PMC

Ca²⁺ responses of PSCs to local application of ATP and adenosine. A, Changes in fluorescence over time caused by the local application of ATP (20 μm) for 200 msec in normal physiological solution. Application of ATP caused a Ca²⁺ response in all PSCs studied. A second application 20 min later (break in thex-axis) induced smaller changes in fluorescence.B, Changes in fluorescence over time caused by the local application of adenosine (20 μm) for 200 msec in normal physiological solution. Application of adenosine caused a Ca²⁺ response in all PSCs studied. A second application 20 min later (break in the x-axis) induced smaller changes in fluorescence. C, Changes in fluorescence caused by the local application of ATP (20 μm, 200 msec) in the presence (solid line) and in the absence (dashed line) of external Ca²⁺ for the same PSCs. Note that ATP induced larger changes in fluorescence in the absence of external Ca²⁺. D, Changes in fluorescence caused by the local application of adenosine in the presence (solid line) and in the absence (dashed line) of external Ca²⁺ for the same PSCs. Note that adenosine induced larger changes in fluorescence in the absence of external Ca²⁺. E, Comparison of mean ± SEM of Ca²⁺ responses induced by a first and a second application of ATP (left) and the application of ATP in the presence and in the absence of external Ca²⁺ (right).F, Comparison of mean ± SEM of Ca²⁺ responses induced by a first and a second application of adenosine (left) and application of adenosine in the presence and in the absence of external Ca²⁺ (right).

Effect of local apamin application on somatic and dendritic excitability. A, Schematic of the experimental setup showing an image of a layer 5 pyramidal neuron filled with the fluorescent dye AlexaFluor 594 together with somatic and dendritic recording and local application pipettes. B, Somatic APs in control (black) and after local somatic (green) or dendritic (red; 710 μm from the soma) apamin application. C, Average effect of local somatic (green) or dendritic (red) apamin application on the somatic mAHP (n = 10; black, control). D, Average F/I curves in control (black) and after somatic apamin application (green; n = 10). E, Average AP firing frequency during somatic current injections (1.5 nA) in control (black) and during local somatic (green) or dendritic (red) apamin application (green; n = 10). F, Somatic (bottom) and dendritic (top; 710 μm from the soma) responses to 300 ms dendritic current injections (middle) in control (black, left) and after local dendritic apamin (red, right). G, Average number of AP bursts during dendritic current injections of different amplitude in control (black) and after local dendritic apamin (red; n = 10). H, Average number of AP bursts during 1.5 nA dendritic current steps in control (black) and after local dendritic apamin (red; n = 10). I, Average effect of apamin on the hyperpolarization after dendritic calcium spikes (dendritic AHP) in control (black) and after local dendritic apamin (red). J, Backpropagating AP (bAP) before (black) and after local dendritic apamin (red; 670 μm from the soma). K, Average bAP width at 25% amplitude in control (black) and after local dendritic apamin (red; n = 10). L, Somatic (left) and dendritic response (right; 710 μm from the soma) to four somatic APs at the critical frequency (130 Hz) before (black) and after local dendritic apamin (red). M, Averaged, normalized dendritic voltage integral during AP trains at the indicated frequencies in control (black) and after local dendritic apamin (red; lines represent sigmoidal fits; n = 10). N, Average critical frequency in control (black) and after local dendritic apamin (red; n = 10).

Effect of somatic BK channels on neuronal excitability. (A) Single somatic AP before (black) and after (light green) local IbTX application to the soma. (B) Average half width of somatic APs before (black) and after (light green) local IbTX application to the soma (n = 7). (C,D) Average amplitude (C) and half width (D) of bAPs before (black) and after (light green) local IbTX application to the soma (n = 7). (E) Somatic and dendritic responses during dendritic current injection before (black) and after (light green) local IbTX application to the soma (dendritic recording site 610 μm from soma). Gray boxes indicate the part of the trace shown in (F). (F) Overlay of dendritic calcium spikes recorded before (black) and after (light green) local IbTX application to the soma (aligned at threshold). (G) Average half width of dendritic calcium spikes before (black) and after (light green) local IbTX application to the soma (n = 7). (H) Average number of APs per burst before (gray) and after (light green) local IbTX application to the soma (n = 7).

Effect of dendritic BK channels on neuronal excitability. (A) Single somatic AP before (black) and after (purple) local IbTX application to the dendritic recording site (640 μm from the soma). (B) Average half width of somatic APs before (black) and after (purple) local IbTX application to the dendritic recording site (n = 7). (C,D) Average amplitude (C) and half width (D) of bAPs before (black) and after (purple) local IbTX application to the dendrite recording site (600–750 μm from the soma; n = 7). (E) Somatic and dendritic responses during dendritic current injection before (black) and after (purple) local IbTX application to the dendritic recording site (640 μm from soma). Gray boxes indicate the part of the traces shown in (F). (F) Overlay of dendritic calcium spikes recorded before (black) and after (purple) local IbTX application to the dendritic recording site (aligned at threshold). (G) Average half width of dendritic calcium spikes before (black) and after (purple) local IbTX application to the dendritic recording site (600–750 μm from the soma; n = 7). (H) Average number of APs per burst before (black) and after (purple) local IbTX application to the dendritic recording site (600–750 μm from the soma; n = 7).