Characterization of predictive power of extracellular signal recordings in a cerebral ischemia animal model

IntroductionGlobal cerebral ischemia leads to substantial and irreversible damage of brain tissue. As it progresses in a less severe course, certain strategies should be implemented to screen this condition on its early onset. The research aimed to characterize the local field potential (LFP) alterations recorded during the subacute phase of the cerebral ischemia animal model and provide their predictive power. MethodsThe extracellular signal recordings from the parietal cortex of animals were registered with a neural probe. The signal was amplified, filtered, digitized, and acquired with Intan amplifier and USB interface boards. The recordings were obtained both in normal conditions and after implementation of unilateral common carotid artery occlusion. The data analysis and classification were performed using NI Diadem software and custom-written code in IPython environment. The respective morphological changes were screened in cerebral cortex and hippocampus. The whole-brain slicing and TTC staining were used for infarct size evaluation. ResultsIn Fourier spectrograms of intact brain recordings, a peak at 14.4-15 Hz frequencies was detected, whereas this phenomenon was absent in cerebral ischemia model recordings. In channels cross-correlograms for intact and ischemic brain recordings, there was a clear difference detected in the maximum peak power. With autocorrelation analysis, the long lag rhythmicity was detected in normal brain recordings, while no rhythmicity was observed in ischemic brains. The morphological and behavioral analyses did not result in any significant changes and neural loss. The TTC staining failed to show any damaged area ipsilateral to the occluded common carotid artery. ConclusionWe have analyzed and described the major characteristics of the electrical activity that vary between neural populations of the parietal cortex of normal and ischemic brains. This data proves that LFP recordings can be used for further investigation of changes occurring in the subacute phase after unilateral common carotid artery occlusion.