生物谷報道：我國科研人員在《神經(jīng)科學通訊》（Neuroscience Letters）發(fā)表論文，揭示痛覺的產(chǎn)生是由一定空間和時間上神經(jīng)網(wǎng)絡(luò)的活動模式來表現(xiàn)的,。
大量研究表明,，痛覺的產(chǎn)生涉及丘腦、大腦皮層以及邊緣系統(tǒng)在內(nèi)廣泛的神經(jīng)網(wǎng)絡(luò)的激活,。但是在痛覺信息加工過程中,，神經(jīng)網(wǎng)絡(luò)活動的時間特性并不清楚。研究人員利用多通道同步記錄電生理技術(shù)記錄了清醒大鼠腦內(nèi)多個部位神經(jīng)元的放電活動,，包括初級軀體感覺皮層(SI),、前扣帶皮層(ACC)、丘腦束旁核(Pf)和丘腦腹后外側(cè)核(VP),。通過在大鼠足底皮膚施加短暫的傷害性和非傷害性電刺激引起上述神經(jīng)核團的放電,。通過比較神經(jīng)元對刺激產(chǎn)生的傷害性和非傷害性反應(yīng)的差異以神經(jīng)元反應(yīng)百分比的差異，在秒水平和毫秒水平兩種時間尺度上改變計算窗口的大小來分析神經(jīng)元群對痛與非痛兩種刺激的分辨反應(yīng),。研究者還使用判別分析方法來尋找與不同感覺刺激相關(guān)的神經(jīng)元群活動的不同模式,，進而估計某一特定腦區(qū)的神經(jīng)元群區(qū)分痛與非痛刺激的能力。
研究結(jié)果表明,，神經(jīng)元群分辨兩種刺激的能力隨著分析窗口的大小和位置的變化而改變,，即負載最多分辨信息的脈沖序列可能出現(xiàn)在刺激后的特定時間范圍內(nèi)。因此,，神經(jīng)元群的最大反應(yīng)只能用特定的窗寬和在某一特定的刺激后時間上得到。此外,，神經(jīng)元群的分辨反應(yīng)是隨時間動態(tài)變化的,，表明痛覺信息的編碼是不連續(xù)的。進一步的分析表明,，中樞對痛覺信息的編碼時程并不依賴于原始的短暫刺激(幾十毫秒),，而是可以在丘腦－皮層環(huán)路中保持相對較長的時間(3-4秒),。通過分析毫秒級水平的移動窗口數(shù)據(jù)，研究者發(fā)現(xiàn)在各個記錄腦區(qū)存在許多集中的“分辨點”(負載信息的特定長度的神經(jīng)元群所發(fā)放的脈沖序列),，能夠很好的區(qū)分痛覺信息和非痛覺信息,，這些“分辨點”隨時間的變化在刺激后離散地分布著；并且,，大腦神經(jīng)元區(qū)分痛與非痛信息的最小脈沖序列長度為40毫秒,。
在自然界中，在時間上精確分辨自然刺激對于物種的生存和繁衍是至關(guān)重要的,。顯然,，在刺激后早期階段將痛覺信息從各種觸覺信息中區(qū)分出來具有重要的生理學意義，它促使我們及時逃避傷害,，從而有效地保護機體,。該研究成果發(fā)表于愛思唯爾期刊《神經(jīng)科學通訊》（Neuroscience Letters）上。
生物谷推薦原始出處：
（Neuroscience Letters）,，Volume 435, Issue 2, 18 April 2008, Pages 163-168,，Jin-Yan Wang，F(xiàn)ei Luo）
Temporal strategy for discriminating noxious from non-noxious electrical stimuli by cortical and thalamic neural ensembles in rats
Jin-Yan Wanga, Jing-Yu Changb, Donald J. Woodwardb and Fei Luoa, ,
aKey Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, 10A Datun Road, Chaoyang District, Beijing 100101, China
bNeuroscience Research Institute of North Carolina, Winston-Salem, NC, USA
Received 30 July 2007; revised 5 February 2008; accepted 7 February 2008. Available online 20 February 2008.
Abstract
Considerable evidence supports that pain is encoded in a large, widespread network that consists of the thalamus, cortex, as well as limbic system. However, the temporal properties of the neural matrix in pain processing were largely unknown. In the present study, we simultaneously recorded thalamic and cortical neuronal discharges elicited by brief noxious or innocuous electrical stimulus in awake rats. The discrimination performance of the neural ensembles in differentiating noxious from innocuous inputs was calculated using different window sizes at the millisecond and second level, respectively. The results demonstrated that coding information emerged in a quantum-like manner; the minimum spike-train length for discriminating noxious from innocuous inputs was 40 ms. The nociceptive coding activity was temporally dynamic, and could be preserved for a relatively long time (3–4 s) within the thalamocortical loops, independent of the initial brief stimuli. These results suggest that the nociceptive signals may be reverberatory within the thalamocortical loops, hence keeping the neurosignature for central pain representation.
