In the article “Cellular, Subcellular, and Subsynaptic Distribution of AMPA-Type Glutamate Receptor Subunits in the Neostriatum of the Rat,” by V. Bernard, P. Somogyi, and J. P. Bolam, which appeared on pages 819–833 of the January 15, 1997 issue, a computational error was made in the construction of the frequency histogram of the distribution of immunolabeling at the subsynaptic level in Figure 10. The figure, legend, and corresponding paragraph of Results are reprinted.
Fig. 10.
Distribution of immunoparticles for GluR1 and GluR2/3 subunits along the postsynaptic membrane specialization of axospinous synapses labeled by the postembedding immunogold method. A similar distribution of GluR1 and GluR2/3 subunits occurred at axospinous synapses [GluR1, n = 30 synapses, (mean length ± SEM, 333.6 ± 21.3 nm), 97 immunoparticles; GluR2/3, n = 88 synapses, (mean length ± SEM, 272.4 ± 7.9 nm), 407 immunoparticles]. The immunoparticles are less concentrated at the center of the postsynaptic membrane specialization. Only synapses labeled by two or more particles are included in the analysis.
The distribution of the immunoparticles along the postsynaptic membrane in two animals was analyzed at axospinous synapses for GluR1 (n = 30 synapses, 97 immunoparticles) and GluR2/3 (n = 88 synapses, 407 immunoparticles (Fig. 10). The immunoparticles were not homogeneously distributed. At axospinous synapses, there was a tendency for the immunoparticles, particularly for the GluR1 subunit, to be less concentrated at the center of the postsynaptic specialization than at the periphery (Fig. 10). In the quantitative analysis, 12.5% of immunoparticles representing GluR1 occurred in the central 20% of the half-width of the synapse, whereas 22.7 and 27.8% of the particles were present at 20–40 and 40–60% of the distance from the center of the synapse, respectively. For the GluR2/3 the density of immunoparticles was relatively even over the central 60% of the half-width of the synapse but increased in density in the outer 40% of the half-width. Only very few particles fell apparently outside of the postsynaptic specialization, but the exact location of immunoparticles at the edge of the synapse is difficult to judge because of a sterical distortion between the image of the membrane specialization formed from the whole thickness of the section and the most superficial layer available for the antibody.