For the first time, researchers have measured the physical evidence of diminished neural processing within the brain after a stroke.

So at her next visit with her doctor, she mentioned her symptoms — and found out she was not alone.

Julia is experiencing poststroke acute dysexecutive syndrome (PSADES), a cognitive dysfunction that people commonly experience after even minor strokes. The condition becomes evident soon after the stroke occurs, and while it correlates to having dead tissue lesion(s) in the brain left behind by the stroke, it does not seem to be related to the location of the lesion(s). Fortunately, PSADES gradually improves in the months after recovery. But what has been going on inside the brain during this time?

Stroke patients have reported these cognitive difficulties to their doctors for a long time. Until now, the evidence of this problem has mostly been anecdotal. A new study by University of Maryland, Johns Hopkins University and New York University researchers for the first time provides measurable physical evidence of diminished neural processing within the brain after a stroke. It suggests that PSADES is the result of a global connectivity dysfunction. The paper, «Poststroke acute dysexecutive syndrome, a disorder resulting from minor stroke due to disruption of network dynamics,» has just been published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

The paper was written by the University of Maryland’s Professor Jonathan Simon (Electrical and Computer Engineering/Biology/Institute for Systems Research), his former postdoctoral researcher Christian Brodbeck, now a visiting assistant professor at the University of Connecticut, and UMD Ph.D. student Joshua Kulasingham; the Johns Hopkins School of Medicine’s Associate Professor Elisabeth Marsh, Professor Rafael Llinas and Dania Mallick, all of the Department of Neurology; and NYU Grossman School of Medicine Research Professor Rodolfo Llinas. Marsh is the lead author.

«We tend to think that certain parts of the brain are responsible for specific functions, but in reality you need your entire brain to think clearly and complete tasks,» Marsh says. «In this study we show how a small lesion anywhere can disrupt the cognitive network and result in a global dysfunction.»

The researchers used magnetoencephalography (MEG) to look at the brain functioning of patients who recently experienced minor strokes. MEG is a non-invasive neuroimaging technology that employs very sensitive magnetometer sensors to make high-speed recordings of naturally occurring magnetic fields produced by electrical currents inside the brain. The subject typically sits under or lies down inside the MEG scanner, which resembles a whole-head hair drier.

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Materials provided by University of Maryland. Note: Content may be edited for style and length.