Biology subjects

Barumerli, R.

Publications and source records attributed to Barumerli, R..

3 recordsLinked to original sources

bioRxiv2022

A Bayesian model for human directional localization of broadband and static sound sources

Humans estimate sound-source directions by combining prior beliefs with sensory evidence. Prior beliefs represent statistical knowledge about the environment while sensory evidence is acquired from auditory features such as interaural disparities and monaural spectral shapes. Models of directional sound localization often impose constraints on the contribution of these features to either the horizontal or vertical dimension. Instead, we propose a Bayesian model that more flexibly incorporates each feature according to its spatial precision and integrates prior beliefs in the inference process. We applied the model to directional localization of a single, broadband, stationary sound source presented to a static human listener in an anechoic environment. We simplified interaural features to be broadband and compared two model variants, each considering a different type of monaural spectral features: magnitude profiles and gradient profiles. Both model variants were fitted to the baseline performance of five listeners and evaluated on the effects of localizing with non-individual head-related transfer functions (HRTFs) and sounds with rippled spectrum. The model variant with spectral gradient profiles outperformed other localization models. This model variant appears particularly useful for the evaluation of HRTFs and may serve as a basis for future extensions towards modeling dynamic listening conditions.

neuroscience↗

bioRxiv2022

Benefits of individualized brain anatomies and EEG electrode positions for auditory cortex localization

Due to its high temporal resolution and non-invasive nature, electroencephalography (EEG) is considered a method of great value for the field of auditory cognitive neuroscience. In performing source space analyses, localization accuracy poses a bottleneck, which precise forward models based on individualized attributes such as subject anatomy or electrode locations aim to overcome. Yet acquiring anatomical images or localizing EEG electrodes requires significant additional funds and processing time, making it an oftentimes inaccessible asset. Neuroscientific software offers template solutions, on which analyses can be based. For localizing the source of auditory evoked responses, we here compared the results of employing such template anatomies and electrode positions versus the subject-specific ones, as well as combinations of the two. All considered cases represented approaches commonly used in electrophysiological studies. We considered differences between two commonly used inverse solutions (dSPM, sLORETA) and targeted the primary auditory cortex; a notoriously small cortical region that is located within the lateral sulcus, thus more prone to errors in localization. Through systematical comparison of the outcomes in terms of auditory activity attributes and leakage quantification, we assessed how the individualization steps impacted the analyses outcomes. Both electrode locations as well as subject anatomies were found to have an effect, which though varied based on the configuration considered. When comparing the inverse solutions, we moreover found that dSPM more consistently benefited from individualization of subject characteristics. Based on the scientific question considered, our results may be used to facilitate the planning of auditory neuroscientific experiments in terms of expected infrastructure, personnel and funds.

neuroscience↗

bioRxiv2020

Action Planning and Affective States Within the Auditory Peripersonal Space.

Fast reaction to approaching stimuli is vital for survival as for sounds entering the individual auditory Peripersonal Space (PPS). Closer sounds have found to provoke higher motor cortex activation particularly for highly arousing sounds, showing the close relationship for perceptual components of the sounds and motor preparation. Here Normal Hearing (NH) individuals and Cochlear Implanted (CI) individuals have been compared in their ability to recognize evaluate and react to affective stimuli entering the PPS. Twenty (seven females) NH and ten (three females) CI participants were asked to react to Positive (P), Negative (Ne), Neutral, (Nu) affective sounds virtually ending at five different distances from their body by performing fast arms flexion. Pre-motor Reaction Times (pm-RTs) were detected via EMG from postural muscles to measure action anticipation at different sound stopping distances; furthermore, the same sounds were evaluated for their level of valence and arousal perceived. Both groups showed the ability to localize the sound distances but only NH individuals modulated their pm-RTs based on the sound distance. Interestingly when the sound was not carrying affective components, as for Nu sounds, both NH and CI individuals triggered the promptest pre-motor reaction time (shorter pm-RT) when compared to P and N sounds. Only NH individuals modulated sound distance with the level of sound arousal, while sounds valence was similarly perceived by both NH and CI individuals. These results underline the role of emotional states in action preparation and describe the specific perceptual components necessary to properly react to approaching sounds within peripersonal space.

neuroscience↗