1. In the present study we used single unit recording techniques in alert rhesus monkeys to investigate a precerebellar nucleus, the nucleus reticularis tegmenti pontis (NRTP), for neurons related to vergence and ocular accommodation. 2. In the medial NRTP, we identified 32 cells with activity that linearly increased with increases in the amplitude of the near response and 33 cells with activity that linearly increased with increases in the amplitude of the far response. These near and far response neurons were often encountered close to neurons displaying saccade-related activity, but their activity was related neither to saccadic nor to smooth pursuit eye movements. Microstimulation at the site of near or far response neurons often produced changes in vergence angle and accommodation. 3. The NRTP is known to receive cortical afferents and to have reciprocal connections with the cerebellum; therefore it is likely that the near and far response neurons in the medial NRTP form part of a cerebropontocerebellar pathway modulating or controlling vergence and ocular accommodation.
