Shi Ying, Buneo Christopher A
School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:4060-3. doi: 10.1109/IEMBS.2011.6091009.
Understanding the neural mechanisms of limb position estimation is important both for comprehending the neural control of goal directed arm movements and for developing neuroprosthetic systems designed to replace lost limb function. Here we examined the role of area 5 of the posterior parietal cortex in estimating limb position based on visual and somatic (proprioceptive, efference copy) signals. Single unit recordings were obtained as monkeys reached to visual targets presented in a semi-immersive virtual reality environment. On half of the trials animals were required to maintain their limb position at these targets while receiving both visual and non-visual feedback of their arm position, while on the other trials visual feedback was withheld. When examined individually, many area 5 neurons were tuned to the position of the limb in the workspace but very few neurons modulated their firing rates based on the presence/absence of visual feedback. At the population level however decoding of limb position was somewhat more accurate when visual feedback was provided. These findings support a role for area 5 in limb position estimation but also suggest that visual signals regarding limb position are only weakly represented in this area, and only at the population level.
理解肢体位置估计的神经机制，对于理解目标导向性手臂运动的神经控制以及开发旨在替代丧失肢体功能的神经假体系统都非常重要。在此，我们研究了后顶叶皮质5区在基于视觉和躯体（本体感觉、传出副本）信号估计肢体位置中的作用。在猴子伸向半沉浸式虚拟现实环境中呈现的视觉目标时，获取了单神经元记录。在一半的试验中，要求动物在接收手臂位置的视觉和非视觉反馈时，将肢体位置保持在这些目标上，而在另一半试验中，视觉反馈被 withheld。单独检查时，许多5区神经元被调整到肢体在工作空间中的位置，但很少有神经元根据视觉反馈的存在与否来调节其放电率。然而，在群体水平上，当提供视觉反馈时，肢体位置的解码在某种程度上更准确。这些发现支持5区在肢体位置估计中的作用，但也表明关于肢体位置的视觉信号在该区域仅得到微弱的表征，且仅在群体水平上。
