Functional connectivity profiles in remitted depression and their relation to ruminative thinking.

The triple network model suggests that dysfunction in three major brain networks - the default mode network (DMN), central executive network (CEN), and salience network (SN) - might contribute to cognitive impairments in various psychiatric disorders, including major depressive disorder (MDD). While hyperconnectivity in the DMN, hypoconnectivity in the CEN, and abnormal SN connectivity have been observed in acutely depressed patients, evidence for network alterations during remission is limited. Further, there are few studies examining connectivity in people in remission from MDD (rMDD) during emotional processing tasks, including during affective cognition (i.

Simultaneous EEG + fMRI study of brain activity during an emotional Stroop task in individuals in remission from depression.

Individuals in remission from depression (MDDR) tend to experience lingering cognitive and emotional processing alterations. However, little is known about the neural profiles underlying these features. Using simultaneous EEG+fMRI, we assessed neural profiles during the emotional word Stroop task (eStroop) in people with MDDR and healthy volunteers (HVs).

Sensory gating in tobacco-naïve cannabis users is unaffected by acute nicotine administration.

Objectives: Long-term cannabis use has been associated with the appearance of psychotic symptoms and schizophrenia-like cognitive impairments; however these studies may be confounded by concomitant use of tobacco by cannabis users. We aimed to determine if previously observed cannabis-associated deficits in sensory gating would be seen in cannabis users with no history of tobacco use, as evidenced by changes in the P50, N100, and P200 event-related potentials. A secondary objective of this study was to examine the effects of acute nicotine administration on cannabis users with no tobacco use history.

Interaction of Background Noise and Auditory Hallucinations on Phonemic Mismatch Negativity (MMN) and P3a Processing in Schizophrenia.

Unlabelled: Auditory hallucinations (AHs) are among the cardinal symptoms of schizophrenia (SZ). During the presence of AHs aberrant activity of auditory cortices have been observed, including hyperactivation during AHs alone and hypoactivation when AHs are accompanied by a concurrent external auditory competitor. Mismatch negativity (MMN) and P3a are common ERPs of interest within the study of SZ as they are robustly reduced in the chronic phase of the illness.

Alterations of Resting EEG in Hallucinating and Nonhallucinating Schizophrenia Patients.

Auditory hallucinations (AHs) are a common symptom of schizophrenia and contribute significantly to disease burden. Research on schizophrenia and AHs is limited and fails to adequately address the effect of AHs on resting EEG in patients with schizophrenia. This study assessed changes in frequency bands (delta, theta, alpha, beta) of resting EEG taken from hallucinating patients (n = 12), nonhallucinating patients (n = 11), and healthy controls (n = 12).

Mismatch negativity-indexed auditory change detection of speech sounds in early and chronic schizophrenia.

Auditory change detection, as indexed by the EEG-derived mismatch negativity, has been demonstrated to be dysfunctional in chronic schizophrenia using both pure-tone and speech (phoneme) sounds. It is unclear, however, whether reduced MMN amplitudes to speech sound deviants are observed within the first 5 years of the illness. The present study investigated MMNs elicited by across-vowel (phoneme) change in early schizophrenia (ESZ; Experiment 1) as well as chronic schizophrenia (CSZ; Experiment 2).

Mismatch negativity in tobacco-naïve cannabis users and its alteration with acute nicotine administration.

Chronic cannabis use may interact with factors, such as age of onset of cannabis use, family history, and genetic factors, to elicit schizophrenia (SZ)-like symptoms, including sensory and cognitive deficits. However, evidence of a relationship between cannabis use and cognitive impairment is confounded by concomitant use of tobacco. The objective of this study was to compare tobacco-naïve cannabis users with individuals without a history of tobacco/cannabis use on the auditory mismatch negativity (MMN) event-related potential (ERP), a neural measure of auditory deviance detection which is diminished in SZ.

Attenuation of mismatch negativity (MMN) and novelty P300 in schizophrenia patients with auditory hallucinations experiencing acute exacerbation of illness.

This study examined measures of early auditory feature analysis, including the mismatch negativity (MMN) and novelty P300 (NP3) in schizophrenia patients (SZ) with persistent auditory hallucinations (AH) during an acute psychotic episode requiring hospitalisation. Neuroelectric activity was recorded in 10 SZ patients and 13 healthy controls (HC) during a passive auditory oddball task including novel environmental sounds. MMN/NP3 amplitudes and latencies were compared between groups and were correlated with trait (PSYRATS) and state measures of AH severity as well as clinical symptom ratings in SZs.

Auditory verbal hallucinations in schizophrenia correlate with P50 gating.

Objective: While auditory verbal hallucinations (AVHs) are a common symptom of schizophrenia, the underlying mechanisms behind these perceptual anomalies and their effects on auditory processing are not fully understood. Patients suffering from schizophrenia have been shown to exhibit impaired sensory gating of acoustic stimuli, evidenced by a failure to inhibit the auditory P50 scalp recorded middle latency evoked potential response to the second of two paired auditory "clicks" (S1-S2).

