Effects Of Low-intensity Ultrasound Stimulation On Cortical Neurovascular Coupling In Mice

Low-intensity transcranial ultrasound stimulation technology is a new brain stimulation method developed in recent years,which has the advantages of no damage,high spatial resolution and high stimulation depth.However,its influence on neurons is still uncertain,so it is important to study the mechanism of ultrasound stimulation on neurons.Neurovascular coupling is the basis of cranial nerve metabolism and is of great significance for maintaining brain activity.Neurological diseases such as stroke,small vessel disease and neurodegenerative diseases are related to it.In this paper,we study the neurovascular coupling mechanism of transcranial ultrasound stimulation on the cortex.The main work is summarized as follows:Firstly,the experimental platform design and construction,this paper redesign and improve the endogenous optical imaging platform for collecting cortical internal source signals;build and debug EEG acquisition system,debug software parameters for collecting EEG signals;Control program,use LabVIEW software to control the signal source to send pulse signal at the required time,and finally send ultrasonic signal through signal modulation;build a hydrophone sound field scanning system,convert the sound signal into voltage signal,write LabVIEW control program,control motor in XYZ The axis scans point by point,measuring the sound field distribution of the ultrasonic transducer,and preparing for the experiment.Then,the neurovascular coupling study of the anesthetized mice under ultrasound stimulation was carried out,and the endogenous signals and brain electrical signals of the mouse cortex were collected to analyze the effect of ultrasound stimulation on the concentration of deoxygenated hemoglobin(HbR)in the cortex of mice and the effects on cranial nerve activity.Experimental results show that ultrasound stimulation affects the cortical neural activity.The coupling relationship between nerve and blood vessel under different ultrasonic stimulation parameters was analyzed,and the influence of ultrasonic stimulation parameters on the coupling coefficient of nerve blood vessels was found.In this paper,it is believed that stimulation can cause a large number of cell-level changes in the brain,which in turn changes the neurovascular coupling relationship.This includes cell body expansion,increased extracellular ion concentration,and changes in local metabolite concentrations.Finally,the effect of ultrasound stimulation on HbR in conscious mouse cortex was studied in response to the problem that anesthesia may affect cerebral blood oxygen metabolism in mice.In this paper,the mouse ultrasonic stimulation experiment was performed under awake state,and the endogenous signal pictures of visual cortex,sensory cortex and motor cortex were collected.By comparing the HbR changes of different cortex before and after ultrasound stimulation by data processing,it was found that ultrasound stimulation can have similar effects on different cortex,which can excite neurons.It was also found that anesthesia inhibited the excitability of neurons,resulting in a slower recovery of hypoxic hemoglobin after ultrasound stimulation.