Laboratory of Neurophysiology of Memory, Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czechia.
Third Faculty of Medicine, Charles University, Prague, Czechia.
Brain Topogr. 2023 Nov;36(6):870-889. doi: 10.1007/s10548-023-00989-2. Epub 2023 Jul 21.
Spatial reference frames (RFs) play a key role in spatial cognition, especially in perception, spatial memory, and navigation. There are two main types of RFs: egocentric (self-centered) and allocentric (object-centered). Although many fMRI studies examined the neural correlates of egocentric and allocentric RFs, they could not sample the fast temporal dynamics of the underlying cognitive processes. Therefore, the interaction and timing between these two RFs remain unclear. Taking advantage of the high temporal resolution of intracranial EEG (iEEG), we aimed to determine the timing of egocentric and allocentric information processing and describe the brain areas involved. We recorded iEEG and analyzed broad gamma activity (50-150 Hz) in 37 epilepsy patients performing a spatial judgment task in a three-dimensional circular virtual arena. We found overlapping activation for egocentric and allocentric RFs in many brain regions, with several additional egocentric- and allocentric-selective areas. In contrast to the egocentric responses, the allocentric responses peaked later than the control ones in frontal regions with overlapping selectivity. Also, across several egocentric or allocentric selective areas, the egocentric selectivity appeared earlier than the allocentric one. We identified the maximum number of egocentric-selective channels in the medial occipito-temporal region and allocentric-selective channels around the intraparietal sulcus in the parietal cortex. Our findings favor the hypothesis that egocentric spatial coding is a more primary process, and allocentric representations may be derived from egocentric ones. They also broaden the dominant view of the dorsal and ventral streams supporting egocentric and allocentric space coding, respectively.
空间参照框架（RFs）在空间认知中起着关键作用，尤其是在感知、空间记忆和导航方面。RFs 主要有两种类型：自我中心（以自我为中心）和客体中心（以客体为中心）。尽管许多 fMRI 研究都探讨了自我中心和客体中心 RFs 的神经关联，但它们无法对潜在认知过程的快速时间动态进行采样。因此，这两种 RFs 之间的相互作用和时间关系仍不清楚。利用颅内 EEG（iEEG）的高时间分辨率，我们旨在确定自我中心和客体中心信息处理的时间，并描述涉及的脑区。我们记录了 37 名癫痫患者的 iEEG，并在一个三维圆形虚拟竞技场中进行空间判断任务时分析了宽伽马活动（50-150 Hz）。我们在许多脑区发现了自我中心和客体中心 RFs 的重叠激活，还有几个额外的自我中心和客体中心选择区域。与自我中心反应相比，在额叶区域，与选择相关的反应比控制反应晚出现，且重叠选择性。此外，在几个自我中心或客体中心选择区域中，自我中心选择性比客体中心选择性更早出现。我们在中颞叶内侧区域确定了最大数量的自我中心选择性通道，在顶叶皮层的顶内沟周围确定了客体中心选择性通道。我们的发现支持了这样一种假设，即自我中心的空间编码是一个更基本的过程，而客体中心的表示可能是从自我中心的表示中衍生出来的。它们还拓宽了支持自我中心和客体中心空间编码的背侧和腹侧流的主导观点。
