Fig. 12.

Roles of calcium-permeable AMPA receptors (CP-AMPARs) in postsynaptic expression of L-LTP in the superficial layer of the IC. A: paired-pulse ratios (slope of fEPSP2/slope of fEPSP1) recorded with intervals of 25, 50, 75, 100, and 200 ms in superficial layer of the IC. Comparison of the paired-pulse ratio revealed no significant difference under 3 conditions (baseline, TBS 1 h, and TBS 3 h), suggesting a postsynaptic locus of insular L-LTP expression. B: representative traces of paired-pulse facilitation (PPF) with an interval of 25 ms recorded in superficial layer of the IC. C: 1 example of 64-channel recordings of insular L-LTP with the CP-AMPAR blocker 1-naphthylacetyl spermine (NASPM, 50 μM) applied from 5 min after TBS until 35 min after TBS. Black lines, baseline; red lines, 3 h after TBS. Red open circle denotes the stimulated channel (Ch. 29), while black filled circle marks the superficial channel showing the L-LTP blockade by NASPM (Ch. 38). Vertical lines demarcate different layers. D: results of 1 channel (Ch. 38) showing suppression of insular L-LTP expression by NASPM. Sample fEPSP recordings taken at times indicated by corresponding numbers are shown above plot. E: summary of averaged data from 4 superficial channels of the same slice as C and D. F: pooled data from 7 slices from 7 mice. Horizontal bars in D–F denote period of NASPM application. Arrows in D–F indicate starting point of TBS application. Calibration in B–D: 100 μV, 10 ms. Error bars in A and F represent SE.