Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
Epilepsia. 2012 Jul;53(7):1245-53. doi: 10.1111/j.1528-1167.2012.03539.x. Epub 2012 Jun 12.
To investigate how kainic acid-induced epileptiform activity is related to hemodynamic changes probed by blood oxygenation level-dependent functional magnetic resonance imaging (BOLD fMRI).
Epileptiform activity was induced with kainic acid (KA) (10 mg/kg, i.p.), and simultaneous fMRI at 7 Tesla, and deep electrode local field potential (LFP) recordings were performed from the right hippocampus in awake and medetomidine-sedated adult Wistar rats.
Recurrent seizure activity induced by KA was detected in LFP both in medetomidine-sedated and awake rats, even though medetomidine sedation reduced the mean duration of individual seizures as compared to awake rats (33 ± 24 and 46 ± 34 s, respectively, mean ± SD p < 0.01). KA administration also triggered robust positive BOLD responses bilaterally in the hippocampus both in awake and medetomidine-sedated rats; however, in both animal groups some of the seizures detected in LFP recording did not cause detectable BOLD signal change.
Our data suggest that medetomidine sedation can be used for simultaneous fMRI and electrophysiologic studies of normal and epileptic brain function, even though seizure duration after medetomidine administration was shorter than that in awake animals. The results also indicate that neuronal activity and BOLD response can become decoupled during recurrent kainic acid-induced seizures, which may have implications to interpretation of fMRI data obtained during prolonged epileptiform activity.
研究海人酸（KA）诱导的癫痫样活动与血氧水平依赖功能磁共振成像（BOLD fMRI）探测到的血液动力学变化有何关系。
用 KA（10 mg/kg，腹腔内注射）诱导癫痫样活动，在 7T 磁共振成像仪上进行同步 fMRI，并在清醒和咪达唑仑镇静的成年 Wistar 大鼠右侧海马进行深部电极局部场电位（LFP）记录。
KA 诱导的复发性癫痫样活动在 LFP 中被检测到，无论是在咪达唑仑镇静还是在清醒大鼠中，尽管咪达唑仑镇静使单个癫痫发作的平均持续时间（分别为 33±24 和 46±34 s，平均值±标准差 p<0.01）较清醒大鼠有所减少。KA 给药还在双侧海马中引发了强烈的正 BOLD 反应，无论是在清醒还是咪达唑仑镇静的大鼠中；然而，在这两个动物组中，在 LFP 记录中检测到的一些癫痫发作没有引起可检测的 BOLD 信号变化。
我们的数据表明，咪达唑仑镇静可用于正常和癫痫大脑功能的同步 fMRI 和电生理研究，尽管咪达唑仑给药后的癫痫持续时间短于清醒动物。结果还表明，在反复 KA 诱导的癫痫发作期间，神经元活动和 BOLD 反应可能会脱耦，这可能对在长时间癫痫样活动期间获得的 fMRI 数据的解释有影响。
