title: Visual orientation and directional selectivity through thalamic synchrony.
abstract: Thalamic neurons respond to visual scenes by generating synchronous spike trains on the timescale of 10-20 ms that are very effective at driving cortical targets. Here we demonstrate that this synchronous activity contains unexpectedly rich information about fundamental properties of visual stimuli. We report that the occurrence of synchronous firing of cat thalamic cells with highly overlapping receptive fields is strongly sensitive to the orientation and the direction of motion of the visual stimulus. We show that this stimulus selectivity is robust, remaining relatively unchanged under different contrasts and temporal frequencies (stimulus velocities). A computational analysis based on an integrate-and-fire model of the direct thalamic input to a layer 4 cortical cell reveals a strong correlation between the degree of thalamic synchrony and the nonlinear relationship between cortical membrane potential and the resultant firing rate. Together, these findings suggest a novel population code in the synchronous firing of neurons in the early visual pathway that could serve as the substrate for establishing cortical representations of the visual scene.
authors: Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, Georgia 30332, USA. garrett.stanley@bme.gatech.edu
authors: Garrett B
authors: GB
authors: Stanley
authors: Jianzhong
authors: J
authors: Jin
authors: Yushi
authors: Y
authors: Wang
authors: Gaëlle
authors: G
authors: Desbordes
authors: Qi
authors: Q
authors: Wang
authors: Michael J
authors: MJ
authors: Black
authors: Jose-Manuel
authors: JM
authors: Alonso
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002415:Cats; D003198:Computer Simulation; D005829:Geniculate Bodies / Q000166:cytology*; D008297:Male; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D017711:Nonlinear Dynamics; D009949:Orientation; D010507:Periodicity; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology*; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology