Fino Elodie, Glowinski Jacques, Venance Laurent
Dynamique et Physiopathologie des Réseaux Neuronaux, Institut National de la Santé et de la Recherche Médicale (INSERM) U-667, Collège de France, 75231 Paris Cedex 05, France.
J Neurosci. 2005 Dec 7;25(49):11279-87. doi: 10.1523/JNEUROSCI.4476-05.2005.
Corticostriatal projections originate from the entire cerebral cortex and provide the major source of glutamatergic inputs to the basal ganglia. Despite the importance of corticostriatal connections in sensorimotor learning and cognitive functions, plasticity forms at these synapses remain strongly debated. Using a corticostriatal slice preserving the connections between the somatosensory cortex and the target striatal cells, we report the induction of both non-Hebbian and Hebbian forms of long-term potentiation (LTP) and long-term depression (LTD) on striatal output neurons (SONs). LTP and LTD can be induced selectively by different stimulation patterns (high-frequency trains vs low-frequency pulses) and were evoked with similar efficiency in non-Hebbian and Hebbian modes. Combination of LTP-LTD and LTD-LTP sequences revealed that bidirectional plasticity occurs at the same SONs and provides efficient homeostatic mechanisms leading to a resetting of corticostriatal synapses avoiding synaptic saturation. The effect of temporal relationship between cortical stimulation and SON activity was assessed using spike-timing-dependent plasticity (STDP) protocols. An LTP was observed when an action potential was triggered in the striatal neuron before the cortical stimulus, and, conversely, an LTD was induced when the striatal neuron discharge was triggered after the cortical stimulation. Such STDP was reversed when compared with those described so far in other mammalian brain structures. This mechanism may be essential for the role of the striatum in learning of motor sequences in which sensory and motor events are associated in a precise time sequence.
皮质纹状体投射起源于整个大脑皮层,是基底神经节谷氨酸能输入的主要来源。尽管皮质纹状体连接在感觉运动学习和认知功能中很重要,但这些突触处的可塑性形式仍存在激烈争论。我们使用保留体感皮层与目标纹状体细胞之间连接的皮质纹状体切片,报告了在纹状体输出神经元(SONs)上诱导出非赫布型和赫布型长时程增强(LTP)及长时程抑制(LTD)。LTP和LTD可通过不同的刺激模式(高频串刺激与低频脉冲刺激)选择性诱导,且在非赫布型和赫布型模式下诱发效率相似。LTP-LTD和LTD-LTP序列的组合表明,双向可塑性发生在相同的SONs上,并提供了有效的稳态机制,导致皮质纹状体突触重置,避免突触饱和。使用依赖于尖峰时间的可塑性(STDP)方案评估了皮质刺激与SON活动之间时间关系的影响。当在皮质刺激之前在纹状体神经元中触发动作电位时观察到LTP,相反,当在皮质刺激之后触发纹状体神经元放电时诱导出LTD。与迄今为止在其他哺乳动物脑结构中描述的情况相比,这种STDP是相反的。这种机制对于纹状体在运动序列学习中的作用可能至关重要,在运动序列学习中,感觉和运动事件以精确的时间顺序相关联。