当一个动物执行某一认知任务时，前额皮质中的单个神经元经常会根据与该行为相关的各种方面进行适应性调整。这样所产生的组合反应经常是难以解读的。对执行一项“目标顺序记忆任务”的猴子的神经活动所做的这项研究，目的是为了确定前额皮质中的混合选择性神经元的主导地位对于所执行的功能是否至关重要。结果表明，具有混合选择性的神经元跟那些高度专注于编码与任务相关的某一方面的神经元所含信息一样多。而且，混合选择性神经元实际上在某些方面相对于专门化的神经元有相当大的计算优势。
为这项工作所开发的、用于从所记录的神经活动提取丰富信息的新的计算方法，应能使对那些被广泛观察到、但很少分析过的混合选择性神经元的研究工作变得容易一些。（生物谷Bioon.com）
生物谷推荐英文摘要：
Nature doi:10.1038/nature12160
The importance of mixed selectivity in complex cognitive tasks
Mattia Rigotti, Omri Barak, Melissa R. Warden, Xiao-Jing Wang, Nathaniel D. Daw, Earl K. Miller & Stefano Fusi
Single-neuron activity in the prefrontal cortex (PFC) is tuned to mixtures of multiple task-related aspects. Such mixed selectivity is highly heterogeneous, seemingly disordered and therefore difficult to interpret. We analysed the neural activity recorded in monkeys during an object sequence memory task to identify a role of mixed selectivity in subserving the cognitive functions ascribed to the PFC. We show that mixed selectivity neurons encode distributed information about all task-relevant aspects. Each aspect can be decoded from the population of neurons even when single-cell selectivity to that aspect is eliminated. Moreover, mixed selectivity offers a significant computational advantage over specialized responses in terms of the repertoire of input–output functions implementable by readout neurons. This advantage originates from the highly diverse nonlinear selectivity to mixtures of task-relevant variables, a signature of high-dimensional neural representations. Crucially, this dimensionality is predictive of animal behaviour as it collapses in error trials. Our findings recommend a shift of focus for future studies from neurons that have easily interpretable response tuning to the widely observed, but rarely analysed, mixed selectivity neurons.
