P50 Suppression Research Articles

Evaluating the association between steroid hormones and filtering of sensory information in healthy women

Sensori (motor) gating is an integral part of information processing. Stress may affect information processing and is a potent risk factor for the onset and worsening of mental disorders. Sensori (motor) gating is affected by sex hormone rhythms, e.g. changes over the menstrual cycle. Here, we investigated if steroid hormones, i.e. cortisol and ovarian sex hormones, influence sensori (motor) gating. Data from 53 naturally cycling healthy women were analyzed in a cross-sectional design. Associations between prepulse inhibition (PPI) and P50 suppression variables and endogenous estradiol, progesterone, testosterone, total daily cortisol, and the cortisol awakening response were evaluated using multiple linear regression and Spearman's correlation. Total daily cortisol was negatively associated with PPI. Estradiol was positively associated with the acoustic startle response in the PPI paradigm and the P50 amplitude to the conditioning stimulus in the P50 paradigm. Steroid hormone levels were not associated with P50 suppression. In conclusion, estrogen and cortisol levels in healthy, naturally cycling women are associated with key brain measures of basic information processing. This finding may stimulate further studies into the role of stress hormones and estrogen transitions in modulating information filtering, which may be critical for risk and resilience to mental disorders.

Prepulse Inhibition and P50 Suppression in Relation to Creativity and Attention: Dispersed Attention Beneficial to Quantitative but Not Qualitative Measures of Divergent Thinking

The current study investigated whether lower sensory and sensorimotor gating were related to higher levels of creativity and/or attentional difficulties in a natural population of primary school children (9- to 13-year-old). Gating abilities were measured with P50 suppression and prepulse inhibition of the startle reflex (PPI). The final sample included 65 participants in the P50 analyses and 37 participants in the PPI analyses. Our results showed that children with a high P50 amplitude to testing stimuli scored significantly higher on the divergent outcome measures of fluency and flexibility but not originality compared to children with a lower amplitude. No significant differences were found on any of the creativity measures when the sample was split on average PPI parameters. No significant differences in attention, as measured with a parent questionnaire, were found between children with low or high levels of sensory or sensorimotor gating. The data suggest that quantitative, but not qualitative measures of divergent thinking benefit from lower psychophysiological gating and that attentional difficulties stem from specific instead of general gating deficits. Future studies should take the effect of controlled attention into consideration.

Dynamic brain functional network based on EEG microstate during sensory gating in schizophrenia

Objective. Cognitive impairment is one of the core symptoms of schizophrenia, with an emphasis on dysfunctional information processing. Sensory gating deficits have consistently been reported in schizophrenia, but the underlying physiological mechanism is not well-understood. We report the discovery and characterization of P50 dynamic brain connections based on microstate analysis. Approach. We identify five main microstates associated with the P50 response and the difference between the first and second click presentation (S1-S2-P50) in first-episode schizophrenia (FESZ) patients, ultra-high-risk individuals (UHR) and healthy controls (HCs). We used the signal segments composed of consecutive time points with the same microstate label to construct brain functional networks. Main results. The microstate with a prefrontal extreme location during the response to the S1 of P50 are statistically different in duration, occurrence and coverage among the FESZ, UHR and HC groups. In addition, a microstate with anterior–posterior orientation was found to be associated with S1-S2-P50 and its coverage was found to differ among the FESZ, UHR and HC groups. Source location of microstates showed that activated brain regions were mainly concentrated in the right temporal lobe. Furthermore, the connectivities between brain regions involved in P50 processing of HC were widely different from those of FESZ and UHR. Significance. Our results indicate that P50 suppression deficits in schizophrenia may be due to both aberrant baseline sensory perception and adaptation to repeated stimulus. Our findings provide new insight into the mechanisms of P50 suppression in the early stage of schizophrenia.

