A Novel Form of Local Plasticity in Tuft Dendrites of Neocortical Somatosensory Layer 5 Pyramidal Neurons

Tuft dendrites of layer 5 pyramidal neurons form a separate biophysical and processing compartment. Presently, little is known about plasticity mechanisms in this isolated compartment. Here, we describe a novel form of plasticity in which unpaired low-frequency (0.1 Hz) stimulation of tuft inputs resulted in prolonged transient (86.3 ± 7.3 min) potentiation of EPSPs (286.1% ± 30.5%) and enhanced local excitability that enabled more-efficient back-propagation of axo-somatic action potentials and dendritic calcium spikes selectively into the activated dendritic segments. This plasticity was exclusive to tuft dendrites and did not occur in basal dendrites. Induction of this plasticity depended on activation of Kv4.2 potassium and NMDAR channels, internalization of membrane proteins, and insertion of AMPAR. This unique form of tuft plasticity increases proximal-distal electrical coupling of activated tuft dendrites and opens a prolonged time window for binding and storing feedforward and feedback information in a branch-specific manner. •Unpaired low-frequency stimulation results in potentiation of tuft dendritic EPSPs•Plasticity was accompanied by enhanced excitability in the activated tuft branches•Kv4.2 channels, NMDAR, membrane internalization, and AMPAR insertion are required•This plasticity was unique to tuft dendrites and did not occur in basal dendrites Sandler et al. describe a novel form of synaptic and dendritic plasticity unique to tuft dendrites, requiring Kv4.2, NMDAR, membrane internalization, and AMPAR insertion. This modulates coupling efficiency of forward and backward signals of activated tuft branches with other compartments.