Sensory stimulation-induced neuroprotection in hyperacute phase of ischemic stroke – a multimodal imaging study

Abstract

Study of cerebral cortical functions affected by ischemic stroke explicates post-stroke brain plasticity. We report an innovative combination of electrocorticography (ECoG) recordings and functional photoacoustic microscopy (fPAM) imaging to investigate cortical functions after photothrombotic ischemia (PTI) in rat brain, with electrical forepaw stimulation applied as treatment. The cortical functions were assessed over a chosen ischemic region via somatosensoryevoked potential (SSEP), resting-state ECoG signals and evoked hemodynamic response. Two-phased experimental protocols based on sensory stimulation treatment are proposed and performed in this study. In the phase 1, the treatment is applied to the left forepaw, contralateral to the ischemic hemisphere, with 2 mA pulses initiated 0, 1, or 2 hours postischemia to determine optimal onset timing. After determining the optimal time window, in the phase 2, the treatment was delivered unilaterally or bilaterally using 2 or 4 mA pulses for validating if bilateral peripheral electrical stimulation with different current intensities could improve cerebral perfusion and restore cortical neurovascular response. Overall, the results demonstrated that our treatment administered bilaterally at 2 mA within 2 hours of ischemia can promote neuroprotection significantly via reversed cortical functions, suggesting effective recovery.