Nonlinear Dendritic Integration Increases Alignment of Basal and Apical Input under Hebbian Plasticity

Experimental studies have shown that the integration of synaptic input and its effect on neural activity depends on the synapse's location within the postsynaptic dendritic structure. In L5 pyramidal neurons, temporally correlated input from basal and apical dendrites can elicit much higher activity than what would be expected from a linear superposition of input currents. We used a simple rate model [1] that accounts for this effect to investigate the influence of these nonlinear interactions on a Hebbian plasticity mechanism in the basal synapses. We found an increased correlation between proximal and distal input sequences. Moreover, this effect was robust against strong distracting basal presynaptic inputs, in contrast to canonical point-neurons, where this alignment could be easily corrupted by distracting input patterns. This indicated that the nonlinear interaction between basal and apical inputs allowed apical inputs to act as a form of “teacher signal” for basal plasticity without adjusting learning rules in the basal synapses.

[1] Shai AS, Anastassiou CA, Larkum ME, Koch C (2015) Physiology of Layer 5 Pyramidal Neurons in Mouse Primary Visual Cortex: Coincidence Detection through Bursting. PLOS Computational Biology 11(3): e1004090.