Department of Neurobiology, Northwestern University, Evanston, United States.
Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States.
Elife. 2018 Jul 2;7:e35261. doi: 10.7554/eLife.35261.
Detection of salient objects in the visual scene is a vital aspect of an animal's interactions with its environment. Here, we show that neurons in the mouse superior colliculus (SC) encode visual saliency by detecting motion contrast between stimulus center and surround. Excitatory neurons in the most superficial lamina of the SC are contextually modulated, monotonically increasing their response from suppression by the same-direction surround to maximal potentiation by an oppositely-moving surround. The degree of this potentiation declines with depth in the SC. Inhibitory neurons are suppressed by any surround at all depths. These response modulations in both neuronal populations are much more prominent to direction contrast than to phase, temporal frequency, or static orientation contrast, suggesting feature-specific saliency encoding in the mouse SC. Together, our findings provide evidence supporting locally generated feature representations in the SC, and lay the foundations towards a mechanistic and evolutionary understanding of their emergence.
在视觉场景中检测显著物体是动物与其环境相互作用的一个重要方面。在这里，我们表明，小鼠上丘（SC）中的神经元通过检测刺激中心和周围之间的运动对比度来编码视觉显著性。SC 最浅层的兴奋性神经元受到上下文调制，从同一方向周围的抑制单调增加到相反方向运动的周围的最大增强。这种增强的程度随 SC 的深度而下降。在所有深度处，抑制性神经元都被任何周围抑制。这两种神经元群体的这些反应调制在方向对比度上比在相位、时间频率或静态方向对比度上更为明显，这表明在小鼠 SC 中存在特征特异性的显著性编码。总之，我们的发现为 SC 中局部产生的特征表示提供了证据，并为理解它们的出现的机制和进化奠定了基础。
