The Study Of Transcranial Ultrasound Stimulation In The Protection Of Ischemic Brain Injury

Transcranial ultrasound stimulation (TUS) is a recently novel brainstimulation technology, which transfers ultrasonic energy through theintact skull and non-invasively modulates neural activity in the brain. Inthe Introduction of this thesis, we reviewed the biomedical applications ofultrasound and the state of art in TUS. Then, we introduced the high spatialresolution TUS system that can be used for neural stimulation. In an in-vivo experiment, we carefully selected for stimulation parameters foreffective neural stimulation. Based on the hypothesis that neuralstimulation immediately after the stroke would activate the neuroprotectionin ischemic brain injury, we designed an experiment to test theneuroprotection of TUS in distal middle cerebral artery occlusion(dMCAO) model of stroke in rats.32SD rats were randomly separated intotwo groups: control group (with regular dMCAO) and TUS group (thesubjects were stimulated by pulsed ultrasound (NC:200, PRF:1.5KHz, NTB:600) which focuses on the ischemic core area). After48hours ofthe stroke, the behavior performances, brain activity in aspect of opticalintrinsic signals, and the histological results of the brain tissue wereanalyzed for all animals. Measure and evaluate the result by means of TTCstaining cortical tissue to measure infarct size (TUS group(13.78%±8.18%,n=16)<control group(43.39%±2.33%,n=16), behavioraltest to assess motor ability of experimential animals (TUS group(n=10,5.5±2.5)<control group (n=10,10.5±1.4)) and optical intrinsicsignals (OIS) imaging techniques to assess brain function to evaluate thepotential for transcranial ultrasound stimulation to protect the ischemicbrain damage after stroke, then employ laser speckle imaging to observethe blood supply of the interested region of brain andimmunohistochemical to analyze the cell apoptosis to study the possiblemechanism of the ptotection of TUS, propose the enhancement ofperfusion and reduction of inflammation are two possible mechanisms forthe protective effect of TUS.This is the first time to report the results of the neuroprotection of TUSin ischemic stroke in this study. Further study will be focused on theoptimal stimulation parameters, the underlying neural mechanisms of theneuroprotection.