FIG. 3.
Characterization of basal synaptic transmission and plasticity in the Schaffer collateral synapses onto CA1 in the young (3-wk-old) S831A mutants. A: normal basal synaptic transmission in the young S831A mutants. Input–output (I-O) curves were generated by increasing stimulation intensities. Measured field potential (FP) slope was plotted against the amplitude of presynaptic fiber volley. There was no difference in the I-O curve of S831A mutants (closed symbols) and that of WT littermates (open symbols). B: normal paired-pulse facilitation (PPF) in the young S831A mutants. PPF ratios measured at different interstimulus intervals (ISIs) did not differ between S831A mutants (closed symbols) and WT littermates (open symbols). C: GluR1–S831A mutants exhibit normal long-term potentiation (LTP) induced by delivering 4 trains of theta burst stimulation (TBS). WTs: open symbols; S831A mutants: closed symbols. Representative traces taken right before (thin line) and 2 h after LTP induction (thick line) are shown to the right. D: the average magnitude of long-term depression (LTD) induced by a 15-min train of 1 Hz was slightly larger in the S831A mutants (closed symbols), but was not statistically significant from that of WT littermates (open symbols) at 1 h. S831A mutants displayed a significantly larger initial depression (average of the first 10 min post-1 Hz). Representative traces taken right before (thin line) and 1 h after the onset of 1-Hz stimulation (thick line) are shown to the right.