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14 April 2005 Three-dimensional optical tomographic brain imaging during kainic-acid-induced seizures in rats
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In this study, we explored the potential of diffuse optical tomography for brain oximetry and describe our efforts towards imaging hemodynamic changes in rat brains during kainic-acid (KA) induced seizures. Using electrophysiological techniques we first showed that KA induces a pronounced transient hypotension in urethane anesthetized rats that is coincident with seizure activity beginning in ventral and spreading to dorsal hippocampus. We observed sustained increases in vagus and sympathetic activity during generalized limbic seizure activity, which alters blood pressure regulation and heart rhythms. Subsequently, we used optical tomographic methods to study KA induced seizures in anesthetized animals to better define the hemodynamic cerebral vascular response. We observed a lateralized increase in deoxyhemoglobin after KA injection at the time when the blood pressure (BP) was decreased. By contrast, injection of phenylephrine produced a symmetric global increase in total hemoglobin. These findings indicate that our instrument is sensitive to the local hemodynamics, both in response to a global increase in blood pressure (phenylephrine injection) and a lateralized decrease in oxyhemoglobin produced by an asymmetric response to KA; a response that may be critically important for severe autonomic nervous system alterations during seizures. The results of this study provide the impetus for combining complimentary modalities, imaging and electrophysiological, to ultimately gain a better understanding of the underlying physiology of seizure activity in the rat.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Avraham Y. Bluestone, Kenichi Sakamoto, Andreas H. Hielscher, and Mark Stewart "Three-dimensional optical tomographic brain imaging during kainic-acid-induced seizures in rats", Proc. SPIE 5746, Medical Imaging 2005: Physiology, Function, and Structure from Medical Images, (14 April 2005);

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