title: Thalamic interneurons and relay cells use complementary synaptic mechanisms for visual processing.
abstract: Synapses made by local interneurons dominate the thalamic circuits that process signals traveling from the eye downstream. The anatomical and physiological differences between interneurons and the (relay) cells that project to cortex are vast. To explore how these differences might influence visual processing, we made intracellular recordings from both classes of cells in vivo in cats. Macroscopically, all receptive fields were similar, consisting of two concentrically arranged subregions in which dark and bright stimuli elicited responses of the reverse sign. Microscopically, however, the responses of the two types of cells had opposite profiles. Excitatory stimuli drove trains of single excitatory postsynaptic potentials in relay cells, but graded depolarizations in interneurons. Conversely, suppressive stimuli evoked smooth hyperpolarizations in relay cells and unitary inhibitory postsynaptic potentials in interneurons. Computational analyses suggested that these complementary patterns of response help to preserve information encoded in the fine timing of retinal spikes and to increase the amount of information transmitted to cortex.
authors.affiliation: Department of Biological Sciences and Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Vishal
authors.initials: V
authors.lastname: Vaingankar
authors.forename: Cristina
authors.initials: C
authors.lastname: Soto Sanchez
authors.forename: Friedrich T
authors.initials: FT
authors.lastname: Sommer
authors.forename: Judith A
authors.initials: JA
authors.lastname: Hirsch
mesh_terms: D000818:Animals; D002415:Cats; D002540:Cerebral Cortex / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010775:Photic Stimulation; D013569:Synapses / Q000502:physiology*; D013788:Thalamus / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*