Jiménez-Capdeville M E, Dykes R W, Myasnikov A A
Département de Physiologie, Faculté de Médecine, Université de Montréal, Québec, Canada.
J Comp Neurol. 1997 Apr 28;381(1):53-67.
Using microdialysis and high-performance liquid chromatography, we measured acetylcholine (ACh) release simultaneously from two cortical sites in anesthetized rats. One site was always in the somatosensory cortex, and the other was in either the visual or the motor cortex. After baseline measurements were obtained, selected sites in the basal forebrain (BF) were stimulated to increase ACh release. Some BF sites provoked more release in one microdialysis probe than in the other, suggesting some degree of corticotropic organization of the cholinergic projections from the BF. BF sites optimal for release from the visual cortex were separated from optimal sites for release from the somatosensory cortex by greater distances than were the best sites for release from the somatosensory and the motor cortex. Stimulation of a single BF site often provoked similar release from the latter two cortical areas. Electrical stimulation of the BF also modified cortical neuronal activity. Activation of some BF sites provoked an intense discharge of many neurons in the vicinity of the cortical recording electrode, and the same stimulus site in the BF provoked release of large amounts of ACh in the cortex. Stimulation of other BF sites produced strong inhibition of ongoing cortical activity and no increase in cortical ACh release. When other sites were stimulated, they had no effect or they generated stereotyped bursting patterns in the cortex without any observable effect on ACh release. BF sites that generated inhibition of cortical neural activity were generally located near the sites that activated the cortex and provoked release of ACh. These data suggest an elaborate control of the sensory cortex by a mechanism involving both gamma-aminobutyric acid-containing and cholinergic neurons of the BF.
我们使用微透析和高效液相色谱法，同时测量了麻醉大鼠两个皮质位点的乙酰胆碱（ACh）释放情况。一个位点始终位于体感皮质，另一个位点位于视觉皮质或运动皮质。在获得基线测量值后，刺激基底前脑（BF）中的选定位点以增加ACh释放。一些BF位点在一个微透析探针中引发的释放比在另一个探针中更多，这表明来自BF的胆碱能投射存在一定程度的促皮质组织化。与体感皮质和运动皮质的最佳释放位点相比，视觉皮质最佳释放位点与体感皮质最佳释放位点之间的距离更远。刺激单个BF位点通常会在后两个皮质区域引发类似的释放。对BF进行电刺激也会改变皮质神经元活动。激活一些BF位点会引发皮质记录电极附近许多神经元的强烈放电，并且BF中的相同刺激位点会在皮质中引发大量ACh释放。刺激其他BF位点会对正在进行的皮质活动产生强烈抑制，且皮质ACh释放没有增加。当刺激其他位点时，它们没有效果，或者在皮质中产生刻板的爆发模式，而对ACh释放没有任何可观察到的影响。产生皮质神经活动抑制的BF位点通常位于激活皮质并引发ACh释放的位点附近。这些数据表明，通过一种涉及BF中含γ-氨基丁酸的神经元和胆碱能神经元的机制，对感觉皮质进行了精细的控制。
