An integrated neuroprotective intervention for brain ischemia validated by ECoG-fPAM

Brain ischemia is a neurological deficit caused by a reduction in the blood supply to tissue, and one of the leading causes of disability in the world. Currently, the most well-known therapeutic agent for ischemia recovery is recombinant tissue plasminogen activator (rtPA), but it is viable for only a small portion (approximately 3.6%) of ischemic patients and may cause side effects such as tissue damage. Thus, introducing a new therapeutic concept for ischemia, we proposed an integrated intervention combining global and focal stimulations in this article. To investigate the potential therapeutic effect of cathodal-transcranial direct current stimulation (C-tDCS) with peripheral sensory stimulation (PSS) during the hyperacute phase of stroke, the present study evaluated neurovascular and neuroprotective responses of the rat cortex following ischemic insult. A hybrid, dual-modality system, including electrocorticography (ECoG) and functional photoacoustic microscopy (fPAM), termed ECoG-fPAM, was used to image cortical functional responses pre- and post-ischemia. Using ECoG-fPAM, results showed that cerebral blood volume (CBV) was able to be recovered during the intervention. In addition, neural activity including somatosensory evoked potentials (SSEPs) and alpha-to-delta ratio (ADR) were restored and greater than the baseline value when the integrated intervention was administered. The results of NeuN/ED-1 immunohistochemical staining and TTC staining also supported the neuroprotective effect of this intervention, protecting more neurons and decreasing the infarct size. Overall, the results acquired from the ECoG-fPAM system demonstrated that C-tDCS + PSS administered immediately following ischemia induction can significantly promote neuroprotection via inhibition of ischemia expansion and reversed cortical neurovascular functions, suggesting effective recovery.