Aging and damage effect on the brain and phase transition

Summary form only given, as follows. Aging and damage effects on the brain were considered on the basis of the Hopfield model. As damage to the brain or debility of neurons by aging is induced, a sudden-change-like critical phenomenon is observed in the ability of retrieval or recognition. This critical behavior is very similar to the percolation phenomena in physics. The relearning effect which corresponds to so-called rehabilitation was also examined