The solitary nucleus connectivity to key autonomic regions in humans

Abstract

The nucleus tractus solitarius (NTS) is a key brainstem structure relaying interoceptive peripheral information to the interrelated brain centres 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: (1) the NTS predominantly processes afferent input and (2) a lateralization towards a predominantly left‐sided NTS processing. Our results lay the foundations for future investigations into the NTS' tripartite role composed 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.

Treatment with Glycyrrhiza glabra Extract Induces Anxiolytic Effects Associated with Reduced Salt Preference and Changes in Barrier Protein Gene Expression

“…The NTS structure is crucial for autonomic and affect regulation [ 48 , 49 ], including salt appetite [ 7 , 8 , 50 , 51 , 52 ]. Projections of the NTS to higher brain areas, in particular the amygdala and prefrontal cortex, appear to be involved in the association between NTS activity and affective states [ 53 , 54 ].…”

Neural, Anti-Inflammatory, and Clinical Effects of Transauricular Vagus Nerve Stimulation in Major Depressive Disorder: A Systematic Review

“…The taVNS effects are mediated by the brain stem nuclei, such as the NTS and LC, that are deeply connected with the cortical and limbic structures ( Breton-Provencher et al, 2021 ; Forstenpointer et al, 2022 ). Although the results are inconclusive at this point, a general decrease in metabolism and connectivity in the limbic structures and an increased activation and communication of areas related to executive function, reward, and motivation were observed.…”

Cerebral autoregulation and autonomic nervous system: A narrative review

“…CBV values are 4 ml of blood per 100 ml of tissue at rest. [11][12][13][14][15] The CBV (aBV) arterial component, equivalent to 30%, contributes approximately 1 ml of cerebral blood vessels per 100 ml of tissue. 16 The amount of oxygen utilized, tissue volume, and time are all represented by the cerebral metabolic rate of oxygen (CMRO 2 ).…”

“…The carotid sinuses, close to the right subclavian artery's origin, and the aortic arch all contain high-pressure baroreceptors. [14][15][16][17][18] The glossopharyngeal nerve (IX cranial nerve) transmits carotid baroreceptor input to the earliest synapses in the brainstem's Nucleus Tractus Solitarii (NTS). Baroreceptor data from the aortic arch is transmitted through the aortic depressor nerve, which connects to the vagus nerve (X cranial nerve) and ascends to the NTS.…”

“…The primary sympathetic output nucleus, which is situated at the level of the rostral ventrolateral medulla (RVLM), receives inhibitory projections from the caudal ventrolateral medulla (CVLM) concerning muscle sympathetic nerve activity (MSNA). 14,21 This type of innervation causes the sympathetic outflow to the muscle vascular bed to decrease. As a result, at the RVLM, the excitatory signal from the baroreceptor afferents is inverted (Figure 1).…”