Min Byoung-Kyong
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA.
Theor Biol Med Model. 2010 Mar 30;7:10. doi: 10.1186/1742-4682-7-10.
[BACKGROUND]: It is reasonable to consider the thalamus a primary candidate for the location of consciousness, given that the thalamus has been referred to as the gateway of nearly all sensory inputs to the corresponding cortical areas. Interestingly, in an early stage of brain development, communicative innervations between the dorsal thalamus and telencephalon must pass through the ventral thalamus, the major derivative of which is the thalamic reticular nucleus (TRN). The TRN occupies a striking control position in the brain, sending inhibitory axons back to the thalamus, roughly to the same region where they receive afferents. [HYPOTHESES]: The present study hypothesizes that the TRN plays a pivotal role in dynamic attention by controlling thalamocortical synchronization. The TRN is thus viewed as a functional networking filter to regulate conscious perception, which is possibly embedded in thalamocortical networks. Based on the anatomical structures and connections, modality-specific sectors of the TRN and the thalamus appear to be responsible for modality-specific perceptual representation. Furthermore, the coarsely overlapped topographic maps of the TRN appear to be associated with cross-modal or unitary conscious awareness. Throughout the latticework structure of the TRN, conscious perception could be accomplished and elaborated through accumulating intercommunicative processing across the first-order input signal and the higher-order signals from its functionally associated cortices. As the higher-order relay signals run cumulatively through the relevant thalamocortical loops, conscious awareness becomes more refined and sophisticated. [CONCLUSIONS]: I propose that the thalamocortical integrative communication across first- and higher-order information circuits and repeated feedback looping may account for our conscious awareness. This TRN-modulation hypothesis for conscious awareness provides a comprehensive rationale regarding previously reported psychological phenomena and neurological symptoms such as blindsight, neglect, the priming effect, the threshold/duration problem, and TRN-impairment resembling coma. This hypothesis can be tested by neurosurgical investigations of thalamocortical loops via the TRN, while simultaneously evaluating the degree to which conscious perception depends on the severity of impairment in a TRN-modulated network.
[背景]：鉴于丘脑被称为几乎所有感觉输入通向相应皮质区域的门户，将丘脑视为意识位置的主要候选者是合理的。有趣的是，在大脑发育的早期阶段，背侧丘脑与端脑之间的通信神经支配必须经过腹侧丘脑，腹侧丘脑的主要衍生物是丘脑网状核（TRN）。TRN在大脑中占据着显著的控制位置，将抑制性轴突发送回丘脑，大致回到它们接收传入神经的同一区域。[假设]：本研究假设TRN通过控制丘脑皮质同步在动态注意力中起关键作用。因此，TRN被视为调节意识感知的功能性网络过滤器，可能嵌入在丘脑皮质网络中。基于解剖结构和连接，TRN和丘脑的特定模态扇区似乎负责特定模态的感知表征。此外，TRN粗略重叠的地形图似乎与跨模态或统一的意识觉知相关。在TRN的整个晶格结构中，意识感知可以通过累积跨一阶输入信号和来自其功能相关皮质的高阶信号的交互处理来完成和细化。随着高阶中继信号在相关丘脑皮质环路中累积运行，意识觉知变得更加精细和复杂。[结论]：我提出，一阶和高阶信息回路之间的丘脑皮质整合通信以及反复的反馈循环可能解释我们的意识觉知。这种关于意识觉知的TRN调制假设为先前报道的心理现象和神经症状提供了全面的理论依据，如盲视、忽视、启动效应、阈值/持续时间问题以及类似于昏迷的TRN损伤。这一假设可以通过对经由TRN的丘脑皮质环路进行神经外科研究来检验，同时评估意识感知在多大程度上取决于TRN调制网络中的损伤严重程度。
