Dypvik Audny T, Bland Brian H
Dept. of Psychology, Behavioral Neuroscience Research Group, Univ. of Calgary, 2500 University Dr., NW, Calgary, Alberta T2N 1N4, Canada.
J Neurophysiol. 2004 Oct;92(4):2040-50. doi: 10.1152/jn.01081.2003. Epub 2004 Jun 2.
Experiments were carried out in urethane-anesthetized rats to evaluate the hypothesis that the red nucleus has functional connections with the hippocampal formation. Depth profiles of electrical stimulation in experiment 1 confirmed that stimulation administered to the red nucleus elicited theta field activity in the hippocampal formation with a linear relationship between stimulus intensity and theta frequency. Experiment 2 showed that microinfusion of local anesthetic procaine hydrochloride into the medial septum resulted in a reversible blockade of theta field activity elicited by electrical stimulation of the red nucleus. In experiment 3, the discharge activity of red nucleus cells was recorded during the field conditions of hippocampal synchrony (theta) and hippocampal asynchrony [large amplitude irregular activity (LIA)]. Analysis revealed that 26/46 (56%) of red nucleus cells were theta-related, whereas the remaining 20 (44%) were nonrelated. The majority of theta-related cells were classified as tonic theta-on. A brief increase above the basal discharge rate of tonic theta-on red nucleus cells during LIA predicted the transition from LIA to theta with 400- to 500-ms latency. Furthermore, higher frequency transitional discharges predicted higher theta frequencies, whereas higher discharge rates during theta predicted shifts to higher theta frequencies. The results supported the conclusion that the red nucleus, traditionally associated with motor functions, is functionally connected with the neural circuitry involved in the generation of theta band oscillation and synchrony in the hippocampal formation, in agreement with the predictions of the sensorimotor integration model of hippocampal function.
实验在经乌拉坦麻醉的大鼠身上进行，以评估红核与海马结构存在功能联系这一假说。实验1中电刺激的深度剖面图证实，对红核施加刺激会在海马结构中引发θ场活动，刺激强度与θ频率之间呈线性关系。实验2表明，向内侧隔微量注入局部麻醉剂盐酸普鲁卡因会导致由红核电刺激引发的θ场活动出现可逆性阻断。在实验3中，记录了海马同步（θ）和海马不同步[大幅不规则活动（LIA）]场条件下红核细胞的放电活动。分析显示，46个红核细胞中有26个（56%）与θ相关，其余20个（44%）不相关。大多数与θ相关的细胞被归类为紧张性θ开启型。在LIA期间，紧张性θ开启型红核细胞的基础放电率短暂升高，预示着从LIA向θ的转变，潜伏期为400至500毫秒。此外，较高频率的过渡性放电预示着较高的θ频率，而在θ期间较高的放电率预示着向较高θ频率的转变。结果支持了这样的结论：传统上与运动功能相关的红核在功能上与参与海马结构中θ频段振荡和同步产生的神经回路相连，这与海马功能的感觉运动整合模型的预测一致。
