Three-Dimensional Optical Tomographic Brain Imaging during Kainic-Acid-Induced Seizures in Rats

摘要

In this study, we explored the potential of diffuse optical tomography for brain oximetry and describe our effortstowards imaging hemodynamic changes in rat brains during kainic-acid (KA) induced seizures. Usingelectrophysiological techniques we first showed that KA induces a pronounced transient hypotension in urethaneanesthetized rats that is coincident with seizure activity beginning in ventral and spreading to dorsal hippocampus. Weobserved sustained increases in vagus and sympathetic activity during generalized limbic seizure activity, which altersblood pressure regulation and heart rhythms.Subsequently, we used optical tomographic methods to study KA induced seizures in anesthetized animals tobetter define the hemodynamic cerebral vascular response. We observed a lateralized increase in deoxyhemoglobin afterKA injection at the time when the blood pressure (BP) was decreased. By contrast, injection of phenylephrine produceda symmetric global increase in total hemoglobin. These findings indicate that our instrument is sensitive to the localhemodynamics, both in response to a global increase in blood pressure (phenylephrine injection) and a lateralizeddecrease in oxyhemoglobin produced by an asymmetric response to KA; a response that may be critically important forsevere autonomic nervous system alterations during seizures. The results of this study provide the impetus for combiningcomplimentary modalities, imaging and electrophysiological, to ultimately gain a better understanding of the underlyingphysiology of seizure activity in the rat.