Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States.
Program in Neuroscience, Vanderbilt University, Nashville, Tennessee, United States.
J Neurophysiol. 2023 Sep 1;130(3):694-705. doi: 10.1152/jn.00245.2023. Epub 2023 Aug 23.
Information represented in working memory is reflected in the firing rate of neurons in the prefrontal cortex and brain areas connected to it. In recent years, there has been an increased realization that population measures capture more accurately neural correlates of cognitive functions. We examined how single neuron firing in the prefrontal and posterior parietal cortex of two male monkeys compared with population measures in spatial working memory tasks. Persistent activity was observed in the dorsolateral prefrontal and posterior parietal cortex and firing rate predicted working memory behavior, particularly in the prefrontal cortex. These findings had equivalents in population measures, including trajectories in state space that became less separated in error trials. We additionally observed rotations of stimulus representations in the neuronal state space for different task conditions, which were not obvious in firing rate measures. These results suggest that population measures provide a richer view of how neuronal activity is associated with behavior, largely confirming that persistent activity is the core phenomenon that maintains visual-spatial information in working memory. Recordings from large numbers of neurons led to a reevaluation of neural correlates of cognitive functions, which traditionally were defined based on responses of single neurons or averages of firing rates. Analysis of neuronal recordings from the dorsolateral prefrontal and posterior parietal cortex revealed that properties of neuronal firing captured in classical studies of persistent activity can account for population representations, though some population characteristics did not have clear correlates in single neuron activity.
工作记忆中的信息反映在前额叶皮层和与之相连的大脑区域的神经元放电率中。近年来，人们越来越认识到，群体测量更准确地捕捉到认知功能的神经相关物。我们研究了两只雄性猕猴的前额叶和后顶叶皮层中的单个神经元放电与空间工作记忆任务中的群体测量相比如何。在背外侧前额叶和后顶叶皮层中观察到持续活动，并且放电率预测了工作记忆行为，尤其是在前额叶皮层中。这些发现与群体测量具有等效性，包括状态空间中的轨迹在错误试验中变得不那么分离。我们还观察到不同任务条件下神经元状态空间中刺激表示的旋转，而在放电率测量中这些旋转并不明显。这些结果表明，群体测量提供了一种更丰富的视角，了解神经元活动如何与行为相关联，这在很大程度上证实了持续活动是维持工作记忆中视觉空间信息的核心现象。大量神经元的记录导致对认知功能的神经相关物的重新评估，这些神经相关物传统上是基于单个神经元的反应或放电率的平均值来定义的。对背外侧前额叶和后顶叶皮层的神经元记录的分析表明，在经典的持续活动研究中捕获的神经元放电特性可以解释群体表示，尽管一些群体特征在单个神经元活动中没有明显的相关性。
