Functions of the Thalamus in Perception and Cognition

描述（由申请人提供）：利用功能性脑制图技术，在理解与人类选择性注意、记忆或决策相关的认知功能的神经基础方面取得了很大进展，并利用单细胞生理学和其他侵入性技术，在猕猴作为人类大脑功能的原型动物模型方面取得了很大进展。这些研究几乎完全集中在大脑皮层的感觉和高阶处理区域。相比之下，人们对丘脑核（如外侧膝状核（LGN））在感知和认知中的作用知之甚少。传统上，下视神经网络被认为是初级视觉皮层的门户，它将视觉信息从视网膜忠实地传递到皮层，没有太多的调制。本研究的目标是通过研究LGN在与视觉意识相关的感知功能和与选择性注意相关的认知功能中的功能作用来挑战这一传统观点。推动本研究的核心假设是，LGN在视觉注意和意识中扮演着中继核之外的重要角色。FMRI和行为学研究旨在解决以下问题：1)有意识知觉的神经关联能否早在LGN的小细胞或大细胞部分被识别？2)选择性注意控制人类LGN增益的神经机制是什么，这种增益控制是否仅限于大细胞LGN？3)阅读障碍受试者的视觉加工异常和注意力缺陷是否与大细胞LGN的功能紊乱有关？在人脑中，由于空间分辨率和脑成像技术的信噪比限制，研究皮层下核已被证明是困难的。拟议的研究将使用创新的人类高分辨率和超分辨率成像技术来克服这些问题。大脑皮层主要依赖于它从丘脑接收到的信息，因为它接收到的其他信息很少。理解皮层功能取决于理解丘脑输入，这是皮层处理的必要第一步。

DESCRIPTION (provided by applicant): Much progress has been made in understanding the neural bases of cognitive functions related to selective attention, memory, or decision making in humans using functional brain mapping techniques and in the macaque as the prototypical animal model for human brain function using single-cell physiology and other invasive techniques. These studies have almost exclusively focused on sensory and higher-order processing areas of the cerebral cortex. In contrast, relatively little is known about the role of thalamic nuclei such as the lateral geniculate nucleus (LGN) in perception and cognition. Traditionally, the LGN has been viewed as the gateway to primary visual cortex, which conveys the visual information faithfully from the retina to cortex without much modulation. The goal of the proposed research is to challenge this traditional view by investigating the functional role of the LGN in perceptual functions related to visual awareness and in cognitive functions related to selective attention. The central hypothesis that motivates this research is that the LGN plays an important role beyond that of a relay nucleus as a gatekeeper in visual attention and awareness. FMRI and behavioral studies in non-impaired and dyslexic subjects are proposed to address the following questions: 1) Can neural correlates of conscious perception be identified as early as in the parvocellular, or magnocellular parts of the LGN?; 2) What is the neural mechanism by which selective attention controls gain in the human LGN, and is this gain control confined to the magnocellular LGN?; 3) Are visual processing abnormalities and attentional deficits in dyslexic subjects associated with a functional disorganization of the magnocellular LGN? In the human brain, it has proven difficult to study subcortical nuclei because of spatial resolution and signal-to-noise limitations of brain mapping techniques. The proposed research will use innovative high- and super-resolution imaging techniques in humans to overcome some of these issues. The cerebral cortex depends critically on the information that it receives from the thalamus, since it receives very little else. Understanding cortical functioning depends on understanding the thalamic inputs that are the necessary first step in cortical processing.