Input rate encoding and gain control in dendrites of neocortical pyramidal neurons

• Published in: Cell reports (Cambridge) 2022-02, Vol.38 (7), p.110382-110382, Article 110382
• Main Authors: Dembrow, Nikolai C., Spain, William J.
• Format: Article
• Language: English
• Subjects: Action Potentials - physiology; Animals; cortical oscillations; Dendrites - physiology; dendritic spines; Dendritic Spines - physiology; extratelencephalic neuron; Female; gain control; glutamate uncaging; intratelencephalic neuron; Male; Mice, Transgenic; neocortex; Neocortex - physiology; Pyramidal Cells - physiology; pyramidal neuron; rate coding; synaptic integration
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2022.110382

Elucidating how neurons encode network activity is essential to understanding how the brain processes information. Neocortical pyramidal cells receive excitatory input onto spines distributed along dendritic branches. Local dendritic branch nonlinearities can boost the response to spatially clustered and synchronous input, but how this translates into the integration of patterns of ongoing activity remains unclear. To examine dendritic integration under naturalistic stimulus regimes, we use two-photon glutamate uncaging to repeatedly activate multiple dendritic spines at random intervals. In the proximal dendrites of two populations of layer 5 pyramidal neurons in the mouse motor cortex, spatially restricted synchrony is not a prerequisite for dendritic boosting. Branches encode afferent inputs with distinct rate sensitivities depending upon cell and branch type. Thus, inputs distributed along a dendritic branch can recruit supralinear boosting and the window of this nonlinearity may provide a mechanism by which dendrites can preferentially amplify slow-frequency network oscillations. [Display omitted] •Testing how dendritic branches integrate natural patterns of spine stimulation•It is the combined input rate to a proximal branch that drives supralinear boosting•Neuron and branch types encode input based upon their distinct rate sensitivities•Rate-based synaptic integration may preferentially amplify slow network oscillations Using repetitive activation of multiple spines distributed along a dendritic branch in neocortical pyramidal neurons, Dembrow and Spain demonstrate that supralinear dendritic boosting depends upon the combined activation rate of spines along a dendritic branch. A rate-based model suggests that such supralinear integration provides amplification of slow network oscillations.