title: Rescue of cortical neurovascular functions during the hyperacute phase of ischemia by peripheral sensory stimulation.
abstract: To investigate the potential therapeutic effects of peripheral sensory stimulation during the hyperacute phase of stroke, the present study utilized electrophysiology and photoacoustic imaging techniques to evaluate neural and vascular responses of the rat cortex following ischemic insult. We employed a rat model of photothrombotic ischemia (PTI), which targeted the forelimb region of the primary somatosensory cortex (S1FL), due to its high reproducibility in creating localized ischemic injury. We also established a hybrid, dual-modality system, including six-channel electrocorticography (ECoG) and functional photoacoustic microscopy (fPAM), termed ECoG-fPAM, to image brain functional responses to peripheral sensory stimulation during the hyperacute phase of PTI. Our results showed that the evoked cerebral blood volume (CBV) and hemoglobin oxygen saturation (SO2) recovered to 84±7.4% and 79±6.2% of the baseline, respectively, when stimulation was delivered within 2.5 h following PTI induction. Moreover, neural activity significantly recovered, with 77±8.6%, 76±5.3% and 89±8.2% recovery for the resting-state inter-hemispheric coherence, alpha-to-delta ratio (ADR) and somatosensory evoked potential (SSEP), respectively. Additionally, we integrated the CBV or SO2 with ADR values as a recovery indicator (RI) to assess functional recovery after PTI. The RI indicated that 80±4.2% of neurovascular function was preserved when stimulation was delivered within 2.5h. Additionally, stimulation treatment within this optimal time window resulted in a minimal infarct volume in the ischemic hemisphere (4.6±2.1%). In contrast, the infarct volume comprised 13.7±1.7% of the ischemic hemisphere when no stimulation treatment was applied.
authors.affiliation: Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, 28 Medical Drive, #05-COR 117456, Singapore. Electronic address: gs336.tw@gmail.com.
authors.forename: Lun-De
authors.initials: LD
authors.lastname: Liao
authors.affiliation: Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, 28 Medical Drive, #05-COR 117456, Singapore; Department of Electrical & Computer Engineering, National University of Singapore, 4 Engineering Drive 3 117583, Singapore.
authors.forename: Yu-Hang
authors.initials: YH
authors.lastname: Liu
authors.affiliation: Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan 333, Taiwan, ROC.
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Lai
authors.affiliation: Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, 28 Medical Drive, #05-COR 117456, Singapore; Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1 117575, Singapore.
authors.forename: Aishwarya
authors.initials: A
authors.lastname: Bandla
authors.affiliation: Department of Neurology, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Yen-Yu Ian
authors.initials: YY
authors.lastname: Shih
authors.affiliation: Department of Biomedical Engineering, National Yang Ming University, No. 155, Sec. 2, Linong St., Taipei 112, Taiwan, ROC.
authors.forename: You-Yin
authors.initials: YY
authors.lastname: Chen
authors.affiliation: Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, 28 Medical Drive, #05-COR 117456, Singapore; Department of Electrical & Computer Engineering, National University of Singapore, 4 Engineering Drive 3 117583, Singapore; Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1 117575, Singapore; Department of Biomedical Engineering, Johns Hopkins University, Traylor 701/720 Rutland Ave, Baltimore, MD 21205, USA.
authors.forename: Nitish V
authors.initials: NV
authors.lastname: Thakor
mesh_terms: D000818:Animals; D001810:Blood Volume / Q000502:physiology; D001811:Blood Volume Determination; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy*; D002560:Cerebrovascular Circulation / Q000502:physiology; D004195:Disease Models, Animal; D004599:Electric Stimulation Therapy / Q000379:methods*; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005552:Forelimb / Q000503:physiopathology; D008297:Male; D033401:Microscopy, Acoustic / Q000295:instrumentation / Q000379:methods; D017208:Rats, Wistar; D020127:Recovery of Function / Q000502:physiology; D013003:Somatosensory Cortex / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors
keywords: Collateral circulation; Electrocorticography (ECoG); Functional photoacoustic microscopy (fPAM); Ischemia; Peripheral somatosensory stimulation; Photothrombotic ischemia