前扣带皮层对丘脑腹侧基底核神经元自发放电的抑制效应

Inhibitory effect of anterior cingulate cortex on spontaneous activity of thalamic ventrobasal nucleus neurons

本文旨在研究前扣带皮层(anterior cingulate cortex,ACC)电刺激对Sprague-Dawley(SD)大鼠丘脑腹侧基底核(ventrobasalnucleus,VB)神经元自发放电活动的影响。实验采用在体细胞外记录法,以不同的电刺激参数刺激SD大鼠ACC(25、32及24区),观察VB神经元自发放电活动的变化。结果显示,以不同延迟时间电刺激ACC,VB神经元(12/53,22.6%)在ACC刺激后不同时程内自发放电活动完全被抑制;其抑制效应与ACC刺激的强度呈现量效关系,在适当范围内,电刺激强度增大和脉冲数增加,VB神经元自发放电活动被完全抑制的时程均明显延长;ACC电刺激对VB神经元自发放电活动抑制性影响形式多样,并具有累积效应。以上结果提示,ACC电刺激对丘脑VB神经元自发放电活动具有抑制性影响。

The purpose of this study was to investigate the influence of electrical stimulation of anterior cingulate cortex （ACC） on spontaneous activity of neurons in thalamic ventrobasal nucleus （VB）. Experiments were performed on 12 male Sprague-Dawley rats weighing 250-310 g （4-5 months old）. According to Paxinos and Watson＇s coordinate atlas of the rat, the frontal and parietal cortical areas were exposed by craniotomy, the recording electrodes were then inserted into the VB （P 2.4-4.1 mm, R 2.0-3.5 mm, H 5.2-6.8 mm） and the stimulating electrodes into the ACC （A 1.1-3.0 mm, R 0.0-1.0 mm, H 1.5-2.4 mm）. Single-unit activities were recorded extracellularly in the VB by glass micropipettes （impedance 3-8 MΩ） filled with 0.5 mol/L sodium acetate solution containing saturated Fast Green. To study the effects of ACC activation on the spontaneous activities of VB cells, single electrical pulse （0.2 ms duration） was delivered to the ACC by a concentric bipolar stainless steel electrode （0.32 mm outer diameter）. An effective ACC stimulation was determined for each VB neuron by gradually increasing the current intensity from 0.1 mA until either a significant change in the spontaneous activity of the VB neuron was observed, or the current intensity reached 0.4 mA. The results showed that ACC stimulation significantly suppressed the spontaneous activities in 12 out of 53 VB neurons （22.6%）. （1） After the stimulation was delivered to ACC, the spontaneous activities of different VB neurons were totally suppressed for different time span. （2） There was obvious dose-effect relevance between ACC stimulation intensity and their inhibitory effect. The duration of complete inhibition was prolonged with the increases in the intensity and number of stimulation impulses in ACC. （3） The stimulation in the ACC depressed the spontaneous activities of VB neurons in different forms and this inhibition exhibited an accumulative effect. All these results indicate that the stimulation of ACC exerts an inhibitory influence on the spontaneous activities of VB neurons.