μblog: engineering from the trenches

Today is the first day of the American Epilepsy Society annual meeting and I attended some lectures on sleep-related epileptic events and another one on the impact of the immune system on epileptic activity. The first part, dealing with sleep and seizures, was mostly clinical results and a strong ties with abnormal electroencephalogram (EEG) recordings during non-REM sleep and cognitive impairment in children. Several specific pathologies were discussed, the main topic being speech impediment. It is known that many children experience epilepsy-like events when they are young, however, most grow out of their seizures and go on to lead normal lives. For some, the speech impediment becomes life-long if the night-time seizures are untreated. The interesting aspect is that the children can read and write, even use sign language, but they cannot understand spoken word or speak. The consensus from the group of people at this special interest group was that it is important for children with sudden speech impediments and a family history of epilepsy to undergo night-time EEG recording to determine if their speech problems can be linked to things like autism, or if it is actually an epileptic event. If clinical epileptic activity is observed, it is suggested that the child is monitored for an extended period of time (12-18 months) to see if there is a natural improvement in their speech, and only start thinking about drug therapy if there is none. The thinking is that if the EEG signals can be brought back to normal early enough, providing they were not on course to do this themselves, the impediment would be reversed.

The second part, dealing with immune response and seizures, was somewhat out of my league. The talks were mostly covering basic science and all seemed to link increased immune response with increased occurance of seizures. Various pathways were demonstrated, mostly in animal models, from linking temperature increases to seizures all the way to demonstrating antibody binding to and blocking ion channels.

I am fairly busy at the conference so today’s IC Friday may become next weeks IC Tuesday or later. With the bad news comes some good news. The chip I have lined up is one that is very close to my heart, the Graphics Synthesizer chip from the Playstation 2. I have most of the images on my laptop already, I mainly need to stitch them, format and upload, so I apologize for the wait.

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I am going to the 2007 American Epilepsy Society annual meeting in Philadelphia, PA next weekend and intend to present a poster half of which will deal with multi-taper spectral analysis. I am presenting it next Monday morning, from 8:00AM to 2:00PM (poster #3.165). I could also use some suggestions for a good place to get a cheese steak.

The novelty of this presentation is that I am using orthogonal Slepian tapers to determine both the amplitude and phase of a complex transfer function, where most of the previous research deals with amplitude spectra alone. The difficulty is that the various tapers have different phase-bias characteristics, so averaging them and then computing the phase and amplitude would not work. Nevertheless, if we first compute the power in different bands, per taper, and then average, the phase dispersion will not play an important role. The second part of the presentation will deal with causing the activity of an on-going, epileptic seizure to become temporarily phase-locked to applied electrical stimulation (entrainment). The technical abstract for the poster presentation is below.

( nchernyy-abstract.pdf )

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I had spent some time yesterday at a NIH grantsmanship seminar so here is a small digest.

Firstly, the NIH is split up into 24 administrative units/institutes each of whom have their own individual budgets and fund their own grants. Although NIH has standardized grants (F, K, R, P series), their funding criteria and value different from institute to institute. For this reason, it is paramount to have your grant sent to the appropriate institute for consideration after it is reviewed by the Center for Scientific Review. It is highly recommended that those who are planning to submit a grant contact a program officer in the individual institute to discuss the scope of the grant to make sure that it complies with the activities of the institute. If not, the program officers can typically recommend a better place to submit your grant. Below are a few useful links.

• Neuroscience research funding contacts in the federal government
• Federal grants clearing house
• NIH program announcements and requests for applications
• “All about grants“
• NIH grant writing tips
• Quick guide for grant applicants

The image above is of gold ore taken from USGS mineral resources program.

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I spend the first half of today participating in an EEG Mu/Beta rhythm experiment which tries to differentiate intent for left and right hand movement based on a four electrode montage. This was the first time that I did such a thing and also the first time that my own EEG was recorded. Although there is plenty of optimism around using EEG recording to control video games, playing Pong (video) is the state of the art. Companies like g.Tec already sell hardware ensembles that have enough processing power for at least rough, single-axis position interpretation. The trouble is that there is a lot of training involved and there is still the propensity for misclassification if the data is analyzed in real-time movement tasks where there is intent but no well-defined success criteria. I am hoping to do some more BCI experiments and will hopefully have some more things to report. Below is a plot of the results of my best trial where I had to think about moving either my left or right arm as per computer instructions. Please note that the classification error is down to almost 8% between 4.5 and 5 seconds after experiment initiation with the instruction being given between 2 and 4 seconds. Since this is technically a single-axis discrimination, I think I may be ready to play some neuro-pong!

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Almost every issue of Journal of Neural Engineering contains some a free article or two. The June 2007 issue happens to have three and all of them are review articles, meaning they are substantial and contain summaries of the ongoing research in the area. Two of them are on brain-computer interfaces and one is on visual prosthetics. The image is said to be Albert Einstein’s EEG according to Scienceblogs.

A review of classification algorithms for EEG-based brian-computer interfaces
F. Lotte, M. Congedo, A. Lecuyer, F. Lamarche and B. Arnaldi
( 2007lotte-eeg-based-bci-review.pdf )

Prosthetic interfaces with the visual system: biological issues
E. D. Cohen
( 2007ethan-prosthetic-interfaces-with-visual-system.pdf )

A survey of signal processing algorithms in brain-computer interfaces based on electrical brain signals
A. Bashashati, M. Fatourechi, R. K. Ward and G. E. Birch
( 2007bashashati-bci-algorithm-survey.pdf )

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