Thus we attempt to form a synapse between every pair of overlapping axonal and dendritic branch segments with the same probability but the acceptance probabilities for these attempts are different. The attempts for every possible configuration changes are equally likely. On each Monte Carlo step, one of the six changes is attempted: formation, elimination, extension or retraction of branches, or creation or elimination of synapses. We simulate the developmental process using the Metropolis Monte Carlo algorithm. Similarly to branches, the synapses can be created, maintained, or retracted, in a stochastic manner, depending on the energy change that results from these actions. The neural connections are formed in the model by creating synapses between the branches of spatially overlapping axons and dendrites. In this model, new branches are created, eliminated, elongated and retracted randomly, with probabilities dependent upon how the energy of the system changes after a segment of a branch is added or removed. We propose a mathematical description of the dynamics of axonal and dendritic arbors, using the theoretical model of stochastic growth. We propose experimental tests that can differentiate the various branching strategies used by axons and dendrites. We show that three prominent features of axon and dendrite dynamics can be viewed as evolutionary adaptations that save time and minimize the number of errors. To answer these questions, we have developed a computational model that allows us to compare different branching strategies, based upon the speed of development of target circuitry and the number of ‘erroneous’ branches formed. Third, we address the asymmetry in the branching rules between axons and dendrites that has been revealed in experiments on NMDA receptor blockade. First, we ask: what is the functional significance of branching, from the standpoint of neural development? Second, we ask why axons and dendrites preferentially form branches in the vicinity of synapses. We ask three questions stemming from the experimental findings mentioned above. Here, we theoretically investigate the role of branching in the formation of neural connectivity.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |