Abstract
The inhibitory neurotransmitter GABA plays a crucial role in anxiety and fear, but its relationship to brain activation during fear reactions is not clear. Previous studies suggest that GABA agonists lead to an attenuation of emotion-processing related BOLD signals in the insula. The aim of this study was to investigate the relationship between GABA concentration and fear-related BOLD responses in this region. In 44 female participants with different levels of fearfulness, GABA concentration in the left insula was measured using a GABA+ MRS acquisition during rest; additionally, BOLD signals were obtained during performance of a fear provocation paradigm. Fearfulness was not associated with GABA+ in the left insula, but could predict fear-related BOLD responses in a cluster in the left anterior insula. The BOLD signal change in this cluster did not correlate with GABA+ concentration. However, we found a significant positive correlation between GABA+ concentration and fear-related BOLD responses in a different cluster that included parts of the left insula, amygdala and putamen. Our findings indicate that low insular GABA concentration is not a predisposition for fearfulness, and that several factors influence whether a correlation between GABA and BOLD can be found.
Highlights
Fear is an acute behavioural and physiological reaction to perceived threat, which has been observed in all mammals and probably evolved because it is useful for survival and avoidance of pain [1]
Recent research using functional magnetic resonance imaging has identified the amygdala and the anterior insula as key brain structures associated with the experience of fear [2,3,4]
We found fear-related BOLD responses brain regions that have been previously associated with emotion processing
Summary
Fear is an acute behavioural and physiological reaction to perceived threat, which has been observed in all mammals and probably evolved because it is useful for survival and avoidance of pain [1]. Recent research using functional magnetic resonance imaging (fMRI) has identified the amygdala and the anterior insula as key brain structures associated with the experience of fear [2,3,4]. While the amygdala is important for the detection of environmental ‘fear’ cues [5], the anterior insula seems to play the role of integrating internal bodily perceptions and information from external cues to create the experienced emotional state [6]. A Magnetic Resonance Spectroscopy Study no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript)
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