Fig. 6. Dynamic coupling between the inertial soma and the excitable, stochastically-fluctuating PDCs.
(A) In a spontaneously firing DA neuron, Ca2+ uncaging was performed in the soma (S) and PDCs (P). Localized Ca2+ rises were seen in the subtracted images, together with firing pauses and different Ca2+ removal kinetics between the soma and dendrite. (B) Normalized Ca2+ decays in the soma (black) and PDCs (red). (C) Half-maximal Ca2+ decay times in the soma (2.02 ± 0.15 s, n = 3) and PDCs (0.79 ± 0.003 s, n = 3). **p < 0.001. (D) Fluorescence-overlapped image of a DA neuron and a magnified dendrite image with cytosolic Ca2+ measuring sites (yellow boxes). Local Ca2+ oscillations are shown at the marked sites of a dendrite. (E) The CV of local dendritic Ca2+ oscillations increased as a function of distance from the soma. (F) Correlation coefficient of the peaks of Ca2+ oscillations (R2 = 0.67, Pearsonʼs product moment correlation coefficient, n = 5). (G) Left, A DA neuron loaded with Fluo 4-AM and Ca2+ measuring sites. Ca2+ measuring site: black circle in the soma (S), red circle in the proximal dendrite (P). Right, raw traces of Ca2+ oscillations and averaged spikes of Ca2+ oscillations in the soma and PDCs. (H) Normalized Ca2+ decay curve of soma (black) and PDCs (red) during spontaneous firing. (I) Half-maximal Ca2+ decay times in the soma (0.11 ± 0.01 s, n = 9) and PDCs (0.09 ± 0.01 s, n = 9) during spontaneous firing. Values are presented as mean ± SE. PDCs, proximal dendritic compartments; DA, dopamine; CV, coefficients of variance; n.s., not significant.
© Korean J Physiol Pharmacol
