生物谷报道：5月8日《神经元》（Neuron）杂志上美加科学家联合发表了一项最新研究成果，他们绕过难题，建立了一个肢体对于神经反应的模型。
是不是在初级运动皮层的神经元对精细的运动行为（如某个肌肉的活动）进行编码？抑或是这些神经元在对高层次的运动行为进行编码？已有的经验表明，要解决这个问题是相当困难的，因为在很大程度上，估计和测量肢体运动产生的关节力矩和肌肉的力量有很多固有的不确定性。此次研究人员通过研究等量肌肉任务的神经元反应（比如，关节力矩和肌肉力量可以直接用肢体几何学计算得到）来绕过这个难题。每个神经元的响应可以作为一个“首选”的关节力矩向量的线性函数来模型化，这个模型适合于肢体姿势变化时的神经反应。
该研究结果的拟合效果表明，在运动皮层的神经元确实编码了运动行为的动力学特点，并表明神经反应性能的“优先方向”和“增益”是一个单一回应向量的两个组成部分。（生物谷www.bioon.com）
生物谷推荐原始出处：
Neuron，Vol 58, 414-428, 08 May 2008，Robert Ajemian, Stephen Grossberg
Assessing the Function of Motor Cortex: Single-Neuron Models of How Neural Response Is Modulated by Limb Biomechanics
Robert Ajemian,1, Andrea Green,2 Daniel Bullock,3,4 Lauren Sergio,5 John Kalaska,2, and Stephen Grossberg3,4
1 McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
2 Groupe de recherche sur le système nerveux central (FRSQ), Département de physiologie, Université de Montréal, QC H3C 3J7, Canada
3 Department of Cognitive and Neural Systems, Boston University, Boston, MA 02215, USA
4 Center of Excellence for Learning in Education, Science, and Technology, Boston, MA 02215, USA
5 School of Kinesiology and Health Science, York University, Toronto, ON ON M3J 1P3, Canada
Summary
Do neurons in primary motor cortex encode the generative details of motor behavior, such as individual muscle activities, or do they encode high-level movement attributes? Resolving this question has proven difficult, in large part because of the sizeable uncertainty inherent in estimating or measuring the joint torques and muscle forces that underlie movements made by biological limbs. We circumvented this difficulty by considering single-neuron responses in an isometric task, where joint torques and muscle forces can be straightforwardly computed from limb geometry. The response for each neuron was modeled as a linear function of a “preferred” joint torque vector, and this model was fit to individual neural responses across variations in limb posture. The resulting goodness of fit suggests that neurons in motor cortex do encode the kinetics of motor behavior and that the neural response properties of “preferred direction” and “gain” are dual components of a unitary response vector.
