古希臘先哲亞里斯多德認(rèn)為,，循環(huán)系統(tǒng)是思想和情感之源。這一觀點(diǎn)長(zhǎng)久以來(lái)被人認(rèn)為不可想象,。但美國(guó)麻省理工學(xué)院的一個(gè)科學(xué)家小組日前近日提出一種假說(shuō),，血液的作用不僅僅在于輸送燃料和氧氣，血液可以幫助我們思考,，因?yàn)樗軌蚍e極地調(diào)整神經(jīng)元處理信息的方式,。 這一假說(shuō)若得到證實(shí)，將會(huì)改變我們對(duì)大腦工作方式的認(rèn)識(shí),。相關(guān)論文10月3日發(fā)表在《神經(jīng)生理學(xué)雜志》(Journal of Neurophysiology)上,。
該假說(shuō)稱為血液-神經(jīng)假說(shuō)，由麻省理工學(xué)院McGovern腦研究所的Christopher Moore提出,。該假說(shuō)認(rèn)為,，血液并不僅僅是生理學(xué)上的支撐系統(tǒng)，它也能幫助控制大腦的活動(dòng),。具體來(lái)說(shuō),，血流的局部變化會(huì)影響鄰近神經(jīng)細(xì)胞的活性，從而改變它們之間信號(hào)的傳輸方式，最終調(diào)節(jié)輸入大腦的信息,。Moore實(shí)驗(yàn)室正在進(jìn)行的研究支持了這一觀點(diǎn),，認(rèn)為血流確實(shí)能夠調(diào)節(jié)單個(gè)神經(jīng)細(xì)胞。
那么,，血流是怎樣影響腦部活動(dòng)的,？研究小組稱，血液含有能夠穿透血管影響神經(jīng)元活動(dòng)的溶解因子,，血流量的改變也可能會(huì)影響到溶解因子的濃度,。此外，神經(jīng)元和神經(jīng)膠質(zhì)細(xì)胞也會(huì)對(duì)血管的擴(kuò)張和收縮產(chǎn)生反應(yīng),。最后,，腦組織的溫度會(huì)在血液的影響下發(fā)生變化，從而影響到神經(jīng)元的活動(dòng),。因此穆?tīng)栒J(rèn)為,，應(yīng)該用全新的方式來(lái)看待人的大腦，血液系統(tǒng)可能是決定大腦活動(dòng)的主要因素,。
這一假說(shuō)對(duì)于理解早老性癡呆,、精神分裂癥、癲癇等腦部疾病有重要意義,。Moore表示,，很多神經(jīng)學(xué)及精神病學(xué)方面的疾病都與脈管系統(tǒng)的變化有關(guān)。他說(shuō)：“大多數(shù)人認(rèn)為,，這些疾病的癥狀是神經(jīng)損傷的后果,。但是我們認(rèn)為，這些癥狀有可能也是導(dǎo)致疾病發(fā)展的因素,。這種認(rèn)識(shí)有可能導(dǎo)致全新的治療方式,。”以癲癇為例，這類病人腦部通常有異常的血管存在,，血液-神經(jīng)假說(shuō)認(rèn)為這些反常的血流可能就是誘發(fā)癲癇的原因,。如果確實(shí)如此，人們將有可能開(kāi)發(fā)出有效的針對(duì)性藥物來(lái)治療癲癇,。
這一假設(shè)對(duì)磁共振成像技術(shù)也有重要意義,，磁共振成像是用來(lái)了解大腦血流變化的常用掃描手段。麻省理工學(xué)院的科學(xué)家認(rèn)為,，如果我們知道了血液對(duì)神經(jīng)元活動(dòng)的影響,，就可以利用磁共振成像來(lái)了解大腦的信息處理過(guò)程。
Moore認(rèn)為,，這一假說(shuō)提供了全新的認(rèn)識(shí)腦部活動(dòng)的方法,，而之前人們從來(lái)沒(méi)有把血流納入大腦處理信息的模型中,。
原始出處:
J Neurophysiol (October 3, 2007). doi:10.1152/jn.01366.2006
The Hemo-Neural Hypothesis: On The Role of Blood Flow in Information Processing
Christopher Irwin Moore1* and Rosa Cao1
1 McGovern Institute for Brain Research, MIT, Cambridge, Massachusetts, United States
* To whom correspondence should be addressed. E-mail: [email protected] .
Brain vasculature is a complex and interconnected network under tight regulatory control that exists in intimate communication with neurons and glia. Typically, hemodynamics are considered to exclusively serve as a metabolic support system. In contrast to this canonical view, we propose that hemodynamics also play a role in information processing through modulation of neural activity. Functional hyperemia, the basis of the fMRI BOLD signal, is a localized influx of blood correlated with neural activity levels. Functional hyperemia is considered by many to be excessive from a metabolic standpoint, but may be appropriate if interpreted as having an activity-dependent neuro-modulatory function. Hemodynamics may impact neural activity through direct and indirect mechanisms. Direct mechanisms include delivery of diffusible blood-borne messengers, and mechanical and thermal modulation of neural activity. Indirect mechanisms are proposed to act through hemodynamic modulation of astrocytes, which can in turn regulate neural activity. These hemo-neural mechanisms should alter the information processing capacity of active local neural networks. Here, we focus on analysis of neocortical sensory processing. We predict that hemodynamics alter the gain of local cortical circuits, modulating the detection and discrimination of sensory stimuli. This novel view of information processing, that includes hemodynamics as an active and significant participant, has implications for understanding neural representation and the construction of accurate brain models. There are also potential medical benefits of an improved understanding of the role of hemodynamics in neural processing, as it directly bears on interpretation of and potential treatment for stroke, dementia and epilepsy.
