Morphometric classification and spatial organization of spiral ganglion neurons in the human cochlea: consequences for single fiber response to electrical stimulation.
Bottom Line: Furthermore, we found evidence of a spatial arrangement of perikarya and their accordant nuclei along the cochlea spiral.Cathodic stimulation was found to induce stronger variations of spikes while also leading to the lowest thresholds and longest latencies.Therefore, anodic stimulation leads to a more uniform excitation profile among SGCs with different cell body size.
Affiliation: Innsbruck Medical University, Department of Otorhinolaryngology, Laboratory for Inner Ear Biology, Anichstrasse 35, Innsbruck, Austria.Show MeSH
Mentions: The applied algorithm of the cluster analysis identified four distinct populations of SGCs in specimen 1 (n = 83). Fig. 4A presents the results of this hierarchical clustering. The distinct groupings of the determined SGC-populations are color-coded in the scatterplot. These populations differ considerably in perikaryal size as well as in their incidence. The smallest identified population 1 of this cochlea is formed by 12% of reconstructed perikarya (Fig. 4A, violet colored) with a mean volume of 1288 ± 496 μm3. Interestingly, their corresponding nuclei are also found to be the smallest within the four populations (228.2 ± 60.4 μm3). The majority of measured cell bodies belonging to specimen 1 are classified as population 2 (80.7%) and have a mean volume of 3878 ± 932.6 μm3 (green colored). Their nuclei are identified to be slightly larger (372.8 ± 80 μm3) compared to the nuclei from population 1. Cell population 3 is represented by 5.8% (6297 ± 140.7 μm3, red) of reconstructed perikarya (red colored). Their associated nuclei have a mean volume of 436.1 ± 97.5 μm3 and represent the third-largest reconstructed group. The largest population 4 is represented by a single cell body with a mean volume of 8148 μm3 (cyan color). The volume of this perikaryon is 632.7% bigger compared to the mean volume calculated for population 1. Similarly, its nucleus measures 506.5 μm3, the largest reconstructed from this specimen. The volumetric difference compared with the corresponding value of the smallest population is 222%.
Affiliation: Innsbruck Medical University, Department of Otorhinolaryngology, Laboratory for Inner Ear Biology, Anichstrasse 35, Innsbruck, Austria.