Gamma Oscillations and Potassium Channel Modulation in Schizophrenia: Targeting GABAergic Dysfunction.

Impairments in gamma-aminobutyric acid (GABAergic) interneuron function lead to gamma power abnormalities and are thought to underlie symptoms in people with schizophrenia. Voltage-gated potassium 3.1 (Kv3.

The effect of ketamine and D-cycloserine on the high frequency resting EEG spectrum in humans.

Rationale: Preclinical studies indicate that high-frequency oscillations, above 100 Hz (HFO:100-170 Hz), are a potential translatable biomarker for pharmacological studies, with the rapid acting antidepressant ketamine increasing both gamma (40-100 Hz) and HFO.

Objectives: To assess the effect of the uncompetitive NMDA antagonist ketamine, and of D-cycloserine (DCS), which acts at the glycine site on NMDA receptors on HFO in humans.

Methods: We carried out a partially double-blind, 4-way crossover study in 24 healthy male volunteers.

Alpha3/alpha2 power ratios relate to performance on a virtual reality shopping task in ageing adults.

Background: Aspects of cognitive function decline with age. This phenomenon is referred to as age-related cognitive decline (ARCD). Improving the understanding of these changes that occur as part of the ageing process can serve to enhance the detection of the more incapacitating neurodegenerative disorders such as Alzheimer's disease (AD).

Identifying Electroencephalography Biomarkers in Individuals at Clinical High Risk for Psychosis in an International Multi-Site Study.

Background: The clinical high-risk for psychosis (CHR-P) paradigm was introduced to detect individuals at risk of developing psychosis and to establish preventive strategies. While current prediction of outcomes in the CHR-P state is based mostly on the clinical assessment of presenting features, several emerging biomarkers have been investigated in an attempt to stratify CHR-P individuals according to their individual trajectories and refine the diagnostic process. However, heterogeneity across subgroups is a key challenge that has limited the impact of the CHR-P prediction strategies, as the clinical validity of the current research is limited by a lack of external validation across sites and modalities.

The effects of roflumilast, a phosphodiesterase type-4 inhibitor, on EEG biomarkers in schizophrenia: A randomised controlled trial.

Background: Patients with schizophrenia have significant cognitive deficits, which may profoundly impair quality of life. These deficits are also evident at the neurophysiological level with patients demonstrating altered event-related potential in several stages of cognitive processing compared to healthy controls; within the auditory domain, for example, there are replicated alterations in Mismatch Negativity, P300 and Auditory Steady State Response. However, there are no approved pharmacological treatments for cognitive deficits in schizophrenia.

Gamma band oscillations in the early phase of psychosis: A systematic review.

Abnormal gamma oscillations, measured by electroencephalography (EEG), have been associated with chronic psychotic disorders, but their prevalence in the early phase of psychosis is less clear. We sought to address this by systematically reviewing the relevant literature. We searched for EEG studies of gamma band oscillations in subjects at high risk for psychosis and in patients with first episode psychosis.

State-of-the-Art Analysis of High-Frequency (Gamma Range) Electroencephalography in Humans.

Gamma oscillations (>30 Hz) in the brain are involved in attention, perception and memory. They are altered in various pathological states, as well as by neuropharmaceuticals, so that they are of interest in drug and clinical investigations. However, when the human electroencephalogram is recorded on the scalp, this neural high-frequency signal is buried under a range of other electrical signals such that, without careful handling, recordings of the high-frequency electroencephalogram cannot be considered reliable.

Delta-9-tetrahydrocannabinol, neural oscillations above 20 Hz and induced acute psychosis.

Rationale: An acute challenge with delta-9-tetrahydrocannabinol (THC) can induce psychotic symptoms including delusions. High electroencephalography (EEG) frequencies, above 20 Hz, have previously been implicated in psychosis and schizophrenia.

Objectives: The objective of this study is to determine the effect of intravenous THC compared to placebo on high-frequency EEG.

Resting EEG in psychosis and at-risk populations--a possible endophenotype?

Background: Finding reliable endophenotypes for psychosis could lead to an improved understanding of aetiology, and provide useful alternative phenotypes for genetic association studies. Resting quantitative electroencephalography (QEEG) activity has been shown to be heritable and reliable over time. However, QEEG research in patients with psychosis has shown inconsistent and even contradictory findings, and studies of at-risk populations are scarce.

