Kempsell Andrew T, Fieber Lynne A
University of Miami, Rosenstiel School of Marine and Atmospheric Science, Department of Marine Biology and Ecology, Miami, Florida, United States of America.
PLoS One. 2015 May 13;10(5):e0127056. doi: 10.1371/journal.pone.0127056. eCollection 2015.
The physiological and molecular mechanisms of age-related memory loss are complicated by the complexity of vertebrate nervous systems. This study takes advantage of a simple neural model to investigate nervous system aging, focusing on changes in learning and memory in the form of behavioral sensitization in vivo and synaptic facilitation in vitro. The effect of aging on the tail withdrawal reflex (TWR) was studied in Aplysia californica at maturity and late in the annual lifecycle. We found that short-term sensitization in TWR was absent in aged Aplysia. This implied that the neuronal machinery governing nonassociative learning was compromised during aging. Synaptic plasticity in the form of short-term facilitation between tail sensory and motor neurons decreased during aging whether the sensitizing stimulus was tail shock or the heterosynaptic modulator serotonin (5-HT). Together, these results suggest that the cellular mechanisms governing behavioral sensitization are compromised during aging, thereby nearly eliminating sensitization in aged Aplysia.
脊椎动物神经系统的复杂性使得与年龄相关的记忆丧失的生理和分子机制变得复杂。本研究利用一个简单的神经模型来研究神经系统衰老，重点关注体内行为敏化和体外突触易化形式的学习和记忆变化。在加州海兔成熟时和年度生命周期后期，研究了衰老对缩尾反射（TWR）的影响。我们发现，老年海兔不存在TWR的短期敏化现象。这意味着在衰老过程中，控制非联想学习的神经机制受到了损害。无论敏化刺激是尾部电击还是异突触调节剂血清素（5-HT），衰老过程中尾部感觉神经元和运动神经元之间以短期易化形式存在的突触可塑性都会降低。这些结果共同表明，在衰老过程中，控制行为敏化的细胞机制受到损害，从而几乎消除了老年海兔的敏化现象。
