Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Avenida Bandeirantes, 3900, CEP: 14049-900, Ribeirão Preto, São Paulo, Brazil.
Neuroscience. 2011 Mar 10;176:318-27. doi: 10.1016/j.neuroscience.2010.12.009. Epub 2010 Dec 14.
The lateral part of intermediate layer of superior colliculus (SCl) is a critical substrate for successful predation by rats. Hunting-evoked expression of the activity marker Fos is concentrated in SCl while prey capture in rats with NMDA lesions in SCl is impaired. Particularly affected are rapid orienting and stereotyped sequences of actions associated with predation of fast moving prey. Such deficits are consistent with the view that the deep layers of SC are important for sensory guidance of movement. Although much of the relevant evidence involves visual control of movement, less is known about movement guidance by somatosensory input from vibrissae. Indeed, our impression is that prey contact with whiskers is a likely stimulus to trigger predation. Moreover, SCl receives whisker and orofacial somatosensory information directly from trigeminal complex, and indirectly from zona incerta, parvicelular reticular formation and somatosensory barrel cortex. To better understand sensory guidance of predation by vibrissal information we investigated prey capture by rats after whisker removal and the role of superior colliculus (SC) by comparing Fos expression after hunting with and without whiskers. Rats were allowed to hunt cockroaches, after which their whiskers were removed. Two days later they were allowed to hunt cockroaches again. Without whiskers the rats were less able to retain the cockroaches after capture and less able to pursue them in the event of the cockroach escaping. The predatory behaviour of rats with re-grown whiskers returned to normal. In parallel, Fos expression in SCl induced by predation was significantly reduced in whiskerless animals. We conclude that whiskers contribute to the efficiency of rat prey capture and that the loss of vibrissal input to SCl, as reflected by reduced Fos expression, could play a critical role in predatory deficits of whiskerless rats.
上丘中间层的外侧部分（SCl）是大鼠成功捕食的关键基质。狩猎引起的活性标记物 Fos 的表达集中在 SCl 中，而在 SCl 中 NMDA 损伤的大鼠进行猎物捕获时则受损。受影响特别严重的是与快速移动猎物捕食相关的快速定向和刻板动作序列。这些缺陷与深 SC 层对运动感觉指导很重要的观点一致。尽管大部分相关证据涉及视觉控制运动，但对来自触须的躯体感觉输入对运动的指导知之甚少。事实上，我们的印象是，触须与猎物的接触很可能是触发捕食的刺激。此外，SCl 直接从三叉神经复合体接收触须和口面部躯体感觉信息，间接从间脑、小细胞网状结构和躯体感觉桶状皮层接收信息。为了更好地理解触须信息对捕食的感觉指导，我们研究了大鼠在去除触须后的猎物捕获情况，以及比较有和没有触须时的狩猎后 Fos 表达，来研究上丘（SC）的作用。允许大鼠捕食蟑螂，然后去除它们的触须。两天后，他们再次被允许捕食蟑螂。没有触须，大鼠在捕获后就不太能够抓住蟑螂，并且在蟑螂逃跑的情况下也不太能够追捕它们。重新长出触须的大鼠的捕食行为恢复正常。与此同时，在没有触须的动物中，SCl 中由捕食引起的 Fos 表达显著减少。我们得出结论，触须有助于大鼠捕获猎物的效率，并且 SC 中触须输入的丧失，如 Fos 表达减少所反映的那样，可能在无触须大鼠的捕食缺陷中发挥关键作用。