Selective 5HT3 antagonists and sensory processing: a systematic review

Ondansetron is a selective serotonin (5HT3) receptor antagonist that is under evaluation as an adjunctive treatment for schizophrenia, and a novel treatment for hallucinations in Parkinson’s disease. Ondansetron reverses sensory gating deficits and improves visuoperceptual processing in animal models of psychosis, but it is unclear to what extent preclinical findings have been replicated in humans. We systematically reviewed human studies that evaluated the effects of ondansetron and other 5HT3 receptor antagonists on sensory gating deficits or sensory processing. Of 11 eligible studies, eight included patients with schizophrenia who were chronically stable on antipsychotic medication; five measured sensory gating using the P50 suppression response to a repeated auditory stimulus; others included tests of visuoperceptual function. Three studies in healthy participants included tests of visuoperceptual and sensorimotor function. A consistent and robust finding (five studies) was that ondansetron and tropisetron (5HT3 antagonist and α7-nicotinic receptor partial agonist) improved sensory gating in patients with schizophrenia. Tropisetron also improved sustained visual attention in non-smoking patients. There was inconsistent evidence of the effects of 5HT3 antagonists on other measures of sensory processing, but interpretation was limited by the small number of studies, methodological heterogeneity and the potential confounding effects of concomitant medication in patients. Despite these limitations, we found strong evidence that selective 5HT3 antagonists (with or without direct α7-nicotinic partial agonist effects) improved sensory gating. Future studies should investigate how this relates to potential improvement in neurocognitive symptoms in antipsychotic naive patients with prodromal or milder symptoms, in order to understand the clinical implications.

Neurophysiological differentiation of personality disorders

The neurophysiological objectification of intranosological differentiation of main clusters (schizoid/paranoid and hysterical/emotionally unstable) within the typology of personality disorders (PD), as well as the differentiation of schizoid/paranoid PD and schizophrenia. Two groups of patients with PD participated in the study: PD1 - with schizoid/paranoid pattern (n=16), and PD2 - with hysterical/emotionally unstable pattern (n=18). The data were compared with the control group of healthy volunteers (n=86) and the group of schizophrenic patients (Sz, n=67). The analysis of four neurophysiological endophenotypes (measures of prepulse inhibition (PPI) of acoustic startle response and of P50 suppression, P300 amplitude, percentage of antisaccade errors) was carried out. The decrease of PPI and P50 suppression (measures of sensorimotor and sensory gating) relative to the control group was found both for Sz (p<0.01) and PD1 (p<0.05) groups. The highest P300 amplitude was observed in the control group, while the lowest values were observed in the Sz group (p<0.001); the values of PD1 and PD2 groups were intermediate. In all clinical groups percent of antisaccade errors was significantly higher compared to the control group (Sz - p<0.001; PD1 - p<0.05; PD2 - p<0.01). However, the level of the fronto-central cortical activation during antisaccade performance (estimated by contingent negative variation amplitude) was significantly reduced only in the Sz group (p<0.01), which is consistent with the concept of «hypofrontality» in schizophrenia. The changes associated with increased emotional reactivity were found in PD2 group only (P300 amplitude frontal maximum, asymmetry of error percent in antisaccade task). The study showed that two personality patterns in PD patients are related to the individual specificity of functional brain networks.

Auditory Sensory Gating in Children With Cochlear Implants: A P50-N100-P200 Study.

Background: While a cochlear implant (CI) can restore access to audibility in deaf children, implanted children may still have difficulty in concentrating. Previous studies have revealed a close relationship between sensory gating and attention. However, whether CI children have deficient auditory sensory gating remains unclear.Methods: To address this issue, we measured the event-related potentials (ERPs), including P50, N100, and P200, evoked by paired tone bursts (S1 and S2) in CI children and normal-hearing (NH) controls. Suppressed amplitudes for S2 compared with S1 in these three ERPs reflected sensory gating during early and later phases, respectively. A Swanson, Nolan, and Pelham IV (SNAP-IV) scale was performed to assess the attentional performance.Results: Significant amplitude differences between S1 and S2 in N100 and P200 were observed in both NH and CI children, indicating the presence of sensory gating in the two groups. However, the P50 suppression was only found in NH children and not in CI children. Furthermore, the duration of deafness was significantly positively correlated with the score of inattention in CI children.Conclusion: Auditory sensory gating can develop but is deficient during the early phase in CI children. Long-term auditory deprivation has a negative effect on sensory gating and attentional performance.

