A brainstem map for visceral sensations

Abstract

The nervous system uses various coding strategies to process sensory inputs. For example, the olfactory system uses large receptor repertoires and is wired to recognize diverse odours, whereas the visual system provides high acuity of object position, form and movement1–5. Compared to external sensory systems, principles that underlie sensory processing by the interoceptive nervous system remain poorly defined. Here we developed a two-photon calcium imaging preparation to understand internal organ representations in the nucleus of the solitary tract (NTS), a sensory gateway in the brainstem that receives vagal and other inputs from the body. Focusing on gut and upper airway stimuli, we observed that individual NTS neurons are tuned to detect signals from particular organs and are topographically organized on the basis of body position. Moreover, some mechanosensory and chemosensory inputs from the same organ converge centrally. Sensory inputs engage specific NTS domains with defined locations, each containing heterogeneous cell types. Spatial representations of different organs are further sharpened in the NTS beyond what is achieved by vagal axon sorting alone, as blockade of brainstem inhibition broadens neural tuning and disorganizes visceral representations. These findings reveal basic organizational features used by the brain to process interoceptive inputs.

An airway-to-brain sensory pathway mediates influenza-induced sickness

“…5a ), not observed in the area postrema, and remote from NTS locations targeted by axons of some other Cre-defined NJP neurons, such as gut-innervating neurons marked by expression of Gpr65 or Glp1r 35 . These findings further support a model for topographic organization in the brainstem 36 , with neurons relaying the presence of an airway infection spatially restricted from at least some other interoceptive inputs.…”

Current state of phoenixin—the implications of the pleiotropic peptide in stress and its potential as a therapeutic target

“…The importance of nesfatin-1 in stress is further underlined by its capability to activate the hypothalamus-pituitary-adrenal (HPA) axis and increase corticosterone levels in plasma after it was applied icv ( Konczol et al, 2010 ). As reported previously, corticosterone treatment for 22 days abolished the effects of phoenixin on NTS neuron excitability ( Grover et al, 2020 ), thereby suggesting an indirect link between nesfatin-1 and phoenixin in chronic stress, where an increase in corticosterone induced by nesfatin-1 signaling reduced phoenixin’s effects on neuron excitability, thereby indirectly reducing neuron excitability in the NTS, which is the “gateway” nucleus for peripheral sensory signals ( Ran et al, 2022 ). This could be interpreted as an adaptation or desensitization towards the stressor in order to avoid an excessive stress response.…”

Position-independent functional refinement within the vagus motor topographic map

“…(e, k) The response tuning index for all motor neurons that repeatedly respond to A or P or both stimulation at 10 dpf ( e , n=84 neurons collected from 7 animals) and 4 dpf ( k , 218 neurons collected from 7 fish). (f) Correlation analysis of responses of motor neurons to stimuli in the same and different locations 57 . Left: Dots represent all analyzed neurons collected from 7 animals, which are plotted based on the GCaMP levels (dF/F0) following two noxious stimulations at the same (top graphs) or different (bottom graphs) locations.…”