Jakobsen, S. | Search bioRxiv

bioRxiv2023

Dopamine dysregulation in Parkinson's disease flattens the pleasurable urge to move to musical rhythms

The pleasurable urge to move to music (PLUMM) elicits activity in motor and reward areas of the brain and is thought to be driven by predictive processes. Dopamine within motor and limbic cortico-striatal networks is implicated in the predictive processes underlying beat-based timing and music-induced pleasure, respectively. This suggests a central role of cortico-striatal dopamine in PLUMM. This study tested this hypothesis by comparing PLUMM in Parkinsons disease patients, healthy age-matched, and young controls. Participants listened to musical sequences with varying rhythmic and harmonic complexity (low, medium, high), and rated their experienced pleasure and urge to move to the rhythm. In line with previous results, healthy younger participants showed an inverted U-shaped relation between rhythmic complexity and ratings, with a preference for medium complexity rhythms, while age-matched controls showed a similar, but weaker, inverted U-shaped response. Conversely, PD patients showed a significantly flattened response for both the urge to move and pleasure. Crucially, this flattened response could not be attributed to differences in rhythm discrimination and did not reflect an overall decrease in ratings. Together, these results support the role of dopamine within cortico-striatal networks in the predictive processes that form the link between the perceptual processing of rhythmic patterns, and the affective and motor responses to rhythmic music.

neuroscience↗

bioRxiv2021

Parasite-probiotic interactions in the gut: Bacillus sp. and Enterococcus faecium regulate type-2 inflammatory responses and modify the gut microbiota of pigs during helminth infection

Dietary probiotics may enhance gut health by directly competing with pathogenic agents and through immunostimulatory effects. These properties are recognized in the context of bacterial and viral pathogens, but less is known about interactions with eukaryotic pathogens such as parasitic worms (helminths). In this study we investigated whether two probiotic mixtures (comprised of Bacillus amyloliquefaciens, B. subtilis, and Enterococcus faecium [BBE], or Lactobacillus rhamnosus LGG and Bifidobacterium animalis subspecies Lactis Bb12 [LB]) could modulate helminth infection kinetics as well as the gut microbiome and intestinal immune responses in pigs infected with the nodular worm Oesophagostomum dentatum. We observed that neither probiotic mixture influenced helminth infection levels. BBE, and to a lesser extent LB, changed the alpha- and beta-diversity indices of the colon and faecal microbiota, notably including an enrichment of faecal Bifidobacterium spp. by BBE. However, these effects were muted by concurrent O. dentatum infection. BBE (but not LB) significantly attenuated the O. dentatum-induced upregulation of genes involved in type-2 inflammation and restored normal lymphocyte ratios in the ileo-caecal lymph nodes that were altered by infection. Moreover, inflammatory cytokine release from blood mononuclear cells and intestinal lymphocytes was diminished by BBE. Collectively, our data suggest that selected probiotic mixtures can play a role in maintaining immune homeostasis during type 2-biased inflammation. In addition, potentially beneficial changes in the microbiome induced by dietary probiotics may be counteracted by helminths, highlighting the complex inter-relationships that potentially exist between probiotic bacteria and intestinal parasites.

microbiology↗