Biology subjects

Pomper, U.

Publications and source records attributed to Pomper, U..

6 recordsLinked to original sources

bioRxiv2025

Common marmosets (Callithrix jacchus) do not differentiate between familiar and unfamiliar conspecifics based on pitch contour information

Previous studies suggest that vocal-learning species use variations of prosodic cues, such as changes in pitch, amplitude, or duration, in the conveying of meaning and emotions as well as individual recognition. Although it is known that the long-distance contact calls ("phee" calls) of common marmosets, a vocal non-learner, vary in prosodic information depending on individual characteristics, evidence of the species use of this information only recently started to emerge. In this study we tested 18 captive common marmosets (Callithrix jacchus) reactions to playbacks of familiar and unfamiliar individuals phee calls and extracted pitch-contour information. The playbacks consisted of i) natural phee calls from group members or unfamiliar conspecifics, or ii) synthesized pitch contours of familiar or unfamiliar phee calls following a natural or artificial syllable order as well as pure tones of similar frequency and duration. We found that although individuals seemed to show different reactions towards the natural calls of familiar and unfamiliar individuals, we did not find group level differences. Marmosets furthermore show significantly reduced interest in synthesized pitch contours compared to natural phee calls and did not differentiate between pitch contour playbacks and pure tone control stimuli, indicating that they did not categorize the pitch contours as conspecific calls. Our results suggest that extracted pitch contour information alone is not sufficient for marmosets to recognise conspecifics, however further studies are required to investigate the exact mechanism of individual recognition in marmosets.

animal behavior and cognition↗

bioRxiv2025

Arousal-related mediation of perceptual belief updating across auditory domains

Belief updating refers to the integration of prior beliefs with incoming evidence and guides decision-making under uncertainty. In response to surprising events, this process is thought to be modulated by the locus-coeruleus-noradrenaline (LC-NA) arousal system, observable via pupil dilations (PDs). Pertinent literature has mostly focused on conscious, high-level decision-making and estimation processes, while assuming that the same principles apply to low-level sensory perceptual decision-making and generalize across tasks, domains and modalities. To address some of these assumptions, we devised a novel perceptual discrimination paradigm, investigating behavior and PDs across auditory domains. Participants were presented with auditory sequences of randomized length at a rapid pace, changing intermittently between two latent states: acceleration vs. deceleration (temporal group, N = 25) and clockwise vs. counterclockwise movement (spatial group, N = 22). Under high uncertainty, participants continuously inferred latent states to report the final state per sequence. To extract per-stimulus estimates of PDs during sequences, we fitted a deconvolution-based general linear model to the continuous pupil traces with a free amplitude parameter reflecting ongoing PDs. A Bayesian observer model was fitted to participants responses and used to estimate information gain and surprisal for every stimulus. Participants performance and PDs showed strong sensitivity to the occurrence of change-points. Both computational variables significantly predicted PDs in both domains, with information gain outperforming surprisal in a model comparison. Further model comparison revealed significant preference for models excluding possible domain-specific effects over models including them, pointing towards a constant effect over domains. We conclude that behavior and associated PDs observed in our purely perceptual auditory task align with Bayesian principles of belief updating. The observed lack of domain specificity supports the assumed generalizability of belief updating.

neuroscience↗

bioRxiv2024

Bayesian Prior Uncertainty and Surprisal Elicit Distinct Neural Patterns During Sound Localization in Dynamic Environments

Estimating the location of a stimulus is a key function in sensory processing, and widely considered to result from the integration of prior information and sensory input according to Bayesian principles. A deviation of sensory input from the prior elicits surprisal, depending on the uncertainty of the prior. While this mechanism is increasingly understood in the visual domain, much less is known about its implementation in audition, especially regarding spatial localization. Here, we combined human EEG with computational modeling to study auditory spatial inference in a noisy, volatile environment and analyzed behavioral and neural patterns associated with prior uncertainty and surprisal. First, our results demonstrate that participants indeed used prior information during periods of stable environmental statistics, but showed evidence of surprisal and discarded prior information following environmental changes. Second, we observed distinct EEG activity patterns associated with prior uncertainty and surprisal in both the time- and time-frequency domain, which are in line with previous studies using visual tasks. Third, these EEG activity patterns were predictive of our participants sound localization error, response uncertainty, and prior bias on a trial-by-trial basis. In summary, our work provides novel behavioral and neural evidence for Bayesian inference during dynamic auditory localization.

