Biology subjects

Arroyo, B.

Publications and source records attributed to Arroyo, B..

3 recordsLinked to original sources

bioRxiv2024

The flow of reward information through neuronal ensembles in the accumbens

Reward information flows through neuronal ensembles in the nucleus accumbens shell (NAcSh), influencing decision-making. We investigated this phenomenon by training rats in a self-guided probabilistic choice task while recording single-unit activity in the NAcSh. We found that rats dynamically adapted their choices based on an internal representation of reward likelihood. Neuronal ensembles in the NAcSh act as dynamic modules to process different aspects of reward-guided behavior. Ensembles dynamically change composition and functional connections throughout reinforcement learning. The NAcSh forms a highly connected network with a heavy-tailed distribution and neuronal hubs, facilitating efficient reward information flow. Reward delivery evokes higher mutual information between ensembles and unifies network activity, while omission leads to less synchronization. Our recordings shed light on how reward information propagates through dynamically changing ensembles of neurons in the NAcSh. These functional ensembles exhibit flexible membership, dropping in and out and even shrinking in number as the rat learns to obtain (energy) rewards in an ever-changing environment. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=189 HEIGHT=200 SRC="FIGDIR/small/580379v2_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@1e870org.highwire.dtl.DTLVardef@1434c90org.highwire.dtl.DTLVardef@157971aorg.highwire.dtl.DTLVardef@1812ca6_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Tesofensine, a novel antiobesity drug, silences GABAergic hypothalamic neurons

Obesity is a major global health epidemic that has adverse effects on both the people affected as well as the cost to society. Several anti-obesity drugs that target GLP-1 receptors have recently come to the market. Here we describe the effects of tesofensine, a novel anti-obesity drug that acts as a triple monoamine neurotransmitter reuptake inhibitor. We investigated its effects on weight loss and underlying neuronal mechanisms in mice and rats using various techniques. These include behavioral tasks, DeepLabCut videotaped analysis, electrophysiological ensemble recordings, optogenetic activation, and chemogenetic silencing of GABAergic neurons in the Lateral Hypothalamus (LH). We found that tesofensine induced greater weight loss in obese than lean rats, which was associated with changes in LH ensemble activity. In Vgat-ChR2 and Vgat-IRES-cre transgenic mice, we found for the first time that tesofensine inhibited a subset of LH GABAergic neurons, reducing their ability to promote feeding behavior, and chemogenetically silencing them enhanced tesofensines food-suppressing effects. Unlike phentermine, a dopaminergic appetite suppressant, tesofensine causes few, if any, head-weaving stereotypy at therapeutic doses. Most importantly, we found that tesofensine prolonged the weight loss induced by 5-HTP, a serotonin precursor, and blocked the body weight rebound that often occurs after weight loss. Behavioral studies on rats with the tastant sucrose indicated that tesofensines appetite suppressant effects are independent of taste aversion and do not directly affect the perception of sweetness or palatability of sucrose. In summary, our data provide new insights into the effects of tesofensine on weight loss and the underlying neuronal mechanisms, suggesting that tesofensine may be an effective treatment for obesity and that it may be a valuable adjunct to other appetite suppressants to prevent body weight rebound.

neuroscience↗

bioRxiv2023

Use of linear features by red-legged partridges in an intensive agricultural landscape: implications for landscape management in farmland

Current agricultural practices and change are the major cause of biodiversity loss. An important change associated with the intensification of agriculture in the last 50 years is the spatial homogenization of the landscape with substantial loss of such biodiversity-rich elements as seminatural linear features (hedgerows, field margins, grassy strips, etc.). In Europe, some management prescriptions serve to increase heterogeneity by the creation of these seminatural linear features which are not being used primarily for agricultural production. However, these elements are not equal in their support for biodiversity according to their structure and composition. The aim of this study is to determine the importance of landscape heterogeneity and specifically linear features on the spatial distribution of red-legged partridges, a small game species in decline in Europe. Through GPS-monitoring of adult birds, we first assess home range size throughout the year and during the breeding season, in relation to breeding status and to linear features (seminatural linear vegetation and tracks-roads for human traffic) density. Then, we focus on habitat selection during the breeding period in relation to linear features. We found that linear elements shape the use of space by red-legged partridges according to their reproductive status. Traffic routes and seminatural features structured by both herbaceous and woody cover, negatively influenced home range size. Further, breeding birds select linear elements with herbaceous cover while non-breeders select linear elements with woody cover, underlining the different needs of birds according to their breeding status. All birds selected areas near tracks, but non-breeders seemed to avoid roads. This study shows the importance for this species of the linear components that structure the agricultural landscape. We propose recommendations to promote the presence of the red-legged partridge in this agricultural environment but also of the biodiversity in general.

ecology↗