Bello-Medina Paola C, Flores Gonzalo, Quirarte Gina L, McGaugh James L, Prado Alcalá Roberto A
Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Queretaro, 76230, Mexico.
Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, 72570, Mexico.
Proc Natl Acad Sci U S A. 2016 Oct 18;113(42):E6516-E6525. doi: 10.1073/pnas.1613680113. Epub 2016 Oct 3.
A growing body of evidence indicates that treatments that typically impair memory consolidation become ineffective when animals are given intense training. This effect has been obtained by treatments interfering with the neural activity of several brain structures, including the dorsal striatum. The mechanisms that mediate this phenomenon are unknown. One possibility is that intense training promotes the transfer of information derived from the enhanced training to a wider neuronal network. We now report that inhibitory avoidance (IA) induces mushroom spinogenesis in the medium spiny neurons (MSNs) of the dorsal striatum in rats, which is dependent upon the intensity of the foot-shock used for training; that is, the effect is seen only when high-intensity foot-shock is used in training. We also found that the relative density of thin spines was reduced. These changes were evident at 6 h after training and persisted for at least 24 h afterward. Importantly, foot-shock alone did not increase spinogenesis. Spine density in MSNs in the accumbens was also increased, but the increase did not correlate with the associative process involved in IA; rather, it resulted from the administration of the aversive stimulation alone. These findings suggest that mushroom spines of MSNs of the dorsal striatum receive afferent information that is involved in the integrative activity necessary for memory consolidation, and that intense training facilitates transfer of information from the dorsal striatum to other brain regions through augmented spinogenesis.
越来越多的证据表明，那些通常会损害记忆巩固的处理方式，在动物接受强化训练时会变得无效。通过干扰包括背侧纹状体在内的多个脑区神经活动的处理方式，已经获得了这种效应。介导这一现象的机制尚不清楚。一种可能性是，强化训练促进了来自强化训练的信息向更广泛的神经元网络的传递。我们现在报告，抑制性回避（IA）在大鼠背侧纹状体的中等棘状神经元（MSN）中诱导蘑菇状棘突生成，这取决于用于训练的足部电击强度；也就是说，只有在训练中使用高强度足部电击时才会出现这种效应。我们还发现细棘的相对密度降低了。这些变化在训练后6小时就很明显，并在之后至少持续24小时。重要的是，仅足部电击并不会增加棘突生成。伏隔核中MSN的棘突密度也增加了，但这种增加与IA中涉及的联想过程无关；相反，它是由单独给予厌恶刺激导致的。这些发现表明，背侧纹状体MSN的蘑菇状棘突接收参与记忆巩固所需整合活动的传入信息，并且强化训练通过增强棘突生成促进信息从背侧纹状体向其他脑区的传递。
