成年雄性斑胸草雀高级发声中枢-弓状皮质栎核突触的长时程可塑性

Long-term plasticity of HVC-RAsynapses in adult male zebra finches

长时程突触可塑性是学习与记忆神经机制的重要组成部分。雄性斑胸草雀的习得性发声与高级发声中枢(high vocal center,HVC)-弓状皮质栎核(robust nucleus of the arcopallium,RA)通路密切相关,而HVC-RA突触的长时程可塑性表现尚不清楚。本文应用在体电生理方法研究了成年雄性斑胸草雀HVC-RA突触的长时程可塑性。结果显示,(1)生理性刺激(δ节律刺激)和低频刺激(3 Hz,3 min)并不能诱导出长时程可塑性,前者不引起任何诱发群体峰电位幅度的变化,而后者可引起配对脉冲诱发的第二个群体峰电位幅度的短时程抑制(short-term depression,STD);(2)高频刺激(400 Hz,2 s)可引起诱发群体峰电位幅度的长时程抑制(long-term depression,LTD)。上述结果提示,LTD是成年雄性斑胸草雀HVC-RA突触长时程可塑性的表现形式,是发声这一感知运动的记忆机制之一,在一定程度上可以解释成年鸟鸣唱的可塑性。

Long-term synaptic plasticity is considered as a key part of the neural mechanism of learning and memory. The production of learned vocalization of male zebra finches is closely related to high vocal center （HVC）-robust nucleus of the arcopallium （RA） pathway. However, the long-term plasticity of HVC-RA synapses is unclear. This study investigated the long-term plasticity of HVC- RA synapses in adult male zebra finches through in vivo field potential recording. The results showed that physiologic stimulation, i.e., rhythmic stimulation and low frequency stimulation could not effectively induce long-term synaptic plasticity. The former leaded to no change of the amplitudes of evoked population spikes, and the latter induced short-term depression （STD） of the amplitudes of the second evoked population spikes caused by paired pulses. But high frequency stimulation induced long-term depression （LTD） of the amplitudes of evoked population spikes to show out long-term synaptic plasticity. These results suggest that LTD represents the long- term plasticity of HVC-RA synapses in adult male zebra finches, which may be a key part of the neural mechanism of vocal learning and memory and can explain the plasticity of adult song to some degree.