Functional Connectivity Analysis Of Structurally Constrained Thalamocortical Circuits In Schizophrenia

Schizophrenia is one of the most damaging neuropsychiatric disorders,affecting approximately 1% of the world’s population.Among them,most studies based on brain connectivity have found that changes in brain circuits involved in subcortical regions such as the basal ganglia and cerebellum contribute significantly to cognitive behavioral abnormalities in schizophrenia.Several recent studies have updated our understanding of the basal ganglia and cerebellum,that these regions are not only involved in motor-related functions.On the contrary,relying on the relay of the thalamus,the basal ganglia and cerebellum are widely connected with the cerebral cortex,and are also involved in higher cognitive functions including emotion regulation,emotion recognition,and error monitoring.Therefore,these regions-related circuits are closely related to the abnormal behavior of schizophrenia,which is also supported by evidence from recent brain network research.However,there are several problems in the previous research on this problem,including the imperfect loop construction method and the inaccurate positioning of loop regions.This study believes that in the study of the subcortical-cortical circuit in schizophrenia,it is necessary to fully consider the topological organization characteristics of the circuit itself,fully integrate the advantages of data analysis,and establish the connection paths between the nodes of the circuit in turn.Based on this,this paper starts from the thalamocortical loop and reasonably integrates the multimodal magnetic resonance data to construct two neural pathways involving the basal ganglia and the cerebellum: the basal ganglia-thalamic-cortex-basal ganglia pathway and the cerebellar-thalamic-cortical-cerebellum pathway.First,the spatial topological pattern of the projections of these two loops within the thalamus was described by fiber tract tracing.White matter connectivity analysis showed that the projections of the basal ganglia and the cerebellum within the thalamus were bilaterally symmetrical.Subsequently,based on the white matter connectivity pattern,the weighted average BOLD signal of the white matter mapping of the two loops was extracted by means of spatial regression.This signal reflects the neural oscillations of the thalamus regulated by the structural information of the basal ganglia and cerebellum.Then,using this oscillation information as the source,using the method of time regression,the functional connection between the thalamus and the cerebral cortex under the control of the basal ganglia and cerebellum was constructed.The functional connectivity abnormalities of thalamocortical circuits in schizophrenia under structural constraints were compared between groups.It was found that patients with schizophrenia showed a broad pattern of increased functional connectivity,mainly distributed in the precentral gyrus,postcentral gyrus,frontal pole,precuneus,temporal lobe and parahippocampal gyrus,which are mainly related to vision,cognition,etc.The increased functional connectivity of these regions may reflect their over-interaction with the cerebral cortex.On the other hand,compared with previous studies that only described the abnormality of the subcortical-cortical ascending loop in schizophrenia,this paper also reconstructs the cortex using the high spatial resolution of structural magnetic resonance data,explored the cortical-subcortical area coupling in more detail,and also explored the descending loop of the entire loop and its disease effects.The specific process is as follows: 1.Constructing subcortical-subcortical surface white matter connections;2.Extracting the time series of BOLD signals on the subcortical surface;3.Calculating the functional connectivity of the two loops under the constraints of structural connectivity;4.Comparing the patient group with the healthy controls Differences in connectivity between groups.It was found that the functional connectivity of the precuneus was increased and the functional connectivity of the insula was decreased in patients with schizophrenia.The weakened connectivity may be related to the decline in the function of emotional processing.The precuneus is the "core node" of the default mode network,and the enhanced connectivity reflects its Self-awareness plays a role.In conclusion,this paper comprehensively integrates the advantages of various data such as functional magnetic resonance,diffusion magnetic resonance and structural magnetic resonance,and explores the abnormal functional connections of thalamic cortical circuits in patients with schizophrenia under structural constraints from multi-modal,multi-pathway and multi-scale perspectives.Validate and complement the functional roles of the basal ganglia and cerebellum in thalamocortical circuits from the perspective of brain structure and brain function.It is hoped that this study can deepen the understanding of the abnormality of key circuits involved in schizophrenia.