在我們走動(dòng)時(shí)，空間信息被大腦海馬體中的“地點(diǎn)”細(xì)胞編碼和處理,。這些神經(jīng)細(xì)胞中的每一個(gè)當(dāng)處在它應(yīng)在的“地點(diǎn)”時(shí)，會(huì)加快其激發(fā)速度，從而使速度編碼等同于地點(diǎn),。
海馬體地點(diǎn)細(xì)胞的激發(fā)模式在過(guò)去40年里已得到廣泛研究，而且人們也提出了一些理論模型來(lái)解釋神經(jīng)回路中地點(diǎn)和時(shí)間的編碼機(jī)制?，F(xiàn)在,，研究人員開(kāi)發(fā)出一種技術(shù)，該技術(shù)能從實(shí)驗(yàn)鼠的地點(diǎn)細(xì)胞內(nèi)來(lái)記錄編碼情況,。實(shí)驗(yàn)中,，研究人員讓小鼠處于清醒狀態(tài)，并讓它們走一個(gè)虛擬現(xiàn)實(shí)迷宮,。這一技術(shù)使得研究人員有可能來(lái)驗(yàn)證這些模型,。初步結(jié)果表明，地點(diǎn)場(chǎng)存在兩個(gè)閾下特征參數(shù)：一個(gè)是膜電位振蕩在Theta頻率處振幅的增加,，另一個(gè)是基線膜電位像坡道一樣的去極化,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 461, 941-946 (15 October 2009) | doi:10.1038/nature08499
Intracellular dynamics of hippocampal place cells during virtual navigation
Christopher D. Harvey1,2,3, Forrest Collman1,2,3, Daniel A. Dombeck1,2,3 & David W. Tank1,2,3
1 Princeton Neuroscience Institute,
2 Lewis-Sigler Institute for Integrative Genomics,
3 Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA
Correspondence to: David W. Tank1,2,3 Correspondence and requests for materials should be addressed to D.W.T.
Hippocampal place cells encode spatial information in rate and temporal codes. To examine the mechanisms underlying hippocampal coding, here we measured the intracellular dynamics of place cells by combining in vivo whole-cell recordings with a virtual-reality system. Head-restrained mice, running on a spherical treadmill, interacted with a computer-generated visual environment to perform spatial behaviours. Robust place-cell activity was present during movement along a virtual linear track. From whole-cell recordings, we identified three subthreshold signatures of place fields: an asymmetric ramp-like depolarization of the baseline membrane potential, an increase in the amplitude of intracellular theta oscillations, and a phase precession of the intracellular theta oscillation relative to the extracellularly recorded theta rhythm. These intracellular dynamics underlie the primary features of place-cell rate and temporal codes. The virtual-reality system developed here will enable new experimental approaches to study the neural circuits underlying navigation.
