MATSAP: An Automated Analysis of Stretch-Attend Posture in Rodent Behavioral Experiments

Stretch-attend posture (SAP) rodent behavioral analysis, often used in preclinical research, is more sensitive to the effects of classical and atypical anxiolytics than traditional spatiotemporal indices. With limited funding in some research labs, there is a need for open source software that detects SAP in rodents. SAP occurs when the rodent lowers its back and elongates its body and either stands still or moves forward slowly. Evaluation with human scorers is time-consuming and susceptible to error due to fatigue. An open source image detecting software using MATLAB is being developed to detect SAP with a flexible yet user friendly GUI. The software analyzes multi-tiff video files from an overhead view. After the user inputs a threshold to convert input images into binary images with the optional assistance of a threshold preview GUI, the eccentricity value of an ellipse fitted around the rodent, along with its speed, is utilized to detect SAP. The program provides plots displaying SAP detection plus the corresponding speed and eccentricity values. When MATSAP was assessed with videos of male Swiss mice in open field (OF) and elevated plus maze (EPM), the accuracy was equivalent to the 5 human scorers with a runtime less than 2 min for a 5 min video. The current version of the software was 90.37% accurate for the OF with a sensitivity and specificity of 79.53% and 91.74%, respectively. For the EPM, MATSAP had an accuracy of 85.46% with a sensitivity and specificity of 78.29% and 89.88%, respectively.