【热点】Nature研究发现大脑多任务处理机制

（图片来自New York University's Langone Medical Center）

近日，来自美国纽约大学Langone医学中心的研究人员表示他们发现哺乳动物脑部中心位置的一块贝壳状区域可能与多任务处理能力有关，这一区域叫做丘脑网状核（TRN）。TRN区域的神经元就像'控制台'一样不断过滤神经感应信息，将脑的注意力切换到其中一种感觉，比如视觉，而将其他感官传递过来的可分散注意力的信息屏蔽。

相关研究结果发表在国际学术期刊Nature上。

在这项研究中，研究人员开发了一种新的行为学实验，以小鼠为研究对象对它们TRN神经元传递的电信号进行了纪录，观察小鼠的行为，同时利用激光抑制脑部不同区域的神经回路。结果发现在小鼠将注意力放在一种视觉闪光信号以获得奖励时，视觉相关的TRN神经元活动度会出现下降，这也与之前发现的TRN神经元在抑制人类脑部信号方面具有一定作用的结果是一致的。

与之相比，研究人员表示当引导小鼠将注意力放在声音上而忽视闪光信号时，控制视觉的TRN神经元会表现得更加活跃，抑制了视觉信号，将脑部注意力更加集中在声音上。早期研究也已经证明不同TRN神经元存在各自特定的基因表达。

研究人员表示，这项最新研究向人们展示了大脑如何将注意力集中在一项特定任务--大脑将TRN区域的神经元作为控制台，控制着大脑接收的信息量，对于我们不想关注的感应信息进行限制和过滤。他们接下来将对TRN神经元究竟可以屏蔽多少'不相关'信息以及这种机制在一些疾病模型中发生了什么样的变化进行进一步研究。

DOI: 10.1038/nature15398

Thalamic control of sensory selection in divided attention

Ralf D. Wimmer L. Ian Schmitt Thomas J. Davidson Miho Nakajima Karl Deisseroth Michael M. Halassa

How the brain selects appropriate sensory inputs and suppresses distractors is unknown. Given the well-established role of the prefrontal cortex (PFC) in executive function1, its interactions with sensory cortical areas during attention have been hypothesized to control sensory selection2, 3, 4, 5. To test this idea and, more generally, dissect the circuits underlying sensory selection, we developed a cross-modal divided-attention task in mice that allowed genetic access to this cognitive process. By optogenetically perturbing PFC function in a temporally precise window, the ability of mice to select appropriately between conflicting visual and auditory stimuli was diminished. Equivalent sensory thalamocortical manipulations showed that behaviour was causally dependent on PFC interactions with the sensory thalamus, not sensory cortex. Consistent with this notion, we found neurons of the visual thalamic reticular nucleus (visTRN) to exhibit PFC-dependent changes in firing rate predictive of the modality selected. visTRN activity was causal to performance as confirmed by bidirectional optogenetic manipulations of this subnetwork. Using a combination of electrophysiology and intracellular chloride photometry, we demonstrated that visTRN dynamically controls visual thalamic gain through feedforward inhibition. Our experiments introduce a new subcortical model of sensory selection, in which the PFC biases thalamic reticular subnetworks to control thalamic sensory gain, selecting appropriate inputs for further processing.

来源：生物谷