Fino Elodie, Deniau Jean-Michel, Venance Laurent
Dynamics and Pathophysiology of Neural Networks, INSERM U-667, Collège de France, 75231 Paris Cedex 05, France.
J Physiol. 2008 Jan 1;586(1):265-82. doi: 10.1113/jphysiol.2007.144501. Epub 2007 Nov 1.
Striatum, the main input nucleus of basal ganglia, is involved in the learning of cognitive and motor sequences in response to environmental stimuli. Striatal output neurons (medium spiny neurons, MSNs) integrate cortical activity and the two main classes of interneurons (GABAergic and cholinergic interneurons) tightly regulate the corticostriatal information transfer. We have explored the transmission between cortex and striatal interneurons and their capability to develop activity-dependent long-term plasticity based on the quasi-coincident cortical and striatal activities (spike-timing-dependent plasticity, STDP). We have observed glutamatergic monosynaptic connections between cortical cells and both striatal interneurons. Excitatory postsynaptic current latencies and rise times revealed that a cortical stimulation activates GABAergic interneurons before cholinergic, and both interneurons before MSNs. In addition, we have observed that striatal interneurons are able to develop bidirectional long-term plasticity and that there is a cell-specificity of STDP among striatal interneurons. Indeed, in GABAergic interneurons, long-term depression (LTD) and long-term potentiation (LTP) are induced by post-pre and pre-post STDP protocols, respectively. Cholinergic interneurons displayed a partially reversed STDP when compared to GABAergic interneurons: post-pre protocols induced LTP as well as LTD (the induction of either LTP or LTD is correlated with rheobase) and pre-post protocols induced LTD. The cell-specificity of STDP also concerned the receptors activated for the induction of LTP and LTD in GABAergic and cholinergic interneurons: in GABAergic interneurons LTP and LTD required NMDA receptor-activation whereas, in cholinergic interneurons, LTP was underlain by NMDA receptor-activation and LTD by metabotropic glutamate receptors.
纹状体是基底神经节的主要输入核团,参与对环境刺激做出反应时认知和运动序列的学习。纹状体输出神经元(中等棘状神经元,MSNs)整合皮质活动,而两类主要的中间神经元(γ-氨基丁酸能和胆碱能中间神经元)紧密调节皮质-纹状体信息传递。我们研究了皮质与纹状体中间神经元之间的传递以及它们基于准同时的皮质和纹状体活动(尖峰时间依赖可塑性,STDP)产生活动依赖的长期可塑性的能力。我们观察到皮质细胞与两类纹状体中间神经元之间存在谷氨酸能单突触连接。兴奋性突触后电流潜伏期和上升时间表明,皮质刺激先激活γ-氨基丁酸能中间神经元,然后是胆碱能中间神经元,两者均先于中等棘状神经元被激活。此外,我们观察到纹状体中间神经元能够产生双向长期可塑性,并且在纹状体中间神经元中存在STDP的细胞特异性。事实上,在γ-氨基丁酸能中间神经元中,长期抑制(LTD)和长期增强(LTP)分别由前-后和后-前STDP协议诱导产生。与γ-氨基丁酸能中间神经元相比,胆碱能中间神经元表现出部分相反的STDP:后-前协议诱导LTP以及LTD(LTP或LTD的诱导与阈强度相关),前-后协议诱导LTD。STDP的细胞特异性还涉及γ-氨基丁酸能和胆碱能中间神经元中诱导LTP和LTD所激活的受体:在γ-氨基丁酸能中间神经元中,LTP和LTD需要NMDA受体激活,而在胆碱能中间神经元中,LTP由NMDA受体激活介导,LTD由代谢型谷氨酸受体介导。