Biology subjects

Zvilichovsky, Y.

Publications and source records attributed to Zvilichovsky, Y..

7 recordsLinked to original sources

bioRxiv2025

Unreal? A Behavioral, Physiological, and Computational Model of the Sense of Reality

Our awareness of dreams, hallucinations, and illusions reflects an intriguing human capacity to recognize potentially false perceptions, known as the Sense of Reality (SoR). Though central to mental health, the study of SoR has been hindered by the subjective nature of hallucinatory experiences. Here we employed a novel virtual reality paradigm simulating virtual hallucinations, mirroring the phenomenology of clinical hallucinations. Combining psychophysics, physiological recordings, and computational modeling in one exploratory (n = 31) and one preregistered experiment (n = 32), we found that SoR varied with virtual hallucination magnitude and domain. SoR judgments were associated with distinct motor, pupillary, and cardiac responses, allowing classification of virtual hallucination exposure. We present a computational model in which SoR judgments arise from comparing current sensory input to an internal model of the world. Our results shed light on the age-old question how do we know what is real?

neuroscience↗

bioRxiv2024

Neural Correlates of the Embodied Sense of Agency

The Sense of Agency (SoA) is the subjective experience that I am in control of my actions. Recent accounts have distinguished two levels in the formation of SoA - early implicit sensorimotor processes (feeling of agency) and later explicit higher-level processes, incorporating ones thoughts and beliefs (judgment of agency). Even though SoA is fundamental to our interactions with the external world and the construct of the self, its underlying neural mechanism remains elusive. In the current pre-registered electroencephalography (EEG) study, we used time-frequency analysis and Multivariate Pattern Analysis (MVPA) to investigate the electrophysiological characteristics associated with SoA. We used an established embodied virtual reality paradigm in which visual feedback of a movement is modulated to examine the effect of conflicts between the predicted and perceived sensory feedback. Participants moved their finger and were shown a virtual hand that either mimicked their movement or differed anatomically (different finger) or spatially (angular shift), then judged their SoA over the observed movement while their brain activity was recorded. In accordance with our pre-registered hypothesis, we found that a reduction of SoA is associated with decreased attenuation in the alpha frequency band. Increased power in the theta frequency band was also associated with SoA reduction. Importantly, we show that trials containing a sensorimotor alteration vs. trials containing no alteration can reliably be decoded with up to 68% accuracy starting around 200ms after the movement onset. Finally, cross-decoding analyses revealed similar neural patterns for reduced SoA in the anatomical and spatial conditions, starting around 500ms after the movement onset. Together, our results reveal a cortical signature of loss of SoA and provide neural evidence supporting the hypothesis of a two-level formation of SoA - an early domain-specific component, possibly the equivalent of the implicit feeling of agency, and a late domain-general component, possibly the equivalent of the explicit judgment of agency.

neuroscience↗

bioRxiv2024

'Eye Know': Gaze reflects confidence in explicit predictions while relying on a distinct computational mechanism

Decisions are naturally accompanied by a feeling of confidence in their correctness. Typically measured via self-reported judgments, decision confidence is also expressed implicitly through sensorimotor behavior. In one exploratory and two preregistered experiments (total N = 115), we combined VR-based probabilistic-learning and spatial-cueing paradigms with computational modeling to examine whether post-decision gaze can serve as an implicit behavioral measure of decision confidence. Gaze direction generally aligned with predictive decisions about a targets upcoming location, while the degree of alignment tracked the model-based probability underlying the decision. Gaze-decision alignment also exhibited previously established statistical hallmarks of confidence. Under increased uncertainty, gaze and decisions tended to diverge, reflecting strategic "hedging" behavior. Gaze-decision alignment and explicit confidence judgments were modestly correlated, and remained correlated after controlling for the decisions probability, suggesting that the two are partially overlapping manifestations of internal confidence. Notably, reported confidence showed higher metacognitive sensitivity and increased serial dependence across trials, while gaze-based confidence expressed a more trial-specific readout of internal confidence. These findings suggest that post-decision gaze in visual-spatial learning tasks is an implicit, embodied manifestation of confidence. The complementary functional characteristics of implicit and explicit expressions of confidence may support adaptive behavior during learning.

neuroscience↗

bioRxiv2024

Neurophysiological Patterns of Attention and Distraction during Realistic Virtual-Reality Classroom Learning in Adults with and without ADHD

Many people, and particularly individuals with Attention Deficit (Hyperactivity) Disorder (AD(H)D), find it difficult to maintain attention during classroom learning. However, traditional paradigms used to evaluate attention do not capture the complexity and dynamic nature of real-life classrooms. Using a novel Virtual Reality platform, coupled with measurement of neural activity, eye-gaze and skin conductance, here we studied the neurophysiological manifestations of attention and distractibility, under realistic learning conditions. Individuals with AD(H)D exhibited higher neural responses to irrelevant sounds and reduced speech tracking of the teacher, relative to controls. Additional neurophysiological measures, such the power of alpha-oscillations and frequency of gaze-shifts away from the teacher, contributed to explaining variance in self-reported AD(H)D symptoms across the sample. These ecologically-valid findings provide critical insight into the neurophysiological mechanisms underlying individual differences in the capacity for sustained attention and the proneness to distraction and mind-wandering, experienced in real-life situations.

