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A Direct Auditory Subcortical Route to the Amygdala Associated with Fear in Humans
Emmanouela Kosteletou-Kassotaki1,2, Martina T Cinca-Tomás3,2, Federico Varriano4
1Department of Clinical Psychology and Psychobiology, University of Barcelona, Barcelona 08035, Spain emmakosteletou@ub.edu.
Summary
Scientists found a direct auditory pathway in the human brain, connecting the inferior colliculus to the amygdala. This "low road" for fear processing is linked to hearing ability and fearfulness, similar to pathways in other species.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Affective Neuroscience
Background:
- Rapid fear processing is vital for survival.
- A subcortical visual pathway (pulvinar to amygdala) supports fear processing in humans.
- An analogous auditory fear pathway has been shown in animals but not confirmed in humans.
Purpose of the Study:
- To investigate the existence and function of a subcortical auditory fear pathway in humans.
- To identify white matter tracts connecting auditory structures to the amygdala.
- To examine the association of these tracts with auditory and affective behaviors.
Main Methods:
- Diffusion-weighted imaging and probabilistic streamline tractography from the Human Connectome Project.
- Fixel-based analysis to reconstruct and quantify white matter tracts.
- Correlation analysis with behavioral measures of hearing ability and fearfulness.
Main Results:
- A robust white matter tract was identified connecting the inferior colliculus to the basolateral amygdala via the medial geniculate body (MGB).
- Higher fiber density in this tract correlated with better hearing in noise and increased self-reported fearfulness.
- A control pathway (ventral MGB to primary auditory cortex) was linked to auditory ability but not affect.
Conclusions:
- Evidence supports an auditory colliculo-geniculo-amygdala pathway, or
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