Decision-Related Activity in Macaque V2 for Fine Disparity Discrimination Is Not Compatible with Optimal Linear Readout
Decision-Related Activity in Macaque V2 for Fine Disparity Discrimination Is Not Compatible with Optimal Linear Readout
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DOI：
10.1523/jneurosci.2445-16.2017
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发表时间：
2017-01-18
影响因子：
5.3
通讯作者：
Nienborg, Hendrikje
中科院分区：
文献类型：
--
作者：
Clery, Stephane;Cumming, Bruce G.;Nienborg, Hendrikje
立体深度的精细判断主要依赖于对象之间的深度相对判断（相对双眼差异），而不是对眼睛固定的距离（绝对差异）的判断。在猕猴中，视觉区域V2是视觉处理层次结构中最早的位点，已经观察到神经元选择性相对差异的选择性（Thomas等，2002）。在这里，我们发现，在接受过良好差异歧视任务的猕猴中，V2中的差异选择性神经元对任务具有很高的选择性，并且它们的活性与动物的感知决定相关（无法解释刺激）。这可能部分解释了下游地区报告的类似相关性。尽管与这些神经元在任务中的感知作用兼容，但这种与决策相关活性的解释使感觉神经元之间的神经元“噪声”相关性的影响变得复杂。最近的工作已经开发了简单的预测，以区分解码方案（Pitkow等，2015），而无需噪声相关度量，发现来自早期感觉区域的数据与具有信息限制相关性的人群的最佳线性读数兼容。相反，我们这里的数据与这些预测显着偏离。我们还测试了该预测的先前报道的V2中与决策相关任务的决策相关活动的结果，即粗略差异（Nienborg and Cumming，2006年），被认为依赖于绝对差异。尽管这些数据遵循了预测模式，但它们数量违反了预测。这表明感觉信号的最佳线性解码通常不是简单感知任务中行为的良好预测指标。
Fine judgments of stereoscopic depth rely mainly on relative judgments of depth (relative binocular disparity) between objects, rather than judgments of the distance to where the eyes are fixating (absolute disparity). In macaques, visual area V2 is the earliest site in the visual processing hierarchy for which neurons selective for relative disparity have been observed (Thomas et al., 2002). Here, we found that, in macaques trained to perform a fine disparity discrimination task, disparity-selective neurons in V2 were highly selective for the task, and their activity correlated with the animals' perceptual decisions (unexplained by the stimulus). This may partially explain similar correlations reported in downstream areas. Although compatible with a perceptual role of these neurons for the task, the interpretation of such decision-related activity is complicated by the effects of interneuronal "noise" correlations between sensory neurons. Recent work has developed simple predictions to differentiate decoding schemes (Pitkow et al., 2015) without needing measures of noise correlations, and found that data from early sensory areas were compatible with optimal linear readout of populations with information limiting correlations. In contrast, our data here deviated significantly from these predictions. We additionally tested this prediction for previously reported results of decision-related activity in V2 for a related task, coarse disparity discrimination (Nienborg and Cumming, 2006), thought to rely on absolute disparity. Although these data followed the predicted pattern, they violated the prediction quantitatively. This suggests that optimal linear decoding of sensory signals is not generally a good predictor of behavior in simple perceptual tasks.