Methods: Because abnormal activation of auditory pathways is associated with a general AVH trait of schizophrenia patients, this study correlated the hallucinatory trait subscale of the Psychotic Symptoms Ratings Scale (PSYRATS) scores of 16 actively hallucinating patients with their P50 responses to S1 and S2 as well as sensory gating indices.

The resting electrophysiological profile in adults with ADHD and comorbid dysfunctional anger: a pilot study.

Although dysfunctional anger is not a Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition, Text Revision [DSM-IV-TR]) diagnosis, it sometimes presents as a primary clinical complaint and as a comorbid feature in a subset of adults with attention-deficit/hyperactivity disorder (ADHD). No known studies have examined electroencephalographic (EEG) profiles in adults with comorbid dysfunctional anger and ADHD (ADHD + anger). Resting EEG was recorded in 14 ADHD + anger adults (11 males) and 14 controls.

Effects of nicotine on electroencephalographic (EEG) and behavioural measures of visual working memory in non-smokers during a dual-task paradigm.

Research in smokers has shown that nicotine may have the ability to improve certain aspects of cognitive performance, including working memory and attention, processes which implicate frontal and frontal-parietal brain networks. There is limited research on the cognitive effects of nicotine and their associated neural underpinnings in non-smokers. This study examined the effects of acute nicotine on a working memory task alone or combined with a visual detection task (single- and dual-task conditions) using electroencephalographic (EEG) recordings and behavioural performance measures.

Alterations of mismatch negativity (MMN) in schizophrenia patients with auditory hallucinations experiencing acute exacerbation of illness.

Auditory verbal hallucinations (AHs), or hearing 'voices', are one of the hallmark symptoms of patients with schizophrenia. The primary objective of this study was to compare hallucinating schizophrenia patients with respect to differences in deviance detection, as indexed by the auditory mismatch negativity (MMN). Patients were recruited during an acute psychotic episode requiring hospitalization, during which time symptoms of psychosis, including auditory hallucinations, are likely to be at their most severe.

Nicotine and the hallucinating brain: effects on mismatch negativity (MMN) in schizophrenia.

Elevated smoking rates have been noted in schizophrenia, and it has been hypothetically attributed to nicotine's ameliorating abnormal brain processes in this illness. There is some preliminary evidence that nicotine may alter pre-attentive auditory change detection, as indexed by the EEG-derived mismatch negativity (MMN), but no previous study has examined what role auditory verbal hallucinations (AVH) may have on these effects. The objective of this study was to examine MMN-indexed acoustic change detection in schizophrenia (SZ) following nicotine administration and elucidate its association with AVH.

Effects of acute nicotine administration on behavioral and neural (EEG) correlates of working memory in non-smokers.

Enhancements in working memory (WM) performance have been previously reported following acute smoking/nicotine. Neuroimaging and behavioral assessments of nicotine's effects on WM have yielded inconsistent findings. Few studies, however, have examined the effects of nicotine on WM-related neural activity in non-smokers.

Effects of acute nicotine administration on resting EEG in nonsmokers.

Smoking/nicotine has been shown to increase brain arousal states, yet previous studies have failed to distinguish between absolute improvements due to nicotine versus relief from withdrawal symptoms in smokers. This study examined the electrocortical response to nicotine in a nonsmoking population, in order to negate potential withdrawal symptoms. Twenty right-handed, nonsmoking participants were administered nicotine (6 mg) or placebo gum within a double-blind, repeated-measures design.

Effects of auditory hallucinations on the mismatch negativity (MMN) in schizophrenia as measured by a modified 'optimal' multi-feature paradigm.

Unlabelled: The recently developed Optimal-3 multi-feature MMN paradigm, a shortened version of the 'optimal' multi-feature MMN paradigm, allows for the focused recording of the most widely reported MMN deviants (frequency, duration, intensity) within an efficient and time-saving paradigm. The objective of this study was to examine MMN acoustic change detection in schizophrenia (SZ), and elucidate its association with auditory verbal hallucinations (AH), using the Optimal-3.

Methods: MMN to duration, frequency and intensity deviants were recorded in 12 SZ outpatients (SZs) with persistent AHs and 12 matched healthy controls (HC).

Separate and combined effects of low dose ketamine and nicotine on behavioural and neural correlates of sustained attention.

Given the cognitive-promoting properties of the nicotinic acetylcholinergic receptor (nAChR) agonist, nicotine, the increased prevalence of smoke-inhaled nicotine in schizophrenia has been interpreted as an attempt to self-correct cognitive deficits, which have been particularly pronounced in the attentional domain. As glutamatergic abnormalities have been implicated in these attentional deficiencies, this study attempted to shed light on the separate and interactive roles of the N-methyl-d-aspartate receptor (NMDAR) and nAChR systems in the modulation of attention by investigating, in healthy volunteers, the separate and combined effects of nicotine and the NMDAR antagonist ketamine on neural and behavioural responses in a sustained attention task. In a randomized, double-blind, placebo controlled study, performance and the P300 event-related brain potential (ERP) in a visual information processing (RVIP) task were examined in 20 smokers and 20 non-smokers (both male and female).

