The Solitary Nucleus Connectivity to Key Autonomic Regions in Humans MRI and Literature based Considerations

Author: Julia Forstenpointner1,2, Anne Margarette S Maallo1, Igor Elman1,3, Scott Holmes1, Roy Freeman4, Ralf Baron2, David Borsook1,5
1 Center for Pain and the Brain, Boston Children's Hospital, Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Boston, MA, USA.
2 Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.
3 Cambridge Health Alliance, Harvard Medical School, Cambridge, MA, USA.
4 Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
5 Department of Radiology and Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Conference/Journal: Eur J Neurosci
Date published: 2022 May 11
Other: Special Notes: doi: 10.1111/ejn.15691. , Word Count: 215

The nucleus tractus solitarius (NTS), is a key brainstem structure relaying interoceptive peripheral information to the interrelated brain centers for eliciting rapid autonomic responses and for shaping longer-term neuroendocrine and motor patterns. Structural and functional NTS' connectivity has been extensively investigated in laboratory animals. But there is limited information about NTS' connectome in humans. Using MRI, we examined diffusion and resting state data from 20 healthy participants in the Human Connectome Project. The regions within the brainstem (n=8), subcortical (n=6), cerebellar (n=2) and cortical (n=5) parts of the brain were selected via a systematic review of the literature and their white matter NTS connections were evaluated via probabilistic tractography along with functional and directional (i.e., Granger-causality) analyses. The underlying study confirms previous results from animal models and provides novel aspects on NTS integration in humans. Two key findings can be summarized: (i) the NTS predominantly processes afferent input and (ii) a lateralization towards a predominantly left-sided NTS processing. Our results lay the foundations for future investigations into the NTS' tripartite role comprised of interoreceptors' input integration, the resultant neurochemical outflow and cognitive/affective processing. The implications of these data add to the understanding of NTS' role in specific aspects of autonomic functions.

Keywords: connectome; interoceptive; laterality; magnetic resonance imaging; medulla oblongata; viscero-sensory.

PMID: 35545280 DOI: 10.1111/ejn.15691