SENSORY INTEGRATION & WORKING MEMORY

为了产生有意义的行为，大脑必须将感觉皮质中代表的信息与参与行为计划和执行的运动回路联系起来。这种联系需要跨时间和通道的感觉线索的整合。我们的研究目标是顶叶和额叶的联合皮质中的神经元，据信它们在工作记忆中扮演着重要的角色。这些神经元在凝视转移到视野中记忆中的位置之前，会放电几秒钟。它们的反应在视觉皮质和动眼神经回路的空间线索之间建立了一座时间桥梁。这些神经元似乎也将视觉运动的表示与知觉决定联系起来。我们从两只恒河猴的前额叶皮质神经元中记录了它们判断随机点显示的运动方向。我们研究了被认为在空间工作记忆和眼球运动规划中发挥作用的神经元。当猴子计划眼球运动时，这些神经元中的大多数都是活跃的，这是一种传达其对运动方向的判断的方式。我们的发现表明，前额叶和顶叶皮质在眼动计划和视觉处理中都发挥着作用。使用反应时范式，我们发现这种活动在猴子做出判断之前就开始了。这是迄今为止最有力的证据，证明感觉处理和偶然行为之间存在神经联系。这些实验已经开始揭示联合皮质神经元进行的计算，为认知及其障碍的神经生物学提供了新的见解。我们乐观地认为，我们的结果将导致对阿尔茨海默病、脑病和中风等有害疾病的新理解和治疗。

To produce meaningful behavior, the brain must link information represented in sensory cortex to motor circuitry involved in the planning and execution of behavior. This linkage requires the integration of sensory cues across time and modality. Our research targets neurons in the association cortex of the parietal and frontal lobes, which are believed to play an essential role in working memory. These neurons discharge for several seconds before gaze is shifted to a remembered location in the visual field. Their response provides a temporal bridge between the spatial cues present in visual cortex and oculomotor circuitry. These neurons also appear to link the representation of visual motion toward a perceptual decision. We have recorded from neurons in the prefrontal cortex of two rhesus monkeys while they judged the direction of motion of a random dot display. We have studied neurons that are thought to play a role in spatial working memory and the planning of eye movements. The majority of these neurons are active when the monkey plans eye movements as a means of communicating its judgment about the direction of motion. Our findings suggest that the prefrontal and parietal cortex plays a role in both eye movement planning and visual processing. Using a reaction time paradigm, we have found that this activity arises before the monkey arrives at a judgment. This is the strongest evidence to date for a neural linkage between sensory processing and a contingent behavior. The experiments have begun to reveal the computations performed by neurons in association cortex, lending novel insight into the neurobiology of cognition and its disorders. We are optimistic that our results will lead to new understanding and treatment of such pernicious disorders as Alzheimer's disease, encephalopathy, and stroke.