title: Deterministic multiplicative gain control with active dendrites.
abstract: Multiplicative gain control is a vital component of many theoretical analyses of neural computations, conferring the ability to scale neuronal firing rate in response to synaptic inputs. Many theories of gain control in single cells have used precisely balanced noisy inputs. Such noisy inputs can degrade signal processing. We demonstrate a deterministic method for the control of gain without the use of noise. We show that a depolarizing afterpotential (DAP), arising from active dendritic spike backpropagation, leads to a multiplicative increase in gain. Reduction of DAP amplitude by dendritic inhibition dilutes the multiplicative effect, allowing for divisive scaling of the firing rate. In contrast, somatic inhibition acts in a subtractive manner, allowing spatially distinct inhibitory inputs to perform distinct computations. The simplicity of this mechanism and the ubiquity of its elementary components suggest that many cell types have the potential to display a dendritic division of neuronal output.
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada. whmehaff@ucalgary.ca
authors.forename: W Hamish
authors.initials: WH
authors.lastname: Mehaffey
authors.forename: Brent
authors.initials: B
authors.lastname: Doiron
authors.forename: Leonard
authors.initials: L
authors.lastname: Maler
authors.forename: Ray W
authors.initials: RW
authors.lastname: Turner
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000166:cytology; D003712:Dendrites / Q000187:drug effects / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D005246:Feedback; D005399:Fishes; D018755:GABA Agonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008959:Models, Neurological; D009118:Muscimol / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D017966:Pyramidal Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D012964:Sodium / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000779:Anesthetics, Local; D018755:GABA Agonists; D009118:Muscimol; D013779:Tetrodotoxin; D012964:Sodium