Sharp P E, Barnes C A, McNaughton B L
Behav Neurosci. 1987 Apr;101(2):170-8. doi: 10.1037//0735-7044.101.2.170.
Evoked responses in the dentate gyrus of the hippocampal formation undergo a long-term enhancement following high-frequency stimulation of the perforant pathway. A similar change results from exposure of animals to a complex spatial environment. The effect of aging on the development and decay of this environmentally induced response enhancement was examined in the present study. Previously it was shown that electrically induced enhancement reaches the same asymptotic level in young and old animals but decays more quickly in old animals. It has been suggested that this faster decay may underlie the faster forgetting of spatial information observed in old animals. Chronic recordings were made from young (14 month) and old (32 month) rats. After exposure to an enriched environment for 11 days, the population spike component of the response increased about 125% over baseline in both groups. No changes were seen in either group in the synaptic component. Following the enrichment treatment, animals were returned to their home cages. The decay of the enhanced population spike during this period differed markedly between age-groups (time constants of 30 and 11 days for the young and old groups, respectively). These results suggest that the factors governing the decay of electrically and environmentally induced response enhancement are similarly affected by the aging process and may share a common mechanism.
海马结构齿状回中的诱发反应在穿通通路高频刺激后会经历长期增强。动物暴露于复杂空间环境也会产生类似变化。本研究考察了衰老对这种环境诱导的反应增强的发展和消退的影响。此前有研究表明，电诱导增强在年轻和老年动物中达到相同的渐近水平，但在老年动物中消退更快。有人认为，这种更快的消退可能是老年动物空间信息遗忘更快的原因。对年轻（14个月）和老年（32个月）大鼠进行了慢性记录。在暴露于丰富环境11天后，两组反应的群体峰电位成分均比基线增加了约125%。两组的突触成分均未见变化。富集处理后，动物被放回其饲养笼。在此期间，增强的群体峰电位的消退在不同年龄组之间存在显著差异（年轻组和老年组的时间常数分别为30天和11天）。这些结果表明，控制电诱导和环境诱导反应增强消退的因素同样受到衰老过程的影响，可能具有共同的机制。
