Cooperative LTP can map memory sequences on dendritic branches

Hebbian synaptic learning requires co-activation of presynaptic and postsynaptic neurons. However, under some conditions, information regarding the postsynaptic action potential, carried by backpropagating action potentials, can be strongly degraded before it reaches the distal dendritic synapse. Can these synapses still exhibit Hebbian long-term potentiation (LTP)? Recent results show that UP can indeed occur at synapses on distal dendrites of hippocampal CA1 neurons, even in the absence of a postsynaptic somatic spike. Instead, local dendritic spikes contribute to the depolarization required to induce LTP. Here, a dendritically constrained synaptic learning rule is proposed, which suggests that nearby synapses can encode temporally contiguous events.