Bailey C H, Chen M
Center for Neurobiology and Behavior, New York State Psychiatric Institute, NY.
Proc Natl Acad Sci U S A. 1988 Dec;85(23):9356-9. doi: 10.1073/pnas.85.23.9356.
We have used the gill and siphon withdrawal reflex of Aplysia to study the morphological basis of the persistent synaptic plasticity that underlies long-term sensitization. One critical locus for storage of the memory for sensitization is the set of monosynaptic connections between identified siphon sensory neurons and gill and siphon motor neurons. To complement previous morphological studies of the presynaptic terminals of identified sensory neurons, we examined the effects of long-term sensitization on the structure of an identified postsynaptic target--the gill motor neuron L7. We found an increase in the frequency, size, and vesicle complement of presynaptic contacts onto L7 processes in sensitized compared to control animals. Combined, these data indicate a striking increase in the percentage of the surface area of L7 that is occupied by synaptic contacts after long-term training. These results are consistent with our observations that sensitization produces an increase in the synapses that the sensory neurons make on their target cells and provide additional support for the hypothesis that changes in synapse number may represent a mechanism underlying long-term memory.
我们利用海兔的鳃和虹吸管收缩反射，来研究构成长期敏感化基础的持续性突触可塑性的形态学基础。敏感化记忆存储的一个关键位点是已识别的虹吸管感觉神经元与鳃和虹吸管运动神经元之间的单突触连接集合。为补充先前对已识别感觉神经元突触前终末的形态学研究，我们研究了长期敏感化对一个已识别的突触后靶点——鳃运动神经元L7结构的影响。我们发现，与对照动物相比，敏感化动物中L7突起上突触前接触的频率、大小和囊泡数量都有所增加。综合这些数据表明，长期训练后，L7表面积中被突触接触占据的百分比显著增加。这些结果与我们的观察结果一致，即敏感化会使感觉神经元在其靶细胞上形成的突触增加，并为突触数量的变化可能代表长期记忆基础的假说提供了额外支持。
