Mitchell Anna S
Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, United Kingdom.
Neurosci Biobehav Rev. 2015 Jul;54:76-88. doi: 10.1016/j.neubiorev.2015.03.001. Epub 2015 Mar 7.
Recent evidence from monkey models of cognition shows that the magnocellular subdivision of the mediodorsal thalamus (MDmc) is more critical for learning new information than for retention of previously acquired information. Further, consistent evidence in animal models shows the mediodorsal thalamus (MD) contributes to adaptive decision-making. It is assumed that prefrontal cortex (PFC) and medial temporal lobes govern these cognitive processes so this evidence suggests that MD contributes a role in these cognitive processes too. Anatomically, the MD has extensive excitatory cortico-thalamo-cortical connections, especially with the PFC. MD also receives modulatory inputs from forebrain, midbrain and brainstem regions. It is suggested that the MD is a higher order thalamic relay of the PFC due to the dual cortico-thalamic inputs from layer V ('driver' inputs capable of transmitting a message) and layer VI ('modulator' inputs) of the PFC. Thus, the MD thalamic relay may support the transfer of information across the PFC via this indirect thalamic route. This review summarizes the current knowledge about the anatomy of MD as a higher order thalamic relay. It also reviews behavioral and electrophysiological studies in animals to consider how MD might support the transfer of information across the cortex during learning and decision-making. Current evidence suggests the MD is particularly important during rapid trial-by-trial associative learning and decision-making paradigms that involve multiple cognitive processes. Further studies need to consider the influence of the MD higher order relay to advance our knowledge about how the cortex processes higher order cognition.
来自猴子认知模型的最新证据表明，丘脑背内侧核的大细胞亚群（MDmc）对学习新信息比保留先前获取的信息更为关键。此外，动物模型中的一致证据表明，丘脑背内侧核（MD）有助于适应性决策。一般认为前额叶皮层（PFC）和内侧颞叶控制这些认知过程，因此这一证据表明MD在这些认知过程中也发挥作用。从解剖学上讲，MD有广泛的兴奋性皮质-丘脑-皮质连接，特别是与PFC的连接。MD还从前脑、中脑和脑干区域接收调节性输入。由于来自PFC第V层（能够传递信息的“驱动”输入）和第VI层（“调制器”输入）的双重皮质-丘脑输入，有人提出MD是PFC的高级丘脑中继。因此，MD丘脑中继可能通过这条间接丘脑途径支持信息在PFC之间的传递。本综述总结了关于MD作为高级丘脑中继的解剖学的当前知识。它还回顾了动物的行为和电生理研究，以探讨MD在学习和决策过程中如何支持信息在皮层之间的传递。目前的证据表明，MD在涉及多个认知过程的快速逐次试验联想学习和决策范式中尤为重要。进一步的研究需要考虑MD高级中继的影响，以推进我们对皮层如何处理高级认知的认识。
