Does a dendritic democracy need a ruler?
Sterratt, D. C, and Van Ooyen, A. (2004). Neurocomputing 58-60: 437-442. [Full text: PDF]
In hippocampal CA1 cells, distance-dependence synaptic scaling helps maintain a "dendritic democracy" where distal and proximal synapses on average contribute equally to the cell's firing. A "dendritic ruler", for example a concentration gradient, might be necessary for synaptic scaling. Alternatively, synapses could "self-regulate" by gauging their distance from the soma using properties of backpropagating spikes. We show in a model CA1 cell that the delay between a synchronous burst of simulated Schaffer colleteral input and the arrival of backpropagating spikes at synapses predicts the synapse's location and amplitude at the soma well, though the amplitude of the spikes does not. This suggests that a dendritic ruler is not required to scale synapses.