Thalamic Neurostimulation To Improve Level Of Consciousness After Seizures: An Electrophysiological And Behavioral Evaluation

The neural structures supporting human consciousness have importance in both neuroscience and medicine. A previously developed rodent model of temporal lobe seizures recapitulates electrophysiological and behavioral aspects of human partial seizures. It models ictal and postictal neocortical slow waves associated with behavioral impairments in level of consciousness seen in human partial seizures. The mechanism of slow wave production in epilepsy may involve suppression of the subcortical arousal systems including the brainstem and intralaminar thalamic nuclei. We hypothesized that intralaminar thalamic stimulation may lead to electrophysiological and functional rescue from postictal slow waves and behavioral arrest. We electrically stimulated the central lateral nucleus, a member of the rostral intralaminar thalamic nuclei, under anesthesia and after electrically-induced hippocampal seizures to demonstrate a proof-of-principle restoration of electrophysiological and behavioral measures of consciousness. We measured decreased cortical slow waves, increased desynchronization, and increased multiunit activity in the cortex with thalamic stimulation following seizures. Functionally, thalamic stimulation produced resumption of exploratory behaviors in the postictal state. Targeting nodes in the neural circuitry of consciousness has important medical implications. Impaired consciousness with epilepsy has dangerous consequences including decreased school/work performance, social stigmatization, impaired airway protection, and accidents (such as motor vehicle accidents, drownings, or burns). These data suggest a novel therapeutic approach for restoring consciousness after seizures. If paired with responsive neurostimulation, this may allow rapid implementation to improve level of consciousness in patients with epilepsy

Effect of Spatial Smoothing on the Performance of Subspace Methods in the Presence of Array Model Errors

ln this paper, the effect of spatial smoothing (Forward smoothing and Forward-Backward smoothing) on the performance of unweighted and weighted subspace methods in the presence of Array Model errors for Direction-Of-Arrival (DOA) estimation is studied. Theoreti- cal expressions for the Mean Squared Error (MSE) in DOA are obtained, based on a common framework of analysis. For weighted subspace methods, optimal weighting matrices are presented which minimize the MSE in DOA. Two typical errors, Random errors and Gain and Phase errors are considered as examples for illustration. Simulations are carried out to substantiate the theory developed. For the cases considered, smoothing improves the performance of ESPRIT and Minimum-Norm method while it is not so for MUSIC. Forward-Backward smoothing improves the per- formance of all methods compared to that of Forward smoothing

On the Performance of Subspace Methods with Array Model Errors and Spatial Smoothing

In this paper, the effect of spatial smoothing (Forward smoothing and Forward-Backward smoothing) on the performance of subspace methods in the presence of Array Model errors for Direction-Of-Arrival (DOA) estimation is studied. Theoretical expressions for the Mean Squared Error (MSE) in DOA are obtained, based on a common framework of analysis. Simulations are carried out to substantiate the theory developed. For the cases considered, smoothing improves the performance of ESPRIT and Minimum-Norm method while it is not so for MUSIC

ASSFN Position Statement on Deep Brain Stimulation for Medication-Refractory Epilepsy

Neuromodulation has taken a foothold in the landscape of surgical treatment for medically refractory epilepsies and offers additional surgical treatment options for patients who are not candidates for resective/ablative surgery. Approximately one third of patients with epilepsy suffer with medication-refractory epilepsy. A persistent underuse of epilepsy surgery exists. Neuromodulation treatments including deep brain stimulation (DBS) expand the surgical options for patients with epilepsy and provide options for patients who are not candidates for resective surgery. DBS of the bilateral anterior nucleus of the thalamus is an Food and Drug Administration-approved, safe, and efficacious treatment option for patients with refractory focal epilepsy. The purpose of this consensus position statement is to summarize evidence, provide recommendations, and identify indications and populations for future investigation in DBS for epilepsy. The recommendations of the American Society of Functional and Stereotactic Neurosurgeons are based on several randomized and blinded clinical trials with high-quality data to support the use of DBS to the anterior nucleus of the thalamus for the treatment of refractory focal-onset seizures