In this paper, Drs Amane Koizumi, Misako Takayasu, and Hideki Takayasu found that spatial and temporal asymmetricity of excitatory connections are able to generate directional selectivity which can be enhanced by asymmetrical inhibitory connections by reconstructing a hexagonally-arranged 3-layered simulation model of retina by NEURON simulator. Asymmetric excitatory inputs to ganglion cells with randomly arborizing dendrites were able to generate weaker directional selectivity to moving stimuli whose speed was less than 10 μm/msec. By just adding asymmetric inhibitory connections via inhibitory amacrine cells, directional selectivity became stronger to respond to moving stimuli at 10 times faster speed (< 100 μm /msec). In conclusion, an excitatory mechanism appeared to generate directional selectivity while asymmetric inhibitory connections enhance directional selectivity in retina.
Asymmetric inhibitory connections enhance directional selectivity in a three-layer simulation model of retinal networks.
Koizumi A, Takayasu M, Takayasu H.
J Integr Neurosci. 2010 Sep;9(3):337-50.
Electronic version of an article published as Journal of Integrative Neuroscience (JIN) © [copyright World Scientific Publishing Company] http://www.worldscinet.com/jin/
