Spatiotemporal inseparability in early visual processing.
We examine the implications of significant inseparable behaviour in centre-surround retinal cell types. From the form of a spatiotemporal centre-surround (CS) model which agrees qualitatively with physiological observations, we find that the sustained/transient dichotomy is a poor distinction for X-type/Y-type retinal ganglion cells since both exhibit inseparability. Static centre-surround models and spatiotemporal separable models are not valid for time-varying stimuli. Our results contradict the models for X- and Y-type ganglion cells proposed by Marr and Hildreth (1980) and Marr and Ullman (1981), and raise doubts about the physiological validity of Marr's zero-crossing theory. The CS filter is an attractive precursor to the extraction of 2-d motion information.
D000818:Animals; D002415:Cats; D003491:Cybernetics; D005724:Ganglia / Q000502:physiology; D008954:Models, Biological; D009039:Motion Perception / Q000502:physiology; D012160:Retina / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception / Q000502:physiology