Figure 5.

Ability of mature granule cells to fire doublets of action potentials in response to synaptic stimulation is greatly impaired in Cav3.2 knockout mice. (A) The medial perforant path was stimulated, and the evoked activity was evaluated in mature granule cells from wild-type and knockout animals. A decreasing series of stimulation intensities was applied. Representative traces of evoked potentials from wild-type mature granule cells and Cav3.2 knockout mature cells are shown. Scale bars: 10 mV/20 ms. (B) The number of action potentials elicited was significantly decreased in knockout animals, especially at intensities higher than 50 μA. (C) The synaptic strength, quantified as the slope of the EPSP, was not different between the groups. (D) The ability of the cells to fire per se was not changed by the absence of Cav3.2. E, The cells from knockout mice had an impaired ability to fire more than one action potential, which was especially the case at intensities higher than 50 μA. These results were confirmed by the comparison of the EPSP slopes required to fire per se (F) or to fire bursts of action potentials (G). *,**,***P < 0.05, P < 0.01 and P < 0.001, Mann–Whitney U-test.