چكيده به لاتين
Abstract:
Working memory is a form of memory that allows us to temporarily keep limited information in use for cognitive tasks and processing. In this project, with the aim of evaluating selectivity and decoding in working memory(WM) task to know more about WM functionality, we used the dataset recorded from the monkey, which was collected from the lateral prefrontal cortex and its two dorsal and ventral regions. we extracted features in the working memory period from measures such as firing rate, spike distance, spike train coupling between two regions, spike index residuals, inner spike intervals, and spike-triggered average neuronal activity. Significant time points of timing measures were selected by statistical test and FDR correction (p <0.05) and we compared these measures for two states of location and stimulus features between the ventral and dorsal regions. Then we did feature selection and we calculated the rank of each feature and the average accuracy of classification( in 10-fold cross-validation for four models) for two preferred and unpreferred feature classes and the two location classes inside and outside the receptive field (RF) of neurons in both regions. According to the results, the dorsal region had more active neurons during the working memory period. This area is also known for encoding location information. if we consider the persistence stimulus duration, the average firing rate is higher for the feature mode in the ventral region and higher for the location mode in the dorsal. However, in the working memory period, due to more plasticity of the ventral regions, connection and coupling between two regions selectivity and discriminability between the two classes in this area had more accuracy in classification results in both task modes (accuracy for location task respectively For the two ventral and dorsal areas in the best classifier, which was the support vector machine, is 100% and 83%, and for the feature mode and the two mentioned areas, is 95% and 99%, respectively). These results are consistent with previous research showing that information is transmitted from the area that has more selectivity in the feature or location during the presence of the stimulus and trail, to another area, and also some neurons in these areas are selective to both location and feature mode. Finally, it was found that stimulus encoding during the working memory period is more related to the coupling measures and connections between dorsal and ventral regions, and previously used measures such as firing rate are not sufficient to examine the selectivity, because connections and correlations of neuronal population activities should be considered.
Keywords: Working memory, selectivity, Feature extraction, Feature selection, Decoding, Encoding.
