Biology subjects

Strauss, D. J.

Publications and source records attributed to Strauss, D. J..

10 recordsLinked to original sources

bioRxiv2026

Immersion as inference: An active inference account of induced realities and its relation to the two-competitor model

Immersive technologies are designed for a single target: the human perceptual system. Engineers of virtual and augmented reality have long recognized that a display does not have to replicate the physical world, it only has to provide the inputs that satisfy the senses at the level at which the brain samples them. This engineering intuition is, in fact, a statement about brain function. Here we develop it into a formal account of immersion within the active inference framework. We treat an induced reality (a virtual, augmented, or mixed reality, but also a book or a daydream) as a candidate generative model that competes with the model of the actual reality for the explanation of a shared sensorium and for the control of action. Immersion is then defined as the ensuant belief that the induced reality best explains the current sensory signals and supports the current perceived reality of the winning model, despite any break in immersion by Bayesian model switching driven by a high-precision prediction error that the induced model cannot absorb. Exogenous and endogenous attention, implemented as weights governing stream selection in our earlier two-competitor model, which treated attention as necessary but not sufficient for immersion, appear as two routes of precision allocation: likelihood precision of evolutionarily entrenched sensory events, and precision that follows the expected free energy of policies. Affect and motivation enter through the pragmatic and epistemic value of remaining in the induced reality and through the rate of change of free energy. We show that the two-competitor attentional focus vector and its angle are recovered from the active inference variables, and we reproduce the two scenarios of the original model, a rewarding and a fatiguing activity interrupted by a slamming door, in a minimal simulation. The account links presence, embodiment, cybersickness, and narrative absorption to a single quantity, and it yields concrete predictions for the psychophysiological assessment and closed-loop control of immersion. We discuss implications for neuroergonomic design in which the evolutionarily entrenched core of perception is non-negotiable while its experience-dependent periphery can be trained.

neuroscience↗

bioRxiv2026

Impact of Driving Dynamic Fluctuations of 6DOF-SVC Model Predictions Across Five Real-World Driving Studies

Despite the use of technological countermeasures, studies show that the sensory conflict, and thus symptoms of motion sickness such as nausea, cannot be completely prevented while traveling as a car passenger. Accordingly, reliable prediction of motion sickness will represent a possible solution for intelligent vehicles to avoid the abortion of the drive, e.g., through adapted driving strategies or route planning. In previous works, the authors were able to demonstrate an application-oriented parameter set for the popular 6DOF-SVC model to estimate motion sickness incidence (MSI) in passengers with a lowered gaze on a non-driving-related task. In the current study, these parameters were validated and further optimized using five previous conducted motion sickness driving experiments. For the first time, it is also shown that the expected natural MSI fluctuations based on the driving dynamic profile, due to route characteristics or driving style, as well as the variation in experimental determined MSI is approximately 10%. Moreover, findings indicate that the participants appear to have an individual MSI threshold that correlates with their susceptibility to motion sickness, however, this threshold fluctuates too strongly across experiments to be suitable for practical application. As a result, the model can successfully estimate motion sickness risk across the test tracks, however, inaccuracies in the predicted MSI trajectories remain.

bioengineering↗

bioRxiv2024

Feeling Senseless Sensations: A Crossmodal study of mismatching tactile and virtual visual experience

To create highly immersive experiences in virtual reality (VR) it is important to not only include the visual sense but also to involve multimodal sensory input. To achieve optimal results, the temporal and spatial synchronization of these multimodal inputs is critical. It is therefore necessary to find methods to objectively evaluate the synchronization of VR experiences with a continuous tracking of the user. In this study a passive touch experience was incorporated in a visual-tactile VR setup using VR glasses and tactile sensations in mid-air. Inconsistencies of multimodal perception were intentionally integrated into a discrimination task. The participants electroencephalogram (EEG) was recorded to obtain neural correlates of visual-tactile mismatch situations. The results showed significant differences in the event-related potentials (ERP) between match and mismatch situations. A biphasic ERP configuration consisting of a positivity at 120 ms and a later negativity at 370 ms was observed following a visual-tactile mismatch. This late negativity could be related to the N400 that is associated with semantic incongruency. These results provide a promising approach towards the objective evaluation of visual-tactile synchronization in virtual experiences.

