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"Hall, Charles W"
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Mutual information in natural position order of electroencephalogram is significantly increased at seizure onset
Epilepsy affects an estimated 60 million people worldwide. As many as 50% of people with epilepsy will continue to have seizures despite therapeutic dosages of appropriately selected antiepileptic drugs. Among proposed treatment modalities for persons with medication refractory epilepsy are implantable devices that rapidly detect and abort seizures. Computational resources in these devices are limited and much effort is directed to improving the efficiency of seizure detection. The goal of this study is to determine if electroencephalogram (EEG) may be reduced by the method of natural position order in a way that increases computation speed and reduces system memory requirements while preserving features relevant to detecting seizure onset. In this study we show increased mutual information (MI) at seizure onset in simultaneous channels of EEG reduced by natural position order with a 40-fold reduction in computation time and a fivefold reduction in system memory requirements. The trade-offs to EEG reduction by natural position order include decreased bandwidth and increased noise sensitivity.
Journal Article
Closed-loop neural stimulation for pentylenetetrazole-induced seizures in zebrafish
Neural stimulation can reduce the frequency of seizures in persons with epilepsy, but rates of seizure-free outcome are low. Vagus nerve stimulation prevents seizures by continuously activating noradrenergic projections from the brainstem to the cortex. Cortical norepinephrine then increases GABAergic transmission and increases seizure threshold. Another approach, responsive nervous stimulation, prevents seizures by reactively shocking the seizure onset zone in precise synchrony with seizure onset. The electrical shocks abort seizures before they can spread and manifest clinically. The goal of this study was to determine whether a hybrid platform in which brainstem activation triggered in response to impending seizure activity could prevent seizures. We chose the zebrafish as a model organism for this study because of its ability to recapitulate human disease, in conjunction with its innate capacity for tightly controlled high-throughput experimentation. We first set out to determine whether electrical stimulation of the zebrafish hindbrain could have an anticonvulsant effect. We found that pulse train electrical stimulation of the hindbrain significantly increased the latency to onset of pentylenetetrazole-induced seizures, and that this apparent anticonvulsant effect was blocked by noradrenergic antagonists, as is also the case with rodents and humans. We also found that the anticonvulsant effect of hindbrain stimulation could be potentiated by reactive triggering of single pulse electrical stimulations in response to impending seizure activity. Finally, we found that the rate of stimulation triggering was directly proportional to pentylenetetrazole concentration and that the stimulation rate was reduced by the anticonvulsant valproic acid and by larger stimulation currents. Taken as a whole, these results show that that the anticonvulsant effect of brainstem activation can be efficiently utilized by reactive triggering, which suggests that alternative stimulation paradigms for vagus nerve stimulation might be useful. Moreover, our results show that the zebrafish epilepsy model can be used to advance our understanding of neural stimulation in the treatment of epilepsy.
Journal Article
Closed loop neural stimulation for pentylenetetrazole seizures in zebrafish
Neural stimulation can reduce the frequency of seizures in persons with epilepsy, but rates of seizure free outcome are low. Vagus nerve stimulation prevents seizures by continuously activating noradrenergic projections from the brainstem to the cortex. Cortical norepinephrine then increases GABAergic transmission and increases seizure threshold. Another approach, responsive nervous stimulation, prevents seizures by reactively shocking the seizure onset zone in precise synchrony with seizure onset. The electrical shocks abort seizures before they can spread and manifest clinically. The goal of this study is to determine if a hybrid platform in which brainstem activation triggered in response to impending seizure activity can prevent seizures. We chose the zebrafish as a model organism for this study because of its ability to recapitulate human disease in conjunction with its innate capacity for tightly controlled - high throughput experimentation. We first set out to determine if electrical stimulation of the hindbrain could have an anticonvulsant effect. We found that pulse train electrical stimulation of the hindbrain significantly increased the latency to onset of pentylenetetrazole seizures, and that this apparent anticonvulsant effect was blocked by noradrenergic antagonists, as is also the case with rodents and humans. We also found that the anticonvulsant effect of hindbrain stimulation could be potentiated by reactive triggering of single pulse electrical stimulations in response to impending seizure activity. Finally, we found that the rate of stimulation triggering was directly proportional to pentylenetetrazole concentration and that the stimulation rate was reduced by the anticonvulsant valproic acid and by larger stimulation currents. Taken as a whole, these results show that that the anticonvulsant effect of brainstem activation can be efficiently utilized by reactive triggering, which suggests that alternative stimulation paradigms for vagus nerve stimulation may be useful. Moreover, our results show that the zebrafish epilepsy model can be used to advance our understanding of neural stimulation in the treatment of epilepsy.
Journal Article
KING RECALLING HIS LAST LEGAL BATTLE
A program hosted by the U.S. District Court for the Western District of Tennessee earlier this month revisited that case, which began before but ended after King's assassination. According to a transcript, available on the court's website (https://www.tnwd.uscourts.gov/), public safety director Frank C. Hollomon testified that a second march posed \"a clear and present danger,\" threatening the entire city, the marchers, and even King himself. With Mr. Halls permission, this article is being reprintedfor NALA's Facts & Findings, as it gives an insight into the court's perspective as it recalls Martin Luther King, Jrs last legal battle in the United States District Court for the Western District of Tennessee literally hours prior to his assignation in Memphis, TN.
Trade Publication Article
Spy Case Sealed by 1990 Letter; Computer Disk Held Agent's Memo to KGB
Weeks after Earl Edwin Pitts was arrested on charges of attempted espionage, following an FBI undercover sting, a computer disk seized from his home provided the first concrete proof that he had actually passed secrets to Moscow. In the letter, Pitts discussed the difficulty of meeting his spy handlers without arousing his wife's suspicions and explained how he would hide film with classified secrets inside milk cartons. Ironically, Pitts also wrote at length about how best to keep his illegal communications from being recorded on computers, where spy catchers might find them. Sources said the discovery made it all but impossible for defense lawyers to argue that the FBI had unfairly trapped Pitts by launching a 16-month \"false flag\" operation, in which federal agents posed as Russian spies willing to pay Pitts for classified secrets. By eliminating an entrapment defense, the disk made it more likely Pitts would plead guilty.
Newspaper Article
Plea Deals Arranged in 2 Spy Cases; Ex-FBI Agent Admits Guilt; Former Officer With CIA to Do Same
Earl Edwin Pitts, the former FBI counterintelligence agent accused of spying for Moscow, pleaded guilty yesterday in federal court in Alexandria, and former CIA case officer Harold James Nicholson has agreed to plead guilty to espionage charges Monday, federal officials announced yesterday. Barely a half-hour before Pitts's hearing was scheduled to start yesterday afternoon, Nicholson, 46, signed an agreement saying he would plead guilty to selling secrets to the Russians from 1994 until his arrest in November, U.S. Attorney Helen F. Fahey said. Both Fahey and Nicholson's attorney, Jonathan Shapiro, declined to discuss the substance of the agreement, saying the case remains under a gag order. Pitts's plea and Nicholson's agreement are tremendous breaks for U.S. intelligence officials, who still do not know exactly what the two men may have given away. As part of the agreement, Pitts, 43, pledged to tell federal officials exactly what he turned over to the Soviets when he was spying actively for them from 1987 to 1992.
Newspaper Article