Independent component analysis for processing of retinal responses to patterned stimuli

To permit the non-invasive study of the response of the retina to spatially patterned stimuli, an optical imaging apparatus that can deliver a video-based visual stimulus to the retina while imaging the functionally correlated intrinsic signal response in the rear infrared (IR) was developed. Measured changes in reflectance in response to the visual stimulus are on the order of 0.1% to 0.5% of the total reflected intensity level, which makes the functional signal difficult to detect by standard methods because it is masked by the other physiological signals. In this paper, we apply principal component analysis (PCA) and independent component analysis (ICA) methods such as JADE and fast-ICA to extract the signals present on the resulting videos. From our dataset of 140 different experiments performed on cats, in 65 % of the cases the algorithms can detect and extract the patterned stimuli. Careful analysis of the results may give an insight of the processes present during the stimulation of the retina.