Temporal hyperacuity in single neurons of electric fish.

Behavioural studies have revealed that animals can resolve temporal disparities in the microsecond range. This resolution is far superior to that of individual receptors, and it must therefore be achieved through central neuronal mechanisms. It is unclear, however, whether such sensitivity ever emerges at the level of single neurons, or whether it is apparent only at the behavioural level through the collective action of many less-sensitive neurons. We have found that single neurons in the pre-pacemaker nucleus of a weakly electric fish are sensitive to temporal disparities as small as 1 microsecond, the highest temporal sensitivity ever observed at the single-neuron level. The remarkable temporal resolution of these pre-pacemaker neurons results from a high degree of spatial convergence of afferent inputs. These neurons represent the final elements of a sensory hierarchy and directly control the jamming avoidance response by which these fish regulate the frequency of their electric organ discharges.