Fig. 7. The breadth of responsiveness of vomeronasal (VN) neurons indicates a degree of diversity on the basis of entropy calculations. (A) The response profiles of 10 VN neurons to five chemicals. Each horizontal line depicts the responses of a different neuron; the height of the columns on each line indicates the amplitude and the direction of the columns indicates the polarity of the chemically evoked current (pA). The outward currents are denoted as positive (upward columns) and the inward currents are denoted as negative (downward columns). The calculated H metric for a given neuron is presented to the left of each response profile. Breadth of responsiveness is minimal (H=0) when a VN neuron responds to only one of five chemicals (narrow selectivity) and it is maximal (H=1.0) when there is an equal response to each of the five chemicals (no selectivity or low diversity in response). (B) Histogram of the breadth of responsiveness of 36 neurons. The arrow denotes the mean H value (0.11±0.02, mean ± S.E.M.) (see Materials and methods for calculation). Cat, catfish extract; M Musk, male musk; F Musk, female musk; M Urine, male urine; F Urine, female urine.