Wanted to share some cool shit related to epilepsy surgery that is out there.
This is a video about a guy who underwent surgery at Detroit Medical Center. They have some cool shots of the brain.
Chris Wells - this one's for you. Called Diffusion Tensor Imaging. They use functional imaging and overlay it on an MRI to actually map the fiber tracts. Fucking awesome.
This one is for those medical marijuana advocates out there - you know who you are.
Tuesday, January 27, 2009
Fucking Seizures
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2 comments:
With respect to the first video, how can one get an accurate mapping of the brain by putting electrodes on the exterior of it? Might not there be tissue on the outside of the brain that doesn't seem to have any effect on speech, for example, but a centimeter or so down be tissue that is crucial to language? Or is that the brain organized in such a way that what goes on in exterior tissue is a good indicator of what goes on in interior tissue, to a certain degree? I guess another possibility is that the electrodes penetrate far enough to detect any such variation (this is coming from a complete ignoramus wrt. brain physiology, so be gentle).
Yeah, so the cortex of the brain is composed of grey matter which is only millimeters thick. Beneath that is white matter which is essentially wiring. So you're right that language, for example, can be affected clinically by both damage to the cortex as well as the underlying circuits linking two cortical areas.
The purpose of the intracranial electrodes is to get a more precise localization of the seizure focus, which is generated by grey matter. Electrodes on the surface of the brain have much less interference and can be placed in closer proximity than those on the scalp. The mapping they refer to is probably more trial and error where they stimulate a small area of cortex and see what clinical effect it has. The imaging techniques are better for localizing functions of cortical areas. The ultimate test is called the Wada test where they administer sodium amytal into the carotid and put half of the brain to sleep. This may be used for language but is often used to determine which hemisphere is responsible for verbal memory in those being considered for temporal lobectomy.
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