Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
Department of Biology, Animal Physiology & Center for Mind, Brain and Behavior-CMBB, Philipps-University Marburg, 35032 Marburg, Germany.
J Exp Biol. 2019 Apr 25;222(Pt 8):jeb196261. doi: 10.1242/jeb.196261.
The central complex, a group of midline neuropils in the insect brain, plays a key role in spatial orientation and navigation. Work in locusts, crickets, dung beetles, bees and butterflies suggests that it harbors a network of neurons which determines the orientation of the insect relative to the pattern of polarized light in the blue sky. In locusts, these 'compass cells' also respond to simulated approaching objects. Here, we investigated in the locust whether compass cells change their activity when the animal experiences large-field visual motion or when the animal is engaged in walking behavior. We recorded intracellularly from these neurons while the tethered animals were allowed to perform walking movements on a slippery surface. We concurrently presented moving grating stimuli from the side or polarized light through a rotating polarizer from above. Large-field motion was combined with simulation of approaching objects to evaluate whether responses differed from those presented on a stationary background. We show for the first time that compass cells are sensitive to large-field motion. Responses to looming stimuli were often more conspicuous during large-field motion. Walking activity influenced spiking rates at all stages of the network. The strength of responses to the plane of polarized light was affected in some compass cells during leg motor activity. The data show that signaling in compass cells of the locust central complex is modulated by visual context and locomotor activity.
中央复合体是昆虫大脑中的一组中线神经节，在空间定位和导航中起着关键作用。在蝗虫、蟋蟀、蜣螂、蜜蜂和蝴蝶中的研究表明，它包含一组神经元网络，这些神经元决定了昆虫相对于蓝天中偏振光模式的方向。在蝗虫中，这些“罗盘细胞”也对模拟接近的物体做出反应。在这里，我们研究了蝗虫中央复合体中的神经元，当动物经历大视野视觉运动或当动物进行行走行为时，这些神经元的活动是否会发生变化。当被束缚的动物在光滑的表面上进行行走运动时，我们对这些神经元进行了细胞内记录。同时，我们从侧面呈现移动的光栅刺激，或者从上方通过旋转的偏振器呈现偏振光。大视野运动与模拟接近物体相结合，以评估它们的反应是否与静止背景下的反应不同。我们首次表明，罗盘细胞对大视野运动敏感。在大视野运动期间，对逼近刺激的反应往往更加明显。行走活动在网络的所有阶段都影响着尖峰率。在某些罗盘细胞中，对偏振光平面的反应强度在腿部运动活动期间受到影响。这些数据表明，蝗虫中央复合体中罗盘细胞的信号传递受到视觉环境和运动活动的调制。
