Integration of concurrent sensory signals in the human spinal cord and brain.

疼痛是一种由外周和中枢神经系统支持的感觉功能。这些器官包括伤害性感受器、脊髓和大脑。伤害感和疼痛构成了一个警报系统，以检测对身体组织的威胁，这些威胁触发了保护性的神经过程和行为。这些神经过程和行为对身体的完整性至关重要。伤害性刺激触发运动反射，如伤害性屈曲反射(NFR)，它允许肢体收缩。这种自动反应是由脊髓产生的，通常伴随着痛觉。反过来，疼痛会触发行为反应，这些反应由大脑协调，并适应背景需求。在这个方案中，我们将研究脊髓和大脑如何整合多种伤害性刺激来产生适应的运动反射和大脑反应。*当大脑处理相互竞争的刺激时，认知功能允许从这些刺激中选择信息并确定优先顺序。所谓的自下而上的过程使显著的刺激具有更强的神经元表征。例如，伤害性刺激本质上是突出的，并能吸引注意力。然而，注意力捕获可能会受到所谓的自上而下过程的影响。自上而下的选择是由工作记忆中的认知目标决定的。认知目标决定了哪些刺激与任务相关(注意定势)。例如，可以选择伤害性刺激来优先考虑响应疼痛感知的保护行为，而不是以任务表现为代价。相反，如果对任务执行进行优先排序，则认知过程可以抑制痛觉。这些自下而上和自上而下的过程之间的平衡对于最佳的行为表现、行为适应甚至生存至关重要。在这个提案中，我们将研究刺激的显着性和认知功能如何改变同时存在的伤害性刺激的大脑整合。*为了调查我们的研究问题，我们将进行实验，检查产生触摸或疼痛感觉的电和激光刺激引起的脊髓和大脑活动。脊髓活动将通过反射来测量，以腿部肌肉活动来测量，大脑活动将以脑电图仪记录的电信号来测量。*这项研究计划将有助于理解伤害整合和反应背后的脊髓和大脑机制。这对于更好地理解疼痛、运动反射以及刺激的显着性和认知如何影响这些过程是至关重要的。这些知识将为理解疼痛作为健康个体神经系统的一种适应性功能提供坚实的基础，并从长远来看可能会改进慢性疼痛患者的治疗。

Pain is a sensory function supported by the peripheral and central nervous systems. These include nociceptors, the spinal cord and the brain. Nociception and pain constitute an alarm system to detect threat to body tissues, which trigger protective neural processes and behaviours. These neural processes and behaviours are critical for the integrity of the body. Nociceptive stimuli trigger motor reflexes, such as the nociceptive flexion reflex (NFR), which allows the withdrawal of a limb. This automatic response is produced by the spinal cord and is generally followed by pain perception. In turn, pain triggers behavioural responses that are coordinated by the brain and adapted to the contextual demands. In this proposal, we will investigate how the spinal cord and brain integrate multiple nociceptive stimuli to produce adapted motor reflexes and cerebral responses. ***When competing stimuli are processed by the brain, cognitive functions allow to select and prioritize information from these stimuli. The so-called bottom-up processes give salient stimuli a stronger neuronal representation. For instance, nociceptive stimuli are intrinsically salient and capture attention. However, attentional capture may be influenced by so-called top-down processes. Top-down selection is determined by cognitive goals represented in working memory. Cognitive goals determine which stimuli are task relevant (attentional set). For instance, a nociceptive stimulus may be selected to prioritize a protective behaviour in response to pain perception at the expense of task performance. Conversely, pain perception can be inhibited by cognitive processes if task execution is prioritized. The balance between these bottom-up and top-down processes is critical for optimal behavioural performance, behavioural adaptation and even survival. In this proposal, we will investigate how stimulus saliency and cognitive functions alter the cerebral integration of concurrent nociceptive stimuli. ***To investigate our research questions, we will conduct experiments to examine spinal cord and brain activity evoked by electrical and laser stimuli that produce touch or pain sensation. Spinal cord activity will be measured with reflexes measured as muscle activity in the legs and brain activity will be measured as electrical signals recorded with electroencephalography. ***This research program will contribute to the understanding of spinal and cerebral mechanisms underlying nociceptive integration and responses. This is essential to better understand pain, motor reflexes and how stimulus saliency and cognition may affect these processes. This knowledge will provide solid bases to understand pain as an adaptive function of the nervous system in healthy individuals and in the long term may improve treatments to patients with chronic pain.