Villa Katherine L, Berry Kalen P, Subramanian Jaichandar, Cha Jae Won, Oh Won Chan, Kwon Hyung-Bae, Kubota Yoshiyuki, So Peter T C, Nedivi Elly
Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Neuron. 2016 Feb 17;89(4):756-69. doi: 10.1016/j.neuron.2016.01.010. Epub 2016 Feb 4.
Older concepts of a hard-wired adult brain have been overturned in recent years by in vivo imaging studies revealing synaptic remodeling, now thought to mediate rearrangements in microcircuit connectivity. Using three-color labeling and spectrally resolved two-photon microscopy, we monitor in parallel the daily structural dynamics (assembly or removal) of excitatory and inhibitory postsynaptic sites on the same neurons in mouse visual cortex in vivo. We find that dynamic inhibitory synapses often disappear and reappear again in the same location. The starkest contrast between excitatory and inhibitory synapse dynamics is on dually innervated spines, where inhibitory synapses frequently recur while excitatory synapses are stable. Monocular deprivation, a model of sensory input-dependent plasticity, shortens inhibitory synapse lifetimes and lengthens intervals to recurrence, resulting in a new dynamic state with reduced inhibitory synaptic presence. Reversible structural dynamics indicate a fundamentally new role for inhibitory synaptic remodeling--flexible, input-specific modulation of stable excitatory connections.
近年来，有关成人脑结构固定的旧观念已被活体成像研究所推翻，这些研究揭示了突触重塑现象，目前认为这一现象介导了微电路连接的重新排列。利用三色标记和光谱分辨双光子显微镜，我们在活体小鼠视觉皮层的同一神经元上并行监测兴奋性和抑制性突触后位点的每日结构动态（组装或去除）。我们发现，动态抑制性突触常常在同一位置消失后又重新出现。兴奋性和抑制性突触动态之间最明显的对比出现在双重支配的棘突上，其中抑制性突触频繁复发，而兴奋性突触则保持稳定。单眼剥夺是一种依赖感觉输入的可塑性模型，它缩短了抑制性突触的寿命，延长了复发间隔时间，导致抑制性突触出现减少的新动态状态。可逆的结构动态表明抑制性突触重塑具有一个全新的作用——对稳定的兴奋性连接进行灵活的、输入特异性调节。