Investigation of auditory P50 sensory gating with sexual visual stimuli in patients with vaginismus

ObjectivesThe aim of the study was to investigate sensory information processing induced by visual sexual stimuli and to assess its relationship with sexual behaviors and symptoms in patients with vaginismus. MethodsTwenty-one patients with vaginismus and 20 controls were included in the study. The sociodemographic information and sexual life history of the patients with vaginismus and controls were examined and electrophysiological measurements related to auditory P50 sensory gating were obtained using a double click paradigm during by sexual/horror visual stimulation, which was thought to be related to the pathophysiology of the disease. ResultsP50 suppression ratios during visual sexual stimuli were lower in vaginismus group compared to the control group. There was no difference in P50 suppression ratios during visual horror stimuli when the two groups were compared. The P50 suppression of the vaginismus group with visual sexual stimuli was found to be lower than P50 suppression with visual horror stimuli. A positive moderate correlation was found between the duration of foreplay and P50 suppression ratio during visual sexual stimuli in vaginismus group. ConclusionOur study revealed that patients with vaginismus had sensory gating impairment during visual sexual stimuli. Increase in the duration of foreplay in vaginismus patients may improve sensory gating impairment by affecting sensory gating functions.

Objective electrophysiological fatigability markers and their modulation through tDCS

ObjectiveCognitive fatigability is a frequent symptom after sustained performance. Fatigability is evident in healthy subjects but is also often comorbid in several neuropsychiatric diseases. However, to date, clinical diagnostic almost solely relies on the self-reported subjective experience of fatigue. The goals of this present study were i) to complement the purely subjective fatigue diagnostic with objective electrophysiological fatigability parameters and ii) to prove the potential therapeutic application of transcranial direct current stimulation (tDCS) as a fatigability intervention. MethodsWe performed a pseudo-randomized, sham-controlled, parallel-group trial. Forty healthy participants received either anodal or sham tDCS over the left dorsolateral prefrontal cortex (DLPFC) while they performed an exhaustive cognitive task to induce cognitive fatigability. To assess fatigability changes, we analyzed variations of prepulse inhibition (PPI) and P50 suppression as well as frontomedial theta and occipital alpha power with time-on-task. ResultsThe task reliably induced subjective exhaustion in all participants. Furthermore, we confirmed fatigability-related increases in frontomedial theta and occipital alpha power throughout the task. Additionally, fatigability significantly reduced PPI as well as P50 sensory gating. Anodal tDCS over the left DLPFC successfully counteracted fatigability and reduced the fatigability-related increase in alpha power as well as the decline in both gating parameters. ConclusionOccipital alpha and sensorimotor/sensory gating are suitable parameters to assess the severity of fatigability objectively. Anodal tDCS can counteract fatigability and has therapeutic potential for the treatment of fatigability in neuropsychiatric diseases. SignificanceFatigability can be objectively assessed by electrophysiological measures and attenuated by tDCS.

Sensory Filtering and Sensory Memory in Breast Cancer Survivors.

Survivors of breast and other cancers often report protracted difficulty in performing tasks involving concentration and memory, even years after the completion of treatment. The current study investigated whether cancer and treatment history is associated with deficits in sensory filtering (gating out) and sensory memory (gating in), early processes in stimulus processing that may contribute to difficulties in later remembering. A group of breast cancer survivors and age-matched healthy control participants (mean age 54 years) underwent testing with paired-click and oddball tasks while electroencephalographic (EEG) signals were recorded. The survivors showed relatively poor inhibition of redundant sensory stimulation (P50 suppression). Dipole source analysis localized the survivors' impairment to the hippocampus, with preservation of function in gating mechanisms of the frontal lobe and auditory cortex. Survivors also showed disruption to sensory memory processes needed to register novel information in an otherwise uniform auditory environment (mismatch negativity). The findings suggest that survivors experience deficits in early, automatic mechanisms of sensory gating, which may trigger a cascade of later perceived attentional and memory deficits. If our account is accurate, ideal therapies might aim to restore early inhibitory processes, such as those gauged by P50 suppression.

