P50, N100, and P200 auditory sensory gating could reflect mechanisms involved in protecting higher-order cognitive functions, suggesting relationships between sensory gating and cognition. This hypothesis was tested in 56 healthy adults who were administered the paired-click paradigm and two adaptations of the continuous performance test (Immediate/Delayed Memory Task, IMT/DMT). Stronger P50 gating correlated with fewer commission errors and prolonged reaction times on the DMT. Stronger N100 and P200 gating correlated with better discriminability on the DMT. Finally, prolonged P200 latency related to better discriminability on the IMT. These findings suggest that P50, N100, and P200 gating could be involved in protecting cognition by affecting response bias, behavioral inhibition, working memory, or attention.

The clinical and neuro-cognitive correlates of the P50 and N100 auditory evoked responses gating deficits in schizophrenia have thus far eluded identification. Based on our prior results, we hypothesized that, in addition to the P50, gating of the N100 is significantly decreased in schizophrenia and that this deficit correlates with the negative symptoms dimension of schizophrenia. Amplitudes and gating measures of the P50 and N100 were compared between stable outpatients (N=45) (mainly on atypical antipsychotics) with chronic schizophrenia and age-and gender-matched healthy controls (N=49) and the clinical correlates examined. All subjects underwent the pairedstimulus paradigm in 3 or 4 different days. Data from day one and the mean of all days (MOAD) were examined. P50 and N100 amplitudes and gating measures were correlated with PANSS and Wisconsin Card Sorting Test data. Utilizing day one data, no amplitude or gating measures were significantly different between the groups. Utilizing MOAD data, both P50 and N100 gating were significantly decreased in schizophrenia patients. The N100 gating deficit correlated with the negative-symptoms cluster and measures of frontal lobe dysfunction. The data suggest a correlation between N100 gating deficit and the negative-cognitive deficits dimensions of schizophrenia. Data also suggest that improving the signal to noise ratio (MOAD data) increases the sensitivity for detecting gating abnormalities and assessing their clinical correlates.Corresponding Author: Nash Boutros, MD. UPC-Jefferson., 2751 E. Jefferson, Suite 305, Detroit, MI 48207. Tel : 313-577-6687, Fax 313-577-5201, Email: nboutros@med.wayne.edu. Contributors: Dr. N.N. Boutros designed and managed the study. Drs. K. Gjini and A. Vedeniapin helped with data analysis and manuscript preparation. Drs. A. Brockhaus-Dumke, and Dr. Keshavan helped with data interpretation and writing of the manuscript. Mr. M. Elfakhani and Mr. S. Burroughs performed all subject recruitment, evoked potential evaluations (including peak picking) and data tabulation (including cross checking for errors).Conflicts of interest: None of the authors of this manuscript has any financial conflict or any form of conflict of interest with material presented. All authors had had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access IntroductionThe ability to inhibit or suppress the response to incoming irrelevant or redundant sensory input is a well do...

P50, N100, and P200 auditory sensory gating reflect distinct mechanisms involved in protecting the integrity of higher-order functions. They have been implicated in multiple psychiatric disorders. Recent studies showed the (limited) effects of age and gender on sensory gating in control subjects, suggesting there may be other sources of variance. Two potential sources may be education and intelligence (intellectual capability), variables that frequently differ across studies and across experimental groups. We explored potential effects of age, gender, education, and intelligence (Shipley intelligence scale) on P50, N100, and P200 sensory gating measured with the paired-click paradigm in 60 healthy subjects recruited from the general population. Increased intellectual capability related to stronger N100 and P200 gating and more pronounced N100 and P200 amplitudes. In addition, increased age related to weaker P200 gating and smaller P200 amplitudes. Gender had negligible effects. Intellectual capability or age could contribute to variation in N100 or P200 auditory sensory gating and should be controlled for when studying sensory gating in clinical and control groups.

