Biology subjects

Zai, A. T.

Publications and source records attributed to Zai, A. T..

9 recordsLinked to original sources

bioRxiv2025

Vib2Sound: Separation of Multimodal Sound Sources

Understanding animal social behaviors, including vocal communication, requires longitudinal observation of interacting individuals. However, isolating individual-level vocalizations in complex environments is challenging due to background noise and frequent overlaps of coincident signals from multiple vocalizers. A promising solution lies in multimodal recordings that combine traditional microphones with animal-borne sensors, such as accelerometers and directional microphones. These sensors, however, are constrained by strict limits on weight, size, and power consumption and often lead to noisy or unstable signals. In this work, we introduce a neural network-based system for sound source separation which leverages multi-channel microphone recordings and body-mounted accelerometer signals. Using a dataset of zebra finches recorded in a social setting, we demonstrate that contact sensing largely outperforms conventional microphone-array recordings. By enabling the separation of overlapping vocalizations, our approach offers a valuable tool for studying animal communication in complex naturalistic environments.

animal behavior and cognition↗

bioRxiv2025

Estimating the motor exploration in reinforcement learning

What motor exploration strategies do animals use to learn a skill from rewards? Reinforcement learning theory provides no guidance for estimating motor exploration -- the behavioral component aimed at discovering better strategies. Inspired by the brains modular organization, we postulate a latent learner that explores via an additive source of ideal randomness it injects into behavior. Assuming the learner is ignorant of other motor components, which is sub-optimal by design, evolutionary fitness argues that these should display mainly non-ideal variability. We test this recipe for behavior decomposition in songbirds subjected to a vocal pitch conditioning task. The explorative component we estimate from vocalizations accounts for the motor contribution of a basal ganglia pathway and the other behavioral component accounts for birds suboptimal learning trajectories. This congruence between normative exploration and brain organization suggests that the evolutionary pressure for behavioral optimality is lesser than to learn from purely random trials.

neuroscience↗

bioRxiv2024

Visually-guided compensation of deafening-induced song deterioration

Human language learning and maintenance depend primarily on auditory feedback but are also shaped by other sensory modalities. Individuals who become deaf after learning to speak (post-lingual deafness) experience a gradual decline in their language abilities. A similar process occurs in songbirds, where deafness leads to progressive song deterioration. However, songbirds can modify their songs using non-auditory cues, challenging the prevailing assumption that auditory feedback is essential for vocal control. In this study, we investigated whether deafened birds could use visual cues to prevent or limit song deterioration. We developed a new metric for assessing syllable deterioration called the spectrogram divergence score. We then trained deafened birds in a behavioral task where the spectrogram divergence score of a target syllable was computed in real-time, triggering a contingent visual stimulus based on the score. Birds exposed to the contingent visual stimulus--a brief light extinction--showed more stable song syllables than birds that received either no light extinction or randomly triggered light extinction. Notably, this effect was specific to the targeted syllable and did not influence other syllables. This study demonstrates that deafness-induced song deterioration in birds can be partially mitigated with visual cues.

neuroscience↗

bioRxiv2024

Familiarity of an environment prevents song suppression in isolated zebra finches

Despite the wide use of zebra finches as an animal model to study vocal learning and production, little is known about impacts on their welfare caused by routine experimental manipulations such as changing their social context. Here we conduct a post-hoc analysis of singing rate, an indicator of positive welfare, to gain insights into stress caused by social isolation, a common experimental manipulation. We find that isolation in an unfamiliar environment reduces singing rate for several days, indicating the presence of an acute stressor. However, we find no such decrease when social isolation is caused by either removal of a social companion or by transfer to a familiar environment. Furthermore, during repeated brief periods of isolation, singing rate remains high when isolation is induced by removal of social companions, but it fails to recover from a suppressed state when isolation is induced by recurrent transfer to an unknown environment. These findings suggest that stress from social isolation is negligible compared to stress caused by environmental changes and that frequent short visits of an unfamiliar environment are detrimental rather than beneficial. Together, these insights can serve to refine experimental studies and design paradigms maximizing the birds wellbeing and vocal output.

zoology↗

bioRxiv2023

Benchmarking nearest neighbor retrieval of zebra finch vocalizations across development

