Fig. 2: Pyramidal cells in different layers are equally innervated by SOM+ interneurons in the somatosensory cortex and in the hippocampal CA1 region.
a Schematic of the experimental configuration in the somatosensory cortex: brief (3 ms) whole-field photo-stimulation of ChR2-expressing SOM+ cells (red circles) and simultaneous recordings from neighboring pyramidal cells from several layers. b Overview image of three recorded and biocytin-filled pyramidal cells in layerIII, layerIV, and layerVI (green) in SOM-ChR2 (red) expressing somatosensory cortex (coronal section). c Light-evoked (blue lines represent time of illumination) postsynaptic potential changes in the three recorded cells. Colored lines are the averages of individual (gray) events. Insets: responses to hyperpolarizing and depolarizing current steps of the recorded cells. d Postsynaptic potential (IPSP, top), input resistance (middle), and resting membrane potentials (bottom) of the layerII–III (red), layerIV (green), and layerV–VI (blue) cells. e Schematic figure of the experimental configuration in the hippocampal CA1 region. f One superficial (top right) and one deep pyramidal cell (bottom left, green) surrounded by ChR2-mCherry-expressing cells in SOM-ChR2 animal (coronal section). l.m. lacunosum moleculare, rad. stratum radiatum, pyr. stratum pyramidale, ori. stratum oriens. g Postsynaptic responses of the two recorded cells to 3 ms photo-stimulations. Colored lines are the averages; gray lines are the individual events. Insets: responses to hyperpolarizing and depolarizing current steps of the recorded cells. h Postsynaptic potential (top), input resistance (middle), and resting membrane potentials (bottom) of the superficial (red) and deep (green) pyramidal cells. Note that the intracellular solution contained 40 mM CsCl solution, producing depolarizing effect of GABAA receptor opening. L.m. stratum lacunosum moleculare, rad stratum radiatum, pyr stratum pyramidale, ori stratum oriens. Scale bars: 50 μm.
