Department of Biology, Freie Universität Berlin, Germany; Institute of Mental Health Research, Ottawa, Canada.
Institute of Mental Health Research, Ottawa, Canada.
Neuroimage. 2014 Feb 1;86:10-8. doi: 10.1016/j.neuroimage.2013.04.042. Epub 2013 Apr 22.
The insula has been identified as a key region involved in interoceptive awareness. Whilst imaging studies have investigated the neural activation patterns in this region involved in intero- and exteroceptive awareness, the underlying biochemical mechanisms still remain unclear. In order to investigate these, a well-established fMRI task targeting interoceptive awareness (heartbeat counting) and exteroceptive awareness (tone counting) was combined with magnetic resonance spectroscopy (MRS). Controlling for physiological noise, neural activity in the insula during intero- and exteroceptive awareness was confirmed in an independent data sample using the same fMRI design. Focussing on MRS values from the left insula and combining them with neural activity during intero- and exteroceptive awareness in the same healthy individuals, we demonstrated that GABA concentration in a region highly involved in interoceptive processing is correlated with neural responses to interoceptive stimuli, as opposed to exteroceptive stimuli. In addition, both GABA and interoceptive signal changes in the insula predicted the degree of depressed affect, as measured by the Beck Hopelessness Scale. On the one hand, the association between GABA concentration and neural activity during interoceptive awareness provides novel insight into the biochemical underpinnings of insula function and interoception. On the other, through the additional association of both GABA and neural activity during interoception with depressed affect, these data also bear potentially important implications for psychiatric disorders like depression and anxiety, where GABAergic deficits, altered insula function and abnormal affect coincide.
脑岛已被确定为参与内脏感知的关键区域。虽然影像学研究已经调查了该区域参与内脏和外部感知的神经激活模式，但潜在的生化机制仍不清楚。为了研究这些，我们将一项针对内脏感知（心跳计数）和外部感知（音调计数）的成熟 fMRI 任务与磁共振波谱（MRS）相结合。在使用相同 fMRI 设计的独立数据样本中，控制生理噪声后，确认了脑岛在内部和外部感知期间的神经活动。专注于左脑岛的 MRS 值，并将其与相同健康个体在内部和外部感知期间的神经活动结合起来，我们证明了高度参与内脏处理的区域中的 GABA 浓度与内脏刺激的神经反应相关，而不是与外部刺激相关。此外，脑岛中的 GABA 和内脏信号变化均预测了抑郁程度，如贝克无望量表所测。一方面，GABA 浓度与内脏感知期间的神经活动之间的关联为脑岛功能和内脏感知的生化基础提供了新的见解。另一方面，通过将 GABA 和内脏感知期间的神经活动与抑郁情绪相关联，这些数据也可能对抑郁和焦虑等精神疾病具有重要意义，因为 GABA 能缺陷、脑岛功能改变和异常情绪同时发生。
