Effects of spatio-temporal conduction anisotropy on critical interval and coherence

The authors hypothesized that spatio-temporal anisotropy may lead to changes in critical interval and time-coherence that are observed experimentally. To test their hypothesis they performed numerical simulations. Using an S1-S2 protocol rotors were induced in the left and right half of a 128/spl times/128 matrix of cells using a Fitzhugh-Nagumo model. Midway through the simulations pseudo potassium conductance (gk) was changed in one half of the matrix. This caused the two rotors to become asynchronous in rotational velocity. The authors observed that the average coherence was high when the rotors were synchronous and it was low when the rotors became asynchronous. For different combinations of gk and pseudo-sodium conductance (gNa) they observed a pronounced change in the critical interval.