Uncovering the human subcortical pathway for auditory threat detection

Introduction

Fast detection of threats is one of the most important abilities for survival, as it allows efficiently responding to potential harms. In humans, such advantage extends well into other cognitive domains, including social communication.

Importance of Threat Detection

Threat detection is paramount in all sensory modalities, but is probably most adaptive in audition. However, research on the neural substrates of fast threat detection in humans has been almost exclusively dedicated to vision.

Neural Pathways

The key neural pathway for visual fast threat detection is the so-called subcortical route for emotion. Having pulled through millions of years of evolution, this shortcut conveys crude direct sensory inputs from the thalamus to the amygdala, facilitating a prompt emotional response.

Hypothesis and Objectives

In the auditory domain, evidence from non-human animals suggests that a similar fast route may exist, but it has never been described in humans. Here, I aim at testing the hypothesis that this auditory subcortical route indeed exists in our species, with neuroanatomical and functional properties that support an optimal response to threat.

Methodology

Using state-of-the-art electrophysiological and neuroimaging techniques, I will identify a pathway compatible with this route and test its functional and temporal dynamics, relative to a cortical route. The techniques include:

1. Scalp electroencephalography (EEG)
2. Intracranial electroencephalography (iEEG)
3. Functional magnetic resonance imaging (fMRI)
4. Diffusion-weighted imaging (DWI)

Each technique will provide essential information for thoroughly depicting the route.

Link to Psychiatric Conditions

Beyond its function, I will examine its link to traits associated with psychiatric conditions.

Confirmation of Anatomical Existence

Then, to confirm its anatomical existence in humans, I will microscopically track its connections directly in postmortem brains.

Conclusion

HumanSUBthreat will restructure current dominant models of human affective neuroscience, strongly biased towards vision, and provide a novel view towards the understanding of disorders associated with amygdala dysfunction.