The effects of partial retinal lesions on activity and size of cells in the dorsal lateral geniculate nucleus.

The nasal parts of the adult cat retina were photocoagulated. In the dorsal lateral geniculate nucleus (dLGN) the projection of the remaining innervation was shown by anterograde transport of 3H-proline after eye injections. The neuronal activity was measured from single cells across the border region between innervated and deafferented parts of layer A of the dLGN contralateral to the lesions. A gradual decrease from normal light-excitability to total inexcitability was observed over a range of 300 micron. The perikaryal cell sizes measured in the same part of the dLGN displayed a concomitant decrease. Blockage of the afferent impulses by chronic application of tetrodotoxin did not change the results, suggesting that it is the loss of connections, not the loss of activity, that produces the transneuronal atrophy in the adult cat dLGN.