ON HEBBIAN-LIKE ADAPTATION IN HEART-MUSCLE - A PROPOSAL FOR CARDIAC MEMORY

Studies on the effects of external pacing of heart suggest that the or gan, like the nervous system, possesses the properties of 'memory' and adaptation. Changes induced in cardiac activation patterns persist lo ng after the agent that induced those changes itself is removed. After the effects of stimulation have disappeared, response to the stimulus applied for a second time is much greater than the earlier response. Motivated by such results, this paper further explores the possibility of a 'cardiac memory'. In particular, we point out that communication via gap junctions in cardiac tissue is similar to synaptic conductanc e in nervous tissue and demonstrate, with the aid of a mathematical mo del, that cardiac tissue can exhibit memory-like behavior if gap-junct ional conductances are allowed to adapt according to a Hebbian-like me chanism.