Zaidel Adam, DeAngelis Gregory C, Angelaki Dora E
Gonda Multidisciplinary Brain Research Center, Bar Ilan University, Ramat Gan, 52900, Israel.
Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA.
Nat Commun. 2017 Sep 28;8(1):715. doi: 10.1038/s41467-017-00766-3.
Trial-by-trial correlations between neural responses and choices (choice probabilities) are often interpreted to reflect a causal contribution of neurons to task performance. However, choice probabilities may arise from top-down, rather than bottom-up, signals. We isolated distinct sensory and decision contributions to single-unit activity recorded from the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas of monkeys during perception of self-motion. Superficially, neurons in both areas show similar tuning curves during task performance. However, tuning in MSTd neurons primarily reflects sensory inputs, whereas choice-related signals dominate tuning in VIP neurons. Importantly, the choice-related activity of VIP neurons is not predictable from their stimulus tuning, and these factors are often confounded in choice probability measurements. This finding was confirmed in a subset of neurons for which stimulus tuning was measured during passive fixation. Our findings reveal decoupled stimulus and choice signals in the VIP area, and challenge our understanding of choice signals in the brain.Choice-related signals in neuronal activity may reflect bottom-up sensory processes, top-down decision-related influences, or a combination of the two. Here the authors report that choice-related activity in VIP neurons is not predictable from their stimulus tuning, and that dominant choice signals can bias the standard metric of choice preference (choice probability).
神经反应与选择之间逐个试次的相关性（选择概率）通常被解释为反映神经元对任务表现的因果贡献。然而，选择概率可能源自自上而下而非自下而上的信号。我们在猴子自我运动感知过程中，分离出了对背内侧颞上叶（MSTd）和腹侧顶内区（VIP）记录的单神经元活动的不同感觉和决策贡献。表面上看，在任务执行过程中，这两个区域的神经元都显示出相似的调谐曲线。然而，MSTd神经元的调谐主要反映感觉输入，而与选择相关的信号在VIP神经元的调谐中占主导。重要的是，VIP神经元与选择相关的活动无法从其刺激调谐中预测，并且这些因素在选择概率测量中常常混淆。在被动注视期间测量刺激调谐的一部分神经元中证实了这一发现。我们的发现揭示了VIP区域中刺激信号和选择信号的解耦，并挑战了我们对大脑中选择信号的理解。神经元活动中与选择相关的信号可能反映自下而上的感觉过程、自上而下的决策相关影响或两者的结合。本文作者报告称，VIP神经元中与选择相关的活动无法从其刺激调谐中预测，并且占主导的选择信号会使选择偏好的标准指标（选择概率）产生偏差。
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