Vocalizations are highly specialized motor gestures that regulate social interactions. The reliable detection of vocalizations from raw streams of microphone data remains an open problem even in research on widely studied animals such as the zebra finch. A promising method for finding vocal samples from potentially few labelled examples (templates) is nearest neighbor retrieval, but this method has never been extensively tested on vocal segmentation tasks. We retrieve zebra finch vocalizations as neighbors of each other in the sound spectrogram space. Based on merely 50 templates, we find excellent retrieval performance in adults (F1 score of 0.93 {+/-} 0.07) but not in juveniles (F1 score of 0.64 {+/-} 0.18), presumably due to the larger vocal variability of the latter. The performance in juveniles improves when retrieval is based on fixed-size template slices (F1 score of 0.72 {+/-} 0.10) instead of entire templates. Among the several distance metrics we tested such as the cosine and the Euclidean distance, we find that the Spearman distance largely outperforms all others. We release our expert-curated dataset of more than 50000 zebra finch vocal segments, which will enable training of data-hungry machine-learning approaches.

animal behavior and cognition↗

bioRxiv2022

Learning the action inventory of a complex skill via an intrinsic reward

Reinforcement learning (RL) is thought to underlie the acquisition of vocal skills like birdsong and speech, where sounding like ones "tutor" is rewarding. Yet, we find that the standard actor-critic RL model of birdsong learning fails to account for juvenile zebra finches efficient learning of an inventory of multiple syllables. But when we replace a single actor with multiple independent actors that jointly maximize a common intrinsic reward, then birds empirical learning trajectories are accurately reproduced. Importantly, the influence of each actor (syllable) on the magnitude of global reward is competitively determined by its acoustic similarity to target syllables. This leads to each actor matching the target it is closest to, and occasionally, to the competitive exclusion of an actor from the learning process (i.e., the learned song). We propose that a competitive-cooperative multi-actor (MARL) algorithm is key for the efficient learning of the action inventory of a complex skill.

animal behavior and cognition↗

bioRxiv2022

Goal-directed vocal planning in a songbird

Songbirds vocal mastery is impressive, but to what extent is it a result of practice? Can they, based on experienced mismatch with a known target, plan the necessary changes to recover the target in a practice-free manner without intermittently singing? In adult zebra finches, we drive the pitch of a song syllable away from its stable (baseline) variant acquired from a tutor, then we withdraw reinforcement and subsequently deprive them of singing experience by muting or deafening. In this deprived state, birds do not recover their baseline song. However, they revert their songs towards the target by about one standard deviation of their recent practice, provided the sensory feedback during the latter signaled a pitch mismatch with the target. Thus, targeted vocal plasticity does not require immediate sensory experience, showing that zebra finches are capable of goal-directed vocal planning.

neuroscience↗

bioRxiv2019

Sensory substitution reveals a manipulation bias

Sensory substitution is a promising therapeutic approach for replacing a missing or diseased sensory organ by translating inaccessible information into another sensory modality. What aspects of substitution are important such that subjects accept an artificial sense and that it benefits their voluntary action repertoire? To obtain an evolutionary perspective on affective valence implied in sensory substitution, we introduce an animal model of deaf songbirds. As a substitute of auditory feedback, we provide binary visual feedback. Deaf birds respond appetitively to song-contingent visual stimuli, they skillfully adapt their songs to increase the rate of visual stimuli, showing that auditory feedback is not required for making targeted changes to a vocal repertoire. We find that visually instructed song learning is basal-ganglia dependent. Because hearing birds respond aversively to the same visual stimuli, sensory substitution reveals a bias for actions that elicit feedback to meet animals manipulation drive, which has implications beyond rehabilitation.

neuroscience↗

bioRxiv2017

Welfare of zebra finches used in research

Over the past 50 years, songbirds have become a valuable model organism for scientists studying vocal communication from its behavioral, hormonal, neuronal, and genetic perspectives. Many advances in our understanding of vocal learning result from research using the zebra finch, a close-ended vocal learner. We review some of the manipulations used in zebra finch research, such as isolate housing, transient/irreversible impairment of hearing/vocal organs, implantation of small devices for chronic electrophysiology, head fixation for imaging, aversive song conditioning using sound playback, and mounting of miniature backpacks for behavioral monitoring. We highlight the use of these manipulations in scientific research, and estimate their impact on animal welfare, based on the literature and on data from our past and ongoing work. The assessment of harm-benefits tradeoffs is a legal prerequisite for animal research in Switzerland. We conclude that a diverse set of known stressors reliably lead to suppressed singing rate, and that by contraposition, increased singing rate may be a useful indicator of welfare. We hope that our study can contribute to answering some of the most burning questions about zebra finch welfare in research on vocal behaviors.

animal behavior and cognition↗