neuroscience↗

bioRxiv2023

Neural Dynamics Underlying Successful Auditory Short-Term Memory Performance

Listeners often operate in complex acoustic environments, consisting of many concurrent sounds. Accurately encoding and maintaining such auditory objects in short-term memory is crucial for communication and scene analysis. Yet, the neural underpinnings of successful auditory short-term memory (ASTM) performance are currently not well understood. To elucidate this issue, we presented a novel, challenging auditory delayed match-to-sample task while recording MEG. Human participants listened to "scenes" comprising 3 concurrent tone pip streams. The task was to indicate, after a delay, whether a probe stream was present in the just-heard scene. We present three key findings: First, behavioural performance revealed faster responses in correct vs. incorrect trials as well as in probe present vs probe absent trials, consistent with ASTM search. Second, successful compared to unsuccessful ASTM performance was associated with a significant enhancement of event-related fields and oscillatory activity in the theta, alpha, and beta frequency ranges. This extends previous findings of an overall increase of persistent activity during short-term memory performance. Third, using distributed source modelling, we found these effects to be confined mostly to sensory areas during encoding, presumably related to ASTM contents per-se. Parietal and frontal sources then became relevant during the maintenance stage, indicating that effective STM operation also relies on ongoing inhibitory processes suppressing task irrelevant information. In summary, our results deliver a detailed account of the neural patterns that differentiate successful from unsuccessful ASTM performance in the context of a complex, multi-object auditory scene.

neuroscience↗

bioRxiv2018

Rapid Brain Responses to Familiar vs. Unfamiliar Music - an EEG and Pupillometry study

Human listeners exhibit marked sensitivity to familiar music - perhaps most readily revealed by popular \"name that tune\" games, in which listeners often succeed in recognizing a familiar song based on extremely brief presentation. In this work we used electro-encephalography (EEG) and pupillometry to reveal the temporal signatures of the brain processes that allow differentiation between familiar and unfamiliar music. Participants (N=10) passively listened to snippets (750 ms) of familiar and, acoustically matched, unfamiliar songs, presented in random order. A group of control participants (N=12), which were unfamiliar with all of the songs, was also used. In the main group we reveal a rapid differentiation between snippets from familiar and unfamiliar songs: Pupil responses showed greater dilation rate to familiar music from 100-300 ms post stimulus onset. Brain responses measured with EEG showed a differentiation between familiar and unfamiliar music from 350 ms post onset but, notably, in the opposite direction to that seen with pupillometry: Unfamiliar snippets were associated with greater responses than familiar snippets. Possible underlying mechanisms are discussed.

neuroscience↗

bioRxiv2017

The impact of visual gaze direction on auditory object tracking

Subjective experience suggests that we are able to direct our auditory attention independent of our visual gaze, e.g when shadowing a nearby conversation at a cocktail party. But what are the consequences at the behavioural and neural level? While numerous studies have investigated both auditory attention and visual gaze independently, little is known about their interaction during selective listening. In the present EEG study, we manipulated visual gaze independently of auditory attention while participants detected targets presented from one of three loudspeakers. We observed increased response times when gaze was directed away from the locus of auditory attention. Further, we found an increase in occipital alpha-band power contralateral to the direction of gaze, indicative of a suppression of distracting input. Finally, this condition also led to stronger central theta-band power, which correlated with the observed effect in response times, indicative of differences in top-down processing. Our data suggest that a misalignment between gaze and auditory attention both reduce behavioural performance and modulate underlying neural processes. The involvement of central theta-band and occipital alpha-band effects are in line with compensatory neural mechanisms such as increased cognitive control and the suppression of task irrelevant inputs.

neuroscience↗