Sensation Questionnaire (BSQ) and Distractibility scale of Sensory Gating Inventory among patients with PD. In conclusion, this study suggests that PD patients exhibited a deficient ability to filter out irrelevant information, and such a defect might lead to cognitive misinterpretation of somatic sensations and distractibility.

Clinical Aspects of Premonitory Urges in Patients with Tourette's Disorder

Most patients with Tourette’s disorder experience an uncomfortable sensory phenomenon called the premonitory urge immediately before experiencing tics. It has been suggested that premonitory urges are associated with comorbidities such as obsessive compulsive disorder, anxiety disorders, and attention-deficit/hyperactivity disorder, although these associations have been inconsistent. Most patients experience tics as a result of the premonitory urges, and after the tics occur, most patients report that the premonitory urges are temporarily relieved. As a consequence, several studies have assessed the premonitory urge and its potential therapeutic utility. Based on the concept that the premonitory urge induces tics, behavioral treatments such as Exposure and Response Prevention and Habit Reversal Therapy have been developed. However, it is still unclear whether habituation, the main mechanism of these therapies, is directly related to their effectiveness. Moreover, the observed effects of pharmacological treatments on premonitory urges have been inconsistent.

Testing a decades' old assumption: Are individuals with lower sensory gating indeed more easily distracted?

The sensory gating deficits in schizophrenia have been theorized to associate with increased distractibility. We explore the potential associations between sensory and sensorimotor gating and subjective and objective indices of distraction in healthy subjects. Forty healthy males were assessed with the P50 suppression and pre-pulse inhibition of the startle reflex (PPI) paradigms. Additionally, a neurocognitive test battery was administered in a cross-over design: with/without auditory distraction. Significant effects of distraction were found in response inhibition, and verbal working memory and attention. Parameters from the PPI and P50 suppression paradigms were significantly associated with the distractor effects on strategy formation, cognitive inhibition and flexibility, visual short-term memory, and the level of subjective distraction. Subjectively reported distraction was significantly associated with verbal working memory and attention as well as executive and supervisory processes. Sensory and sensorimotor gating efficiency do not reflect the effect of distraction across executive and attention functions i.e. we did not observe a generalized distractor effect. Gating only related to the effect of distraction on strategy formation, cognitive inhibition and flexibility, as well as visual short term memory. Future studies should investigate if gating deficits affect the distractibility of the same specific cognitive functions in patients with schizophrenia.

Perception in attention deficit hyperactivity disorder

A large body of research demonstrated that individuals with attention deficit hyperactivity disorder (ADHD) suffer from various neuropsychological deficits. In contrast, less is known and only divergent evidence exists on perceptual functions of individuals with ADHD. This is problematic as neuropsychological and perceptual functions are closely interrelated and are often difficult to disentangle in behavioral assessments. This study presents the conduct and results of a systematic literature review on perceptual functions in children and adults with ADHD. This review considers studies using psychophysical methods (objective measurements) and self- and informant reports (subjective measurements). Results indicate that individuals with ADHD have altered perceptual functions in various domains as compared to typically developing individuals. Increased perceptual functions in individuals with ADHD were found with regard to olfactory detection thresholds, whereas reduced perceptual functions were evident for aspects of visual and speech perception. Moreover, individuals with ADHD were found to experience discomfort to sensory stimuli at a lower level than typically developing individuals. Alterations of perceptual functions in individuals with ADHD were shown to be moderated by various factors, such as pharmacological treatment, cognitive functions, and symptom severity. We conclude by giving implications for daily life functioning and clinical practice.

The development of the SGI-16: a shortened sensory gating deficit and distractibility questionnaire for adults with ADHD

The Sensory Gating Inventory (SGI) is a questionnaire composed of 36 items designed to investigate abnormal perception related to the inability to control sensitivity to sensory stimuli frequently reported in adult with ADHD. This questionnaire can be considered too lengthy to be taken by people with ADHD, and a shortened version is needed. One hundred and sixty-three adults with ADHD responded to the SGI-36. An item reduction process took into account both the results of statistical analyses and the expertise of a steering committee. Construct validity, reliability, and external validity were tested for a short version (16 items). The structure of the SGI-16 was confirmed by principal components factor analysis. Cronbach's alpha coefficients ranged from 0.78 to 0.89. The SGI-16 dimension scores were highly correlated with their respective SGI-36 dimension scores. The SGI-16 seems to be both appropriate and useful for use in clinical practice to investigate perceptual abnormalities in adults with ADHD.

Electrophysiological approaches to noise sensitivity

BACKGROUND

Noise sensitivity describes an individual's general reactivity to sound. It is a common trait found in many clinical populations and describes approximately 20% of the general population. Little is known about its underlying mechanisms, however.

OBJECTIVES

Here we present findings from three studies designed to expose differences in electrophysiological measures between noise-sensitive and noise-resistant individuals.

METHOD

Noise sensitivity was estimated using self-report measures, while electrophysiological indices included both cardiac (heart rate, heart rate variability) and electroencephalographic (event-related potential) measures. All three studies were designed with reference to preexisting theoretical frameworks.

