Soma location, dendrite morphology, and synaptic innervation may represent key determinants
Soma location, dendrite morphology, and synaptic innervation may represent key determinants of functional responses of individual neurons, such as sensory-evoked spiking. spine distribution of neuron to the total spine distribution of all neurons in the column, to the bouton distribution of presynaptic cell type and denotes MSH6 a term to correct for missing neuron populations (i.e., inhibitory interneurons). All density distributions were presented with 50-m voxel resolution. Innervation volumes, 1D, and 2D profiles were derived from these distributions. Only neurons with their somata located within a cylindrical subvolume (i.e., cross-section: 121?000 m2 [Wimmer et al. 2010], height: vertical extents of L2-6) were used for analysis. Neurons outside the cylinder were regarded as septal neurons. The present approach thus accounts for the effect that VPM synapses may be located on dendrites from septal neurons. All data are given as mean standard deviation (SD). Significance level was set 0.05, and statistical analysis was performed in Igor Pro Software. Results Reconstruction and Registration of Individual 3D Neuron Morphologies Figure 1 illustrates the anatomical data used to reconstruct thalamocortical circuits between VPM and excitatory neurons in a cortical barrel column. We reconstructed the 3D dendrite morphology of neurons (= 95) located in cytoarchitectonic L2-6 and the 3D axon morphology of neurons located in VPM (= 12). All neurons were filled with biocytin CAY10505 in vivo. Previously, a subset of the cortical neurons were physiologically characterized for spontaneous and whisker-evoked spiking activity CAY10505 after passive touch (de Kock et al. 2007). Figure 1. Three-dimensional reconstruction and registration of in vivo-labeled dendrite and axon morphologies in a rat barrel column. (and Table 2). All dendriteCspine innervation domains extended beyond the tangential borders of the soma column, which was particularly pronounced for L2 and L5tt pyramids (Supplementary Fig. S4), with 9.2% and 11.2% of their spines being located within adjacent septal regions, respectively (Table 2). Furthermore, collapsing the density distribution to 1D profiles along the vertical axis (Fig. 4= 1050) along the VPM axons. We found swellings that were likely to correspond to en passant, and in some cases, terminaux boutons (De Paola et al. 2006) along all axon branches and in all regions. The interbouton distance was 3.43 0.13 m and, more importantly, independent of the axons location and animal (= 5). Thus, we converted the VPM axon distribution into a 3D VPM bouton distribution (Fig. 3(left panel) was located at the BCC, had 503 VPM synapses and displayed an almost symmetric dendrite and thus VPM innervation pattern. In contrast, the L4ss cell shown in Figure 7(right panel) was located at the column border, had only CAY10505 235 VPM synapses and displayed a polarized dendrite morphology pointing toward the BCC. Thus, location-depended differences in dendrite morphology, in combination with location-depended differences in VPM bouton density, critically influenced the total number and subcellular innervation patterns of individual neurons, even if they were of the same cell type. In consequence, innervation patterns averaged across all neurons of a particular cell type (e.g., L3, Fig. 7our M4ss, Fig. 7= 0.76, < 0.0001, Fig. 9= 0.22, = 0.11, Fig. 9= 0.79, = 0.11 at development level), M4ss (= 0.92, CAY10505 = 0.03) and L6closed circuit neurons (= 0.89, = 0.04). The staying cell types shown no or just vulnerable correlations, for example, M5st (= 0.22, = 0.49) and L5tt (= ?0.22, = 0.57) neurons (Fig. 9= 0.85 and = 0.80, = 0.004 and = 0.01, Fig. 9= 0.68, = 0.04), but we did not look for a significant relationship between the amount of VPM synapses and spiking activity during whisker movement (= 0.54, = 0.21, Fig. 9= 0.07 at style level). M6ct neurons stay sedentary during free of charge whisking also, recommending that the linked corticothalamic path (Deschenes et al. 1998) may just become energetic after mixed insight.