The Design And Test Of Transcranial Focused Ultrasound Stimulation System

Transcranial focused ultrasound stimulation（tFUS）is emerging as a promising neuromodulation technique for its noninvasiveness,high spatial resolution and good electromagnetic compatibility.In recent years,low intensity transcranial focused ultrasound stimulation has been applied to human.In this thesis,after reviewing the state of art in tFUS technique and applications,we proposed a design for tFUS system that can be used to human brain,which is compatible with simultaneous electroence-phalographical（EEG）recording.We tested the system on both macaque and human.Firstly,we tested the safety of the system on macaque by stimulating the motor cortex at a high intensity(F=0.5MHz,DC=50%,PRF=1k Hz,ISI=4～6s,I_sppa=10 W/cm²).We didn’t observe a long-term effect on the behavior.Then we applied a low intensity suppressive tFUS(DC=5%,PRF=1k Hz,I_sppa=6 W/cm²)to the right frontal cortex of human when the subjects are performing a spatial-cueing attention task.Behavior performance andα-band electroencephalography were recorded and analyzed.The preliminary results based on a small number of subjects（n=4）showed that tFUS could slightly decrease the response accuracy though with marginal significance（R＿all:p=0.128;L＿all:p=0.081）.Response to the left cueing showed a tendency of higher accuracy than that to the right cueing except L＿all group.Meanwhile,ultrasound stimulation could lead to a significant increase of response time（Control:307.5±4.23 ms;R＿all:375.1±5.38ms;p<0.001）,especially when stimulating the right frontal cortex（L＿all:330.3±3.91 ms;R＿all:375.1±5.38 ms;p<0.001）.In aspect of electro-neurophysiolgy,tFUS on the right frontal cortex could lead to the increase of the left posteriorα-band power,indicating the inhibition in the contralateral occipital lobe sensory cortex in visual spatial attention task.Nevertheless,due to the small sample size,the mechanisms of tFUS need further work.This tFUS system facilitated to study the noninvasive modulation on the human brain activity,which may be clinically translational.