| The standard brain model can represent the typical structure of a species’ brain.Construction of the standard brain model is not only important for the study of the anatomical structure and function of the brain,but also for building the brain neuronal circuit.In this study,we first used immunohistochemical staining and laser scanning confocal microscopy to obtain images of the adult Helicoverpa armigera brain,and then used Amira software to analyse and reconstruct the three-dimensional model of adult brain.Finally,we used the Iterative Shape Averaging to construct the standard brain model and the neuropils standard model.The research results are as follows:(1)The optic lobe,antennal lobe,anterior optic tubercle,mushroom body,central complex and other neuropils in adult H.armigera brain were segmented and reconstructed,and their absolute volumes and relative volumes were calculated by using the image analysis software Amira.The results show that the brain of the male H.armigera was larger than that in the female(the volume of the male H.armigera brain was 1.02 × 108 ± 0.86 × 107 μm3;the volume of the female H.armigera brain was 9.64 × 107 ± 0.81 × 107μm3).There were significant difference in the volume of neuropil structures between the optic lobe,antennal lobe,anterior optic tubercle and central complex(P < 0.05),however their relative volume results showed that the proportion of each neuropil in the male and female brain is similar,for instance,the relative volume of the optic lobe is 33.5% in male and 33.21% in female,the antennal lobes is 6.34% in male and 6.34% in female,the mushroom body is 5.47% in male and 5.94% in female,the central complex is 1.39% in male and 1.38% in female,and the anterior optic tubercle is 0.85% in male and 0.84% in female.The optic lobe and the anterior optic tubercle,the mushroom body and antennal lobe have a significant positive correlation(P < 0.01).(2)The three-dimensional models of 15 male and 20 female of adult H.armigera,were constructed by using the image analysis software Amira,and all brain models were transformed via one affine deformation,five elastic deformations and six averages with the Iterative Shape Averaging,for generating the standard brain model of H.armigera.We analyzed the volume size and degree of variation of the source brain model and the standard brain model after each deformation.The volume size and degree of variation of the source brain model and the first affine deformation of the standard brain model were varied in a large extent.However,after elastic deformation,the standard error of the volume between each model is reduced,and the difference between the average volume of neuropils and the volume of each generated averaging structures is minimized.From the first elastic deformation to the fifth elastic deformation,the variability of model volume size after each deformation is similar.Therefore,we take the fifth elastic deformed brain model,e.g.the sixth averaged model,as the standard brain model.Applied the same method,we constructed the standard model of the whole brain,midbrain,olfactory center,visual center,and navigation and motor centers of the adult H.armigera.The standard brain model of the whole brain includes the optic lobe,antennal lobe,anterior optic tubercle,mushroom body,central complex,and other brain neuropil structures;The standard model of the midbrain only includes the brain structure between the left and right optic lobes;The standard model of the olfactory center includes antennal lobe,calyx,pedunculus and mushroom body lobes;The standard model of the visual center includes the medulla,lobule,lobule plate and anterior optic tubercle;The standard model for navigation and motor centers includes the central body,protocerebral bridge and noduli.The statistical analysis results showed that the standard model of the whole brain and the standard model of each neuropil structure are similar in morphology and volume size.The above results indicate that we have successfully constructed the standard brain model of adult H.armigera,they provided a standard framework for the study of brain structure,analysis of multiple sensory neurons,and construction of neural circuits in H.armigera.They also provided ideas and methods for the research in the other insect. |
