J Neurosci：脑震荡可致大脑功能障碍

近日，来自弗吉尼亚州立邦连大学（VCU）的研究者表示，轻度的脑部损伤可以导致长达数日的大脑功能明显异常，这就能解释为什么因为运动、事故等引发的脑部损伤患者会出现神经学上的某些症状。相关研究成果刊登在了5月份的杂志Journal of Neuroscience上。

研究者致力于外伤性脑部损伤研究（TBI），研究者试图去理解并研究经过创伤后的患者大脑结构和功能性的改变，这个问题目前研究者并不清楚。以前的研究表明，轻度的外伤脑部损伤可以导致患者出现长时间的神经问题，包括认知过程缓慢、意识模糊、慢性头痛、外伤性神经症以及抑郁症。

由Kimberle M.Jacobs教授领导VCU的研究团队运用高精尖的生物成像以及电生理学方法，揭示了轻度的脑部损伤可以引起大脑轴突结构性的破坏以及改变神经元的运动方式。轴突是大脑中的神经纤维，负责在大脑中传导电脉冲，研究小组用轻度外伤性脑损伤模型进行研究，并且对大脑中活的外皮质层的神经元进行形态学上的相关研究。

研究者的发现对于推动该领域研究有极大帮助，并且提供了一套生物成像和电生理学的方法来评估TBI的改变以及潜在的治疗调节方法，另外研究者也研究了是否重复性的脑部损伤可以加重原先的脑部异常等症状。

doi:10.1523/​JNEUROSCI.0881-12.2012
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Electrophysiological Abnormalities in Both Axotomized and Nonaxotomized Pyramidal Neurons following Mild Traumatic Brain Injury

John E. Greer, John T. Povlishock, and Kimberle M. Jacobs

Mild traumatic brain injury (mTBI) often produces lasting detrimental effects on cognitive processes. The mechanisms underlying neurological abnormalities have not been fully identified, in part due to the diffuse pathology underlying mTBI. Here we employ a mouse model of mTBI that allows for identification of both axotomized and intact neurons in the living cortical slice via neuronal expression of yellow fluorescent protein. Both axotomized and intact neurons recorded within injured cortex are healthy with a normal resting membrane potential, time constant (τ), and input resistance (Rin). In control cortex, 25% of cells show an intrinsically bursting action potential (AP) firing pattern, and the rest respond to injected depolarizing current with a regular-spiking pattern. At 2 d postinjury, intrinsic bursting activity is lost within the intact population. The AP amplitude is increased and afterhyperpolarization duration decreased in axotomized neurons at 1 and 2 d postinjury. In contrast, intact neurons also show these changes at 1 d, but recover by 2 d postinjury. Two measures suggest an initial decrease in excitability in axotomized neurons followed by an increase in excitability within intact neurons. The rheobase is significantly increased in axotomized neurons at 1 d postinjury. The slope of the plot of AP frequency versus injected current is larger for intact neurons at 2 d postinjury. Together, these results demonstrate that intact and axotomized neurons are both affected by mTBI, resulting in different changes in neuronal excitability that may contribute to network dysfunction following TBI.