Figure 7.

Schematic diagrams illustrating GluA2 and PKMζ distributions and densities in relation to aging, learning, and memory. GluA2 and PKMζ double-labeled spines (shown above the dendrite) had larger PSDs (gray line) than GluA2 single- and PKMζ single-labeled spines (shown below the dendrite), regardless of age. A, Compared with young adults, aged monkeys had decreased densities of synaptic GluA2 in double-labeled spines. Aged monkeys also had a lower density of total GluA2 in double- and single-labeled spines. B, Fast DNMS task acquisition was associated with high densities of cytoplasmic, plasmalemmal, and total GluA2; and high densities of synaptic, cytoplasmic, and total PKMζ in double-labeled spines. C, DNMS delay accuracy was positively associated with densities of synaptic GluA2 and PKMζ in double-labeled perforated synapse (broken gray line) spines. Densities of cytoplasmic GluA2 and total PKMζ in double-labeled spines also correlated with DNMS accuracy. In single-labeled spines, densities of total GluA2 and total PKMζ correlated with DNMS accuracy.