Diagnostic specificity and familiality of early versus late evoked potentials to auditory paired stimuli across the schizophrenia-bipolar psychosis spectrum.

Disrupted sensory processing is a core feature of psychotic disorders. Auditory paired stimuli (PS) evoke a complex neural response, but it is uncertain which aspects reflect shared and/or distinct liability for the most common severe psychoses, schizophrenia (SZ) and psychotic bipolar disorder (BDP). Evoked time-voltage/time-frequency domain responses quantified with EEG during a typical PS paradigm (S1-S2) were compared among proband groups (SZ [n = 232], BDP [181]), their relatives (SZrel [259], BDPrel [220]), and healthy participants (H [228]).

Spatiotemporal and frequency domain analysis of auditory paired stimuli processing in schizophrenia and bipolar disorder with psychosis.

Individuals with schizophrenia (SZ) or bipolar disorder with psychosis (BPP) may share neurophysiological abnormalities as measured in auditory paired-stimuli paradigms with electroencephalography (EEG). Such investigations have been limited, however, by quantifying only event-related potential peaks and/or broad frequency bands at limited scalp locations without considering possible mediating factors (e.g.

Target probability affects the likelihood that a P300 will be generated in response to a target stimulus, but not its amplitude.

The ensemble-averaged P300 amplitude is affected by global and local target probability and interstimulus interval. We hypothesize that the local target probability-induced amplitude changes arise from a failure to consistently produce a P300 rather than producing lower amplitude responses. Single-trial analysis was conducted on auditory P300 data from 13 healthy subjects to determine the absence or presence of a P300 component for each target response separately.

Generators of the intracranial P50 response in auditory sensory gating.

Clarification of the cortical mechanisms underlying auditory sensory gating may advance our understanding of brain dysfunctions associated with schizophrenia. To this end, data from nine epilepsy patients who participated in an auditory paired-click paradigm during pre-surgical evaluation and had grids of electrodes covering temporal and frontal lobe were analyzed. A distributed source localization approach was applied to the intracranial P50 response and the Gating Difference Wave obtained by subtracting the response to the second stimuli from the response to the first stimuli.

Genetic and environmental influences on sensory gating of mid-latency auditory evoked responses: a twin study.

A deficit in sensory gating measured by the suppression of P50 auditory event-related potential (ERP) has been implicated in the biological bases of schizophrenia and some other psychiatric disorders and proposed as a candidate endophenotype for genetic studies. More recently, it has been shown that gating deficits in schizophrenics extend to ERP components reflecting early attentive processing (the N1/P2 complex). However, evidence for heritability of sensory gating in the general population is very limited.

Habituation of auditory evoked potentials in intracranial and extracranial recordings.

Effects of stimulus repetition are investigated in short-term habituation experiments. In these experiments, trains of stimuli are applied with longer intervals of no stimulation between the trains. In scalp recordings, an amplitude and latency decrease of the auditory N100 is usually observed at the beginning of the train.

gamma-Aminobutyric acid-serotonin interactions in healthy men: implications for network models of psychosis and dissociation.

Background: This study tested the hypothesis that deficits in gamma-aminobutyric acid type A (GABA(A)) receptor function might create a vulnerability to the psychotogenic and perceptual altering effects of serotonergic (5-HT(2A/2C)) receptor stimulation. The interactive effects of iomazenil, an antagonist and partial inverse agonist of the benzodiazepine site of the GABA(A) receptor complex, and m-chlorophenylpiperazine (m-CPP), a partial agonist of 5-HT(2A/2C) receptors, were studied in 23 healthy male subjects.

Methods: Subjects underwent 4 days of testing, during which they received intravenous infusions of iomazenil/placebo followed by m-CPP/placebo in a double-blind, randomized crossover design.

Risk factors for experiencing psychosis during cocaine use: a preliminary report.

Unlabelled: Cocaine induced psychosis (CIP) is a common, but not universal side effect of cocaine abuse. Factors underlying the development and severity of CIP remain poorly understood. This study tests the hypothesis that earlier age of initiation of regular use may increase the likelihood of developing CIP, or the severity of CIP symptoms.

Subdural recordings of the mismatch negativity (MMN) in patients with focal epilepsy.

Mismatch negativity (MMN) is elicited by discernible changes in an otherwise regular stream of auditory stimulation and reflects a pre-attentive detection mechanism. In the current study, auditory evoked potentials were recorded intracranially and electrode contacts sensitive for stimulus deviance were selected in order to further elucidate the contribution of different brain areas to MMN generation. Data were obtained from patients with frontal and temporal lobe epilepsy undergoing a presurgical evaluation by subdural and depth electrodes.

Cortical excitability in cocaine-dependent patients: a replication and extension of TMS findings.

Cortical excitability can be assessed by transcranial magnetic stimulation (TMS). Previously we observed that TMS motor threshold (MT) was elevated in abstinent cocaine-dependent subjects. In the current study we aimed at replicating our initial finding, exploring other TMS-based measures of excitability, and examining association with personality characteristics.

Short-term habituation of the intracranially recorded auditory evoked potentials P50 and N100.

At an interstimulus interval (ISI) of 500-ms stimulus repetition leads to a strong decrease in cortical response. The functional foundation of this response suppression (or sensory gating) is yet not fully understood. Experiments on short-term habituation using the same stimulus material as sensory gating experiments and same ISI might help to elucidate the mechanisms behind the P50 suppression.

