Study Functional Circuits Of Macaque Rhesus' S Amygdala With Infrared Neural Stimulation Combined With Ultra-high Field FMRI

As an important node of the limbic system,the amygdala is involved in many brain functional circuits.In non-human primate studies,the amygdala is thought to be primarily involved in the three main functional circuits of cognition behavior:(1)the reading and encoding of input information from the external environment by the sensory system;(2)the evaluation and integration of input information by the intrinsic evaluation system;and(3)the planning and execution of behavior by the motor system.The brain areas related to these three loops are widespread,and interacted complexly,but research into brain functional networks,which are both holistic and more exquisite,has been limited.This study combined Infrared Neural Stimulation(INS)with ultra-high field Magnetic Resonance imaging(fMRI).INS-fMRI has the advantages of high spatial and temporal resolution of functional Magnetic Resonance Imaging(fMRI)at whole brain size,as well as the advantages of anti-interference and high accuracy of Infrared Neural Stimulation(Xu et al.2019).In this experiment,1875 nm infrared laser was used,delivered through the optical fiber which core diameter is 200?m for accurate deep brain stimulation.At the same time,collecting data with 7T fMRI.The paper explored if INSfMRI is an efficient method for functional network study,what the relationship between functional and anatomical network,and what is the relationship among the functional circuits in which different subnuclei in amygdala involved.Energy dependent,accurate and restricted activation was obtained at the tip of fiber.The activated connection signal is stable and also intensity dependent.The number of activated voxels instead of the response amplitude showed intensity relationship.Also compare to the stimulate paradigm and intensity,the results from different stimulate sites showed more variations,wider range of response amplitude and activated voxels number.For the activated brain areas,there were consistent with previous anatomical studies in generally.In the sensory system,stimulation of different locations in the amygdala activated vision,somatosensory,auditory,gustatory,and olfactory cortex separately or simultaneously.In the value measurement system,stimulation of the amygdala activated the limbic areas such as the frontal lobe,cingulate gyrus,insula and hippocampus.In the motor system,stimulation of the amygdala activated areas such as the premotor,motor and parietal lobes.The whole activated functional map was widespread than the anatomical map reported,and the functional circuits activated at different sites in amygdala intersected,proved that amygdala is a functional unite.These activated functional connections are consistent with the reported structural connections,which further proved that compare with existing technology,INS-fMRI has more advantage in timeliness and reliability.