Modelling input selection at synaptic clusters on dendrites

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Several findings support the notion that synaptic clusters at a dendritic branch together with passive and active dendritic processes allow calculating operations such as filtering, gating, routing, and multiplexing of the incoming information. A central remaining question, however, is how a dendritic sub-compartment “knows” which synapses – hence which of its inputs – would be “useful” for the desired operation and which not? Useful synapses should be selected by structural plasticity and strengthened by synaptic plasticity, while all others should be weakened and removed, leading to a process of input selection supporting the desired operation. We are systematically addressing this question in this proposal by utilizing an abstract model for large-scale parameter analyses and a biologically detailed model to link our findings with specific biophysical processes allowing experimentally verifiable predictions. In our first aim, we assume that post-synaptic processing emulates a certain operator and investigate how synaptic clusters at one dendritic branch perform input selection dependent on the specific operator, local dendritic signals such as dendritic spikes, and plasticity. In the second aim, we will investigate the influence of global dendritic signals, such as back-propagating spikes, and plastic synapses at dendritic junctions on operator execution and input selection. We suggest that the interplay between these different processes form complex operators by combing and adapting individual operators, each being realized on an individual dendritic branch. Taken together, the outcome of this project will be a biophysically realistic model of dendritic input selection under the constraints of different operators, accompanied by a more abstract model that allows a more general understanding of parameter dependencies. This is novel, because so far models of dendritic computation have not considered the interplay between dendritic operation and the combination of synaptic and structural plasticity.