Figure 1: Kenyon cell recordings in acutely isolated honeybee brain.

(a, b) Images of an acutely isolated honeybee brain (mb, mushroom body) and a KC whole-cell recording with the fluorescent dye Lucifer Yellow in the patch electrode; to the left is a second micropipette used for pressure application of ACh. (c) Top, the current response to voltage steps (10 mV increments from a holding potential of −73 mV) showing activation of inward Na⁺ and outward K⁺ currents. Below, mean (±s.e.m.) I/V relationships (n=11) for the peak inward current (black circle), peak outward current (grey circle) and sustained outward current (open circle). The N-shape of the I/V relationship (open circle) indicates that Ca²⁺-activated K⁺ channels contribute to the sustained current^25,26. (d) Under current clamp, current injection (+20–+40 pA) evokes AP firing that exhibits adaptation in both frequency and amplitude, and a short delay between the current step and the first AP. Repetitive AP firing is therefore inhibited by sustained depolarization.