title: Focal Gain Control of Thalamic Visual Receptive Fields by Layer 6 Corticothalamic Feedback.
abstract: The projections between the thalamus and primary visual cortex (V1) are a key reciprocal neural circuit, relaying retinal signals to cortical layers 4 & 6 while being simultaneously regulated by massive layer 6 corticothalamic feedback. Effectively dissecting the influence of this corticothalamic feedback circuit in higher mammals remains a challenge for vision research. By pharmacologically increasing the focal gain of visually driven layer 6 responses of cat V1 in a controlled fashion, we examined the effects of such focal cortical changes on the response amplitudes and spatial structure of the receptive fields (RFs) of individual dorsal lateral geniculate nucleus (dLGN) cells. We found that enhancing visually driven cortical feedback could facilitate or suppress the overall responses of dLGN cells, and such an effect was linked to the orientation preference of the cortical neuron. Related to these selective retinotopic gain changes, enhanced feedback induced the RFs of dLGN cells to expand, contract or shift their spatial focus. Our results provide further evidence for a functional mechanism through which the cortex can selectively gate visual information flow from the thalamus back to the visual cortex.
authors.affiliation: Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Andolina
authors.affiliation: Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Yiliang
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK.
authors.forename: Helen E
authors.initials: HE
authors.lastname: Jones
authors.affiliation: Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Sillito
mesh_terms: D000818:Animals; D001931:Brain Mapping; D002415:Cats; D025461:Feedback, Physiological / Q000502:physiology*; D005260:Female; D005829:Geniculate Bodies / Q000502:physiology*; D008839:Microelectrodes; D009474:Neurons / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology
keywords: LGN; V1; corticofugal; iontophoresis; receptive field