A Quantitative Statistic And Analysis Of The Distribution Of CRH Neurons In Whole Mouse Brain

Neurons play various functions in diversity brain activities and can be classified into different sub-types according to their morphologies or functions.The study of the distribution of type-specific neurons helps to further understand the structure and function of the brain.However,previous studies of type-specific neuron distribution are mainly focused on local areas or acquired with only qualitative description.The scale or precision of these study are very limited.The development of genetic labeling and imaging technology are the basis of the acquisition of the type-specific neuron dataset.But the quantitative analysis of the distribution of type-specific neurons in the whole brain is still challenging:(1)Neuron recognition is the basis of the statistics of neuron distribution and there is a lack of a robust method for the neuron recognition in complex dataset of the whole brain.(2)For the study of the neuron distribution in numerous brain regions in the whole brain,an accurate and effective scheme is needed.This dissertation proposed an approach for the quantitative statistic of the distribution of type-specific neurons based on the whole brain dataset accquired by the brain-wide positioning system(BPS).The distribution of corticotropin-releasing hormone(CRH)neurons in mouse brain is acquired using the above method.The detailed work is described as follows.(1)A robust neuron recognition method for the whole brain neuron recognition was proposed.We extracted the morphology of somas or neurites using the rayburst method.Then we classified the two neuronal structures using support vector machine(SVM),eliminating interference from the neurites and proposed a robust method for neuron recognition.The average precision/recall of the method proposed in this dissertation were 94.0%/96.5% and higher than that of the traditional methods.Furthermore,we achieved neuron recognition in whole brain effectively using a data blocking strategy and parallel optimization.With this method,we recognized the CRH neurons in four CRH-IRES-Cre;Ai3 mouse brains and the number of CRH neurons in whole mouse brain was 752,586 ± 80,699.(2)An accurate and effective statistic scheme for the quantitative analysis of the neuron distribution in whole brain was proposed.We registered the cytoarchitecture propidium iodide(PI)dataset acqured by BPS with digital brain atlas and then segmented the brain regions automatically.We checked and amended the partition result using fine-grained registration strategy and PI cytoarchitecture information.Combined with the neuron recognition method,we can acqurie the neuron number in different brain regions.With the above pipeline,we acquired the number of CRH neurons in different brain regions in the whole brain.The CRH neurons were widely distributed in the whole mouse brain.Particularly,relatively large number of CRH neurons were distributed throughout the cortex,and there were only a few CRH neurons in the cerebellum.These results provide a basis for the understanding of cell types in the brain.(3)We quantitatively analyzed the distribution of CRH neurons in whole brain.Based on the statistics of CRH neuron distribution,we analyzed the neuron distribution differences among the brain regions.The results presented that there were densely distributed CRH neurons in the much concerned regions in previous study such as CEA,PVH and so on.There were also a large number of CRH neurons in the olfactory bulb,the brain regions near the midline of thalamus and ECU.The above quantitative analysis of the distribution of CRH neurons will contribute to the study of CRH neuronal function.Furthermore,we analyzed the CRH neuronal soma shape in typical brain regions and the result indicated the shape diversity of the somas.The morphological analysis of somas facilitates the classification study of CRH neuron sub-types.This dissertation proposed a method for the analysis for the distribution of CRH neurons in the whole mouse brain.The method can also be used for the analysis of the distribution of other types of neurons,even in other mamalian brains.These distribution results may help to enhance current understanding of the cell types in the brain and deepen the study of brain functions.