Role of the inhibitory system in shaping the BOLD fMRI response
Role of the inhibitory system in shaping the BOLD fMRI response
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DOI：
10.1016/j.neuroimage.2019.116034
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发表时间：
2019-11-01
期刊：
影响因子：
5.7
通讯作者：
Wyrwicz, Alice M.
中科院分区：
文献类型：
--
作者：
Aksenov, Daniil P.;Li, Limin;Wyrwicz, Alice M.
即使在同一感觉通路的结构中，血氧水平依赖性 (BOLD) 功能磁共振成像 (fMRI) 信号的形状也可能有很大差异。在这里，我们描述了清醒兔子视觉和体感胡须系统的初级皮质和皮质下区域中刺激引起的 BOLD 反应的时间行为。尽管丘脑核团有类似的 BOLD 反应，但感觉皮层之间的形状和持续时间存在相当大的差异。虽然须桶皮层 (WBC) 中的 BOLD 反应是非适应性的，但视觉皮层 (V1) 中的 BOLD 表现出与同时记录的 LFP 和单个单位活动类似的适应性。基线神经元活动分析显示，V1 放电率明显低于 WBC。我们假设这些变化表明抑制系统存在区域依赖性差异，从而影响了每个结构的血流动力学反应。为了测试神经元基线水平抑制对 BOLD 信号形状的影响，我们在 WBC 中局部注射 GABA(A) 激动剂蝇蕈醇。注射后 BOLD 反应出现了适应，同时基线放电率总体下降。这些发现指出了区域特异性抑制塑造在确定不同大脑区域 BOLD 反应的时间行为方面的重要性。
The shape of the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal can vary considerably even across structures of the same sensory pathway. Here, we characterized the temporal behavior of the stimulus-evoked BOLD response in the primary cortical and subcortical regions of the visual and somatosensory whisker systems in awake rabbits. Despite similar BOLD responses in the thalamic nuclei, considerable differences in shape and duration emerged between the sensory cortices. Whereas the BOLD response in the whisker barrel cortex (WBC) was non-adaptive, BOLD in the visual cortex (V1) showed adaptation similar to simultaneously-recorded LFP and single unit activity. Analysis of baseline neuronal activity revealed significantly lower firing rates in V1 vs. WBC. We hypothesized that these changes point to region-dependent differences in the inhibitory systems which shape the hemodynamic response in each structure. To test the effect of neuronal baseline level inhibition on the BOLD signal shape, we locally injected the GABA(A) agonist muscimol in WBC. Adaptation emerged in the BOLD response after injection, along with an overall decrease in baseline firing rate. These findings point to the importance of region-specific inhibitory shaping in determining the temporal behavior of the BOLD response in different brain areas.