Lateral geniculate neuron responses to drifting sine-wave gratings in rabbits

Neurons of the lateral geniculate body in rabbits were excited with drifting sine-wave gratings. Rabbits were anesthetized and paralyzed under conventional methods to record action potentials of single cells using tungsten in glass microelectrodes. All classes of geniculate cells responded in a modulatory pattern. It appears that the unmodulatory pattern typical of complex cell types of the cortex is extremely infrequent or absent. In the spatial domain most cells are low pass and bandpass. Only one unit was high pass. In the temporal domain low-pass and bandpass cells were the most frequently recorded. Four geniculate cells were high pass. It appears, therefore, that neurons of rabbits' geniculate are tuned over spatial and temporal frequencies of sine-wave gratings. The comparison with cortical recordings revealed that geniculate cells are more broadly tuned than cortical neurons. This study suggests that the rabbit's visual system is sensitive to gratings. However cells respond optimally to lower values, e.g., broader gratings, than neurons of frontalized eye animals.