EXCLUSIVE-OR FUNCTION OF SINGLE ARBORIZED NEURON

We designed four arborized neurons which are able to evaluate the excl usive-or (XOR) function from two inputs. The input neurons form exclus ively excitatory synapses on a dendritic tree which is a patchwork of ''passive'' (ohmic) and ''active'' cable segments. The active segments are described by the Hodgkin-Huxley model. The dynamics of the neuron s and their output are obtained by numerical integration of the cable equation. In neurons 1 and 2 the XOR function is based on the annihila tion of colliding action potentials. In neuron No. 3 the design takes advantage of the refractory period of action potentials. In neuron No. 4 voltage inversion is used as it occurs for inactivated sodium condu ctance in the Hodgkin-Huxley model. In all cases the XOR function depe nds critically on an appropriate timing of the input signals and on de lays of the voltage transients in different branches of the dendrite.