Figure 1.

Visual neuro-system connects similarly to a public switched telephone network to produce an image versus a conversation.

Photoreceptors and local telephone convert light and sound signal to electrical signal, respectively, and form only one-direction connections. Retinal ganglion cell is comparable to switchboard office, which receiving, integrating and transmitting information. The optic nerve is the long-distance fiber cable in the visual system. The challenge of stem cell-based therapies to treat retinal degeneration diseases by replacing injured or dead ganglion cells is one of making the correction connections to produce a true image versus a series of mis-placed bright spots because of mis-guided complex connections with inappropriate targets, which we call “Switchboard Dilemma”. This would be analogous to transmitting a garbled conversation to the wrong person.