A common ankyrin-G-based mechanism retains KCNQ and NaV channels at electrically active domains of the axon.

KCNQ (KV7) potassium channels underlie subthreshold M-currents that stabilize the neuronal resting potential and prevent repetitive firing of action potentials. Here, antibodies against four different KCNQ2 and KCNQ3 polypeptide epitopes show these subunits concentrated at the axonal initial segment (AIS) and node of Ranvier. AIS concentration of KCNQ2 and KCNQ3, like that of voltage-gated sodium (NaV) channels, is abolished in ankyrin-G knock-out mice.

A multi-feature and multi-channel univariate selection process for seizure prediction.

Objective: To develop a prospective method for optimizing seizure prediction, given an array of implanted electrodes and a set of candidate quantitative features computed at each contact location.

Methods: The method employs a genetic-based selection process, and then tunes a probabilistic neural network classifier to predict seizures within a 10 min prediction horizon. Initial seizure and interictal data were used for training, and the remaining IEEG data were used for testing.

High-frequency oscillations and seizure generation in neocortical epilepsy.

Neocortical seizures are often poorly localized, explosive and widespread at onset, making them poorly amenable to epilepsy surgery in the absence of associated focal brain lesions. We describe, for the first time in an unselected group of patients with neocortical epilepsy, the finding that high-frequency (60-100 Hz) epileptiform oscillations are highly localized in the seizure onset zone, both before and temporally removed from seizure onset. These findings were observed in all six patients with neocortical epilepsy out of 23 consecutive patients implanted with intracranial electrodes for pre-surgical evaluation during the study period.

Electrical stimulation of the anterior nucleus of the thalamus for the treatment of intractable epilepsy.

Purpose: Animal studies and sporadic case reports in human subjects have suggested that intermittent electrical stimulation of the anterior nucleus of the thalamus reduces seizure activity. We embarked on an open-label pilot study to determine initial safety and tolerability of bilateral stimulation of the anterior nucleus of the thalamus (ANT), to determine a range of appropriate stimulation parameters, and to begin to gather pilot efficacy data.

Methods: We report an open-label pilot study of intermittent electrical stimulation of the anterior nucleus of the thalamus in five patients (three men, two women; age range, 24-47 years), with follow-up between 6 and 36 months.

Blood pO2 and blood flow at the optic disc.

A fundus camera-based phosphorometer to noninvasively and quasicontinuously measure the blood partial pressure of oxygen (pO(2,blood)) in the microvasculature of the pig optic nerve using the principle of the phosphorescence quenching by O(2) is described. A porphyrin dye is injected into the venous circulation and the decay of its phosphorescence emission is detected locally in the eye, after excitation with a flash of light. Combined with blood flow measurements by means of a laser Doppler flowmeter mounted on the phosphorometer, we demonstrate the capability of the instrument to determine the time course of optic nerve blood flow and pO(2,blood) in response to various physiological stimuli, such as hyperoxia and hypercapnia.

Evidence for self-organized criticality in human epileptic hippocampus.

Self-organized criticality (SOC) is a property of complex dynamic systems that evolve to a critical state, capable of producing scale-free energy fluctuations. A characteristic feature of dynamical systems exhibiting SOC is the power-law probability distributions that describe the dynamics of energy release. We show experimental evidence for SOC in the epileptic focus of seven patients with medication-resistant temporal lobe epilepsy.

Time-frequency spectral estimation of multichannel EEG using the Auto-SLEX method.

In this paper, we apply a new time-frequency spectral estimation method for multichannel data to epileptiform electroencephalography (EEG). The method is based on the smooth localized complex exponentials (SLEX) functions which are time-frequency localized versions of the Fourier functions and, hence, are ideal for analyzing nonstationary signals whose spectral properties evolve over time. The SLEX functions are simultaneously orthogonal and localized in time and frequency because they are obtained by applying a projection operator rather than a window or taper.