Impedance Rhythms in Human Limbic System.

The impedance is a fundamental electrical property of brain tissue, playing a crucial role in shaping the characteristics of local field potentials, the extent of ephaptic coupling, and the volume of tissue activated by externally applied electrical brain stimulation. We tracked brain impedance, sleep-wake behavioral state, and epileptiform activity in five people with epilepsy living in their natural environment using an investigational device. The study identified impedance oscillations that span hours to weeks in the amygdala, hippocampus, and anterior nucleus thalamus.

Flexible learning program for acoustic consultants.

There is a demand around the world for professional staff to join acoustic consulting companies, and in Australasia this demand is increasing. The extent of acoustics covered in undergraduate programs varies greatly, and there is usually the need to provide additional learning opportunities for new employees. While larger companies may provide training in-house, there are times when they are not in a position to release the senior members to provide such training.

Minimally Invasive, Endoscopic-Assisted Device for Subdural Electrode Implantation in Epilepsy.

Background: Subdural grids and strip electrodes provide wide coverage of the cerebral cortex, precise delineation of the extent of the seizure onset zone, and improved spatial sampling to perform functional mapping for eloquent cortex.

Objective: To describe a novel device that allows for a minimally invasive approach to implantation of subdural grid and strip electrodes.

Methods: A skull mounted device was created to allow for implantation of subdural electrodes through a keyhole craniotomy with direct visualization using the aid of a flexible neurovideoscope.

Fast gray matter acquisition T1 inversion recovery MRI to delineate the mammillothalamic tract for preoperative direct targeting of the anterior nucleus of the thalamus for deep brain stimulation in epilepsy.

When medically intractable epilepsy is multifocal or focal but poorly localized, neuromodulation can be useful therapy. One such technique is deep brain stimulation (DBS) targeting the anterior nucleus of the thalamus (ANT). Unfortunately, the ANT is difficult to visualize in standard MRI sequences and its indirect targeting is difficult because of thalamic variability and atrophy in patients with epilepsy.

Differences in functional connectivity profiles as a predictor of response to anterior thalamic nucleus deep brain stimulation for epilepsy: a hypothesis for the mechanism of action and a potential biomarker for outcomes.

OBJECTIVE Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is a promising therapy for refractory epilepsy. Unfortunately, the variability in outcomes from ANT DBS is not fully understood. In this pilot study, the authors assess potential differences in functional connectivity related to the volume of tissue activated (VTA) in ANT DBS responders and nonresponders as a means for better understanding the mechanism of action and potentially improving DBS targeting.

Chronic subthreshold cortical stimulation for adult drug-resistant focal epilepsy: safety, feasibility, and technique.

OBJECTIVE Epilepsy surgery is effective for lesional epilepsy, but it can be associated with significant morbidity when seizures originate from eloquent cortex that is resected. Here, the objective was to describe chronic subthreshold cortical stimulation and evaluate its early surgical safety profile in adult patients with epilepsy originating from seizure foci in cortex that is not amenable to resection. METHODS Adult patients with focal drug-resistant epilepsy underwent intracranial electroencephalography monitoring for evaluation of resection.

Dissecting gamma frequency activity during human memory processing.

Gamma frequency activity (30-150 Hz) is induced in cognitive tasks and is thought to reflect underlying neural processes. Gamma frequency activity can be recorded directly from the human brain using intracranial electrodes implanted in patients undergoing treatment for drug-resistant epilepsy. Previous studies have independently explored narrowband oscillations in the local field potential and broadband power increases.

Gamma oscillations precede interictal epileptiform spikes in the seizure onset zone.

Objective: To investigate the generation, spectral characteristics, and potential clinical significance of brain activity preceding interictal epileptiform spike discharges (IEDs) recorded with intracranial EEG.

Methods: Seventeen adult patients with drug-resistant temporal lobe epilepsy were implanted with intracranial electrodes as part of their evaluation for epilepsy surgery. IEDs detected on clinical macro- and research microelectrodes were analyzed using time-frequency spectral analysis.

Pathological and physiological high-frequency oscillations in focal human epilepsy.

High-frequency oscillations (HFO; gamma: 40-100 Hz, ripples: 100-200 Hz, and fast ripples: 250-500 Hz) have been widely studied in health and disease. These phenomena may serve as biomarkers for epileptic brain; however, a means of differentiating between pathological and normal physiological HFO is essential. We categorized task-induced physiological HFO during periods of HFO induced by a visual or motor task by measuring frequency, duration, and spectral amplitude of each event in single trial time-frequency spectra and compared them to pathological HFO similarly measured.

Confinement of halide ions within homologous inverse coordination hosts; modification of halide-ion selectivity.

The structures of a series of spherical host-guest complexes [{MeE(PPh)(3)Li(4)·3thf}(4)(μ(4)-X)](-) (E = Al, [1X](-); E = Ga, [2X](-); E = In, [3X](-)) reveal that changing the halide ions (X = Cl, Br, or I) within their central tetrahedral Li(4) sites has negligible effect on the structural parameters.

Attention enhances the retrieval and stability of visuospatial and olfactory representations in the dorsal hippocampus.

A key question in the analysis of hippocampal memory relates to how attention modulates the encoding and long-term retrieval of spatial and nonspatial representations in this region. To address this question, we recorded from single cells over a period of 5 days in the CA1 region of the dorsal hippocampus while mice acquired one of two goal-oriented tasks. These tasks required the animals to find a hidden food reward by attending to either the visuospatial environment or a particular odor presented in shifting spatial locations.

Intracranial electroencephalography seizure onset patterns and surgical outcomes in nonlesional extratemporal epilepsy.

Object: Patients with normal MR imaging (nonlesional) findings and medically refractory extratemporal epilepsy make up a disproportionate number of nonexcellent outcomes after epilepsy surgery. In this paper, the authors investigated the usefulness of intracranial electroencephalography (iEEG) in the identification of surgical candidates.

Methods: Between 1992 and 2002, 51 consecutive patients with normal MR imaging findings and extratemporal epilepsy underwent intracranial electrode monitoring.

Phase I trial: safety and feasibility of intracranial electroencephalography using hybrid subdural electrodes containing macro- and microelectrode arrays.

Object: Cerebral cortex electrophysiology is poorly sampled using standard, low spatial resolution clinical intracranial electrodes. Adding microelectrode arrays to the standard clinical macroelectrode arrays increases the spatial resolution and may ultimately improve the clinical utility of intracranial electroencephalography (iEEG). However, the safety of hybrid electrode systems containing standard clinical macroelectrode and microelectrode arrays is not yet known.

Structural, solid-state NMR and theoretical studies of the inverse-coordination of lithium chloride using group 13 phosphide hosts.

The reaction of MeAlCl2 with 'PhPLi2' in THF gives [{MeAl(PPh)3Li(4).3 THF}4(mu4-Cl)]-Li+ (1). The GaIII and InIII analogues, [{MeE(PPh)3Li(4).