Threat induces cardiac and metabolic changes that negatively impact survival in flies

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Dynamic visual cues induce jaw opening and closing by tiger beetles during pursuit of prey

In dynamic locomotory contexts, visual cues often trigger adaptive behaviour by the viewer, yet studies investigating how animals determine impending collisions typically employ either stationary viewers or objects. Here, we describe a dynamic situation of visually guided prey pursuit in which both impending prey contact and escape elicit observable adaptive behaviours in the pursuer, a predatory beetle. We investigated which visual cues may independently control opening and closing of the beetle''s jaws during chases of prey dummies. Jaw opening and closing typically occur when prey is within the 60° binocular field, but not at specific distances, angular sizes or time-to-collision. We show that a sign change in the expansion rate of the target image precedes jaw opening (16 ms) and closing (35 ms), signalling to the beetle that it is gaining on the target or that the target is getting away. We discuss the ‘sloppiness'' of such variation in the lag of the behavioural response, especially jaw closing, as an adaptation to uncertainty about target position due to degradation of the target image by motion blur from the fast-running beetle.     

The effect of size on the timing of visually mediated escape behaviour in staghorn sculpin Leptocottus armatus

The effect of prey size on the timing of the startle response in the sculpin Leptocottus armatus was investigated. Escape responses were triggered visually by a looming image obtained using a computer‐generated animation of an approaching black disk. The results showed that apparent looming threshold ( T _AL, i.e. the threshold at which the rate of change of the visual angle subtended by predator frontal profile onto the prey's eye triggers an escape response by the prey) decreased with increasing prey size. Distance travelled within a fixed time was unaffected by size. Theoretical considerations suggest that larger prey would need to travel a longer distance (and so they would need more time) in order to move their whole body outside the predator's approaching gape. Therefore, the scaling of T _AL may be explained by taking into account both ultimate and proximate considerations that need not be mutually exclusive. At an ultimate level, lower T _AL in larger fish may be explained in terms of offsetting the disadvantage of offering a larger volume to be intercepted by the predator. At a proximate level, T _AL may be related to the fish's visual acuity, which is higher in larger fish.     

Neural processing of imminent collision in humans

Detecting a looming object and its imminent collision is imperative to survival. For most humans, it is a fundamental aspect of daily activities such as driving, road crossing and participating in sport, yet little is known about how the brain both detects and responds to such stimuli. Here we use functional magnetic resonance imaging to assess neural response to looming stimuli in comparison with receding stimuli and motion-controlled static stimuli. We demonstrate for the first time that, in the human, the superior colliculus and the pulvinar nucleus of the thalamus respond to looming in addition to cortical regions associated with motor preparation. We also implicate the anterior insula in making timing computations for collision events.     

OFF-transient alpha RGCs mediate looming triggered innate defensive response

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Neural Basis for Looming Size and Velocity Encoding in the Drosophila Giant Fiber Escape Pathway

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综述: 渐近优先性及其机制

对渐近信号的优先加工被称为渐近优先性,该效应普遍存在于人类和动物的视觉、听觉和跨感觉通道中.人类神经影像学研究发现负责加工渐近信号的脑区涉及一个大规模相互协作和沟通的分布式神经网络,包括颞上沟、颞顶叶连接处以及一些运动区.对多种动物的细胞水平研究也发现了对渐近信号选择性敏感的神经元和神经通路.威胁论、注意捕获理论和自动加工理论从不同角度解释了渐近优先性产生的原因.未来研究可进一步考察刺激的社会、情绪等属性对渐近优先性的影响,探索多通道渐近渐远信息的整合和注意分配机制.