YALE DAILY NEWS · FRIDAY, JANUARY 28, 2022 · yaledailynews.com
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Yale researchers receive grant to develop novel epilepsy brain-computer chip treatment BY VALENTINA SIMON STAFF REPORTER An interdisciplinary team of Yale researchers has designed brain-machine interface chips that, when implanted in humans, can reduce the rate of epileptic seizures. More than three million people experience epileptic seizures in the United States, with 60 to 70 percent of patients able to successfully treat the condition with medicine. For the remaining individuals, surgically removing the parts of the brain where seizures arise, regardless of their role in everyday function, has been the only path toward mitigating the issue. A team of Yale computer scientists, engineers and surgeons have found that short-circuiting the path neurons fire during an epileptic seizure can successfully reduce the rate of seizures in patients. The Swebilius Foundation recently awarded the team a grant to continue its research. “When the signature traits of a seizure are observed, the device stimulates that part of the brain, and it is not curative, but over time 60 percent of patients will get 50 percent fewer seizures than they had before,” said Dennis Spencer, professor emeritus of neurosurgery, who implants these brain-computer interface chips in patients. The team is still working to increase the success rate. Currently, each chip contains two electrodes with four contacts. When attempting to short-circuit a seizure, a surgeon can only stimulate the brain on the linear path between those two electrodes. The chips are uniquely targeted, both spatially and temporally, mak-
ing them superior to medication or surgery for seizures that extend into critical regions of the brain. However, the chips’ targeted nature makes them inadequate in many cases when sei-
need to do a lot more real-time processing, and the algorithms are more sophisticated and demanding, but we need to deliver all this on a tight power budget.”
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zures follow a network of connections, moving quickly around the brain. “There are multiple nodes we need to monitor and modulate in order to manage a seizure,” said Hitten Zaveri, assistant professor of neurology. “We
The team is working to increase processing power through hardware-software synergies. Concrete subroutines, such as algorithms that store information, are hardcoded into the chips and are combined to cre-
ate new treatment plans specific to the disease in question. It is similar to how a set of chords, or subroutines of a piano, can be joined together to create a beautiful composition. “At the power budget that we have, which is 10-15 milliwatts, you really need to optimize down to the wire what you keep on board. It is literally a matter of life and death,” said assistant professor of computer science Aurag Khandelwal, who is a collaborator on the project. Many patients have comorbidities associated with their epilepsy. These can include severe anxiety and depression. According to Spencer, such disorders often follow the same neural pathways in the brain as epileptic seizures. The Yale chips have been designed to be multipurpose, meaning that the programs can be coded and uploaded to target other neurological and psychological disorders as well. “The networks for anxiety and depression overlap a great deal with the networks we see responsible for seizures,” Spencer said. “Ultimately, the attempted treatment to help patients with horrible epilepsy may be a simultaneous attempt to control their anxiety and their seizures. That is the long term mission.” The team’s paper outlining its design for the chip, “Hardware-Software Co-Design for Brain-Computer Interfaces,” was selected for inclusion in Institute of Electrical and Electronics Engineers, or IEEE, Micro’s Top Picks in Computer Architecture magazine as one of the top computer architecture papers published in 2020. Contact VALENTINA SIMON at valentina.simon@yale.edu .
Joint Yale and Harvard study shows people may be infectious beyond five-day isolation BY MANAS SHARMA STAFF REPORTER New research from scientists at the Yale and Harvard Schools of Public Health suggests that the commonly-accepted fiveday isolation period for those who test positive for COVID19 may end when people are still infectious. The study, which is currently prepublished — meaning it has not yet been peer-reviewed — investigates the time period of viral proliferation and clearance for the SARS-CoV-2 Omicron variant. Researchers analyzed PCR COVID-19 tests of 537 individuals and found that many samples remained positive for between five and 10 days following the initial positivity. “This study demonstrates that the current 5 day isolation period may well be too short for a significant number of infected individuals,” Howard Forman, professor of economics, management and public health policy wrote in an email to the News. “If our intention is to stamp outspread, we should reconsider a time-based process to exit isolation and reconsider using antigen testing to test out.” The Omicron COVID-19 variant is highly transmissible and infects a higher proportion of individuals who are vaccinated or have prior immunity than other variants, research conducted on the variant over the last several months has shown. These traits of the variant make it necessary to research how long the virus takes to clear up and how often it proliferates in individuals, according to Nathan Gru-
baugh, an associate professor of epidemiology. “Over the past two years, we have been collecting data on the PCR values from very dense samplings. … Our goal was to
PCR test samples from 537 individuals for analysis. The testing program periodically tested symptomatic and asymptomatic individuals, and tested positive individu-
on isolation for individuals who test positive, as it describes the general period of time that an individual could be infectious. “These findings and others indicate that there is much
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use the data we had collected to determine what is the potential fraction of individuals in our sampling that still might be infectious on day five, day six, or day seven so we might better inform our isolation protocols,” Grubaugh, a senior author of the paper, said in an interview with the News. Through its occupational health program, the National Basketball Association provided the research team with
als daily in order to obtain this dense sampling. Through this analysis, the researchers were able to measure viral RNA, or the genetic material of viruses. An analysis of the viral RNA allowed for a deeper understanding of the extent of viral shedding of the Omicron variant. Viral shedding is the rate and intensity by which the virus reproduces inside host cells. Rates of viral shedding help inform policies
variability in the period that people can infect others,” Harlan Krumholz ’80, professor of medicine and public health policy, wrote in an email to the News. “Some people may clear the virus rapidly and others continue to spread it to others for 10 or more days. Setting a time amount and applying it to everyone will promote the spreading of the virus.” Through the PCR tests, the researchers analyzed the Ct
values, or cycle threshold values, of individuals. Ct values represent how many cycles of DNA amplification it takes for the COVID-19 genetic material to be detected within the sample. Ct values less than 30 usually correspond to a positive COVID-19 rapid antigen test, while values above 30 indicate non-infectiousness for COVID-19. The study showed that most individuals tested reached high viral RNA after initially testing positive, with many individuals having Ct values less than 30 even five days after the initial positive test result. This meant that those individuals would still be testing positive on the rapid antigen test five days after their initial positive result. Per the study’s findings, positivity does not persist beyond day 10, as all individuals in the study had Ct values above 30 by day 11. Grubaugh’s lab and colleagues aim to replicate the study in a larger, more representative population in order to best model the viral shedding and infectiousness, leading to better creation of isolation policies. Currently, the CDC recommends that positive individuals quarantine for five days if they are asymptomatic and then strictly wear a mask around others for five days after. Yale requires that students who test positive quarantine in isolation housing, and, if by day five they have waning or no symptoms, they may test and be released from quarantine if they test negative. Contact MANAS SHARMA at manas.sharma@yale.edu .
