In summary, anatomical and physiological considerations suggest that the recipient neurons in primary visual cortex could, in principle, act as coincidence detectors for synchronous firing patterns among ganglion cells. Once relieved of the constraints imposed by the physical bottleneck of the optic nerve, the visual system may thus revert to a different neural code, again spreading the visual message over many independently firing neurons. Such a representation may be more adapted to the requirements for subsequent neural processing. Whether such decoding of concerted firing patterns does in fact occur must be resolved by future experiments which will provide a critical test of the retinal coding mechanisms proposed here.

I thank Drs. Leon Lagnado and Denis Baylor for their role in the early experiments leading to this work and the members of my laboratory for many discussions elaborating the ideas discussed here. Recent research has been supported by grants from the National Eye Institute (EY10020), the Office of Naval Research (N00014-92-J4072), the Human Frontiers Science Program Organization (RG17576), the Whitaker Foundation, a Presidential Faculty Fellow Award, and scholarships from the Markey Charitable Trust and the Pew Scholars Program.

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