The Spatiotemporal Frequency Tuning of LGN Receptive Field Facilitates Neural Discrimination of Natural Stimuli

The efficient coding hypothesis suggests that the early visual system is optimized to represent stimuli in the natural environment. While it is believed that LGN processing removes the redundant information of natural scenes, it is not clear whether the early visual processing can selectively amplify important signals in natural stimuli to facilitate discrimination. In this study, we examined the functional role of LGN spatiotemporal frequency tuning in the processing of natural scenes. First, we characterized the relationship between spatial and temporal frequency tuning for LGN receptive fields. We found that LGN neurons exhibit inseparable spatiotemporal frequency tuning in a manner consistent with the feature of optimal filters that can maximize information transmission of natural scenes. Second, we analyzed the spatiotemporal power spectrum of natural scenes and found that some frequencies exhibit larger variation in power across different scenes. Interestingly, the preferred frequency of ensemble LGN neurons matches the range of frequencies in which natural power spectrum varies most. Comparison of neural discrimination for natural stimuli and for artificial stimuli with similar mean power spectra but different variation structure showed that the match between LGN tuning and natural spectra variation enhances neural discrimination for natural stimuli. Our results indicate that, in addition to removing redundancy, the spatiotemporal frequency characteristics of LGN neurons can facilitate neural discrimination of natural stimuli.