title: Cortical Dependence of Whisker Responses in Posterior Medial Thalamus In Vivo.
abstract: Cortical layer 5B (L5B) thick-tufted pyramidal neurons have reliable responses to whisker stimulation in anesthetized rodents. These cells drive a corticothalamic pathway that evokes spikes in thalamic posterior medial nucleus (POm). While a subset of POm has been shown to integrate both cortical L5B and paralemniscal signals, the majority of POm neurons are suggested to receive driving input from L5B only. Here, we test this possibility by investigating the origin of whisker-evoked responses in POm and specifically the contribution of the L5B-POm pathway. We compare L5B spiking with POm spiking and subthreshold responses to whisker deflections in urethane anesthetized mice. We find that a subset of recorded POm neurons shows early (<50 ms) spike responses and early large EPSPs. In these neurons, the early large EPSPs matched L5B input criteria, were blocked by cortical inhibition, and also interacted with spontaneous Up state coupled large EPSPs. This result supports the view of POm subdivisions, one of which receives whisker signals predominantly via L5B neurons.
authors.affiliation: Institute for Neuroscience of the Technische Universität München, 80802 Munich, Germany Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, 81675 Munich, Germany.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Mease
authors.affiliation: Institute for Neuroscience of the Technische Universität München, 80802 Munich, Germany.
authors.forename: Anton
authors.initials: A
authors.lastname: Sumser
authors.affiliation: Institute for Neuroscience of the Technische Universität München, 80802 Munich, Germany Max Planck Institute for Neurobiology, 82152 Martinsried, Germany.
authors.forename: Bert
authors.initials: B
authors.lastname: Sakmann
authors.affiliation: Institute for Neuroscience of the Technische Universität München, 80802 Munich, Germany Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, 81675 Munich, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Groh
mesh_terms: D000200:Action Potentials; D000818:Animals; D019706:Excitatory Postsynaptic Potentials; D008822:Mice, Transgenic; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D062308:Optogenetics; D017966:Pyramidal Cells / Q000166:cytology / Q000502:physiology*; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology*; D013788:Thalamus / Q000166:cytology / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D014738:Vibrissae / Q000502:physiology*
keywords: barrel cortex; cortex layer 5; corticothalamic feedback; higher order thalamus; somatosensory