Carmichael James E, Gmaz Jimmie M, van der Meer Matthijs A A
Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755.
Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755
J Neurosci. 2017 Aug 16;37(33):7962-7974. doi: 10.1523/JNEUROSCI.2944-15.2017. Epub 2017 Jul 17.
Local field potentials (LFPs) recorded from the human and rodent ventral striatum (vStr) exhibit prominent, behaviorally relevant gamma-band oscillations. These oscillations are related to local spiking activity and transiently synchronize with anatomically related areas, suggesting a possible role in organizing vStr activity. However, the origin of vStr gamma is unknown. We recorded vStr gamma oscillations across a 1.4 mm grid spanned by 64 recording electrodes as male rats rested and foraged for rewards, revealing a highly consistent power gradient originating in the adjacent piriform cortex. Phase differences across the vStr were consistently small (<15°) and current source density analysis further confirmed the absence of local sink-source pairs in the vStr. Reversible occlusions of the ipsilateral (but not contralateral) nostril, known to abolish gamma oscillations in the piriform cortex, strongly reduced vStr gamma power and the occurrence of transient gamma-band events. These results imply that local circuitry is not a major contributor to gamma oscillations in the vStr LFP and that piriform cortex is an important driver of gamma-band oscillations in the vStr and associated limbic areas. The ventral striatum (vStr) is an area of anatomical convergence in circuits underlying motivated behavior, but it remains unclear how its inputs from different sources interact. A major proposal about how neural circuits may switch dynamically between convergent inputs is through temporal organization reflected in local field potential (LFP) oscillations. Our results show that, in the rat, the mechanisms controlling gamma-band oscillations in the vStr LFP are primarily located in the in the adjacent piriform cortex rather than in the vStr itself, providing a novel interpretation of previous rodent work on gamma oscillations in the vStr and related circuits and an important consideration for future work seeking to use oscillations in these areas as biomarkers for behavioral and neurological disorders.
从人类和啮齿动物腹侧纹状体（vStr）记录的局部场电位（LFP）表现出显著的、与行为相关的伽马波段振荡。这些振荡与局部尖峰活动相关，并与解剖学相关区域瞬时同步，表明其在组织vStr活动中可能发挥作用。然而，vStr伽马振荡的起源尚不清楚。我们在由64个记录电极跨越的1.4毫米网格上记录了雄性大鼠休息和觅食奖励时vStr的伽马振荡，发现了一个高度一致的功率梯度，其起源于相邻的梨状皮质。vStr上的相位差始终很小（<15°），电流源密度分析进一步证实vStr中不存在局部汇-源对。已知同侧（而非对侧）鼻孔的可逆性阻塞会消除梨状皮质中的伽马振荡，这会强烈降低vStr伽马功率以及瞬态伽马波段事件的发生率。这些结果表明，局部电路不是vStr LFP中伽马振荡的主要贡献者，梨状皮质是vStr和相关边缘区域中伽马波段振荡的重要驱动因素。腹侧纹状体（vStr）是动机行为潜在回路中的一个解剖学汇聚区域，但尚不清楚其来自不同来源的输入如何相互作用。关于神经回路如何在汇聚输入之间动态切换的一个主要提议是通过局部场电位（LFP）振荡中反映的时间组织。我们的结果表明，在大鼠中，控制vStr LFP中伽马波段振荡的机制主要位于相邻的梨状皮质而非vStr本身，这为先前关于vStr和相关回路中伽马振荡的啮齿动物研究提供了新的解释，并为未来试图将这些区域的振荡用作行为和神经疾病生物标志物的工作提供了重要考虑因素。
