Cortical area related to lens accommodation in cat.

Lens accommodation was evoked by microstimulation in the lateral suprasylvian (LS) area in cats. The accommodative response was monitored continuously with an infrared optometer. The low threshold areas related to lens accommodation were located in the lower parts of the medial banks of the middle suprasylvian sulcus from A1 to A4, and also in the fundus of the sulcus at A8 in the stereotaxic coordinates. The latency of the onset of the accommodative responses evoked by stimulating the caudal area (A1-A4) was shorter than that evoked by stimulating the rostral area (around A8). Electrical stimulation was also attempted at the subcortical area in order to study the output pathway from the LS area. It was determined that the low threshold sites in the LS cortex of A1-A4 extend rostrally along the lateral ventricle in the brainstem, then ventrally into the midbrain. These findings suggest that there are two cortical areas related to lens accommodation: caudal and rostral, and the caudal accommodation area may provide the output signal for the subcortical system.