• The rod system is convergent. That is, many rods make synapses on the same target (the bipolar cell). It implies that the signals are pooled together and therefore reinforce one another. As a result, it increases the ability of the brain to detect dim light. However, convergence reduces the ability of the rod system to transmit spatial variation on the visual image. The cones: • They mediate day vision and colour vision. • They are concentrated in the foveola. • Cones provide much better spatial resolution than rods because the signals from the individual cones are not pooled. F.6. Stimulus transduction and neural encoding : These 2 processes are carried out by separate cells of the retina: 1. Phototransduction occurs in the photoreceptors. 2. Neural encoding occurs in the ganglion cells. The signals emitted by the photoreceptors are relayed to the ganglion cells via other cells: the bipolar cells and other interneurons (Fig. 10-37) . F.7. Light transduction (phototransduction) in rods:
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