The shift-effect in the lateral geniculate body of the rhesus monkey

Responses to sudden shifts of a pattern far away from the receptive field (shift-effect) were found in 73 out of 81 cells of the ventral, magnocellular LGN layers, but in only 26 out of 85 cells of the dorsal, parvocellular layers. Most of the former responses were clear and excitatory, and most of the latter were weak and inhibitory. Excitatory responses were stronger for steady receptive field illumination which when turned on also yielded an excitation. No convincing dependence on the colour of the receptive field illumination was observed. The results are discussed with respect to the hypothesis of transmission of steady illumination via the shift-effect (“restoration”), and with respect to a hypothesis assigning a signalling function of low stimulus specificity to the ventral layers.