The vertebrate retina has a layered structure in which somata of photoreceptors, interneurons and the output ganglion cells are located in the distalmost outer nuclear layer, the inner nuclear layer in the middle and the ganglion cell layer in the inner retina, respectively. Among the interneurons, bipolar cells relay information from photoreceptors to ganglion cells, whereas horizontal and amacrine cells provide inhibitory synapses to transversally signaling photoreceptors, bipolar and ganglion cells. Excitation occurs via glutamate release by photoreceptors, bipolar cells and ganglion cells whereas inhibition takes place by the release of GABA or glycine from horizontal and amacrine cells. Apart from chemical synapses electrical synaptic interactions take place in the retina as well. Very characteristic interactions are established by ganglion and/or amacrine cells whose electrical synapses correlate ganglion cell activity to generate a population code. As each ganglion cell population creates a feature movie of the visual world, each of these movies in turn streamed through parallel signaling pathways towards visual centers in the brain. Parallel signaling is maintained at the level of both the thalamus and the visual cortex. Since most ganglion cells maintain electrical synapses with their ganglion and amacrine cell neighbors gap junction mediated synchronous activity must be impinged in the information transmitted by parallel visual pathways. Our research focus is to examine how electrical synapse mediated synchronization contributes to the spike code, how the flow of synchronized information through these parallel feature channels contributes to activity of neuron populations in the visual cortex and how visually guided behavior mediated by synchronized signals passed through each of these parallel feature pathways. Our long-term plan is to utilize collected data on the above topic for machine/computer vision, robotics, drone technology and perhaps in retinal prosthetic devices as well.
Over 940 million people suffer in various forms of vision loss worldwide. Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work. Our long-term goal is to establish a frame-work describing various signaling mechanisms retinal ganglion cells utilize to encrypt each of the features in our visual environment. Beyond the obvious benefits this project may provide for neuroscience and computer vision, the dataset will also be used to generate algorithms suitable for epiretinal implants.
Hungarian Brain Research Program (grant number: KTIA_NAP_13-2-2015-0008)
European Union and the State of Hungary, co-financed by the European Social Fund in the framework of ‘National Excellence Program’ (grant number: EFOP-3.6.1.-16-2016-00004)
European Union and the State of Hungary, co-financed by the European Social Fund in the framework of ‘National Excellence Program’ (grant number: TÁMOP-4.2.4.A/2-11/1-2012-0001)
Tempus Public Fundation (grant number: PPP 152214)