The Journal of Neurophysiology Vol. 79 No. 3 March 1998, pp. 1255-1269
Copyright ©1998 The American Physiological Society

Neurons in the Posterior Interposed Nucleus of the Cerebellum Related to Vergence and Accommodation. I. Steady-State Characteristics

Hongyu Zhang and Paul D. R. Gamlin

Vision Science Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294

Zhang, Hongyu and Paul D. R. Gamlin. Neurons in the posterior interposed nucleus of the cerebellum related to vergence and accommodation. I. Steady-state characteristics. J. Neurophysiol. 79: 1255-1269, 1998. The present study used single-unit recording and electrical microstimulation techniques in alert, trained rhesus monkeys to examine the involvement of the posterior interposed nucleus (IP) of the cerebellum in vergence and accommodative eye movements. Neurons related to vergence and ocular accommodation were encountered within a circumscribed region of the IP and their activity during changes in viewing distance was characterized. The activity of these neurons increased with decreases in vergence angle and accommodation (the far-response) but none showed changes in activity during changes in conjugate eye position and we therefore term them "far-response neurons." Far-response neurons were found within a restricted region of the IP that extended ~1 mm rostrocaudally and mediolaterally and 2 mm dorsal to the fourth ventricle. Microstimulation of this far-response region of the IP with low currents (<30 µA) often elicited divergence and accommodation for far. The behavior of 37 IP far-response neurons was examined during normal binocular viewing, during monocular viewing (blur cue alone), and during binocular viewing with accommodation open-loop (disparity cue alone). The activity of all cells was modulated under all three conditions. However, the change in activity of some of these neurons was significantly different under these three viewing conditions. The behavior of 70 IP far-response neurons was compared during normal binocular viewing and during viewing in which the accommodative response was significantly dissociated from the vergence response. The data from these two conditions was pooled and multiple regression analyses for each neuron generated two coefficients expressing the activity of the neuron relative to the vergence and to accommodative response respectively. On the basis of these coefficients, the overall activity of the neurons were classified as follows: 34 positively correlated with divergence, 11 positively correlated with far accommodation, 14 positively correlated with divergence and far accommodation, 9 positively correlated with divergence and accommodation, and 2 positively correlated with convergence and far accommodation. The results of this study demonstrate the involvement of a specific region of the posterior interposed nucleus of the cerebellum in vergence and accommodation. IP far-response neurons are active for vergence and accommodation irrespective of whether or not these eye movements are elicited by blur or disparity cues. The data in the present study strongly suggest that this cerebellar region is a far-response region that is involved in vergence as well as accommodative eye movements.

This article has been cited by other articles:

				M. R. Van Horn, P. A. Sylvestre, and K. E. Cullen The Brain Stem Saccadic Burst Generator Encodes Gaze in Three-Dimensional Space J Neurophysiol, May 1, 2008; 99(5): 2602 - 2616. [Abstract] [Full Text] [PDF]

				T. Nitta, T. Akao, S. Kurkin, and K. Fukushima Involvement of the Cerebellar Dorsal Vermis in Vergence Eye Movements in Monkeys Cereb Cortex, May 1, 2008; 18(5): 1042 - 1057. [Abstract] [Full Text] [PDF]

				C. Busettini and L. E. Mays Saccade-Vergence Interactions in Macaques. II. Vergence Enhancement as the Product of a Local Feedback Vergence Motor Error and a Weighted Saccadic Burst J Neurophysiol, October 1, 2005; 94(4): 2312 - 2330. [Abstract] [Full Text] [PDF]

				T. Akao, M. J. Mustari, J. Fukushima, S. Kurkin, and K. Fukushima Discharge Characteristics of Pursuit Neurons in MST During Vergence Eye Movements J Neurophysiol, May 1, 2005; 93(5): 2415 - 2434. [Abstract] [Full Text] [PDF]

				C. Busettini and L. E. Mays Pontine Omnipause Activity During Conjugate and Disconjugate Eye Movements in Macaques J Neurophysiol, December 1, 2003; 90(6): 3838 - 3853. [Abstract] [Full Text] [PDF]

				R. Kono, S. Hasebe, H. Ohtsuki, K. Kashihara, and Y. Shiro Impaired Vertical Phoria Adaptation in Patients with Cerebellar Dysfunction Invest. Ophthalmol. Vis. Sci., March 1, 2002; 43(3): 673 - 678. [Abstract] [Full Text] [PDF]

				D. M. Clower, R. A. West, J. C. Lynch, and P. L. Strick The Inferior Parietal Lobule Is the Target of Output from the Superior Colliculus, Hippocampus, and Cerebellum J. Neurosci., August 15, 2001; 21(16): 6283 - 6291. [Abstract] [Full Text] [PDF]

				F. R. Robinson Role of the Cerebellar Posterior Interpositus Nucleus in Saccades I. Effect of Temporary Lesions J Neurophysiol, September 1, 2000; 84(3): 1289 - 1302. [Abstract] [Full Text] [PDF]