title: Thalamocortical Innervation Pattern in Mouse Auditory and Visual Cortex: Laminar and Cell-Type Specificity.
abstract: Despite many previous studies, the functional innervation pattern of thalamic axons and their target specificity remains to be investigated thoroughly. Here, in primary auditory cortical slices, we examined thalamic innervation patterns for excitatory and different types of inhibitory neurons across laminae, by optogenetically stimulating axons from the medial geniculate body. We found that excitatory cells and parvalbumin (PV)-expressing inhibitory neurons across layer 2/3 (L2/3) to L6 are directly innervated by thalamic projections, with the strongest innervation occurring in L4. The innervation of PV neurons is stronger than that of excitatory neurons in the same layer, with a relatively constant ratio between their innervation strengths across layers. For somatostatin and vasoactive intestinal peptide inhibitory neurons, essentially only L4 neurons were innervated by thalamic axons and the innervation was much weaker compared with excitatory and PV cells. In addition, more than half of inhibitory neurons in L1 were innervated, relatively strongly, by thalamic axons. Similar innervation patterns were also observed in the primary visual cortex. Thus, thalamic information can be processed independently and differentially by different cortical layers, in addition to the generally thought hierarchical processing starting from L4. This parallel processing is likely shaped by feedforward inhibition from PV neurons in each individual lamina, and may extend the computation power of sensory cortices.
authors.affiliation: Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China Zilkha Neurogenetic Institute.
authors.forename: Xu-Ying
authors.initials: XY
authors.lastname: Ji
authors.affiliation: Zilkha Neurogenetic Institute Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Zingg
authors.affiliation: Zilkha Neurogenetic Institute Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
authors.forename: Lukas
authors.initials: L
authors.lastname: Mesik
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 Department of Biophysics and Physiology.
authors.forename: Li I
authors.initials: LI
authors.lastname: Zhang
authors.affiliation: Zilkha Neurogenetic Institute Department of Cell and Neurobiology.
authors.forename: Huizhong W
authors.initials: HW
authors.lastname: Tao
mesh_terms: D000818:Animals; D001303:Auditory Cortex / Q000166:cytology* / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology; D008297:Male; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D056347:Neuroanatomical Tract-Tracing Techniques; D009474:Neurons / Q000166:cytology* / Q000502:physiology; D062308:Optogenetics; D010320:Parvalbumins / Q000378:metabolism; D018408:Patch-Clamp Techniques; D013004:Somatostatin / Q000378:metabolism; D013788:Thalamus / Q000166:cytology* / Q000502:physiology; D046509:Tissue Culture Techniques; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism; D014793:Visual Cortex / Q000166:cytology* / Q000502:physiology
chemical_list: D010320:Parvalbumins; D014660:Vasoactive Intestinal Peptide; D013004:Somatostatin
keywords: SOM neuron; VIP neuron; cortical inhibitory neuron; laminar distribution; pyramidal cell; sensory cortex; thalamic innervation; thalamocortical projection