Department of Medicine and Surgery, University of Parma, via Volturno 39, 43125, Parma, Italy.
Center for Neural Science, New York University, New York, NY, United States of America.
Sci Rep. 2019 Aug 12;9(1):11700. doi: 10.1038/s41598-019-48216-y.
Premotor neurons play a fundamental role in transforming physical properties of observed objects, such as size and shape, into motor plans for grasping them, hence contributing to "pragmatic" affordance processing. Premotor neurons can also contribute to "semantic" affordance processing, as they can discharge differently even to pragmatically identical objects depending on their behavioural relevance for the observer (i.e. edible or inedible objects). Here, we compared the response of monkey ventral premotor area F5 neurons tested during pragmatic (PT) or semantic (ST) visuomotor tasks. Object presentation responses in ST showed shorter latency and lower object selectivity than in PT. Furthermore, we found a difference between a transient representation of semantic affordances and a sustained representation of pragmatic affordances at both the single neuron and population level. Indeed, responses in ST returned to baseline within 0.5 s whereas in PT they showed the typical sustained visual-to-motor activity during Go trials. In contrast, during No-go trials, the time course of pragmatic and semantic information processing was similar. These findings suggest that premotor cortex generates different dynamics depending on pragmatic and semantic information provided by the context in which the to-be-grasped object is presented.
运动前神经元在将观察到的物体的物理属性（如大小和形状）转换为抓取它们的运动计划方面发挥着基本作用，从而有助于进行“实用”的可供性加工。运动前神经元也可以有助于“语义”可供性加工，因为即使对于实用上相同的物体，它们也可以根据观察者的行为相关性（即可食用或不可食用的物体）而不同地放电。在这里，我们比较了在实用（PT）或语义（ST）视觉运动任务中测试的猴子腹侧运动前区 F5 神经元的反应。在 ST 中，物体呈现反应的潜伏期更短，物体选择性更低，而在 PT 中则相反。此外，我们在单细胞和群体水平上发现了语义可供性的瞬时表示和实用可供性的持续表示之间的差异。事实上，在 ST 中，反应在 0.5 秒内恢复到基线，而在 PT 中，它们在 Go 试验中表现出典型的持续视觉运动活动。相比之下，在 No-go 试验中，实用和语义信息处理的时间过程相似。这些发现表明，运动前皮层根据呈现待抓取物体的上下文提供的实用和语义信息产生不同的动力学。