The Influence of Background Auditory Noise on P50 and N100 Suppression Elicited by the Paired-Click Paradigm

Abstract. Auditory sensory gating is commonly assessed using the Paired-Click Paradigm (PCP), an electroencephalography (EEG) task in which two identical sounds are presented sequentially and the brain’s inhibitory response to the second sound is measured. Many clinical populations demonstrate reduced P50 and/or N100 suppression. Testing sensory gating in children may help to identify individuals at risk for neurodevelopmental disorders earlier, including autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD), which could lead to more optimal outcomes. Minimal research has been done with children because of the difficulty of performing lengthy EEG experiments with young children, requiring them to sit still for long periods of time. We designed a modified, potentially child-friendly version of the PCP and evaluated it in typically developing adults. The PCP was administered twice, once in a traditional silent room (silent movie condition) and once with an audible movie playing (audible movie condition) to minimize boredom and enhance behavioral compliance. We tested whether P50 and N100 suppression were influenced by the presence of the auditory background noise from the movie. N100 suppression was observed in both hemispheres in the silent movie condition and in the left hemisphere only during the audible movie condition, though suppression was attenuated in the audible movie condition. P50 suppression was not observed in either condition. N100 sensory gating was successfully elicited with an audible movie playing during the PCP, supporting the use of the modified task for future research in both children and adults.

Benzisothiazolone Derivatives Exhibit Cytotoxicity in Hodgkin's Lymphoma Cells through NF-κB Inhibition and are Synergistic with Doxorubicin and Etoposide.

The authors investigated the NF-κB inhibitory role of three Benzisothiazolone (BIT) derivatives (1, 2 and 3) in Hodgkin's Lymphoma cells (L428) which constitutively express activated NF-κB. All three compounds showed dose-dependent NF-κB inhibition (78.3, 70.7 and 34.6%) in the luciferase reporter gene assay and were found cytotoxic at IC50 values of 3.3μg/ml, 4.35μg/ml and 13.8μg/ml, respectively by the XTT assay. BIT 1and BIT 2 (but not BIT 3) suppressed both NF-κB subunits p50 and p65 in cytoplasmic and nuclear extracts in a concentration-dependent manner. Furthermore, BIT 1 showed a moderate synergistic effect with the standard chemotherapy drugs etoposide and doxorubicin, whereas BIT 2 and 3 showed a moderate additive effect to antagonistic effect. Cisplatin exhibited an antagonist effect on all the compounds tested under various concentrations, except in the case of 1.56μg/ml of BIT 3 with 0.156μg/ml of cisplatin. The compounds also inhibited the migration of adherent human lung adenocarcinoma cells (A549) in vitro. We conclude that especially BIT 1 and BIT 2 have in vitro anti-inflammatory and anti-cancer activities, which can be further investigated for future potential therapeutic use. Inspired by the electrophilic sulfur in Nuphar alkaloids, monomeric and dimeric benzisothiazolones were synthesized from dithiodibenzoic acid and their NF-κB inhibitory role was explored. NF-κB inhibition and cytotoxicity of the synthesized derivatives were studied using luciferase reporter gene assay and XTTassay. Immunocytochemistry studies were performed using L428 cells. Cell migration assay was conducted using the A549 cell line. L428 cells were used to conduct combination studies and the results were plotted using CompuSyn software. Benzisothiazolone derivatives exhibited cytotoxicity in Hodgkin's Lymphoma cells through NF-κB inhibition. Potent compounds showed suppression of both NF-κB subunits p50 and p65 in a concentrationdependent manner, both in cytoplasmic and nuclear extracts. Combination studies suggest that benzisothiazolone derivatives possess a synergistic effect with etoposide and doxorubicin. Furthermore, the compounds also inhibited the migration of A549 cells. Benzisothiazolones bearing one or two electrophilic sulfur atoms as part of the heterocyclic framework exhibited cytotoxicity in Hodgkin's Lymphoma cells through NF-κB inhibition. In addition, these derivatives also exhibited a synergistic effect with etoposide and doxorubicin along with the ability to inhibit the migration of A549 cells. Our study suggests that BIT-based new chemical entities could lead to potential anticancer agents.

Sensorimotor and sensory gating in depression, anxiety, and their comorbidity

Objectives Abnormal attentional and cognitive processes are thought to increase the risk for depression and anxiety. To improve understanding of brain mechanisms of anxiety and depressive disorders and condition of their comorbidity, the study of early attentional processes was provided. Methods Participants were patients with depressive (80 s.), anxiety (69 s.), and comorbid (41 s.) disorders, and healthy volunteers (50 s.). Acoustic startle response (ASR) and P50 component of the auditory event-related potential were recorded. Results In the ASR model decreased startle response amplitude at the left eye in patients with comorbid disorder was found, and ASR latency was lengthened in all clinical groups. Deficit of prepulse inhibition was unique for comorbid disorder, and might be considered as risk of evolution to more serious condition. Reduced prepulse facilitation was revealed in patients with comorbid and anxiety disorders. In P50 suppression paradigm decreased S1 response amplitude was revealed in all clinical groups, P50 latency was prolonged in depressive and comorbid patients, and P50 suppression deficit was observed in depression and anxiety groups. Conclusions The obtained results might be useful for development of integrative neural models of comorbidity of anxiety and depression, and elaboration of diagnostic and therapeutic approaches.

