In order to determine whether the increased encounter with GluR1-immunoreactive asymmetric LA synapses from the paired group was due to an increase in their synaptic size, we measured the lengths of the PSDs of asymmetric synapses that we encountered randomly from each animal and were analyzed for GluR1 immunoreactivity within single two-dimensional digitized images. A one-way ANOVA indicated no effect of the treatment. The mean PSD lengths were 258 ± 9 nm for the paired group, 279 ± 11 nm for the unpaired group, and 265 ± 9 nm for the naïve group. Although these measurements do not reflect true sizes of synapses (because we did not attempt three-dimensional reconstructions), the similarity in the PSD lengths across the treatment groups indicate that the rate of encounter with synaptic profiles within two-dimensional images is not likely to have been affected by differences in their sizes.
