Neromyliotis Eleftherios, Moschovakis A K
Institute of Applied and Computational Mathematics, Foundation for Research and TechnologyHeraklion, Greece.
Department of Basic Sciences, Faculty of Medicine, University of CreteHeraklion, Greece.
Front Behav Neurosci. 2017 Apr 12;11:61. doi: 10.3389/fnbeh.2017.00061. eCollection 2017.
To study the response properties of cells that could participate in eye-hand coordination we trained two macaque monkeys to perform center-out saccades and pointing movements with their right or left forelimb toward visual targets presented on a video display. We analyzed the phasic movement related discharges of neurons of the periarcuate cortex that fire before and during saccades and movements of the hand whether accompanied by movements of the other effector or not. Because such cells could encode an abstract form of the desired displacement vector without regard to the effector that would execute the movement we refer to such cells as motor equivalence neurons (Meq). Most of them (75%) were found in or near the smooth pursuit region and the grasp related region in the caudal bank of the arcuate sulcus. The onset of their phasic discharges preceded saccades by about 70 ms and hand movements by about 150 ms and was often correlated to both the onset of saccades and the onset of hand movements. The on-direction of Meq cells was uniformly distributed without preference for ipsiversive or contraversive movements. In about half of the Meq cells the preferred direction for saccades was the preferred direction for hand movements as well. In the remaining cells the difference was considerable (>90 deg), and the on-direction for eye-hand movements resembled that for isolated saccades in some cells and for isolated hand movements in others. A three layer neural network model that used Meq cells as its input layer showed that the combination of effector invariant discharges with non-invariant discharges could help reduce the number of decoding errors when the network attempts to compute the correct movement metrics of the right effector.
为了研究可能参与眼手协调的细胞的反应特性，我们训练了两只猕猴，让它们用右前肢或左前肢向视频显示器上呈现的视觉目标进行中心向外的扫视和指向动作。我们分析了弓状周围皮质神经元的相位运动相关放电，这些神经元在扫视和手部运动之前及期间放电，无论是否伴有另一个效应器的运动。由于这类细胞可以编码所需位移矢量的抽象形式，而不考虑执行运动的效应器，我们将这类细胞称为运动等效神经元（Meq）。它们中的大多数（75%）位于弓状沟尾侧岸的平稳跟踪区域和抓握相关区域内或附近。它们的相位放电起始比扫视提前约70毫秒，比手部运动提前约150毫秒，并且常常与扫视起始和手部运动起始都相关。Meq细胞的运动方向均匀分布，对同侧或对侧运动没有偏好。在大约一半的Meq细胞中，扫视的偏好方向也是手部运动的偏好方向。在其余细胞中，差异相当大（>90度），并且在一些细胞中，眼手运动的运动方向类似于孤立扫视的运动方向，而在另一些细胞中则类似于孤立手部运动的运动方向。一个以Meq细胞作为输入层的三层神经网络模型表明，当网络试图计算右效应器的正确运动指标时，效应器不变放电与非不变放电的组合有助于减少解码错误的数量。
