Electrophysiological characterization of the subthalamic nucleus.

<p><i>(</i><b><i>A</i></b><i>)</i> Firing rate of STN glutamatergic neurons. Baseline firing rate (white bars) was significantly different between the groups (F_(4,307) = 15.25, <i>p</i><0.0001, one-way ANOVA). The acute L-DOPA challenge (grey bars), induced an increase in firing rate in sham saline animals only. <i>(</i><b><i>B</i></b><i>)</i> Coefficient of variation (%). Baseline activity recording (white bars) showed significant differences between groups (F_(4,307) = 11.85, <i>p</i><0.0001, one-way ANOVA) and acute L-DOPA treatment produced a significant reduction in the sham saline group. <i>(</i><b><i>C</i></b><i>)</i> Percentage of bursting, random and tonic neurons. Baseline burst firing pattern (white bars) was significantly increased in 6-OHDA lesioned groups (<i>p</i><0.05, Fisher's test). Both sham groups showed a trend to increase the number of bursting neurons after an acute L-DOPA dose (sham saline, <i>p</i> = 0.08, and sham L-DOPA, <i>p</i> = 0.06 vs its baseline). Data are expressed as mean ± S.E.M. All data included in the acute L-DOPA challenge were obtained between 20 and 120 min after L-DOPA injection (time period corresponding to high dyskinetic behaviour). * <i>p</i><0.05 vs sham saline and sham L-DOPA (one-way ANOVA, followed by Bonferroni <i>post-hoc</i>). ^&<i>p</i><0.05 vs before L-DOPA administration (unpaired t test). ^#<i>p</i><0.05 vs sham saline and sham L-DOPA (Fisher's exact test for firing pattern).