title: A feedforward inhibitory circuit mediates lateral refinement of sensory representation in upper layer 2/3 of mouse primary auditory cortex.
abstract: Sensory information undergoes ordered and coordinated processing across cortical layers. Whereas cortical layer (L) 4 faithfully acquires thalamic information, the superficial layers appear well staged for more refined processing of L4-relayed signals to generate corticocortical outputs. However, the specific role of superficial layer processing and how it is specified by local synaptic circuits remains not well understood. Here, in the mouse primary auditory cortex, we showed that upper L2/3 circuits play a crucial role in refining functional selectivity of excitatory neurons by sharpening auditory tonal receptive fields and enhancing contrast of frequency representation. This refinement is mediated by synaptic inhibition being more broadly recruited than excitation, with the inhibition predominantly originating from interneurons in the same cortical layer. By comparing the onsets of synaptic inputs as well as of spiking responses of different types of neuron, we found that the broadly tuned, fast responding inhibition observed in excitatory cells can be primarily attributed to feedforward inhibition originating from parvalbumin (PV)-positive neurons, whereas somatostatin (SOM)-positive interneurons respond much later compared with the onset of inhibitory inputs to excitatory neurons. We propose that the feedforward circuit-mediated inhibition from PV neurons, which has an analogous function to lateral inhibition, enables upper L2/3 excitatory neurons to rapidly refine auditory representation.
authors.affiliation: Zilkha Neurogenetic Institute, Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, and.
authors.forename: Ling-yun
authors.initials: LY
authors.lastname: Li
authors.affiliation: Zilkha Neurogenetic Institute, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China.
authors.forename: Xu-ying
authors.initials: XY
authors.lastname: Ji
authors.affiliation: Zilkha Neurogenetic Institute, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China.
authors.forename: Feixue
authors.initials: F
authors.lastname: Liang
authors.affiliation: Zilkha Neurogenetic Institute, Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, and.
authors.forename: Ya-tang
authors.initials: YT
authors.lastname: Li
authors.affiliation: Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China.
authors.forename: Zhongju
authors.initials: Z
authors.lastname: Xiao
authors.affiliation: Zilkha Neurogenetic Institute, Cell and Neurobiology, liizhang@usc.edu htao@usc.edu.
authors.forename: Huizhong W
authors.initials: HW
authors.lastname: Tao
authors.affiliation: Zilkha Neurogenetic Institute, Departments of Physiology and Biophysics and liizhang@usc.edu htao@usc.edu.
authors.forename: Li I
authors.initials: LI
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001931:Brain Mapping; D025461:Feedback, Physiological / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D009434:Neural Pathways / Q000502:physiology*; D010320:Parvalbumins / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010775:Photic Stimulation; D012677:Sensation / Q000502:physiology*; D013004:Somatostatin / Q000502:physiology
chemical_list: D010320:Parvalbumins; D013004:Somatostatin
keywords: excitatory-inhibitory balance; inhibitory neuron; lateral inhibition; surround suppression; tonal receptive field; whole-cell recording