Using high density EEG to assess TMS treatment in patients with schizophrenia.

We present preliminary results from the ongoing study entitled “Icelandic AVH-TMS” which aim is to study the effectiveness of repetitive transcranial magnetic stimulation (rTMS) treatment for patients with schizophrenia and with persistent auditory verbal hallucinations (AVH) using symptoms and psychometric scales and high-density EEG system (256 channels). The aim of the present work was to describe cortical topography of the auditory evoked responses like P50 and N100-P300 complex in healthy participants and patients with schizophrenia and to define a robust methodology of signal quantification using dense-array EEG. Preliminary data is shown for three healthy participants and three patients in baseline conditions and for two patients we show the results recorded before and after 10 days rTMS treatment. Our results show differences in sensory gating (P50 suppresion) and a stronger N100-P300 response to rare audio stimulus after the treatment. Moreover we show the value of assessing brain electrical activity from high-density EEG (256 channels) analyzing the results in different regions of interest. However, it is premature and hazardous to assume that rTMS treatment effectiveness in patients with AVH can be assessed using P50 suppression ratio.

Association of cognitive and P50 suppression deficits in chronic patients with schizophrenia

ObjectiveCognitive deficits are core symptoms of schizophrenia; however, their pathophysiological mechanisms are still unclear. A sensory gating deficit, as reflected by P50 suppression, has been repeatedly shown in schizophrenia patients, which may be associated with cognitive deficits in this disorder. The present study was to examine the relationship between the P50 suppression and cognitive deficits in patients with schizophrenia, which is still under-investigated. MethodWe recruited 38 chronic schizophrenia patients and 32 matched healthy controls, and assessed their cognition with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and P50 suppression with the electroencephalography system. ResultsThe total and its 4 index scores (all p < 0.05) except for the visuospatial/ constructional index of RBANS were significantly lower in patients compared with healthy controls. However, only the language and attention passed Bonferroni corrections. Patients displayed a significantly higher P50 ratio, higher S2 amplitude, and lower S1 amplitude (all p < 0.05) than healthy controls. Interestingly, only in the patients, the S1 amplitude was associated with both language and attention, and the S2 amplitude with both visuospatial/ constructional and language (all p < 0.05), although all of these significances did not pass the Bonferroni corrections. The P50 ratio was not associated with any of the RBANS scores (all p > 0.05). ConclusionsOur results suggest the P50 suppression deficits in Chinese patients with schizophrenia, which may be associated with cognitive impairments of this illness. Moreover, the amplitude of S1 and the amplitude of S2 may be involved in the different cognitive domain deficits in schizophrenia patients. SignificanceThis study suggests that the P50 components may possibly be effective biomarkers for cognitive deficits in patients with schizophrenia.

The comparative study of the early stages of sensory and sensory-motor information processing in aggressive and non-aggressive schizophrenic patients

To study the early stages of sensory (P50 suppression) and sensorimotor (prepulse modification of acoustic startle reaction - ASR) information processing in aggressive and non-aggressive patients with schizophrenia. Two groups (aggressive group A, 44 s. and non-aggressive group NA, 27 s.) and 48 healthy people were studied using oculography and encephalography. Symptoms of schizophrenia were assessed by PANSS. The analysis of ASR and P50 revealed the increased ASR latency, deficit of prepulse inhibition (PPI) with 60 ms leading interval, and P50 suppression in patients compared to controls. Aggressive behavior impacted on lateral features of ASR changes in the group A. The increase of ASR amplitude and the decline of prepulse facilitation were found in the group NA. The P50 analysis revealed the increased P50 amplitude and the shortened latency in response to 2nd stimulus in the pair. The increase in scores on item G14 of the PANSS (Poor impulse control) in the group A and its correlations with ASR and P50 parameters in this group suggested the important role of impulsivity in aggressive behavior in the studied sample of aggressive patients. ASR and P50 characteristics in the group NA are associated with increased sensitivity to incoming stimuli and such personality traits as increased alertness and fear, which might inhibit aggression. Thus, indicators of the early stages of information processing can be considered as potential predictors of aggressive behavior.

