HumanSUBthreat · Uncovering the human subcortical pathway for auditory threat detection

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. 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. 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. 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. Using state-of-the-art electrophysiological and neuroimaging techniques (scalp and intracranial electroencephalography, functional magnetic resonance and diffusion-weighted imaging), I will identify a pathway compatible with this route and test its functional and temporal dynamics, relative to a cortical route. Each technique will provide essential information for thoroughly depicting the route. Beyond its function, I will examine its link to traits associated to psychiatric conditions. Then, to confirm its anatomical existence in humans, I will microscopically track its connections directly in postmortem brains. 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 to amygdala dysfunction.