Simulation of an inner plexiform layer neural circuit in vertebrate retina leads to sustained and transient excitation

摘要

The conversion of sustained into transient responses to a step of light in the visual system is first accomplished at the amacrine cells in the vertebrate retina. Neurobiological data from the vertebrate retina have provided some of the key synaptic connections between bipolar and amacrine cells that are thought to underlie the formation of transient and sustained amacrine cell responses to light. Using a neural network model that incorporates data from patch clamp recording techniques in the retinal slice preparation, we have constructed and simulated a connectionist model of the local circuits within the inner plexiform layer of the vertebrate retina that leads to the conversion of sustained to transient excitatory signals similar to those observed in retinal amacrine cells. The model incorporates sustained glutamate release from bipolar cells, GABA(sub)B feedback to bipolar cell axon terminals, GABA(sub)A feedforward input from sustained to transient amacrine cells, and rapidly desensitizing glutamate receptors in the transient amacrine cell.