RESULTS

Significant differences in heart rate change and heart rate variability indices between noise-sensitive and noise-resistant groups were found. Further, the noise-sensitive group exhibited less sensory gating than the noise-resistant group.

CONCLUSIONS

While the findings from all three studies were not definitive in indicating a likely biological mechanism underlying noise sensitivity, they do suggest that electrophysiological investigation of noise sensitivity is viable and has potential to inform clinical research into a relatively understudied symptom.

Perceptual abnormalities related to sensory gating deficit are core symptoms in adults with ADHD

This study investigated and compared perceptual abnormalities related to sensory gating deficit in adult patients with Attention Deficit Disorder with Hyperactivity (A-ADHD) and adult patients with schizophrenia. Subjects were evaluated with the Sensory Gating Inventory (SGI). We compared SGI scores between patients with A-ADHD, patients with schizophrenia and healthy subjects. We also assessed the relationship between SGI scores and clinical symptoms, and evaluated the ability of the SGI to detect perceptual abnormalities in A-ADHD. Seventy adult patients with ADHD reported higher SGI scores than the 70 healthy subjects and the 70 patients with schizophrenia. The inattention factor of the ASRS correlated significantly with the overall SGI score. The ROC AUC for the overall SGI score in the A-ADHD group (versus the healthy group) illustrated good performance. The findings suggest that i) perceptual abnormalities are core symptoms of adult patients with ADHD and ii) the attention of patients with A-ADHD may be involuntarily drowned by many irrelevant environmental stimuli leading to their impaired attention on relevant stimuli. They also confirm that the SGI could be a useful self-report instrument to diagnose the clinical features of A-ADHD.

Reduced contextual effects on visual contrast perception in schizophrenia and bipolar affective disorder

BACKGROUND

The salience of a visual stimulus is often reduced by nearby stimuli, an effect known as surround suppression of perceived contrast, which may help in locating the borders of an object. Weaker surround suppression has been observed in schizophrenia but it is unclear whether this abnormality is present in other mental disorders with similar symptomatology, or is evident in people with genetic liability for schizophrenia.

METHOD

By examining surround suppression among subjects with schizophrenia or bipolar affective disorder, their unaffected biological relatives and healthy controls we sought to determine whether diminished surround suppression was specific to schizophrenia, and if subjects with a genetic risk for either disorder would show similar deficits. Measuring perceived contrast in different surround conditions also allowed us to investigate how this suppression depends on the similarity of target and surrounding stimuli.

RESULTS

Surround suppression was weaker among schizophrenia patients regardless of surround configuration. Subjects with bipolar affective disorder showed an intermediate deficit, with stronger suppression than in schizophrenia but weaker than control subjects. Surround suppression was normal in relatives of both patient groups. Findings support a deficit in broadly tuned (rather than sharply orientation- or direction-selective) suppression mechanisms.

CONCLUSIONS

Weak broadly tuned suppression during visual perception is evident in schizophrenia and bipolar affective disorder, consistent with impaired gain control related to the clinical expression of these conditions.

Association of metabolic syndrome with sensory gating deficits in patients with chronic schizophrenia

Metabolic syndrome is more prevalent in schizophrenia than in the general population and is associated with an increased rate of morbidity. It has been associated with cognitive impairments in schizophrenia, which are a core deficit in patients with chronic schizophrenia. Sensory gating deficit is also a core deficit in schizophrenia. The principal objective of this study was to investigate the relationship between sensory gating deficit and metabolic syndrome in patients with schizophrenia, after adjusting for key confounding factors. We hypothesized that patients with metabolic syndrome exhibit a higher rate of sensory gating deficit compared to those without metabolic syndrome. This study investigated sensory gating with the auditory event-related potential method by measuring P50 amplitude changes in a double click conditioning-testing procedure in 51 patients with schizophrenia. Patients with metabolic syndrome (n = 14) had a higher rate of sensory gating deficit (P50 suppression <50%) (p < 0.001) compared to those without metabolic syndrome (n = 37). This result remained significant (B = 2.94, Wald = 8.32, p = 0.004) after taking into account 5 potential confounding factors (age, gender, duration of disorder, Fagerström test, presence of clozapine or olanzapine). In patients without metabolic syndrome, sensory gating deficit was linked to a poorer attentional performance (rho = -0.371, p = 0.05). In patients with metabolic syndrome, sensory gating deficit was linked to poorer memory performance (rho = -0.635, p = 0.02). These findings suggest that metabolic syndrome may be linked to sensory gating deficit in patients with schizophrenia and that the relationship between neurocognitive function and sensory gating deficit could be affected by the metabolic status of the patients. Further studies are needed to address the causal relationship between sensory gating deficit related to schizophrenia, cognitive impairments and metabolic syndrome.

