title: Dendrites impact the encoding capabilities of the axon.
abstract: This study highlights a new and powerful direct impact of the dendritic tree (the input region of neurons) on the encoding capability of the axon (the output region). We show that the size of the dendritic arbors (its impedance load) strongly modulates the shape of the action potential (AP) onset at the axon initial segment; it is accelerated in neurons with larger dendritic surface area. AP onset rapidness is key in determining the capability of the axonal spikes to encode (phase lock to) rapid changes in synaptic inputs. Hence, our findings imply that neurons with larger dendritic arbors have improved encoding capabilities. This "dendritic size effect" was explored both analytically as well as numerically, in simplified and detailed models of 3D reconstructed layer 2/3 cortical pyramidal cells of rats and humans. The cutoff frequency of spikes phase locking to modulated inputs increased from 100 to 200 Hz in pyramidal cells of young rats to 400-600 Hz in human cells. In the latter case, phase locking reached close to 1 KHz in in vivo-like conditions. This work highlights new and functionally profound cross talk between the dendritic tree and the axon initial segment, providing new understanding of neurons as sophisticated nonlinear input/output devices.
authors.affiliation: Department of Neurobiology.
authors.forename: Guy
authors.initials: G
authors.lastname: Eyal
authors.affiliation: Center for Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, 1081 The Netherlands.
authors.forename: Huibert D
authors.initials: HD
authors.lastname: Mansvelder
authors.affiliation: Center for Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, 1081 The Netherlands.
authors.forename: Christiaan P J
authors.initials: CP
authors.lastname: de Kock
authors.affiliation: Department of Neurobiology, the Interdisciplinary Center for Neural Computation, and Edmond and Lily Safra Center for Brain Sciences, the Hebrew University of Jerusalem, Jerusalem, 91904 Israel, and idan@lobster.ls.huji.ac.il.
authors.forename: Idan
authors.initials: I
authors.lastname: Segev
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001369:Axons / Q000502:physiology*; D003198:Computer Simulation; D003712:Dendrites / Q000502:physiology*; D004558:Electric Stimulation; D006801:Humans; D008959:Models, Neurological; D017966:Pyramidal Cells / Q000166:cytology*; D051381:Rats; D013003:Somatosensory Cortex / Q000166:cytology*
keywords: cable theory; dendritic modeling; linking dendrites to axon; spike sharpness; spike tracking of input modulation