Another extension involves investigating a pair of populations of neurons, one excitatory and one inhibitory [41].
A convenient way to quantify the number of shared gametes is by means of the proportion μ P of shared gametes between populations characterized by distributions P and Q, with respect to the total number of gametes in the population characterized by P. We emphasize that μ P is not only a property of population P, but of the pair of populations being compared.
Between any pair of populations among which a genetic flow has been detected (as described in the previous section, this occurs when their genetic distance is smaller than the given percolation threshold), a directionality index I P Q is defined between meadows characterized by gamete distributions P and Q.
Given a mutually inhibitory pair of populations where one is active and the other is silent, the silent population may become active by reaching the jump up (left) knee of its V nullcline (i.e., left fold of its family of V nullclines, parameterized by the synaptic strength s controlled by the other population).
Figure 4 shows that the oscillation frequency in sparse networks varies with either a network-level parameter, the connectivity between a pair of populations, or with a single-neuron parameter, the synaptic strength between a pair of populations.
The differentiation among human populations was estimated through the FST measure [32] among each pair of populations.
The obtained 28×28 matrix is then a measure of the dissimilarity of recombination rates between each pair of populations.
The distance via migration waypoints corresponds to the divergent part of the prehistoric migration trajectories of each pair of populations.
For each pair of populations we used a 'burn-in' period of 1×106 steps and a sampling period of 1×107 steps.
We have used the isolation with migration model [29], which is a Markov chain Monte Carlo calculation using DNA sequence data to estimate the relative effects of migration and isolation on genetic diversity in a pair of populations.
For each species, genotypic population differentiation was analyzed for each pair of populations and over all populations by estimating FST values following Weir and Cockerham [63], and tested using exact tests with the program GENEPOP 3.3 [56].
