Fig. 7. The relatively constant and longer STN bursts in response to MC activities in parkinsonian rats.

a Four consecutive electrical stimuli at 10, 20, or 50 Hz on cortico-subthalamic fibers were applied to trigger burst discharges in STN neurons at ∼ −65 mV (“Evoked”). The burst duration gets shorter with higher frequency (and thus shorter duration) of stimuli in control (n = 8), but much less so in parkinsonian rats (6-OHDA) (n = 7). Also note that the mean burst duration is in general longer in parkinsonian than in control rats. In addition, the STN neurons from parkinsonian rats (n = 37) spend a larger proportion of time in spontaneous burst discharges than those from control rats (n = 15, with an evaluation time of 1 min in each neuron) (“Spontaneous”). b The burst duration in STN neurons from parkinsonian rats (n = 3–5) is very similar, whether the burst is elicited by 2, 3, or 4 stimuli given at 10, 20, or 50 Hz to the cortico-subthalamic fibers. c 25 μM dopamine shortens burst discharges in STN before a tonic or spike mode of discharges is finally achieved in ∼4 min (n = 5). The sample size denotes the number of neurons. Scale bars represent 1 s/20 mV. Data were presented as mean ± S.E.M. Data with two groups were analyzed with Mann–Whitney U test, and data with three groups were analyzed with Friedman tests (followed by the Wilcoxon signed-rank tests for further pairwise comparison). *P < 0.05, **P < 0.01, N.S., nonsignificant, N.A. indicates no bursts for analysis.