Abstract:

Objective To study the activation patterns of the cerebral cortex under different accommoda⁃ tive loads of the human ciliary muscles ，the relevant functional brain networks and the effective connections between these brain regions. Methods Thirty⁃three normal subjects were recruited to perform different accommo⁃ dative tasks under MRI. The acquired data from MRI scanning were processed using SPM12 and Group Ⅰ CATv4.0a software packages on MATLAB platform. One⁃sample t⁃test was used to analyze the normal brain activation pattern diagrams. Using the Informax algorithm，the task state data was decomposed into independent spatial components， followed by extracting the corresponding components in two dimensions of time and space and analyzing the corre⁃ sponding functional network. Based on dynamic causal modelling，the effective connections between these areas were analyzed. The voxel level threshold P < 0.001 and the FWE cluster level P ≤ 0.05 were used as multiple com⁃ parison correction methods. Results The brain BOLD signal under ⁃3D and ⁃6D accommodative stimulation indi⁃ cated that the neural signals controlling the ciliary muscle were involved in a wide range of cerebral cortex，includ⁃ ing the occipital lobe，temporal lobe，cerebellum，limbic lobe，thalamus，parietal lobe and frontal lobe，and the area and intensity of brain activation under different accommodative loads varied with the different accommodative loads. Based on independent component analysis，task⁃state⁃related activated brain regions in the spatial and tempo⁃ ral dimensions mainly included visual networks，cerebellar networks，and attention networks. Based on DCM，the analysis of the effective connection between these areas discovered two neural circuits involving in the ocular accom⁃ modation，one the circuit of occipital lobe⁃cerebellum⁃parietal lobe and the other the circuit of occipital lobe⁃cere⁃ bellum⁃frontal lobe，with the thalamus acting as the mediator of information transmission. Conclusion Brain pro⁃cesses signals by engaging multiple cerebral regions，involving multiple cerebral networks and two neural circuits. The activated area and intensity vary with different accommodative loads.

Key words:

task state, neural circuit, functional magnetic resonance imaging, ciliary muscle, ac? commodation, brain network, functional connection, independent component, dynamic causal modelling