EEG-Based Brain Functional Connectivity in First-Episode Schizophrenia Patients, Ultra-High-Risk Individuals, and Healthy Controls During P50 Suppression.

Dysfunctional processing of auditory sensory gating has generally been found in schizophrenic patients and ultra-high-risk (UHR) individuals. The aim of the study was to investigate the differences of functional interaction between brain regions and performance during the P50 sensory gating in UHR group compared with those in first-episode schizophrenia patients (FESZ) and healthy controls (HC) groups. The study included 128-channel scalp Electroencephalogram (EEG) recordings during the P50 auditory paradigm for 35 unmedicated FESZ, 30 drug-free UHR, and 40 HC. Cortical sources of scalp electrical activity were recomputed using exact low-resolution electromagnetic tomography (eLORETA), and functional brain networks were built at the source level and compared between the groups (FESZ, UHR, HC). A classifier using decision tree was designed for differentiating the three groups, which uses demographic characteristics, MATRICS Consensus Cognitive Battery parameters, behavioral features in P50 paradigm, and the measures of functional brain networks based on graph theory during P50 sensory gating. The results showed that very few brain connectivities were significantly different between FESZ and UHR groups during P50 sensory gating, and that a large number of brain connectivities were significantly different between FESZ and HC groups and between UHR and HC groups. Furthermore, the FESZ group had a stronger connection in the right superior frontal gyrus and right insula than the HC group. And the UHR group had an enhanced connection in the paracentral lobule and the middle temporal gyrus compared with the HC group. Moreover, comparison of classification analysis results showed that brain network metrics during P50 sensory gating can improve the accuracy of the classification for FESZ, UHR and HC groups. Our findings provide insight into the mechanisms of P50 suppression in schizophrenia and could potentially improve the performance of early identification and diagnosis of schizophrenia for the earliest intervention.

P50-N100-P200 sensory gating deficits in adolescents and young adults with autism spectrum disorders

Sensory symptoms are common in individuals with autism spectrum disorder (ASD). Altered sensory gating may cause sensory overload. However, whether ASD individuals have P50 gating deficits is controversial in childhood and lacks evidence in adulthood. Beyond P50, fewer studies have examined N100 or P200, although N100 is considered to be more reliable than P50. Also, the clinical correlates of these parameters are mostly unknown. This study aimed to investigate P50, N100, and P200 sensory gating in adolescents and young adults with ASD and examine their clinical correlates. In a sample of 34 ASD participants (mean age 20.6 ± 4.1, female 5.9%) and 34 sex- and age-matched typically-developing controls (TDC, mean age 20.4 ± 3.1), we investigated P50, N100, and P200 sensory gating by a paired-click paradigm, which generated the data of S1 amplitude after the first click and S2 amplitude after the second click. We found that compared to TDC, ASD participants had significant N100 suppression deficits reflected by a larger N100 S2 amplitude, smaller N100 ratio of S2 over S1, and the difference between the two amplitudes. N100 S2 amplitude was significantly associated with sensory sensitivity independent of the diagnosis. Although there was no group difference in P50 suppression, S1 amplitude was negatively associated with social deficits in ASD. P200 gating parameters were correlated with attention switching difficulty. Our findings suggest N100 gating deficit in adolescents and young adults with ASD. The relationships between P50 S1 and social deficits and between N100 S2 and sensory sensitivity warrant further investigation.