Impaired auditory selective attention ameliorated by cognitive training with graded exposure to noise in patients with traumatic brain injury

Patients who suffer traumatic brain injury frequently report difficulty concentrating on tasks and completing routine activities in noisy and distracting environments. Such impairments can have long-term negative psychosocial consequences. A cognitive control function that may underlie this impairment is the capacity to select a goal-relevant signal for further processing while safeguarding it from irrelevant noise. A paradigmatic investigation of this problem was undertaken using a dichotic listening task (study 1) in which comprehension of a stream of speech to one ear was measured in the context of increasing interference from a second stream of irrelevant speech to the other ear. Controls showed an initial decline in performance in the presence of competing speech but thereafter showed adaptation to increasing audibility of irrelevant speech, even at the highest levels of noise. By contrast, patients showed linear decline in performance with increasing noise. Subsequently attempts were made to ameliorate this deficit (study 2) using a cognitive training procedure based on attention process training (APT) that included graded exposure to irrelevant noise over the course of training. Patients were assigned to adaptive and non-adaptive training schedules or to a no-training control group. Results showed that both types of training drove improvements in the dichotic listening and in naturalistic tasks of performance in noise. Improvements were also seen on measures of selective attention in the visual domain suggesting transfer of training. We also observed augmentation of event-related potentials (ERPs) linked to target processing (P3b) but no change in ERPs evoked by distractor stimuli (P3a) suggesting that training heightened tuning of target signals, as opposed to gating irrelevant noise. No changes in any of the above measures were observed in a no-training control group. Together these findings present an ecologically valid approach to measure selective attention difficulties after brain injury, and provide a means to ameliorate these deficits.

Effects of clozapine on perceptual abnormalities and sensory gating: a preliminary cross-sectional study in schizophrenia

The aim of the present study was to investigate the effect of second-generation antipsychotics (clozapine or another second-generation antipsychotic) on perceptual abnormalities related to sensory gating deficit. Although clozapine is known to improve sensory gating assessed neurophysiologically, we hypothesized that patients with schizophrenia treated with clozapine would report less perceptual abnormalities related to sensory gating deficit than patients treated with other second-generation antipsychotics do. Forty patients with a diagnosis of schizophrenia were investigated (10 patients treated with clozapine and 30 patients treated with another second-generation antipsychotic drug). Perceptual abnormalities were assessed with the Sensory Gating Inventory. Sensory gating was assessed through electroencephalogram with the auditory event-related potential method by measuring P50 amplitude changes in a dual click conditioning-testing procedure. Patients treated with clozapine present normal sensory gating and report less perceptual abnormalities related to sensory gating than patients treated with other second-generation antipsychotics do. Although the cross-sectional design of this study is limited because causal inferences cannot be clearly concluded, the present study suggests clinical and neurophysiological advantages of clozapine compared with other second-generation antipsychotics and provides a basis for future investigations on the effect of this treatment on perceptual abnormalities related to sensory gating deficit in patients with schizophrenia.

On the correlation between perceptual inundation caused by realistic immersive environmental auditory scenes and the sensory gating inventory in schizophrenia

BACKGROUND

In schizophrenia, perceptual inundation related to sensory gating deficit can be evaluated "off-line" with the sensory gating inventory (SGI) and "on-line" during listening tests. However, no study investigated the relation between "off-line evaluation" and "on-line evaluation". The present study investigates this relationship.

METHODS

A sound corpus of 36 realistic environmental auditory scenes was obtained from a 3D immersive synthesizer. Twenty schizophrenic patients and twenty healthy subjects completed the SGI and evaluated the feeling of "inundation" from 1 ("null") to 5 ("maximum") for each auditory scene. Sensory gating deficit was evaluated in half of each population group with P50 suppression electrophysiological measure.

RESULTS

Evaluation of inundation during sound listening was significantly higher in schizophrenia (3.25) compared to the control group (2.40, P<.001). The evaluation of inundation during the listening test correlated significantly with the perceptual modulation (n=20, rho=.52, P=.029) and the over-inclusion dimensions (n=20, rho=.59, P=.01) of the SGI in schizophrenic patients and with the P50 suppression for the entire group of controls and patients who performed ERP recordings (n=20, rho=-.49, P=.027).

CONCLUSION

An evaluation of the external validity of the SGI was obtained through listening tests. The ability to control acoustic parameters of each of the realistic immersive environmental auditory scenes might in future research make it possible to identify acoustic triggers related to perceptual inundation in schizophrenia.

Validation of the French sensory gating inventory: a confirmatory factor analysis

The Sensory Gating Inventory (SGI) is an instrument investigating daily experiences of sensory gating deficit developed for English speaking schizophrenia patients. The purpose of this study is to design and validate a French version of the SGI. A forward-backward translation of the SGI was performed. The psychometric properties of the French SGI version were analyzed. A confirmatory factor analysis (CFA) was carried out to determine whether factor structure of the French version is similar to the original English version. In a sample of 363 healthy subjects (mean age=31.8 years, S.D.=12.2 years) the validation process revealed satisfactory psychometric properties: the internal consistency reliability was confirmed for each dimension; each item achieved the 0.40 standard threshold for item-internal consistency; each item was more highly correlated with its contributive dimension than with the other dimensions; and based on a CFA, we found a 4-factor structure for the French version of the SGI similar to the original instrument. Test-retest reliability was not determined. The French version of the SGI is a psychometrically sound self-report for measuring phenomenological sensory gating experiences.