Remodeling of synaptic structure in sensory cortical areas in vivo
Remodeling of synaptic structure in sensory cortical areas in vivo
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DOI：
10.1523/jneurosci.4454-05.2006
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发表时间：
2006-03-15
影响因子：
5.3
通讯作者：
Sur, M
中科院分区：
文献类型：
--
作者：
Majewska, AK;Newton, JR;Sur, M
尽管已知在发育中和成年的皮质中会发生可塑性变化，但目前尚不清楚这些变化是否需要重新构建皮质电路，从而形成和消除突触，或者它们是否依赖于现有突触强度的变化。为了确定体内树突棘和轴突终末的结构稳定性，我们选择了两种方法。首先，我们对幼年[出生后28天(P28)]小鼠的视觉、听觉和躯体感觉皮质的第5层锥体神经元的树突棘运动进行了时间推移双光子成像。我们发现，同一神经元类型的树突棘在不同皮质的基础运动率存在差异，其中视觉皮质表现出最小的结构动力学。然而，在出生时将视觉输入重新连接到听觉皮质，并没有改变树突棘的运动性，这表明结构可塑性可能是大脑皮层区域固有的。其次，我们利用体内不同感觉区域的慢性双光子成像技术，研究了幼年小鼠突触前(轴突终末)和突触后(树突)结构(P40-P61)的持久性。终末和脊椎都相对稳定，80%的脊椎在所有感觉区持续3周以上。轴突终末比树突棘更稳定。这些数据表明，在成人学习和记忆过程中，网络功能的变化可能是通过改变现有突触的强度和有效性，以及通过突触的丢失和获得而重新塑造连接性。
Although plastic changes are known to occur in developing and adult cortex, it remains unclear whether these changes require remodeling of cortical circuitry whereby synapses are formed and eliminated or whether they rely on changes in the strength of existing synapses. To determine the structural stability of dendritic spines and axon terminals in vivo, we chose two approaches. First, we performed time-lapse two-photon imaging of dendritic spine motility of layer 5 pyramidal neurons in juvenile [postnatal day 28 (P28)] mice in visual, auditory, and somatosensory cortices. We found that there were differences in basal rates of dendritic spine motility of the same neuron type in different cortices, with visual cortex exhibiting the least structural dynamics. Rewiring visual input into the auditory cortex at birth, however, failed to alter dendritic spine motility, suggesting that structural plasticity rates might be intrinsic to the cortical region. Second, we investigated the persistence of both the presynaptic (axon terminals) and postsynaptic (dendritic spine) structures in young adult mice (P40 - P61), using chronic in vivo two-photon imaging in different sensory areas. Both terminals and spines were relatively stable, with > 80% persisting over a 3 week period in all sensory regions. Axon terminals were more stable than dendritic spines. These data suggest that changes in network function during adult learning and memory might occur through changes in the strength and efficacy of existing synapses as well as some remodeling of connectivity through the loss and gain of synapses.