Fig. 4. Histograms of nearest neighbor distances calculated between neuron response patterns observed in reference (first) vs comparison (second) populations for (A) parent vs parent, (B) parent vs F₁ hybrid, and (C) F₁ hybrid vs parent analyses. Also given are mean nearest neighbor distances for each comparison (mean NND), and the probability level (P value) for the mean NND as determined by Monte Carlo parametric bootstrapping. For the parent vs F₁ hybrid and F₁ hybrid vs parent analyses (B,C), P values indicate the proportions of randomly drawn parent and F₁ hybrid data sets sampled with replacement from a combined neuron response sampling pool that had mean NND as great or greater than the observed value in 10 000 trials. For the parent to parent analysis, the P value represents the proportion of randomly drawn data sets of 77 neurons sampled with replacement from the F₁ hybrid population that had a mean NND to the actual parent population the same or less than the observed parent to parent value in 10 000 trials.