DENDRITE CLASSIFICATION IN RAT HIPPOCAMPAL-NEURONS ACCORDING TO SIGNAL PROPAGATION PROPERTIES - OBSERVATION BY MULTICHANNEL OPTICAL-RECORDING IN CULTURED NEURONAL NETWORKS

Two-dimensional neuronal networks were formed using a dissociated cult ure of rat hippocampal neurons on glass plates. Neural activity in res ponse to pulse stimuli applied to the neurons by whole-cell clamp elec trodes was observed with a 128-channel optical recording apparatus usi ng a voltage-sensitive dye, RH482. Dendrites emerging from the somata of single neurons were classified according to two signal-transmission properties, those with lower conduction velocities (0.12+/-0.034 m/s, n=24) and those with very fast conduction velocity (faster than 1.0 m /s), by evaluating the conduction velocities of pulse responses. The d istinction between these two properties seemed to be related to the mo rphological differences in input connectivity with the axons of neighb oring neurons.