Division of Biology, University of California San Diego, La Jolla, CA 92093, USA.
Research and Early Development, Biogen, Cambridge, MA 02142, USA.
Cereb Cortex. 2020 Mar 14;30(3):1040-1055. doi: 10.1093/cercor/bhz147.
The cortical code that underlies perception must enable subjects to perceive the world at time scales relevant for behavior. We find that mice can integrate visual stimuli very quickly (<100 ms) to reach plateau performance in an orientation discrimination task. To define features of cortical activity that underlie performance at these time scales, we measured single-unit responses in the mouse visual cortex at time scales relevant to this task. In contrast to high-contrast stimuli of longer duration, which elicit reliable activity in individual neurons, stimuli at the threshold of perception elicit extremely sparse and unreliable responses in the primary visual cortex such that the activity of individual neurons does not reliably report orientation. Integrating information across neurons, however, quickly improves performance. Using a linear decoding model, we estimate that integrating information over 50-100 neurons is sufficient to account for behavioral performance. Thus, at the limits of visual perception, the visual system integrates information encoded in the probabilistic firing of unreliable single units to generate reliable behavior.
支持感知的皮质代码必须使主体能够在与行为相关的时间尺度上感知世界。我们发现，老鼠可以非常快速地（<100 毫秒）整合视觉刺激，从而在方向辨别任务中达到稳定表现。为了定义在这些时间尺度上支持表现的皮质活动的特征，我们在与任务相关的时间尺度上测量了老鼠视觉皮层中的单个神经元的反应。与诱发单个神经元产生可靠活动的长时间高对比度刺激相比，在感知阈值的刺激下，初级视觉皮层中会产生非常稀疏和不可靠的反应，以至于单个神经元的活动不能可靠地报告方向。然而，跨神经元整合信息可以快速提高表现。使用线性解码模型，我们估计整合 50-100 个神经元的信息足以解释行为表现。因此，在视觉感知的极限下，视觉系统整合了不可靠单个神经元的概率放电所编码的信息，以产生可靠的行为。
