Elie, B. | bioRxiv Science

bioRxiv2024

Modeling speech adaptation to altered sensory feedback through continuous learning of internal sensory predictions

The paper presents a version of an optimization-based model of speech production that reproduces key acoustic and articulatory features of motorsensory adaptation to altered sensory feedback. In the presented approach, the mechanism of motorsensory adaptation is based on regular updates, based on the sensory feedback perceived by the speaker, of two of the speakers internal models used for computing (near)-optimal articulation. These internal models, modeled as separate Artificial Neural Networks, are 1) a model that predicts the acoustic consequences of motor (articulatory commands) and 2) a model that predicts the somatosensory sensations from given motor commands. The paper presents simulations of adaptation experiments that successfully reproduce key acoustic and articulatory features of motorsensory adaptation of speech to altered sensory feedback. These include gradual and incomplete motorsensory adaptation when the auditory (or the somatosensory) feedback is suddenly altered (F1-shifted for the altered auditory feedback, forced jaw movement for altered somatosensory feedback). The presented simulations also show that the rate and magnitude of adaptation behavior depend on a small number of parameters. Variation in the values of these parameters can potentially explain inter-speaker differences in terms of adaptation behavior, including sensory preference.

neuroscience↗

bioRxiv2023

Viral expansion after transfer is a primary driver of influenza A virus transmission bottlenecks

For many viruses, narrow bottlenecks acting during transmission sharply reduce genetic diversity in a recipient host relative to the donor. Since genetic diversity represents adaptive potential, such losses of diversity are thought to limit the opportunity for viral populations to undergo antigenic change and other adaptive processes. Thus, a detailed picture of evolutionary dynamics during transmission is critical to understanding the forces driving viral evolution at an epidemiologic scale. To advance this understanding, we used a barcoded virus library and a guinea pig model of transmission to decipher where in the transmission process influenza A virus populations lose diversity. In inoculated guinea pigs, we show that a high level of viral barcode diversity is maintained. Within-host continuity in the barcodes detected across time furthermore indicates that stochastic effects are not pronounced within the inoculated hosts. Importantly, in both aerosol-exposed and direct contact animals, we observed many barcodes at the earliest time point(s) positive for infectious virus, indicating robust transfer of diversity through the environment. This high viral diversity is short-lived, however, with a sharp decline seen 1-2 days after initiation of infection. Although major losses of diversity at transmission are well described for influenza A virus, our data indicate that events that occur following viral transfer and during the earliest stages of natural infection have a central role in this process. This finding suggests that host factors, such as immune effectors, may have greater opportunity to impose selection during influenza A virus transmission than previously recognized.

microbiology↗