通常地圖都使用互成直角的經(jīng)線和緯線來幫助定位,，而英國一項(xiàng)最新研究顯示，人類大腦中的“導(dǎo)航系統(tǒng)”使用的卻是由正三角形組成的網(wǎng)格,。
英國倫敦大學(xué)學(xué)院的研究人員在《自然》雜志上報(bào)告說，他們首次確認(rèn)人類大腦中存在這種利用正三角形網(wǎng)格來幫助定位的“網(wǎng)格細(xì)胞”,。過去曾有研究發(fā)現(xiàn)實(shí)驗(yàn)鼠大腦中存在這種細(xì)胞,。
研究人員因此設(shè)計(jì)了一套虛擬現(xiàn)實(shí)系統(tǒng)，請受試者戴上專用設(shè)備,，“游覽”虛擬的山谷草地等景色,，同時(shí)利用功能磁共振成像技術(shù)測量受試者大腦相應(yīng)區(qū)域的活動(dòng)情況。結(jié)果發(fā)現(xiàn),，人類大腦中相應(yīng)細(xì)胞的活動(dòng)同樣呈現(xiàn)出明顯的正三角形網(wǎng)格模式,，并且受試者的空間記憶能力越強(qiáng)，這種模式就越明顯,。
參與研究的卡斯韋爾·巴里說,，這些網(wǎng)格細(xì)胞為大腦提供了空間認(rèn)知地圖，它們使用了與通常地圖中經(jīng)線和緯線非常相似的方式,，所不同的是采用了三角形網(wǎng)格而不是方形網(wǎng)格,。
網(wǎng)格細(xì)胞是大腦中最容易遭受早老性癡呆癥等疾病影響的細(xì)胞之一，這也可以幫助解釋為什么這些疾病的常見癥狀就是記不住路,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature advance online publication 20 January 2010 | doi:10.1038/nature08704
Evidence for grid cells in a human memory network
Christian F. Doeller1,2, Caswell Barry1,3,4 & Neil Burgess1,2
1 UCL Institute of Cognitive Neuroscience, London WC1N 3AR, UK
2 UCL Institute of Neurology, London WC1N 3BG, UK
3 UCL Department of Cell and Developmental Biology, London WC1E 6BT, UK
4 UCL Institute of Behavioural Neuroscience, University College London, London WC1H 0AP, UK
5 Correspondence to: Christian F. Doeller1,2Neil Burgess1,2 Correspondence and requests for materials should be addressed to C.F.D. or N.B.
Grid cells in the entorhinal cortex of freely moving rats provide a strikingly periodic representation of self-location1 which is indicative of very specific computational mechanisms2, 3, 4. However, the existence of grid cells in humans and their distribution throughout the brain are unknown. Here we show that the preferred firing directions of directionally modulated grid cells in rat entorhinal cortex are aligned with the grids, and that the spatial organization of grid-cell firing is more strongly apparent at faster than slower running speeds. Because the grids are also aligned with each other1, 5, we predicted a macroscopic signal visible to functional magnetic resonance imaging (fMRI) in humans. We then looked for this signal as participants explored a virtual reality environment, mimicking the rats’ foraging task: fMRI activation and adaptation showing a speed-modulated six-fold rotational symmetry in running direction. The signal was found in a network of entorhinal/subicular, posterior and medial parietal, lateral temporal and medial prefrontal areas. The effect was strongest in right entorhinal cortex, and the coherence of the directional signal across entorhinal cortex correlated with spatial memory performance. Our study illustrates the potential power of combining single-unit electrophysiology with fMRI in systems neuroscience. Our results provide evidence for grid-cell-like representations in humans, and implicate a specific type of neural representation in a network of regions which supports spatial cognition and also autobiographical memory.
