Dendritic control of spontaneous bursting in cerebellar Purkinje cells - PubMed (original) (raw)
Contribution of BK, T-type calcium, and hyperpolarization-activated channels to spontaneous bursting. Extracellular recordings were made from Purkinje neurons under control conditions and in the presence of specific ion channel blockers. Cumulative probability plots of burst parameters similar to those shown in Figure 8 B were made. The average of the ratio of the median value in blocker to the median value in control conditions was determined for each burst parameter. These ratios accurately reflected the changes seen in the cumulative probability plots and are shown in this figure for each blocker. The horizontal bars indicate a value of 1. Ratios that significantly differ from 1 are indicated by asterisks. A, Recordings were made under control conditions and in the presence of iberiotoxin (100 n
m
) to block BK channels (*p < 0.05; *p < 0.01; determined by one-way ANOVA). Error bars represent ±SEM, (n = 11). The number of bursts analyzed was 11,172 under control conditions and 8517 in iberiotoxin. B, Burst firing was recorded under control conditions and in the presence of mibefradil (1 μ
m
) to block T-type calcium channels (*p < 0.02; *p < 0.002; determined by one-way ANOVA). Error bars represent ±SEM, (n = 5). The number of bursts analyzed was 2184 under control conditions and 3567 in mibefradil. C, The effect of mibefradil (1 μ
m
) was examined in the continuous presence of iberiotoxin (100 n
m
). (*p < 0.002; **p < 0.001; determined by one-way ANOVA). Error bars represent ±SEM (n = 5). The number of bursts analyzed was 3479 in iberiotoxin alone and 2100 in iberiotoxin plus mibefradil. D, The effect of iberiotoxin (100 n
m
) was examined in the continuous presence of mibefradil (1 μ
m
) (*p < 0.05; **p < 0.005; determined by one-way ANOVA). Error bars represent ±SEM (n = 6). The number of bursts analyzed was 2639 in mibefradil alone and 2329 in mibefradil plus iberiotoxin. E, Cesium (1 m
m
) was used to block _I_H. Ratios significantly different from 1 are indicated by asterisks (*p < 0.002; determined by one-way ANOVA). Error bars represent ±SEM, (n = 5). The number of bursts analyzed was 2783 under control conditions and 2864 in cesium. For each cell, all bursts from at least two cycles of the trimodal pattern of activity were analyzed under control conditions and at least two cycles in the presence of the channel blocker.