neuroscience↗

bioRxiv2024

Fifty Years After: The N1 Effect Travels Down to the Brainstem

Fifty years ago, it was reported that selective attention affects the N1 wave in auditory event-related potentials. We revisited the original study design but integrated the state of the art knowledge on short auditory stimuli and neural signal processing. In particular, one series of tone bursts has been replaced by chirp stimuli which are optimized to evoke consistent brainstem potentials at low and medium stimulation levels. Auditory selective attention affected the chirp- evoked response in subcortical structures, even at level of the inferior colliculi. A single-trial time-frequency analysis of the full-range (0-250ms) event-related potentials showed that selective attention increases the spectrotemporal consistency across trials in the corticofugal auditory pathway, at least from the N1 wave down to the auditory brainstem response.

neuroscience↗

bioRxiv2023

Electromyographic Correlates of Effortful Listening in the Vestigial Auriculomotor System

Recently, electromyographic (EMG) signals of auricular muscles have been shown to be an indicator of spatial auditory attention in humans, based on a vestigial pinna-orienting system. Because spatial auditory attention in a competing speaker task is closely related to the more gen-eralized concept of attentional effort in listening, the current study inves-tigated the possibility that the EMG activity of auricular muscles could also reflect correlates of effortful listening in general. Twenty subjects were recruited. EMG signals from the left and right superior and poste-rior auricular muscles (SAM, PAM) were recorded while subjects attended a target podcast in a competing speaker paradigm. Three different lev-els of listening effort, low, medium, and high, were generated by varying the number and pitch of distractor streams, as well as the signal-to-noise ratio. All audio streams were either presented from a loudspeaker placed in front of the participants (0{degrees}), or in the back (180{degrees}). Averaged PAM activity was not affected by different levels of listening effort, but was sig-nificantly larger when stimuli were presented from the back, as opposed to the front. Averaged SAM activity, however, was significantly larger in the high listening effort condition, compared to low and medium, but was not affected by stimulus direction. We hypothesize that the increased SAM activity is a response of the vestigial pinna-orienting system to effortful stream segregation task.

neuroscience↗

bioRxiv2023

Linear modeling of brain activity during selectiveattention to continuous speech: the critical role of the N1 effect in event-related potentials to acoustic edges

Recent work in the field of neural speech tracking provided evidence for a cortical rep-resentation of speech through superposition of event-related responses to acoustic edges, an idea closely related to the popular linear modeling approach to study cortical syn-chronization to speech via magneto- or electroencephalography (M/EEG). However, it is still unclear to what extent speech-evoked event-related potentials (ERPs) including well-established phenomena, e.g., the N1 selective attention effect, contribute to the regression-based analyses. Here, we addressed this question by analyzing an EEG dataset obtained during a simple multispeaker selective attention task in which participants were cued to attend to only one of two competing speakers. Segmenting the ongoing EEG based on acoustic edges, we were able to replicate previous findings of event-related responses to speech in MEG data with particularly clear P1-N1-P2 complexes. Crucially, speech-evoked ERPs exhibited significant effects of attention in line with the auditory N1 effect. Comparing speech-evoked ERPs to the linear regression results revealed two major find-ings. First, temporal response functions (TRFs) obtained from forward modeling were strongly temporally as well as spatially correlated with corresponding true ERPs. Sec-ond, effects of attention demonstrated by the stimulus reconstruction (SR) accuracies obtained from backward modeling appeared to be driven by a consistent generation of speech-evoked ERPs including the N1 effect. Taken together, our observations reveal a direct link between ERPs to acoustic edges in speech and the linear TRF and SR mod-eling techniques. We emphasize the enhancement in signal-to-noise ratio provided by repeatedly evoked N1 responses to be a critical factor in facilitating the tracking and subsequent higher-order processing of selectively attended speech. In addition to that, the findings imply a cortical speech representation through superimposed speech-evoked ERPs in accordance with recent arguments promoting the neural evoked-response speech tracking model.

