Instituto de Fisiología Celular, UNAM, División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 Mexico City, Mexico.
Instituto de Fisiología Celular, UNAM, División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 Mexico City, Mexico.
Neurobiol Learn Mem. 2023 Nov;205:107845. doi: 10.1016/j.nlm.2023.107845. Epub 2023 Oct 20.
The presentation of novel stimuli induces a reliable dopamine release in the insular cortex (IC) from the ventral tegmental area (VTA). The novel stimuli could be associated with motivational and emotional signals induced by cortical glutamate release from the basolateral amygdala (BLA). Dopamine and glutamate are essential for acquiring and maintaining behavioral tasks, including visual and taste recognition memories. In this study, we hypothesize that the simultaneous activation of dopaminergic and glutamatergic projections to the neocortex can underlie synaptic plasticity. High-frequency stimulation of the BLA-IC circuit has demonstrated a reliable long-term potentiation (LTP), a widely acknowledged synaptic plasticity that underlies memory consolidation. Therefore, the concurrent optogenetic stimulation of the insula's glutamatergic and dopaminergic terminal fibers would induce reliable LTP. Our results confirmed that combined photostimulation of the VTA and BLA projections to the IC induces a slow-onset LTP. We also found that optogenetically-induced LTP in the IC relies on both glutamatergic NMDA receptors and dopaminergic D1/D5 receptors, suggesting that the combined effects of these neurotransmitters can trigger synaptic plasticity in the neocortex. Overall, our findings provide compelling evidence supporting the essential role of both dopaminergic and glutamatergic projections in modulating synaptic plasticity within the IC. Furthermore, our results suggest that the synergistic actions of these projections have a pivotal influence on the formation of motivational memories.
新颖刺激的呈现会从腹侧被盖区（VTA）诱导出岛叶皮层（IC）中可靠的多巴胺释放。新颖刺激可能与外侧杏仁核（BLA）皮质谷氨酸释放引起的动机和情绪信号有关。多巴胺和谷氨酸对于获取和维持行为任务（包括视觉和味觉识别记忆）至关重要。在这项研究中，我们假设多巴胺能和谷氨酸能投射到新皮层的同时激活可以作为突触可塑性的基础。BLA-IC 回路的高频刺激已证明可产生可靠的长时程增强（LTP），这是一种广泛认可的记忆巩固的突触可塑性。因此，同时对岛叶的谷氨酸能和多巴胺能末梢纤维进行光遗传学刺激会诱导可靠的 LTP。我们的结果证实，VTA 和 BLA 投射到 IC 的光遗传学联合刺激会诱导缓慢发作的 LTP。我们还发现，IC 中的光遗传学诱导的 LTP 依赖于谷氨酸能 NMDA 受体和多巴胺能 D1/D5 受体，这表明这些神经递质的联合作用可以触发新皮层中的突触可塑性。总的来说，我们的发现提供了令人信服的证据，支持多巴胺能和谷氨酸能投射在调节 IC 内突触可塑性中的重要作用。此外，我们的结果表明，这些投射的协同作用对动机记忆的形成具有关键影响。
