Antzoulatos Evangelos G, Byrne John H
Department of Neurobiology and Anatomy, W. M. Keck Center for the Neurobiology of Learning and Memory, University of Texas Medical School at Houston, Houston, Texas 77030, USA.
J Neurosci. 2007 Jan 17;27(3):676-83. doi: 10.1523/JNEUROSCI.4025-06.2007.
Both short- and long-term sensitization of withdrawal reflexes of Aplysia are attributable at least in part to facilitation of the sensorimotor synapse. Previously, short-term synaptic facilitation has been associated with spike broadening and no change in temporal dynamics of burst transmission. In the present study, we examined whether long-term sensitization (LTS) is also associated with spike broadening and whether long-term synaptic facilitation is accompanied by changes in temporal dynamics. The results indicate that the temporal dynamics of the sensorimotor synapse are preserved after long-term facilitation. However, in contrast to short-term sensitization, LTS was accompanied by spike narrowing. The spike narrowing was observed both in centrally triggered spikes in isolated ganglia and in peripherally triggered spikes in reduced tail preparations. In addition, in reduced tail preparations, fewer spike failures in the afferent discharge of sensory neurons occurred in response to tail stimulation after ipsilateral LTS. Collectively, the results reveal that long-term sensitization affects the spike waveform of sensory neurons and enhances the sensory neuron responses to peripheral stimuli, but does not modify the synaptic dynamics of homosynaptic depression.
海兔撤离反射的短期和长期敏感化至少部分归因于感觉运动突触的易化。此前，短期突触易化与动作电位展宽有关，且爆发式传递的时间动态没有变化。在本研究中，我们研究了长期敏感化（LTS）是否也与动作电位展宽有关，以及长期突触易化是否伴随着时间动态的变化。结果表明，长期易化后感觉运动突触的时间动态得以保留。然而，与短期敏感化不同，LTS伴随着动作电位变窄。在分离神经节中由中枢触发的动作电位以及在简化尾部标本中由外周触发的动作电位中均观察到了动作电位变窄。此外，在简化尾部标本中，同侧LTS后，感觉神经元传入放电中动作电位失败的情况在尾部刺激时减少。总体而言，结果表明长期敏感化会影响感觉神经元的动作电位波形，并增强感觉神经元对外周刺激的反应，但不会改变同突触抑制的突触动态。
