Eye Movement Signal Transformation by Midbrain Neurons

描述（由申请人提供）： 人类必须快速准确地重新定向他们的视线，以便看到感兴趣的新目标。因此，凝视系统必须以眼睛和头部的精确移动来响应感官输入，以将凝视正确地定位在该目标上。中央中脑网状结构（cMRF）与上级丘（SC）和旁正中桥网状结构（PPRF）相互作用以控制眼睛的运动。然而，这些区域的神经元携带的信号非常不同。SC神经元对运动的子集做出响应，因此SC被空间编码。PPRF中的兴奋性爆发神经元（EBN）随着运动的幅度和速度的变化而改变其放电频率，因此EBN被时间编码。在这两个区域之间如何发生从空间编码到时间编码的转换尚不清楚。作为SC投入的主要接受者，并直接向PPRF进行预测，CMRF处于进行这种转换的理想位置。事实上，cMRF中的神经元具有空间和时间特性。我们目前的假设是，cMRF前扫视神经元提供的生理机制进行时空转换。该建议将检查cMRF神经元的行为，允许比较不同速度的扫视，但类似的幅度，以辨别cMRF神经元是否暂时编码眼球运动速度。这将与神经元空间特性和逆向刺激的分析相结合，以确认下游投射。

DESCRIPTION (provided by applicant): Humans must quickly and accurately redirect their gaze in order to look at new targets of interest. Thus, the gaze system must respond to sensory input with precise movement of the eyes and head to correctly position gaze on that target. The central Mesencephalic Reticular Formation (cMRF) interacts with the superior colliculus (SC) and the paramedian pontine reticular formation (PPRF) to control movement of the eyes. However, the signals carried by neurons in these regions are very different. SC neurons respond for a subset of movements, thus the SC is spatially encoded. The excitatory burst neurons (EBNs) in the PPRF change their firing rate with changes in the amplitude and velocity of the movement, thus the EBNs are temporally encoded. How a transformation from spatial to temporal encoding occurs between these two regions is not known. As a major recipient of input from the SC and with direct projections to the PPRF, the cMRF is ideally situated to perform this transformation. Indeed, neurons in the cMRF have BOTH spatial and temporal characteristics. Our current hypothesis is that cMRF pre-saccadic neurons provide the physiologic machinery to perform a spatial to temporal transformation. This proposal will examine cMRF neurons during behaviors that permit comparison of saccades of different velocities, but similar amplitudes to discern whether cMRF neurons temporally encode eye movement velocity. This will be coupled with analysis of the neurons spatial properties and antidromic stimulation to confirm downstream projections.