Uncovering the human subcortical pathway for auditory threat detection

Project Information

HumanSUBthreat

Grant agreement ID: 101088954

DOI

10.3030/101088954

EC signature date 30 May 2023

Start date 1 October 2023

End date 30 September 2028

Funded under

• European Research Council (ERC)

Total cost

€ 1 900 285,00

EU contribution

€ 1 900 285,00

Coordinated by

UNIVERSITAT DE BARCELONA
Spain

Periodic Reporting for period 1 - HumanSUBthreat (Uncovering the human subcortical pathway for auditory threat detection)

Reporting period: 2023-10-01 to 2026-03-31

Summary of the context and overall objectives of the project

How does the human brain detect danger rapidly, even before we have fully processed what we hear? Animal research has long proposed the existence of fast, subcortical “low-road” pathways that send emotionally significant information straight to the amygdala. However, the existence, organisation, and functional role of such pathways in the human auditory system has remained largely unknown.
This project aims to determine whether humans possess subcortical pathways capable of transmitting auditory threat-related information rapidly to the amygdala, how these pathways are organised anatomically, and how they contribute to emotional responses. The project also examines whether these pathways rely on neural mechanisms similar to those supporting rapid visual processing, and how individual differences in pathway structure relate to emotional traits such as fearfulness or anxiety.
By addressing these questions, the project tackles a fundamental gap in our understanding of human emotion. Its current results provide convergent functional and anatomical evidence for subcortical mechanisms of auditory threat processing in humans, consistent with evolutionarily conserved “low-road” pathways. These advances are expected to influence current models of emotion and guide future research on clinical conditions involving amygdala dysfunction.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

We have advanced in understanding how rapid subcortical pathways may support auditory affective processing in humans. Our work has focused on three main scientific goals:
1) Anatomical characterisation of subcortical pathways: using advanced diffusion MRI and optimised tractography methods, we have identified direct connections between the thalamus and the amygdala and generated high-precision maps of distinct subcortical projections. These developments have enabled a level of anatomical detail and reliability not previously achieved for these structures.
2) Functional evidence for subcortical auditory threat processing: through behavioural testing, EEG, pupillometry and fMRI, we examined how humans respond to emotionally salient sounds. Across studies, we observed patterns suggesting that specific acoustic features elicit rapid neural and physiological responses, and that these responses relate to individual variability in subcortical connectivity.
3) Linking structure, function and emotional traits: measures of fearfulness, anxiety and related traits were collected throughout the experiments. Analyses point to associations between these traits and both structural and functional aspects of the pathways, offering new insight into mechanisms that may underlie affective processes and vulnerability.
In parallel, the project has generated new multimodal paradigms, analysis pipelines and datasets that will be released upon publication. Current work is expanding these findings to broader sets of sounds and sensory modalities, with the aim of building a more comprehensive understanding of how rapid subcortical circuits contribute to human emotion.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Our results provide new evidence that specific subcortical pathways may support affective auditory processing in humans under particular acoustic conditions. By integrating high-resolution anatomical mapping with multimodal neural and physiological measures, the project offers convergent insight into how emotionally relevant sounds can engage fast thalamo-amygdala mechanisms.
Upcoming research will examine how these pathways operate across different sensory and emotional contexts, and how individual variability in their structure and function relates to emotional sensitivity. Together, the findings outline a framework for understanding subcortical contributions to human emotion and lay the foundation for future translational applications involving amygdala-related conditions.