Waitzman David M, Van Horn Marion R, Cullen Kathleen E
Department of Neurology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, USA.
Prog Brain Res. 2008;171:143-50. doi: 10.1016/S0079-6123(08)00619-5.
Previous single unit recordings and electrical stimulation have suggested that separate regions of the MRF participate in the control of vergence and conjugate eye movements. Neurons in the supraoculomotor area (SOA) have been found to encode symmetric vergence [Zhang, Y. et al. (1992). J. Neurophysiol., 67: 944-960] while neurons in the central MRF, the cMRF, located ventral to the SOA and lateral to the oculomotor nucleus are associated with conjugate eye movements [Waitzman, D.M. et al. (1996). J. Neurophysiol., 75(4): 1546-1572]. However, it remains unknown if cMRF neurons are strictly associated with conjugate movements since eye movements were recorded with a single eye coil in monkeys viewing visual stimuli at a distance of at least 50 cm. In the current study we addressed whether neurons in the cMRF might also encode vergence-related information. Interestingly, electrical stimulation elicited disconjugate saccades (contralateral eye moved more than the ipsilateral eye) from locations previously thought to elicit only conjugate saccades. Single unit recordings in this same area made in two rhesus monkeys trained to follow visual stimuli moved rapidly in depth along the axis of sight of an individual eye demonstrate that cMRF neurons do not simply encode conjugate information during disconjugate saccades; in fact our findings provide evidence that cMRF neurons are most closely associated with the movement of an individual eye. These results support the hypothesis that the midbrain shapes the activity of the pre-motor saccadic neurons by encoding integrated conjugate and vergence commands.
先前的单神经元记录和电刺激研究表明，中脑网状结构（MRF）的不同区域参与了辐辏和共轭眼球运动的控制。已发现动眼神经上区域（SOA）的神经元编码对称辐辏[Zhang, Y.等人（1992年）。《神经生理学杂志》，67: 944 - 960]，而位于SOA腹侧和动眼神经核外侧的中央MRF（cMRF）中的神经元与共轭眼球运动有关[Waitzman, D.M.等人（1996年）。《神经生理学杂志》，75(4): 1546 - 1572]。然而，由于在至少50厘米距离观看视觉刺激的猴子中，使用单眼线圈记录眼球运动，cMRF神经元是否严格与共轭运动相关仍不清楚。在当前研究中，我们探讨了cMRF中的神经元是否也可能编码与辐辏相关的信息。有趣的是，电刺激从先前认为仅能引发共轭扫视的位置引发了非共轭扫视（对侧眼比同侧眼移动更多）。在两只经过训练以跟随沿单眼视线轴在深度上快速移动的视觉刺激的恒河猴的同一区域进行的单神经元记录表明，cMRF神经元在非共轭扫视期间不仅仅编码共轭信息；事实上，我们的研究结果提供了证据，表明cMRF神经元与单眼的运动最密切相关。这些结果支持了这样一种假设，即中脑通过编码整合的共轭和辐辏指令来塑造运动前扫视神经元的活动。
