Figure 2. Im neuron diversity based on cluster analysis.

A, dendrogram illustrating the results from a hierarchical cluster analysis. Intersection of the dendrogram branches with the y-axis represents individual neurons. The x-axis is the rescaled distance (squared Euclidian) between group centroids at each branch point. Longer horizontal lines indicate greater distance. Note the existence of three groups of Im neurons: I (n = 11; blue); II (n = 5; red); III (n = 11; green). B, representative action potentials generated by Im cells of group (a), (b) or (c). Left: action potential evoked by a short depolarizing current pulse (100 pA, 3 ms); right: firing pattern evoked by a long depolarizing current pulse (150 pA, 1 s). All cells shown had a resting membrane potential of −77 mV.