Altered NMDA glutamate receptor antagonist response in individuals with a family vulnerability to alcoholism.

Objective: A family history of alcoholism is a risk factor for the development of ethanol dependence. Ethanol is an antagonist of the N-methyl-d-aspartate (NMDA) glutamate receptor, and alterations in NMDA receptor function are thought to be involved in ethanol abuse and dependence. The purpose of this study was to determine in healthy individuals with no ethanol dependence whether response to the NMDA receptor antagonist ketamine would differentiate those with a family history of ethanol dependence from those without such a family history.

Morphological and latency abnormalities of the mid-latency auditory evoked responses in schizophrenia: a preliminary report.

Introduction: Evoked potential (EP) amplitude and latency abnormalities have been extensively examined in schizophrenia. Morphological abnormalities of the mid-latency auditory evoked responses (MLAERs; P50, N100, P200), on the other hand, received very little attention.

Methods: Based on a priori defined set of morphological criteria, the morphology and latency of the MLAERs were blindly compared between stable outpatients with schizophrenia (N=27) and age- and gender-matched healthy control subjects (N=22).

Sensory gating deficits during the mid-latency phase of information processing in medicated schizophrenia patients.

Sensory gating during preattentive phases of information processing has been extensively examined. Sensory gating processes that occur during subsequent phases of information processing have not been fully examined. The relationship between P50 sensory gating and schizophrenia symptoms remains underspecified and the clinical correlates of N100 and P200 gating are yet to be examined.

Contribution of different EEG frequencies to auditory evoked potential abnormalities in schizophrenia.

Objective: We have shown previously [Clin Neurophysiol 2003;114:79] that phase reorganization of the ongoing electroencephalogram (EEG) plays an important role in the generation of auditory evoked potential (EP) components with a latency between 50 and 200 ms. In the present study, we investigate whether schizophrenia patients suffer from phase synchronization deficits as compared to normal subjects.

Methods: The auditory EPs from 20 normal subjects and 19 schizophrenia patients were analyzed.

Altered NMDA glutamate receptor antagonist response in recovering ethanol-dependent patients.

Ethanol is an antagonist of the N-methyl-D-aspartate (NMDA) glutamate receptor. Ethanol dependence upregulates NMDA receptors and contributes to crosstolerance with selective NMDA receptor antagonists in animals. This study evaluated whether recovering ethanol-dependent patients show evidence of a reduced level of response to the effects of the NMDA receptor antagonist, ketamine.

Electrophysiological aberrations in borderline personality disorder: state of the evidence.

Electrophysiological technology is noninvasive and relatively inexpensive. In order to assess the usefulness of this technology in probing the pathophysiology of borderline personality disorder (BPD), we reviewed the literature in which an electrophysiological modality was used to examine BPD. Twenty-two articles were identified, from which diagnostic criteria and data on comorbidity and control groups were extracted.

Neuronal substrates of sensory gating within the human brain.

Background: For the human brain, habituation to irrelevant sensory input is an important function whose failure is associated with behavioral disturbances. Sensory gating can be studied by recording the brain's electrical responses to repeated clicks: the P50 potential is normally reduced to the second of two paired clicks but not in schizophrenia patients. To identify its neural correlates, we recorded electrical traces of sensory gating directly from the human hippocampus and neocortex.

Lack of a therapeutic effect of a 2-week sub-threshold transcranial magnetic stimulation course for treatment-resistant depression.

Stimulation parameters seem to strongly influence the efficacy of repetitive transcranial magnetic stimulation (rTMS) in the management of treatment-resistant depressed patients. The most effective and safest parameters are yet to be defined. Moreover, systematic follow-up data available to document the duration of the therapeutic effects remain sparse.

Phase synchronization of the ongoing EEG and auditory EP generation.

Objective: We investigated the role of phase synchronization of the spontaneous electroencephalogram (EEG) in auditory evoked potential (EP) generation in a sample of healthy individuals.

Methods: Auditory responses were obtained from 20 healthy subjects following a double stimulus paradigm, using two identical tone bursts (S1 and S2) separated by 0.5s.

The health-related effects of alcohol use in older persons: a systematic review.

Increased alcohol consumption is associated with substantial morbidity and mortality in young and middle-aged adult populations, but its effects on the health of older adults have received less attention. The objective of the study was to review published studies that assessed the effects of alcohol on falls or fall injuries, functional impairment, cognitive impairment, and all-cause mortality among older adults. MEDLINE database and bibliographies of selected citations were searched for English language studies published between 1966 and 1998 that examined the relationship between alcohol and one or more of the above outcomes.

The effect of tryptophan depletion on alcohol self-administration in non-treatment-seeking alcoholic individuals.

Background: Alcohol self-administration in the laboratory has been used to evaluate pharmacological treatments and neurobiological mechanisms that underlie alcohol use in alcohol-dependent individuals. This study evaluated whether attenuation of serotonin synthesis via depletion of its precursor tryptophan reduces the amount of alcohol consumed in a self-administration paradigm in non-treatment-seeking individuals with alcohol use disorders.

Methods: Individuals with alcohol dependence (n = 8) and alcohol abuse (n = 4) who were not seeking treatment were recruited by advertisement and participated in two test days, 1 week apart.