neuroscience↗

bioRxiv2023

The Role of Attention in Immersion: The Two-Competitor Model

Currently, we face an exponentially increasing interest in immersion, especially sensory-driven immersion, mainly due to the rapid development of ideas and business models centered around a digital virtual universe as well as the increasing availability of affordable immersive technologies for education, communication, and entertainment. However, a clear definition of immersion, in terms of established neurocognitive concepts and measurable properties, remains elusive, slowing research on the human side of immersive interfaces. To address this problem, we propose a conceptual, taxonomic model of attention in immersion. We argue (a) modeling immersion theoretically as well as studying immersion experimentally requires a detailed characterization of the role of attention in immersion, even though (b) attention, while necessary, cannot be a sufficient condition for defining immersion. Our broader goal is to characterize immersion in terms that will be compatible with established psychophysiolgical measures that could then in principle be used for the assessment and eventually the optimization of an immersive experience. We start from the perspective that immersion requires the projection of attention to an induced reality, and build on accepted taxonomies of different modes of attention for the development of our two-competitor model. The two-competitor model allows for a quantitative implementation and has an easy graphical interpretation. It helps to highlight the important link between different modes of attention and affect in studying immersion.

neuroscience↗

bioRxiv2021

Software for Non-Parametric Image Registration of 2-Photon Imaging Data

Functional 2-photon microscopy is a key technology for imaging neuronal activity. The recorded image sequences, however, can contain non-rigid movement artifacts which requires high-accuracy movement correction. Variational optical flow (OF) estimation is a group of methods for motion analysis with established performance in many computer vision areas. However, it has yet to be adapted to the statistics of 2-photon neuroimaging data. In this work, we present the motion compensation method Flow-Registration that outperforms previous alignment tools and allows to align and reconstruct even low signal-to-noise ratio 2-photon imaging data and is able to compensate high-divergence displacements during local drug injections. The method is based on statistics of such data and integrates previous advances in variational OF estimation. Our method is available as an easy-to-use ImageJ / FIJI plugin as well as a MATLAB toolbox with modular, object oriented file IO, native multi-channel support and compatibility with existing 2-photon imaging suites.

neuroscience↗

bioRxiv2020

Fast Variational Alignment of non-flat 1D Displacements for Applications in Neuroimaging

BackgroundIn the context of signal analysis and pattern matching, alignment of 1D signals for the comparison of signal morphologies is an important problem. For image processing and computer vision, 2D optical flow (OF) methods find wide application for motion analysis and image registration and variational OF methods have been continuously improved over the past decades. New MethodWe propose a variational method for the alignment and displacement estimation of 1D signals. We pose the estimation of non-flat displacements as an optimization problem with a similarity and smoothness term similar to variational OF estimation. To this end, we can make use of efficient optimization strategies that allow real-time applications on consumer grade hardware. ResultsWe apply our method to two applications from functional neuroimaging: The alignment of 2-photon imaging line scan recordings and the denoising of evoked and event-related potentials in single trial matrices. We can report state of the art results in terms of alignment quality and computing speeds. Existing MethodsExisting methods for 1D alignment target mostly constant displacements, do not allow native subsample precision or precise control over regularization or are slower than the proposed method. ConclusionsOur method is implemented as a MATLAB toolbox and is online available. It is suitable for 1D alignment problems, where high accuracy and high speed is needed and non-constant displacements occur.

neuroscience↗

bioRxiv2019

Vestigial Auriculomotor Activity Indicates the Direction of Auditory Attention in Humans

It is commonly assumed that, unlike dogs and cats, we humans do not make ear movements when focusing our attention reflexively toward novel sounds or voluntarily toward those that are goal-relevant. In fact, it has been suggested that we do have a pinna-orienting system. Although this system became vestigial about 25 million years ago, it still exists as a \"neural fossil\" within the brain. Consistent with this hypothesis, we demonstrate for the first time that the direction of auditory attention is reflected in the sustained electrical activity of muscles within the vestigial auriculomotor system.\n\nSurface electromyograms (EMGs) were taken from muscles that either move the pinna or alter its shape. To assess reflexive, stimulus-driven attention we presented novel sounds from speakers at four different lateral locations while the participants silently read a boring text in front of them. To test voluntary, goal-directed attention we instructed participants to listen to a short story coming from one of these speakers, while ignoring a competing story from the corresponding speaker on the opposite side.\n\nIn both experiments, EMG recordings showed larger activity at the ear on the side of the attended stimulus, but with slightly different patterns. Upward movement (perking) differed according to the lateral focus of attention only during voluntary orienting; rearward folding of the pinnas upper-lateral edge exhibited such differences only during reflexive orienting. The existence of a pinna-orienting system in humans, one that is experimentally accessible, offers opportunities for basic as well as applied science. It could lead to a better understanding of the evolution of auditory attention and support the near real-time decoding of auditory attention in technical applications, for example, for attentionally controlled hearing aids that preferentially amplify sounds the user is attempting to listen to.

neuroscience↗