Fig. 2.

Calcium channel blockade eliminates complex spikes when applied locally to the dendrites but not the soma.A, A complex spike was evoked with dendritic current injection (500 pA through a single dendritic patch pipette 220 μm from the soma). B, Local pressure application of 5 mm Ni²⁺ to the somatic region caused repetitive firing of calcium spike bursts and increased the number of individual calcium spikes within a burst. C, The effects of Ni²⁺ were quickly reversed when the pressure application was interrupted. D, E, Calcium spikes were eliminated completely and reversibly when Ni²⁺ was applied to the dendrite, ∼100 μm distal to the recording pipette. There was an increase in excitability of the neuron upon washout of Ni²⁺. In schematic illustrations, the area targeted by the local application is indicated by gray ovals, and the direction of the local bath flow is indicated by a gray arrow.