Superlinear population encoding of dynamic hand trajectory in primary motor cortex
Superlinear population encoding of dynamic hand trajectory in primary motor cortex
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DOI：
10.1523/jneurosci.0919-04.2004
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发表时间：
2004-09-29
影响因子：
5.3
通讯作者：
Donoghue, JP
中科院分区：
文献类型：
--
作者：
Paninski, L;Shoham, S;Donoghue, JP
已知初级运动皮层（MI）中的神经活动与手的位置和速度相关。先前对这种调谐的描述是（1）在位置或速度上是线性的，（2）仅瞬时依赖于这些信号，和/或（3）不包括神经元间依赖性对放电率的影响。我们在这里表明，许多MI细胞编码的全时变手轨迹的超线性函数。大约20%的MI细胞在手轨迹中携带信息，而不仅仅是在单个时间滞后时的位置、速度和加速度。此外，大约三分之一的MI细胞编码的轨迹在一个显着的超线性的方式，作为一个结果，即使是很小的位置变化可以显着调制的MI细胞的速度调谐的增益，在最近的心理物理证据。我们引入了一个紧凑的非线性“首选轨迹”模型，预测在以前的工作中描述的时空调谐功能的复杂结构。最后，观察MI网络中相邻细胞的活动显着增加了单个MI细胞放电率的可预测性;然而，我们发现MI中的神经元间依赖性比最近在海马中描述的更锁定于外部运动学参数。然而，这种邻居的活动是大约一样的信息手的速度，支持的观点，在MI的神经编码是最好的理解在人口水平。
Neural activity in primary motor cortex (MI) is known to correlate with hand position and velocity. Previous descriptions of this tuning have (1) been linear in position or velocity, (2) depended only instantaneously on these signals, and/or (3) not incorporated the effects of interneuronal dependencies on firing rate. We show here that many MI cells encode a superlinear function of the full time-varying hand trajectory. Approximately 20% of MI cells carry information in the hand trajectory beyond just the position, velocity, and acceleration at a single time lag. Moreover, approximately one-third of MI cells encode the trajectory in a significantly superlinear manner; as one consequence, even small position changes can dramatically modulate the gain of the velocity tuning of MI cells, in agreement with recent psychophysical evidence. We introduce a compact nonlinear "preferred trajectory" model that predicts the complex structure of the spatiotemporal tuning functions described in previous work. Finally, observing the activity of neighboring cells in the MI network significantly increases the predictability of the firing rate of a single MI cell; however, we find interneuronal dependencies in MI to be much more locked to external kinematic parameters than those described recently in the hippocampus. Nevertheless, this neighbor activity is approximately as informative as the hand velocity, supporting the view that neural encoding in MI is best understood at a population level.