Figure 2.

Temperature dependency of MF-CA3 and Schaffer collaterals-CA1 synaptic transmission. (a) Paired-pulse stimulation of MF at 24°C evoked no responses to the first stimulus but some to the second one (P4 rat). Raising the temperature from 24°C to 32°C resulted in the appearance of responses to the first stimulus and increased the number of successes to the second (ten traces are shown for both conditions). (b) Mean percentage of successes to the first and to the second stimulus at 24°C and 32°C for all P2-P7 CA3 pyramidal neurons examined (n = 7). The percentage of successes to the first stimulus at 32°C was significantly higher than at 24°C (P < 0.05, Wilcoxon test). (c) Peak amplitude of the first (open circles) and second (filled circles) EPSCs recorded from the CA1 region at 24°C and at 32°C (bars) plotted against time. (Insets) Five individual traces of EPSCs evoked by paired stimulation of Schaffer collaterals at 24°C and 32°C. Calibration bars: vertical, 20 pA; horizontal, 20 ms (P2 rat). Note absence of responses to the first stimulus at 24°C. Increasing the temperature from 24°C to 32°C resulted in the appearance of some responses to the first stimulus and enhanced the number of successes to the second. (d) Mean percentage of successes to the first and to the second stimulus at 24°C and 32°C for all P2-P6 CA1 pyramidal neurons tested (n = 8). The values at 32°C are significantly higher for both the first and the second EPSC (P < 0.01, Wilcoxon test). (e) Pair of fEPSPs (average of three traces) evoked at 0.05 Hz by stimulation of Schaffer collaterals at 24°C and 32°C from a P6 rat. (f) Amplitude of the afferent volley, normalized to the maximum amplitude vs. stimulus strength, expressed as X times the threshold at 24°C (filled squares) and 32°C (open squares). Each symbol represents the mean of four experiments. Bars are SEM.