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BackgroundWhile there is increasing evidence of altered brain connectivity in autism, the degree and direction of these alterations in connectivity and their uniqueness to autism has not been established. The aim of the present study was to compare connectivity in children with autism to that of typically developing controls and children with developmental delay without autism.MethodsWe assessed EEG spectral power, coherence, phase lag, Pearson and partial correlations, and epileptiform activity during the awake, slow wave sleep, and REM sleep states in 137 children aged 2 to 6 years with autism (n = 87), developmental delay without autism (n = 21), or typical development (n = 29).FindingsWe found that brain connectivity, as measured by coherence, phase lag, and Pearson and partial correlations distinguished children with autism from both neurotypical and developmentally delayed children. In general, children with autism had increased coherence which was most prominent during slow wave sleep.InterpretationFunctional connectivity is distinctly different in children with autism compared to samples with typical development and developmental delay without autism. Differences in connectivity in autism are state and region related. In this study, children with autism were characterized by a dynamically evolving pattern of altered connectivity.

Purpose Hypsarrhythmia, the pathognomonic EEG pattern of West syndrome, is typically characterized by a high amplitude, arrhythmic, and asynchronous pattern. While this severely aberrant pattern would suggest severe abnormalities in connectivity, coherence has not yet been systematically assessed in hypsarrhythmia. Methods We evaluated the EEGs of 28 infants, 12 with infantile spasms with hypsarrhythmia and 16 similarly age control infants for coherence and spectral power. Results Children with infantile spasms and hypsarrhythmia EEGs had marked abnormalities in coherence and spectral power compared to normal children of similar ages. During sleep increases in delta, theta, alpha and beta coherences were seen, particularly at long inter-electrode distances while at short inter-electrode distances coherences were decreased in the theta and beta range, particularly in the frontal region. The enhanced coherences at long inter-electrode distances suggest that during sleep in children with infantile spasms widely spread cortical region do not have functional differentiation whereas in the frontal lobe there is reduced functional connectivity and integration of local cortical regions. Children with continued seizures and developmental delay showed persistent abnormalities in coherence. Conclusion This study demonstrates that hypsarrhythmic EEGs have marked abnormalities in coherence spectral power and such abnormalities may be related to cognitive impairment.

The paired-click paradigm (PCP) is widely used to study sensory habituation or gating in a number of psychiatric and neurological conditions. The classic paradigm does not control for attentional factors. In order to assess the influences of incorporating attentional control measures we administered the auditory PCP (S1–S2) in three different attention (passive, auditory attention to S2, visual attention to a concurrent continuous performance task [CPT]) conditions to a group of chronic, medicated schizophrenia patients (N=12) and a group of healthy subjects (N=15) to evaluate the effects of attention on sensory gating measures. A significant effect of attention on S1 amplitudes was shown for P50 in both groups, and N100 or P200 in schizophrenia patients. Attention status had a significant effect on S2 amplitudes for N100 and P200, and N100 and P200 gating ratios. Despite the effect of attention on S1 P50 amplitudes there was no effect on the gating ratio. In terms of group differences, visual attention to the concurrent CPT during the paired-click sensory gating task significantly enhanced the detection of deficient gating of the N100 and P200 components in schizophrenia patients. The data support the continued utilization of the passive gating paradigm for examining P50 gating but strongly suggest that for studies examining gating of the N100 or P200 components, a visual distraction paradigm may enhance the detection of abnormal gating in schizophrenia patients.

Although there are several reports of patients with cocaine dependence displaying cognitive deficits, the nature of their information processing deficits is not well characterized. In the present study, the attentional performance of cocaine-dependent patients (n = 14) was examined and compared with that of healthy control individuals (n = 15). Attention was assessed using an auditory oddball eventrelated task as well as the Continuous Performance Test (CPT; Identical Pairs version). The cocainedependent group displayed P300 amplitude reduction compared to controls. The group difference in P300 response latency did not reach significance. On the CPT, the cocaine-dependent patients displayed significantly poorer discriminability and greater errors of commission than the controls. There was a positive correlation between performance on the oddball event-related task and performance on the CPT. This investigation provides converging behavioral and electrophysiological evidence of attentional deficits in cocaine-dependent patients.