In all cases EPZ-6438 purchase the number of neighboring spines with highly enriched values in the analyzed neuron was significantly greater than what was observed when the enrichment values were randomly shuffled (Figures S3A and S3B). We next examined SEP-GluR2 on a fully reconstructed neuron from a whisker-trimmed animal. In this case highly enriched spines were not found on distal regions, as was the case for SEP-GluR1 (Figure 4B). There was a tendency for highly

enriched spines (n = 150) to be proximal relative to nonenriched spines (p < 0.005, n = 851 spines; Figures 4C, S3B, and S3C). We also noted that neighboring spines were no more likely to have high enrichment values than randomly shuffled values (p = 0.29; Figures 4E, S3A, and S3B). Taken together, these results suggest that there are distinct trafficking patterns produced by experience-driven synaptic potentiation and deprivation-driven synaptic upscaling. The data above suggest that the clustering of plasticity is observed for GluR1, but not GluR2, consistent with their dependence on LTP and experience (Hayashi et al., 2000, Takahashi et al., 2003 and Zamanillo et al., 1999). However, when expressed alone, OSI-906 price these AMPA receptor subunits form homomeric receptors,

which normally comprise a small proportion of endogenously expressed receptors (Wenthold et al., 1996). To examine the trafficking of heteromeric receptors, which constitute

the predominant species of receptors (Wenthold et al., 1996), we transiently coexpressed SEP-GluR1 with untagged-GluR2, or untagged-GluR2 and SEP-GluR3 (see Experimental Procedures). We first confirmed, using electrophysiological measures, that heteromeric receptors were formed when expressing SEP-GluR1 with GluR2. We obtained whole-cell recordings from neurons expressing recombinant receptors and measured responses from focally applied glutamate on spines (Figure 5A; see Experimental Procedures). Homomeric receptors display inward rectification, which was observed in neurons expressing SEP-GluR1 (0.28 ± 0.02, n = 15 spines; Figure 5B). However, no such inward rectification was observed from neurons expressing SEP-GluR1 and GluR2 (0.49 ± 0.03, p < 0.00003, n = 13 spines; Figure 5B), indicating that heteromeric receptors were formed. We examined in Terminal deoxynucleotidyl transferase animals with whiskers intact the spine enrichment values in neurons transiently expressing SEP-GluR1 and GluR2 (Figures 5C and 5E). Spine enrichment of SEP-GluR1/GluR2 heteromeric receptors (0.84 ± 0.006, n = 1865 spines) did not differ from that of SEP-GluR1 homomeric receptors (0.84 ± 0.005, p = 0.70, n = 2701 spines; Figures 5C, 5E, S4A, and S4C). Similarly, spine enrichment of GluR2/SEP-GluR3 (1.29 ± 0.01, n = 1390 spines) was not different from that of SEP-GluR2 (1.30 ± 0.01, p = 0.08, n = 1057 spines; Figures 5D, 5E, S4B, and S4C).