The operating regime of local computations in primary visual cortex

by Marcel Stimberg, Klaus Wimmer, Robert Martin, Lars Schwabe, Jorge Mariño, James Schummers, David C. Lyon, Mriganka Sur, Klaus Obermayer
Abstract:
In V1, local circuitry depends on the position in the orientation map: close to pinwheel centers, recurrent inputs show variable orientation preferences; within iso-orientation domains, inputs are relatively uniformly tuned. Physiological properties such as cell’s membrane potentials, spike outputs, and temporal characteristics change systematically with map location. We investigate in a firing rate and a Hodgkin-Huxley network model what constraints these tuning characteristics of V1 neurons impose on the cortical operating regime. Systematically varying the strength of both recurrent excitation and inhibition, we test a wide range of model classes and find the likely models to account for the experimental observations. We show that recent intracellular and extracellular recordings from cat V1 provide the strongest evidence for a regime where excitatory and inhibitory recurrent inputs are balanced and dominate the feed-forward input. Our results are robust against changes in model assumptions such as spatial extent and strength of lateral inhibition. Intriguingly, the most likely recurrent regime is in a region of parameter space where small changes have large effects on the network dynamics, and it is close to a regime of “runaway excitation,” where the network shows strong self-sustained activity. This could make the cortical response particularly sensitive to modulation.
Reference:
Marcel Stimberg, Klaus Wimmer, Robert Martin, Lars Schwabe, Jorge Mariño, James Schummers, David C. Lyon, Mriganka Sur, Klaus Obermayer, 2009. The operating regime of local computations in primary visual cortex, Cerebral cortex (New York, N.Y. : 1991), volume 19.
Bibtex Entry:
@article{Stimberg2009,
 abstract = {In V1, local circuitry depends on the position in the orientation map: close to pinwheel centers, recurrent inputs show variable orientation preferences; within iso-orientation domains, inputs are relatively uniformly tuned. Physiological properties such as cell's membrane potentials, spike outputs, and temporal characteristics change systematically with map location. We investigate in a firing rate and a Hodgkin-Huxley network model what constraints these tuning characteristics of V1 neurons impose on the cortical operating regime. Systematically varying the strength of both recurrent excitation and inhibition, we test a wide range of model classes and find the likely models to account for the experimental observations. We show that recent intracellular and extracellular recordings from cat V1 provide the strongest evidence for a regime where excitatory and inhibitory recurrent inputs are balanced and dominate the feed-forward input. Our results are robust against changes in model assumptions such as spatial extent and strength of lateral inhibition. Intriguingly, the most likely recurrent regime is in a region of parameter space where small changes have large effects on the network dynamics, and it is close to a regime of "runaway excitation," where the network shows strong self-sustained activity. This could make the cortical response particularly sensitive to modulation.},
 author = {Stimberg, Marcel
and Wimmer, Klaus
and Martin, Robert
and Schwabe, Lars
and Mari{~n}o, Jorge
and Schummers, James
and Lyon, David C.
and Sur, Mriganka
and Obermayer, Klaus},
 day = {16},
 doi = {10.1093/cercor/bhn240},
 issn = {1460-2199},
 journal = {Cerebral cortex (New York, N.Y. : 1991)},
 keyword = {Visual Perception},
 language = {eng},
 month = {Sep},
 number = {9},
 pages = {2166--2180},
 title = {The operating regime of local computations in primary visual cortex.},
 url = {https://academic.oup.com/cercor/article-pdf/19/9/2166/795354/bhn240.pdf},
 volume = {19},
 year = {2009}
}