Discriminating schizophrenia disease progression using a P50 sensory gating task with dense-array EEG, clinical assessments, and cognitive tests

ABSTRACTBackground: Schizophrenia affects approximately 10% of the world’s population. Early detection of schizophrenia may significantly delay its progression. Although sensory gating deficits are reported in schizophrenia, it remains challenging how sensory gating deficits can be used with other metrics for risk detection and early diagnosis.Research design and methods: Using EEG, the authors examined effects of sensory gating on the performance of 136 participants in a P50 sensory gating task, including patients with first-episode schizophrenia (FESZ), ultra-high risk (UHR) individuals, high-risk (HR) individuals, and age- and sex-matched healthy controls (HCs). The authors also explored the differences among all groups using clinical assessments and cognitive tests.Results: Compared with HCs, HR, UHR and FESZ groups showed significant P50 suppression impairment. Furthermore, EEG source localization analyses identified successively stronger activation in prefrontal and anterior temporal regions in the HR, UHR and FESZ groups than in the HC group. Moreover, brain connectivity (HC < HR < UHR < FESZ) in the gamma band of P50 components was increasingly enhanced in accordance with the level of psychosis risks.Conclusions: These findings suggest that EEG source imaging techniques, brain network dynamics, and behavioral tests, can help clearly distinguish different stages of schizophrenia, and may assist in the early diagnosis of schizophrenia.

Enhanced high-frequency precuneus-cortical effective connectivity is associated with decreased sensory gating following total sleep deprivation

Sleep deprivation decreases an individual's cognitive function. When cognitive impairment reaches a certain level, human errors occur and may even result in accidents. Previous research has shown that sensory gating is a basic mechanism in cognitive function, but only limited studies have so far reported how it is affected by sleep deprivation. This study aimed to analyze the effects of sleep deprivation on sensory gating and its cognitive and neural mechanisms. Thirty-six healthy subjects participated in our study. The resting-state, auditory P50-task electroencephalography (EEG) recordings and the psychomotor vigilance task (PVT) were performed at resting wakefulness (RW) and after 36 h of total sleep deprivation (TSD). Changes in P50 suppression before and after sleep deprivation were recorded, and the isolated effective coherence (iCoh) was employed for analyzing effective connectivity based on EEG data during the resting-state and P50 tasks. Subjects demonstrated reduced P50 suppression and prolonged PVT reaction time after TSD compared with RW. Effective connectivity analysis of resting-state EEG data showed that sleep deprivation decreased the connectivity from the right middle occipital gyrus (RMOG)/Rcuneus to left inferior/middle temporal gyrus (LITG/LMTG) and left parahippocampal/fusiform gyrus (LPH/LFG). EEG data analysis during the P50 task showed that, in addition to the aforementioned connectivity changes, the directed high-frequency effective connectivity from the left precuneus to the left superior/middle frontal gyrus (LSFG/LMFG), LITG/LMTG, LPH/LFG, and left middle occipital gyrus (LMOG)/Lcuneus increased. P50 suppression in Cz positively correlated with PVT reaction time. This study reveals that the precuneus is a key brain region in neural network correlates of sensory gating, and that changes in its effective connectivity with other regions (including LSFG/LMFG, LPH/LFG, LMOG/LCuneus, and LITG/LMTG) are important for decreasing sensory gating after TSD.

Startle habituation, sensory, and sensorimotor gating in trauma-affected refugees with posttraumatic stress disorder.

Impairments in mechanisms underlying early information processing have been reported in posttraumatic stress disorder (PTSD); however, findings in the existing literature are inconsistent. This current study capitalizes on technological advancements of research on electroencephalographic event-related potential and applies it to a novel PTSD population consisting of trauma-affected refugees. A total of 25 trauma-affected refugees with PTSD and 20 healthy refugee controls matched on age, gender, and country of origin completed the study. In two distinct auditory paradigms sensory gating, indexed as P50 suppression, and sensorimotor gating, indexed as prepulse inhibition (PPI), startle reactivity, and habituation of the eye-blink startle response were examined. Within the P50 paradigm, N100 and P200 amplitudes were also assessed. In addition, correlations between psychophysiological and clinical measures were investigated. PTSD patients demonstrated significantly elevated stimuli responses across the two paradigms, reflected in both increased amplitude of the eye-blink startle response, and increased N100 and P200 amplitudes relative to healthy refugee controls. We found a trend toward reduced habituation in the patients, while the groups did not differ in PPI and P50 suppression. Among correlations, we found that eye-blink startle responses were associated with higher overall illness severity and lower levels of functioning. Fundamental gating mechanisms appeared intact, while the pattern of deficits in trauma-affected refugees with PTSD point toward a different form of sensory overload, an overall neural hypersensitivity and disrupted the ability to down-regulate stimuli responses. This study represents an initial step toward elucidating sensory processing deficits in a PTSD subgroup.