AN ANALYSIS OF THE CROSS-CORRELATION BETWEEN GANGLION-CELLS IN THE RETINA OF GOLDFISH

Neighboring ganglion cells in the retinae of vertebrates show cross-co rrelation between their impulse trains. Cross-correlation is found bot h in maintained discharges and during responses to visual stimulation. There has been speculation about the function of this statistical dep endence, but little is known about its genesis. This study examines th e statistics of the interimpulse intervals preceding and those followi ng impulses that coincide with an impulse in the other train. Short in tervals are rarer than expected preceding a coincidence, regardless of the form of the cross-correlation. Short intervals are more common th an expected following a coincidence when the cross-correlation is posi tive, but rarer than expected following coincidences during negative c rosscorrelation. These results contradict the extant models for cross- correlation, but may be explained by the multiplicative combination of a variable common input and the variability within each cell. In addi tion, the lag (relative timing of coincident impulses in the two cells ) is found to be related to the maintained discharge rates of the cell s, implying that the lags may be explained without invoking specific d elay circuits.