Cocaine-assisted epithelial debridement for the treatment of anterior basement membrane dystrophy.

Purpose: To describe a method of epithelial debridement with the adjunctive use of topical cocaine for the treatment of symptomatic anterior basement membrane dystrophy (ABMD).

Methods: Retrospective consecutive chart review. Symptomatic patients with ABMD were treated with 4% topical cocaine followed by epithelial debridement.

Removing ballistocardiogram artifact from EEG using short- and long-term linear predictor.

In this paper, a novel source extraction method is proposed for removing ballistocardiogram (BCG) artifact from EEG. BCG appears in EEG signals recorded simultaneously with functional magnetic resonance imaging. The proposed method is a semiblind source extraction algorithm based on linear prediction technique.

Treatment of mucous membrane pemphigoid with mycophenolate mofetil.

Purpose: To evaluate the clinical outcomes of mycophenolate mofetil (MMF) treatment of mucous membrane pemphigoid (MMP).

Methods: This is a retrospective analysis of consecutive patients with clinical MMP seen in the Ocular Surface Disease Clinic at the Wills Eye Institute, between January 1, 2004, and December 31, 2010, treated with MMF. The main outcomes measured were control of inflammation and discontinuation of MMF.

Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment.

Community-based studies suggest that cannabis products that are high in Δ⁹-tetrahydrocannabinol (THC) but low in cannabidiol (CBD) are particularly hazardous for mental health. Laboratory-based studies are ideal for clarifying this issue because THC and CBD can be administered in pure form, under controlled conditions. In a between-subjects design, we tested the hypothesis that pre-treatment with CBD inhibited THC-elicited psychosis and cognitive impairment.

Indications, visual outcome, and ectasia in clear corneal transplants 20 years old or more.

Purpose: To report the indications, visual outcome, and development of ectasia in clear corneal transplants at least 20 years or more after penetrating keratoplasty (PK).

Methods: A computer search of all post-PK patients in the electronic medical records of the Cornea Service was done. Only patients with clear primary grafts aged 20 years or more were included.

A novel method for reducing the effect of tonic muscle activity on the gamma band of the scalp EEG.

Neural oscillations in the gamma band are of increasing interest, but separating them from myogenic electrical activity has proved difficult. A novel algorithm has been developed to reduce the effect of tonic scalp and neck muscle activity on the gamma band of the EEG. This uses mathematical modelling to fit individual muscle spikes and then subtracts them from the data.

Persistent corneal edema after collagen cross-linking for keratoconus.

Purpose: To present a new complication of persistent corneal edema after collagen cross-linking (CXL) in keratoconus patients.

Design: Retrospective case series of postoperative corneal edema after CXL.

Methods: study population: All patients who underwent CXL treatment with subsequent corneal edema.

Dry eye syndrome in aromatase inhibitor users.

Background: Aromatase inhibitors are frequently used as an adjuvant therapy in the treatment of breast cancer. We observed that several patients taking aromatase inhibitors presented with severe dry eye symptoms, and we investigated whether there is a relationship between aromatase inhibitors and dry eyes in these patients.

Design: Retrospective chart review.

Descemet membrane detachment among siblings: role of anatomic and familial predisposition.

Purpose: To describe 2 siblings with Descemet membrane detachment (DMD) after intraocular surgery and discuss the potential role of anatomic and familial predisposition.

Method: Case reports.

Results: A 64-year-old woman had bilateral DMDs after trabeculectomy in her right eye and during combined cataract extraction and trabeculectomy in her left eye.

Endothelial keratoplasty without Descemet's stripping in eyes with previous penetrating corneal transplants.

Aims: To evaluate techniques, outcomes and complications of endothelial keratoplasty (EK) without Descemet's stripping in eyes with previous penetrating keratoplasty (PK).

Methods: A retrospective, consecutive analysis of patients who underwent EK in eyes with previous PK.

Results: 33 eyes of 31 consecutive patients underwent EK without Descemet's stripping in eyes with previous PK.

Disruption of frontal θ coherence by Δ9-tetrahydrocannabinol is associated with positive psychotic symptoms.

The main ingredient in cannabis, Δ(9)-tetrahydrocannabinol (THC), can elicit acute psychotic reactions in healthy individuals and precipitate relapse in schizophrenic patients. However, the neural mechanism of this is unknown. We tested the hypothesis that THC psychopathology is related to changes in electroencephalography (EEG) power or inter-regional coherence.