据美国物理学家组织网10月25日报道,英国布里斯托尔大学神经科学家最新研究发现,大麻成分会造成注意力不集中和记忆混乱,使脑部活动变得协调脱节,准确性下降,神经系统在生理和功能上均受到损害,出现类似精神分裂症患者所看到的景象。相关论文发表在10月25日出版的《神经科学期刊》上。
大脑的活动方式就像一个包含着弦乐、铜管乐、木管乐和打击乐部分的交响乐团,这些乐部按照指挥的节奏和谐连接,编排组织在一起。与此类似,大脑也有着多种特殊结构,能从一种频率调到另一种确定的频率,这些有节率活动产生了脑波,正常调整这些脑波,就能处理各种信息以指导自身行为。
该研究由布里斯托尔大学英国医学研究理事会(MRC)非临床成员、生理与药理博士马特·琼斯领导。他们给一些小鼠服用了大麻中影响精神活动的药物成分,然后用最先进的技术检测小鼠脑中数百个神经元的电活动。结果发现,药物在个别脑区产生了微妙的效果,跨越海马回和前额叶皮质区的脑波的协调性完全被打乱,好像这两部分无法同步发挥作用。而这些脑区对记忆和决策功能至关重要,也和精神分裂病理学密切相关。由于海马回和前额叶皮质协调脱节,把小鼠放到一个迷宫里时,它们无法做出正确决策。
论文第一作者迈克尔·卡斯维茨说:“这些发现有助于人们研究大脑怎样有节奏地运作,以及健康大脑和疾病大脑思维过程的差别。”
琼斯表示:“这些发现对人们理解精神疾病有重要意义。为了治疗精神分裂,滥用大麻很普遍,我们的研究表明,大麻药物成分也会使健康人产生某些精神分裂症状,这可能是由于‘大脑解编’的结果,可以通过重新调整脑活动来治疗。”(生物谷 Bioon.com)
doi:10.1523/JNEUROSCI.2970-11.2011
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Dysfunctional Prefrontal Cortical Network Activity and Interactions following Cannabinoid Receptor Activation
Michal T. Kucewicz1,2, Mark D. Tricklebank2, Rafal Bogacz3, and Matthew W. Jones1,2
Coordinated activity spanning anatomically distributed neuronal networks underpins cognition and mediates limbic–cortical interactions during learning, memory, and decision-making. We used CP55940, a potent agonist of brain cannabinoid receptors known to disrupt coordinated activity in hippocampus, to investigate the roles of network oscillations during hippocampal and medial prefrontal cortical (mPFC) interactions in rats. During quiet wakefulness and rest, CP55940 dose-dependently reduced 0.1–30 Hz local field potential power in CA1 of the hippocampus while concurrently decreasing 30–100 Hz power in mPFC; these contrasting population-level effects were paralleled by differential effects on underlying single-unit activity in the two structures. During decision-making phases of a spatial working memory task, CP5540-induced deficits in hippocampal theta and prefrontal gamma oscillations were observed alongside disrupted theta-frequency coherence between the two structures. These changes in coordinated limbic–cortical network activities correlated with (1) reduced accuracy of task performance, (2) impaired phase-locking of prefrontal single-unit spiking to the local gamma and hippocampal theta rhythms, and (3) impaired task-dependent activity in a subset of mPFC units. In addition to highlighting the importance of CA1–mPFC network oscillations for cognition, these results implicate disrupted theta-frequency coordination of CA1–mPFC activity in t