MMN responsivity to manipulations of frequency and duration deviants in chronic, clozapine-treated schizophrenia patients.

Event-related potential (ERP) probing of abnormal sensory processes in schizophrenia with the mismatch negativity (MMN) has shown impairments in auditory change detection, but knowledge of the acoustic features leading to this deficit is incomplete. Changes in the duration and frequency properties of sound stimuli result in diminished MMNs in schizophrenia but it is unclear as to whether this reduced responsiveness is seen with more subtle changes in sound frequency. In a sample of 19 healthy controls and 21 patients with chronic schizophrenia treated with clozapine, MMN was assessed in response to tone frequency changes of 5%, 10% and 20%, and to tone duration changes.

Effects of deviant probability on the 'optimal' multi-feature mismatch negativity (MMN) paradigm.

Unlabelled: The introduction of the multi-feature 'optimal' mismatch negativity (MMN) paradigm was a significant innovation that allows for the collection of MMNs from five different deviant types in a relatively short period of time. Given the very specific stimulus presentation structure of this paradigm, the deletion of deviants results in an increase in the stimulus probability of each remaining deviant while holding constant the probability of the standard stimulus. The focus of this paper is two-fold: first, to examine the effects of altering deviant probability, but not standard probability, on MMN generation and, secondly, to validate a shorter, 3-stimulus version of the 'optimal' paradigm.

Auditory hallucinations and the P3a: attention-switching to speech in schizophrenia.

Background: In line with emerging research strategies focusing on specific symptoms rather than global syndromes in psychiatric disorders, we examined the functional neural correlates of auditory verbal hallucinations (AHs) in schizophrenia. Recent neuroimaging and behavioural evidence suggest altered early cognitive processes may be seen in patients with AH as a result of limited processing resources.

Methods: The P3a subcomponent of the P300, an event-related potential (ERP) index of early attention switching, was assessed in 12 hallucinating patients (HP), 12 non-hallucinating patients (NP) and 12 healthy controls (HC) within a passive two-tone auditory oddball paradigm using vowel phonemes.

Acute nicotine alteration of sensory memory impairment in smokers with schizophrenia.

Context: Patients with schizophrenia have a high rate of cigarette smoking and also exhibit profound deficits in sensory processing, which may in part be ameliorated by the acute actions of smoke-inhaled nicotine. The mismatch negativity (MMN), a preattentive event-related potential index of auditory sensory memory, is diminished in schizophrenia. The MMN is increased in healthy controls with acute nicotine.

Light up and see: enhancement of the visual mismatch negativity (vMMN) by nicotine.

Both smoking and nicotine can facilitate cognitive efficiency in humans, however the exact mechanism underlying this improvement in cognitive performance is unclear. Nicotine-related improvements in visual task performance may stem from facilitation of the identification and encoding of rare deviant stimuli at early sensory levels. Visual processes at these early levels are thought to be indexed by the visual mismatch negativity (vMMN), an event-related potential (ERP) measure of pre-conscious deviant detection.

Effects of acute nicotine on event-related potential and performance indices of auditory distraction in nonsmokers.

Introduction: Although nicotine has been purported to enhance attentional processes, this has been evidenced mostly in tasks of sustained attention, and its effects on selective attention and attentional control under conditions of distraction are less convincing.

Methods: This study investigated the effects of nicotine on distractibility in 21 (11 males) nonsmokers with event-related potentials (ERPs) and behavioral performance measures extracted from an auditory discrimination task requiring a choice reaction time response to short- and long-duration tones, with and without imbedded deviants. Administered in a randomized, double-blind, placebo-controlled crossover design, nicotine gum (6 mg) failed to counter deviant-elicited behavioral distraction characterized by longer reaction times and increased response errors.

Craving-induced EEG reactivity in smokers: effects of mood induction, nicotine dependence and gender.

Background/aims: Cigarette craving is a core symptom of smoking withdrawal, which is more intense and more frequently observed in smokers with depressed mood. Using self-reports and electroencephalographic (EEG) indices of frontal hemispheric asymmetry, which has been shown to be sensitive to mood states, the purpose of this study was to investigate the neural basis of cue-elicited cigarette craving, its variation with experimentally induced depressed mood, and with differences in gender and smoker type.

Methods: Cigarette-cue reactivity was examined in 11 (5 male) regular and 11 (6 male) light smokers in two sessions involving the induction of neutral or depressed mood.

Auditory hallucinations and the mismatch negativity: processing speech and non-speech sounds in schizophrenia.

Background: In line with emerging research strategies focusing on specific symptoms rather than global syndromes in psychiatric disorders, we examined the functional neural correlates of auditory verbal hallucinations (AHs) in schizophrenia. Recent neuroimaging and behavioural evidence suggest a reciprocal relationship between auditory cortex response to external sounds versus that induced by AHs.

Methods: The mismatch negativity (MMN), a well established event-related potential (ERP) index of auditory cortex function, was assessed in 12 hallucinating patients (HP), 12 non-hallucinating patients (NP) and 12 healthy controls (HC).