Figure 1
From: Artificial Shape Perception Retina Network Based on Tunable Memristive Neurons
(a) Light changes the membrane potential of rod cells in retina. Light is absorbed by pigments (include opsin and retinal) which located in the rhodopsin. Photon will induce the isomerization of retinal and the concentration of cGMP (a kind of intracellular messenger) will decrease. The activity of Na+ channels has a positive correlation with the concentration of cGMP. So the light will hyperpolarize the cell membrane and the spiking frequency of rod cells will decrease. (b) The on-center receptive field and off-center receptive field of ganglion cells (GCs). The yellow bar represents the specific illumination period and the blue bars represent the spikes which recorded from the neuron. For the on-center cells, center illumination will increase the spiking frequency and the surrounding illumination will decrease the spiking frequency. For off-center cells, by contrast, the surrounding illumination will increase the spiking frequency and the center illumination will decrease the spiking frequency. For two types of cells, the dispersed light makes no difference to their spiking frequency. In summary, the GCs are sensitive to the difference of light rather than the light itself. By this feature, GCs can extract the shape of objects and code them into spike trains.
