Biology subjects

Roeser, A.

Publications and source records attributed to Roeser, A..

7 recordsLinked to original sources

bioRxiv2026

Parrots imitate song and dance with mixed vocal-gestural neural signals

Humans shrug when saying "I don't know" and nod when saying "yes," yet it remains unclear how the brain coordinates vocal and gestural motor systems for learned, multimodal communication. Here we find that budgerigar parrots precisely imitate the fine temporal alignment between song and affiliative headbob gestures. Distinct colonies developed unique vocal-gestural motifs, which reorganized into new shared forms following social re-pairing. Neural recordings from the central nucleus of the anterior arcopallium (AAC), the cortical output of the parrot song system, revealed intermixed representations of vocalizations and head kinematics, including mixed selectivity at the level of single neurons. These findings show that socially learned multimodal communication is implemented by the joint representation of vocal and gestural motor signals within single neurons, revealing neural mechanisms that may extend to frontal cortical regions controlling speech and gesture in humans.

neuroscience↗

bioRxiv2023

Songbird mesostriatal dopamine pathways are spatially segregated before the onset of vocal learning

Diverse dopamine (DA) pathways send distinct reinforcement signals to different striatal regions. In adult songbirds, a DA pathway from the ventral tegmental area (VTA) to Area X, the striatal nucleus of the song system, carries singing-related performance error signals important for learning. Meanwhile, a parallel DA pathway to a medial striatal area (MST) arises from a distinct group of neighboring DA neurons that lack connectivity to song circuits and do not encode song error. To test if the structural and functional segregation of these two pathways depends on singing experience, we carried out anatomical studies early in development before the onset of song learning. We find that distinct VTA neurons project to either Area X or MST in juvenile birds before the onset of substantial vocal practice. Quantitative comparisons of early juveniles (30-35 dph), late juveniles (60-65 dph), and adult (>90 dph) brains revealed an outsized expansion in the number of Area X-projecting and MST-projecting VTA neurons over development. These results show that a mesostriatal DA system dedicated to social communication can exist and be spatially segregated before the onset of vocal practice and associated sensorimotor experience.

neuroscience↗

bioRxiv2023

Omicron BA.1 breakthrough infection drives long-term remodeling of the memory B cell repertoire in vaccinated individuals.

How infection by a viral variant showing antigenic drift impacts a preformed mature human memory B cell (MBC) repertoire remains an open question. Here, we studied the MBC response up to 6 months after Omicron BA.1 breakthrough infection in individuals previously vaccinated with three doses of mRNA vaccine. Longitudinal analysis, using single-cell multi-omics and functional analysis of monoclonal antibodies from RBD-specific MBCs, revealed that a BA.1 breakthrough infection mostly recruited pre-existing cross-reactive MBCs with limited de novo response against BA.1-restricted epitopes. Reorganization of clonal hierarchy and new rounds of germinal center reaction, however, combined to maintain diversity and induce progressive maturation of the MBC repertoire against common Hu-1 and BA.1, but not BA.5-restricted, SARS-CoV-2 Spike RBD epitopes. Such remodeling was further associated with marked improvement in overall neutralizing breadth and potency. These findings have fundamental implications for the design of future vaccination booster strategies.

immunology↗

bioRxiv2021

Immune escape of SARS-CoV-2 Omicron variant from mRNA vaccination-elicited RBD-specific memory B cells.

Memory B cells (MBCs) represent a second layer of immune protection against SARS-CoV-2. Whether MBCs elicited by mRNA vaccines can recognize the Omicron variant is of major concern. We used bio-layer interferometry to assess the affinity against the receptor-binding-domain (RBD) of Omicron spike of 313 naturally expressed monoclonal IgG that were previously tested for affinity and neutralization against VOC prior to Omicron. We report here that Omicron evades recognition from a larger fraction of these antibodies than any of the previous VOCs. Additionally, whereas 30% of these antibodies retained high affinity against Omicron-RBD, our analysis suggest that Omicron specifically evades antibodies displaying potent neutralizing activity against the D614G and Beta variant viruses. Further studies are warranted to understand the consequences of a lower memory B cell potency on the overall protection associated with current vaccines.

immunology↗

bioRxiv2021

Memory B cells control SARS-CoV-2 variants upon mRNA vaccination of naive and COVID-19 recovered individuals.

How a previous SARS-CoV-2 infection may amplify and model the memory B cell (MBC) response elicited by mRNA vaccines was addressed by a comparative longitudinal study of two cohorts, naive individuals and disease-recovered patients, up to 2 months after vaccination. The quality of the memory response was assessed by analysis of the VDJ repertoire, affinity and neutralization against variants of concerns (VOC), using unbiased cultures of 2452 MBCs. Upon boost, the MBC pool of recovered patients selectively expanded, further matured and harbored potent neutralizers against VOC. Maturation of the MBC response in naive individuals was much less pronounced. Nevertheless, and as opposed to their weaker neutralizing serum response, half of their RBD-specific MBCs displayed high affinity towards multiple VOC and one-third retained neutralizing potency against B.1.351. Thus, repeated vaccine challenges could reduce these differences by recall of affinity-matured MBCs and allow naive vaccinees to cope efficiently with VOC.

immunology↗

bioRxiv2020

Maturation and persistence of the anti-SARS-CoV-2 memory B cell response.

Memory B cells play a fundamental role in host defenses against viruses, but to date, their role have been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 Spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory B cells, including preexisting cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and largely contributed to the late remarkably stable memory B-cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6 months after SARS-CoV-2 infection and may provide long-term protection.

immunology↗

bioRxiv2017

A Balance Of Outward And Linear Inward Ionic Currents Is Required For The Generation Of Slow Wave Oscillations

Regenerative inward currents help produce slow oscillations through a negative-slope conductance region of their current-voltage relationship that is well approximated by a linear negative conductance. We used dynamic clamp injections of a linear current with this conductance, INL, to explore why some neurons can generate intrinsic slow oscillations whereas others cannot. We addressed this question, in synaptically isolated neurons of the crab Cancer borealis, after blocking action potentials. The pyloric network consists of distinct pacemaker group and follower neurons, all of which express the same complement of ionic currents. When the pyloric dilator (PD) neuron, a member of the pacemaker group, was injected with INL using dynamic clamp, it consistently produced slow oscillations. In contrast, the lateral pyloric (LP) or ventral pyloric (VD) follower neurons, failed to oscillate with INL. To understand these distinct behaviors, we compared outward current levels of PD, LP and VD neurons. We found that LP and VD neurons had significantly larger high-threshold potassium currents (IHTK) than PD, and LP had lower transient potassium current, IA. Reducing IHTK pharmacologically enabled both LP and VD neurons to produce oscillations with INL, whereas modifying IA levels did not affect INL-induced oscillations. Using phase-plane and bifurcation analysis of a simplified model cell, we demonstrate that large levels of IHTK can block INL-induced oscillatory activity, whereas generation of oscillations is almost independent of IA levels. These results demonstrate the importance of a balance between inward pacemaking currents and high-threshold K+current levels in determining slow oscillatory activity.

neuroscience↗