neuroscience↗

bioRxiv2024

The Body Knows Better: Sensorimotor signals reveal "Suboptimal" inference of the Sense of Agency in the human mind

Sense of Agency (SoA) is the feeling of control over our actions. SoA has been suggested to arise from both implicit sensorimotor integration as well as higher-level decision processes. SoA is typically measured by collecting participants subjective judgments, conflating both implicit and explicit processing. Consequently, the interplay between implicit sensorimotor processing and explicit agency judgments is not well understood. Here, we evaluated in one exploratory and one preregistered experiment (N=60), using a machine learning approach, the relation between a well-known mechanism of implicit sensorimotor adaptation and explicit SoA judgments. Specifically, we examined whether subjective judgments of SoA and sensorimotor conflicts could be inferred from hand kinematics in a sensorimotor task using a virtual hand (VH). In both experiments participants performed a hand movement and viewed a virtual hand making a movement that could either be synchronous with their action or include a parametric temporal delay. After each movement, participants judged whether their actual movement was congruent with the movement they observed. Our results demonstrated that sensorimotor conflicts could be inferred from implicit motor kinematics on a trial by trial basis. Moreover, detection of sensorimotor conflicts from machine learning models of kinematic data provided more accurate classification of sensorimotor congruence than participants explicit judgments. These results were replicated in a second, preregistered, experiment. These findings show evidence of diverging implicit and explicit processing for SoA and suggest that the brain holds high-quality information on sensorimotor conflicts that is not fully utilized in the inference of conscious agency.

neuroscience↗

bioRxiv2024

An ecological investigation of the effect of background noise on speech processing in a Virtual Classroom

Many real-life situations can be extremely noisy. Psychoacoustic studies have shown that background noise can have a detrimental effect on the ability to process and understand speech. However, most studies use stimuli and task designs that are highly artificial, limiting their generalization to more realistic contexts. Moreover, to date, we do not fully understand the neurophysiological consequences of trying to pay attention to speech in a noisy place. To address this lab to real-life gap and increase the ecological validity of speech in noise research, here we introduce a novel audiovisual Virtual Reality (VR) experimental platform. Combined with neurophysiological measurements of neural activity (EEG), eye-gaze and skin conductance (GSR) we studied the effects of background noise in a realistic context where the ability to process and understand continuous speech is especially important: A VR Classroom. Participants (n=32) sat in a VR Classroom and were told to pay attention to mini-lecture segments by a virtual teacher. Trials were either Quiet or contained background construction noise, emitted from outside the classroom window, which was either Continuous (drilling) or Intermittent (air hammers). Result show that background noise had a detrimental effect on learning outcomes, which was also accompanied by reduced neural tracking of the teachers speech. Comparison of the two noise types showed that the intermittent construction noise was more disruptive than continuous noise, as index by both behavioral and neural measures, and it also elicited higher skin-conductance levels, reflecting heightened arousal. Interesting, eye-gaze dynamics were not affected by the presence of noise. This study advances our understanding of the neurophysiological effects of background noise and extends it to more ecologically relevant contexts. It also emphasizes the role that temporal dynamics play for processing speech in noise, highlighting the need to consider the features of realistic noises, as we expand speech in noise research to increasingly realistic circumstances.

neuroscience↗

bioRxiv2022

Covert detection of own-name and semantic violations in task-irrelevant speech, in a realistic Virtual Cafe

Detecting that someone has said your name is one of the most famous examples for incidental processing of supposedly-unattended speech. However, empirical investigation of this so-called "cocktail party effect" has yielded conflicting results. We present a novel empirical approach for revisiting this effect under highly ecological conditions, by immersing participants in a multisensory virtual cafe environment and using realistic stimuli and tasks. Participants listened to conversational speech from a character sitting across from them, while a barista in the back of the cafe called out food orders. Unbeknownst to them, the barista sometimes called orders containing their own name or semantic violations. We used combined measurements of brain activity (EEG), eye-gaze and galvanic skin response to assess the response-profile to these two probes in the task-irrelevant barista-stream. Both probes elicited unique neural and physiological responses relative to control stimuli, indicating that the system indeed processed these words and detected their unique status, despite being task-irrelevant. Interestingly, these responses were covert in nature and were not accompanied by gaze-shifts towards the barista character. This pattern demonstrates that under these highly ecological conditions, listeners incidentally pick up information from task-irrelevant speech, emphasizing the dynamic and non-binary nature of attention in real-life environments.

neuroscience↗