Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada N6A 5K8.
Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada N6A 5K8.
Cereb Cortex. 2018 Feb 1;28(2):561-573. doi: 10.1093/cercor/bhw391.
In complex environments, tripping over an unexpected obstacle evokes the stumbling corrective reaction, eliciting rapid limb hyperflexion to lift the leg over the obstruction. While stumbling correction has been characterized within a single limb in the cat, this response must extend to both forelegs and hindlegs for successful avoidance in naturalistic settings. Furthermore, the ability to remember an obstacle over which the forelegs have tripped is necessary for hindleg clearance if locomotion is delayed. Therefore, memory-guided stumbling correction was studied in walking cats after the forelegs tripped over an unexpected obstacle. Tactile input to only one foreleg was often sufficient in modulating stepping of all four legs when locomotion was continuous, or when hindleg clearance was delayed. When obstacle height was varied, animals appropriately scaled step height to obstacle height. As tactile input without foreleg clearance was insufficient in reliably modulating stepping, efference, or proprioceptive information about modulated foreleg stepping may be important for producing a robust, long-lasting memory. Finally, cooling-induced deactivation of parietal area 5 altered hindleg stepping in a manner indicating that animals no longer recalled the obstacle over which they had tripped. Altogether, these results demonstrate the integral role area 5 plays in memory-guided stumbling correction.
在复杂的环境中，绊倒一个意想不到的障碍物会引起绊倒的纠正反应，引发快速的肢体过度伸展，将腿抬过障碍物。虽然在猫身上已经描述了单肢的绊倒纠正，但这种反应必须扩展到前肢和后肢，以便在自然环境中成功避免。此外，如果运动延迟，那么记住前腿绊倒的障碍物对于后腿的清除是必要的。因此，在猫行走时，研究了前腿意外绊倒障碍物后的记忆引导绊倒纠正。当运动连续或后腿清除延迟时，仅对一只前脚的触觉输入通常足以调节所有四只脚的步态。当障碍物高度变化时，动物会适当调整步高与障碍物高度的比例。由于没有前脚清除的触觉输入不足以可靠地调节步态，关于调制前脚步态的传出或本体感觉信息对于产生稳健、持久的记忆可能很重要。最后，顶叶区域 5 的冷却诱导失活以一种表明动物不再回忆起它们绊倒的障碍物的方式改变了后腿的步态。总之，这些结果表明，区域 5 在记忆引导的绊倒纠正中起着不可或缺的作用。
