title: The stimulus selectivity and connectivity of layer six principal cells reveals cortical microcircuits underlying visual processing.
abstract: Sensory computations performed in the neocortex involve layer six (L6) cortico-cortical (CC) and cortico-thalamic (CT) signaling pathways. Developing an understanding of the physiological role of these circuits requires dissection of the functional specificity and connectivity of the underlying individual projection neurons. By combining whole-cell recording from identified L6 principal cells in the mouse primary visual cortex (V1) with modified rabies virus-based input mapping, we have determined the sensory response properties and upstream monosynaptic connectivity of cells mediating the CC or CT pathway. We show that CC-projecting cells encompass a broad spectrum of selectivity to stimulus orientation and are predominantly innervated by deep layer V1 neurons. In contrast, CT-projecting cells are ultrasparse firing, exquisitely tuned to orientation and direction information, and receive long-range input from higher cortical areas. This segregation in function and connectivity indicates that L6 microcircuits route specific contextual and stimulus-related information within and outside the cortical network.
authors.affiliation: The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors.forename: Mateo
authors.initials: M
authors.lastname: Vélez-Fort
authors.affiliation: The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors.forename: Charly V
authors.initials: CV
authors.lastname: Rousseau
authors.affiliation: The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Niedworok
authors.affiliation: Genetic Neuroengineering Group, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Wickersham
authors.affiliation: The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors.forename: Ede A
authors.initials: EA
authors.lastname: Rancz
authors.affiliation: The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors.forename: Alexander P Y
authors.initials: AP
authors.lastname: Brown
authors.affiliation: The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors.forename: Molly
authors.initials: M
authors.lastname: Strom
authors.affiliation: The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK; Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK. Electronic address: tmargri@nimr.mrc.ac.uk.
authors.forename: Troy W
authors.initials: TW
authors.lastname: Margrie
mesh_terms: D000818:Animals; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D010775:Photic Stimulation; D014793:Visual Cortex / Q000166:cytology* / Q000502:physiology*; D014795:Visual Pathways / Q000166:cytology* / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*