title: Subtractive, divisive and non-monotonic gain control in feedforward nets linearized by noise and delays.
abstract: The control of input-to-output mappings, or gain control, is one of the main strategies used by neural networks for the processing and gating of information. Using a spiking neural network model, we studied the gain control induced by a form of inhibitory feedforward circuitry-also known as "open-loop feedback"-, which has been experimentally observed in a cerebellum-like structure in weakly electric fish. We found, both analytically and numerically, that this network displays three different regimes of gain control: subtractive, divisive, and non-monotonic. Subtractive gain control was obtained when noise is very low in the network. Also, it was possible to change from divisive to non-monotonic gain control by simply modulating the strength of the feedforward inhibition, which may be achieved via long-term synaptic plasticity. The particular case of divisive gain control has been previously observed in vivo in weakly electric fish. These gain control regimes were robust to the presence of temporal delays in the inhibitory feedforward pathway, which were found to linearize the input-to-output mappings (or f-I curves) via a novel variability-increasing mechanism. Our findings highlight the feedforward-induced gain control analyzed here as a highly versatile mechanism of information gating in the brain.
authors.affiliation: Department of Physics, University of Ottawa Ottawa, ON, Canada ; Center for Neural Science, New York University New York, NY, USA.
authors.forename: Jorge F
authors.initials: JF
authors.lastname: Mejias
authors.affiliation: Department of Physics, University of Ottawa Ottawa, ON, Canada.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Payeur
authors.affiliation: Department of Physics, University of Ottawa Ottawa, ON, Canada.
authors.forename: Erik
authors.initials: E
authors.lastname: Selin
authors.affiliation: Department of Cell and Molecular Medicine, University of Ottawa Ottawa, ON, Canada.
authors.forename: Leonard
authors.initials: L
authors.lastname: Maler
authors.affiliation: Department of Physics, University of Ottawa Ottawa, ON, Canada.
authors.forename: André
authors.initials: A
authors.lastname: Longtin
keywords: divisive; feedforward network; gain control; linearization by delay; non-monotonic; subtractive; weakly electric fish