Contextual modulation of orientation tuning contributes to efficient processing of natural stimuli

• Published in: Network (Bristol) 2005-06, Vol.16 (2-3), p.139-149
• Main Authors: Felsen, Gidon, Touryan, Jon, Dan, Yang
• Format: Article
• Language: English
• Subjects: Animals; Applications; Biological and medical sciences; Biology, psychology, social sciences; Cat; Cats; Computer Simulation; Discrimination Learning - physiology; Evoked Potentials, Visual - physiology; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General aspects. Models. Methods; Information Storage and Retrieval - methods; Mathematics; Models, Neurological; Nerve Net - physiology; neuronal response properties; Neurons - physiology; Orientation - physiology; Pattern Recognition, Visual - physiology; Photic Stimulation - methods; Probability and statistics; Probability theory and stochastic processes; Sciences and techniques of general use; Special processes (renewal theory, markov renewal processes, semi-markov processes, statistical mechanics type models, applications); Statistics; Vertebrates: nervous system and sense organs; visual cortex; Visual Cortex - physiology; Visual Pathways - physiology
• ISSN: 0954-898X; 1361-6536
• DOI: 10.1080/09548980500463347

It has been proposed that sensory neurons are adapted to the statistical structure of the natural environment in order to encode natural stimuli efficiently. While spatiotemporal correlations in luminance signals may be decorrelated by neurons in early visual processing stages, higher-order correlations, such as those in the orientation domain, are likely to persist in the input representation until the cortical level. In this study, we first examine orientation correlations in natural stimuli across brief time intervals and across nearby regions of space, and find strong correlations in both domains. We then examine contextual modulation of orientation tuning. We find that both temporal and spatial contexts exert a common influence on orientation tuning, shifting tuning away from the orientation of either the adapting (temporal) or surrounding (spatial) grating. Finally, we incorporate this context-mediated repulsive shift in orientation tuning into a model of cortical responses. We find that a direct result of the shift is a reduction of the redundancy in the population responses evoked by the orientation configurations that are most common in natural stimuli. Thus, cortical neurons may be adapted to the statistics of orientation in natural stimuli in order to increase the efficiency of natural stimulus representation.