Figure 4

Altered Granule Cell Excitability and Mossy Fiber Synaptic Transmission in Alpha-CaMKII+/- Mice. (A) Examples of action potential firing of granule cells in wild-type and mutant mice evoked by steady depolarizing currents (320 pA, 400 ms). (B) Increased input resistance in mutant mice (P = 0.0029). (C) Reduced spike latency in mutant mice (P < 0.0001). Depolarizing currents (320 pA) were injected into granule cells and the latency of the first action potential was measured. (D) The maximal number of spikes evoked by 400 ms depolarizing currents was decreased in mutant mice (P < 0.0001). (E) The efficacy of basal transmission at the mossy fiber synapse was increased in mutant mice (P < 0.0001). The ratio of the peak EPSP amplitude to fiber volley amplitude is shown. (F) Reduced paired-pulse facilitation ratios of EPSPs at intervals ranging from 50 to 5000 ms in mutant mice. (G) Mutant mice had greatly reduced frequency facilitation at 1 Hz. Sample EPSPs were recorded at the time indicated by the numbers in the graph. Error bars indicate s.e.m.