title: The role of thalamic population synchrony in the emergence of cortical feature selectivity.
abstract: In a wide range of studies, the emergence of orientation selectivity in primary visual cortex has been attributed to a complex interaction between feed-forward thalamic input and inhibitory mechanisms at the level of cortex. Although it is well known that layer 4 cortical neurons are highly sensitive to the timing of thalamic inputs, the role of the stimulus-driven timing of thalamic inputs in cortical orientation selectivity is not well understood. Here we show that the synchronization of thalamic firing contributes directly to the orientation tuned responses of primary visual cortex in a way that optimizes the stimulus information per cortical spike. From the recorded responses of geniculate X-cells in the anesthetized cat, we synthesized thalamic sub-populations that would likely serve as the synaptic input to a common layer 4 cortical neuron based on anatomical constraints. We used this synchronized input as the driving input to an integrate-and-fire model of cortical responses and demonstrated that the tuning properties match closely to those measured in primary visual cortex. By modulating the overall level of synchronization at the preferred orientation, we show that efficiency of information transmission in the cortex is maximized for levels of synchronization which match those reported in thalamic recordings in response to naturalistic stimuli, a property which is relatively invariant to the orientation tuning width. These findings indicate evidence for a more prominent role of the feed-forward thalamic input in cortical feature selectivity based on thalamic synchronization.
authors.affiliation: Coulter Dept. of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Sean T
authors.initials: ST
authors.lastname: Kelly
authors.affiliation: Department of Biological Sciences, State University of New York, College of Optometry, New York, New York, United States of America.
authors.forename: Jens
authors.initials: J
authors.lastname: Kremkow
authors.affiliation: Department of Biological Sciences, State University of New York, College of Optometry, New York, New York, United States of America.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Biological Sciences, State University of New York, College of Optometry, New York, New York, United States of America.
authors.forename: Yushi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, New York, United States of America.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Biological Sciences, State University of New York, College of Optometry, New York, New York, United States of America.
authors.forename: Jose-Manuel
authors.initials: JM
authors.lastname: Alonso
authors.affiliation: Coulter Dept. of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Garrett B
authors.initials: GB
authors.lastname: Stanley
mesh_terms: D000465:Algorithms; D000818:Animals; D002415:Cats; D002540:Cerebral Cortex / Q000502:physiology*; D003198:Computer Simulation; D055724:Electrophysiological Phenomena; D005829:Geniculate Bodies / Q000502:physiology; D008297:Male; D008959:Models, Neurological; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D016011:Normal Distribution; D011336:Probability; D013788:Thalamus / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology