Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal.
Nat Commun. 2024 Feb 12;15(1):849. doi: 10.1038/s41467-024-44934-8.
The visual continuity illusion involves a shift in visual perception from static to dynamic vision modes when the stimuli arrive at high temporal frequency, and is critical for recognizing objects moving in the environment. However, how this illusion is encoded across the visual pathway remains poorly understood, with disparate frequency thresholds at retinal, cortical, and behavioural levels suggesting the involvement of other brain areas. Here, we employ a multimodal approach encompassing behaviour, whole-brain functional MRI, and electrophysiological measurements, for investigating the encoding of the continuity illusion in rats. Behavioural experiments report a frequency threshold of 18±2 Hz. Functional MRI reveal that superior colliculus signals transition from positive to negative at the behaviourally-driven threshold, unlike thalamic and cortical areas. Electrophysiological recordings indicate that these transitions are underpinned by neural activation/suppression. Lesions in the primary visual cortex reveal this effect to be intrinsic to the superior colliculus (under a cortical gain effect). Our findings highlight the superior colliculus' crucial involvement in encoding temporal frequency shifts, especially the change from static to dynamic vision modes.
视觉连续错觉涉及当刺激以高时间频率到达时，从静态视觉模式到动态视觉模式的视觉感知转变，对于识别环境中移动的物体至关重要。然而，这种错觉如何在视觉通路上被编码仍然知之甚少，视网膜、皮层和行为水平的离散频率阈值表明其他大脑区域的参与。在这里，我们采用了一种多模态方法，包括行为、全脑功能磁共振成像和电生理测量，用于研究大鼠中连续性错觉的编码。行为实验报告的频率阈值为 18±2 Hz。功能磁共振成像显示，与丘脑和皮层区域不同，上丘信号在行为驱动的阈值处从正变为负。电生理记录表明，这些转变是由神经激活/抑制支持的。初级视皮层的损伤表明，这种效应是上丘固有的（在皮层增益效应下）。我们的发现强调了上丘在编码时间频率变化中的关键作用，特别是从静态视觉模式到动态视觉模式的变化。
