Variations in axonal conduction velocity in olfactory peduncle neurons of the armadillo

Following electrical stimulation of the ipsi- or contralateral olfactory bulb, antidromically invaded neurons in the olfactory peduncle (OP) of the armadillo (a primitive mammal with a low brain temperature) show progressive decreases in conduction velocity when challenged with stimulation frequencies of 1-40 Hz. Antidromic latency also decreased or increased in a gradual, additive manner during the super- and subnormal period following twin pulses at intervals of 8-2000 ms. Since centrifugal OP axons excite inhibitory granular cells in the olfactory bulb, these effects may bear on the problem of the control of mitral cell excitability by central structures.