title: Regulation of Cortical Dynamic Range by Background Synaptic Noise and Feedforward Inhibition.
abstract: The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve a broad dynamic range. Contrary to this explanation, we show here through dynamic clamp experiments in vitro and computer simulations that pyramidal neurons have a broad dynamic range under the noisy conditions that exist in the intact brain due to background synaptic input. Feedforward inhibition capitalizes on those noise effects to control neuronal gain and thereby regulates the population dynamic range. Importantly, noise allows neurons to be recruited gradually and occludes the staggered recruitment previously attributed to heterogeneous excitation. Feedforward inhibition protects spike timing against the disruptive effects of noise, meaning noise can enable the gain control required for rate coding without compromising the precise spike timing required for temporal coding.
authors.affiliation: Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A4 School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
authors.forename: Ayah
authors.initials: A
authors.lastname: Khubieh
authors.affiliation: Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A4 Department of Physiology and the Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Ratté
authors.affiliation: Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A4 Department of Physiology and the Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.
authors.forename: Milad
authors.initials: M
authors.lastname: Lankarany
authors.affiliation: Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A4 Department of Physiology and the Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Prescott
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D003198:Computer Simulation; D008297:Male; D008959:Models, Neurological; D009433:Neural Inhibition / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology*; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D013997:Time Factors; D046509:Tissue Culture Techniques
keywords: dynamic range; feedforward inhibition; gain control; noise; pyramidal neuron