Proceedings Article | 20 February 2009
Proc. SPIE. 7186, Optical Diagnostics and Sensing IX
KEYWORDS: Mathematical modeling, Optical imaging, Lithium, Biomedical optics, Ischemia, Wavefronts, Wave propagation, Convolution, Cerebral cortex, Brain
Cortical spreading depression (CSD) is an important neurophysiological phenomenon correlating with some neural
disorders, such as migraine, cerebral ischemia and epilepsy. By now, we are still not clear about the mechanisms of
CSD's initiation and propagation, also the relevance between CSD and those neural diseases. Nevertheless,
characterization of CSD, especially the spatiotemporal evolution, will promote the understanding of the CSD's nature
and mechanisms. Besides the previous experimental work on charactering the spatiotemporal evolution of CSD in rats by
optical intrinsic signal imaging, a computational study based on a generalized cellular automaton (CA) model was
proposed here. In the model, we exploited a generalized neighborhood connection rule: a central CA cell is related with a
group of surrounding CA cells with different weight coefficients. By selecting special parameters, the generalized CA
model could be transformed to the traditional CA models with von Neumann, Moore and hexagon neighborhood
connection means. Hence, the new model covered several properties of CSD simulated in traditional CA models: 1)
expanding from the origin site like a circular wave; 2) annihilation of two waves traveling in opposite directions after
colliding; 3) wavefront of CSD breaking and recovering when and after encountering an obstacle. By setting different
refractory period in the different CA lattice field, different connection coefficient in different direction within the defined
neighborhood, inhomogeneous propagation of CSD was simulated with high fidelity. The computational results were
analogous to the reported time-varying CSD waves by optical imaging. So, the generalized CA model would be useful to
study CSD because of its intuitive appeal and computational efficiency.
