μblog: engineering from the trenches

The last two days of the meeting started to blend together as the 8am to 8pm days started taking their toll. Sunday was mostly taken up by an investigators’ workshop dealing with basic principles behind epilepsy. Jack Parent had some interesting words to say about a protein called reelin. This protein has been implicated in limiting the process by which neurons form new connections, as though it somehow helped regulate “good” networking. The it seemed that, in animal models, seizures were associated with reduced reelin concentration and increased neuronal proliferation which led to more seizures.

Monday was divided between visiting Brian Litt’s and Marc Dichter’s labs at U Penn, presenting my poster, and more lectures. Visiting the labs made it apparent that while we have more space at Penn State, the U Penn labs have a more strategically located near civilization. The poster presentation went fairly smoothly with the toughest questions being about my choice of multi-taper spectral estimation approach over something like wavelet transform. The final lectures that I attended were covering new definitions of seizures. The basic idea was that clinicians had access to new equipment that could record more EEG channels at higher frequency as well as higher density electrode grids/arrays. The result was that neurological signals could be recorded with finer spatial and temporal resolution. These newer systems could pick up the huge electrographic seizures that have been recorded for decades, as well as shorter discharges termed “microseizures”. This could certainly give medical professionals better tools to diagnose neurological disorders and localize seizure foci, however, I think that the definition of a clinical seizure will consequently be broadened in the upcoming years to include some of these smaller discharges. This may lead to a broader definition of the disease and would lead to more people becoming clinically epileptic. This, coupled with an increased epilepsy risk as a result of traumatic brain injury,  will lead to a great jump in the number of reported clinical epilepsy cases of epilepsy in the upcoming decades which the analysts will probably attribute to things like mobile phones, wireless internet, and video games.

During the breaks, I had a chance to walk around the convention center visiting places like the city hall and the reading terminal market. In addition to the pictures of the city and the market, I am including pictures of the exhibitor section of the American Epilepsy Society meeting. Since the target audiences of the meeting are medical doctors, the drug companies really spend money on marketing and give away cell phone chargers, thumb drives, usb battery chargers and laser pointer pens which include usb flash drives which can also recharged through the usb connector.

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This day was split into three sections: Merritt-Putnam lectures, Engineering special interest group, and a set of lectures on high-frequency EEG recordings.

The morning was dedicated to the Merritt-Putnam lecture series, with this one focusing on traumatic brain injury (TBI) and the resulting possibility of epilepsy. The key theme was that there was a correlation between TBI, such as getting hit with a baseball, and developing epileptic seizures down the road (epileptogenesis). There are some clinical measures which can sort the severity of the TBI into mild, moderate and severe categories, however, the specifics were not presented. Various mechanisms, ranging from molecular to neural network organization, were implicated as potential targets for epileptogenesis, however, the key point that was reiterated by every presenter was that there was concern that troops coming back from Iraq were looking forward to epilepsy in their later years. Part of the reason for this is that explosives play a much larger role in modern warfare, as compared to bullets, which have a higher propensity to generate shock waves and thereby contribute to TBI. According to the statistics presented, there are over 2,000 “official” cases of severe TBI as of October 2007 with an estimated 10,000-20,000 more at risk.

The main focus of the SIG was to demonstrate to try to define what a seizure was. Several groups were presenting data from tiny electrodes embedded in standard electrode arrays to help get better spatial resolution of EEG measurement for seizure focus detection. The most entertaining talk, however, came at the very end and provided an overview of stimulation efficacy for seizures. The point was that in many cases, simply implanting the electrodes was enough to stop seizures. It didn’t statistically matter if the stimulator was turned on or not, providing that the seizure focus was located correctly.

The last session was titled “Broadband EEG”, but the range of talks was very wide. Gyorgy Buzsaki gave the first talk part of which dealt with qualitative energetics. The idea can be explained with this analogy: when people clap at the end of a musical performance, they clap randomly at first, then, a pattern develops and people clap rhythmically. When people clap in unison, they typically clap slower than they did before, expending less energy. The same can be seen on functional MRI (something that measures metabolism) where things like the hippocampus, a popular seizure focus, shows decreased energy usage during seizure activity.

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