Biology subjects

Giersch, A.

Publications and source records attributed to Giersch, A..

4 recordsLinked to original sources

bioRxiv2026

Passage of time at the level of milliseconds: a new approach and a selective difficulty in individuals with schizophrenia

Background and HypothesisIndividuals with schizophrenia report that to them time sometimes feels discontinuous. Previous work has shown a link between the sense of self, and the ability to prepare to react to a target and to benefit from the passage of time, at the level of a few hundreds of milliseconds. However, the sense of time continuity requires a higher time resolution than examined in previous studies. Here we investigate to which extent individuals with schizophrenia and controls benefit from an increased delay when detecting asynchronies in the order of tens of milliseconds (stimulus onset asynchronies, i.e. SOA) between two successive visual stimuli. Study DesignWe re-analyzed three datasets and contrasted performance when the SOA increases, remains identical or decreases from trial t-1 to trial t. Study ResultsPerformance of all participants improved with an increase in the SOA, as the task became easier, but for controls more so than individuals with schizophrenia. These results are replicated across datasets, and were specific to the condition when SOA increased from one trial to the next. There was no significant group difference when the SOA decreased or remained identical. This was true even when the latter condition was more frequent, and when SOA magnitude was equalized across the conditions. Importantly, the difference between the two groups was specific to temporal judgements, and was not observed in a control masking task. ConclusionsWe suggest the results reveal a difficulty for individuals with schizophrenia to experience time at the level of milliseconds.

neuroscience↗

bioRxiv2026

Modeling how contextual and structural biases shape duration perception

Human time perception is flexible and shaped by both structural constraints and contextual influences. Disentangling these sources of bias is essential for understanding the predictive mechanisms underlying temporal perception, yet no unified model currently integrates them. Here, we quantified precisely the structural and contextual biases in a duration discrimination task to constrain models of duration perception. Using a two-interval duration discrimination task, participants judged which of the two stimuli lasted longer. Stimuli were both visual, both auditory, or one of each modality. Consistent with previous findings, auditory stimuli were perceived longer than visual stimuli of equal duration, reflecting intrinsic properties of audiovisual neural processing. Contextual biases were manipulated through different duration distributions from which stimuli were drawn, a procedure known to influence temporal judgments. Our results show that duration discrimination relies on distinct representations of each stimulus distribution and is best explained by a combination of Bayesian inference and rescaling. While Bayesian inference accounts for contextual effects that bring perceived durations closer to the mean of each distribution, rescaling mechanisms have the opposite effects. These findings challenge existing accounts of contextual effects in time perception and suggest that the brain normalizes temporal representations to adapt to environmental statistics. FundingsThis work was supported by the FRC and the UNAFAM association, and scientific expertise is provided by the FRCs Scientific Advisory Board, and the Anneliese Maier Award to Pascal Mamassian from the Alexander von Humboldt Foundation. Data availabilityBehavioral data and modeling codes will be open-access upon publication.

neuroscience↗

bioRxiv2025

Medial prefrontal cortex encodes implicit temporal expectations in mice

Temporal prediction allows animals to align their actions with upcoming events, yet most work has focused on explicit duration judgments rather than the implicit timing that shapes ongoing behavior. Here, we ask how medial prefrontal cortex implements such latent temporal expectations and how cerebellar input contributes. Head-fixed mice learned a cued water-delivery task in which reward occurred after either a short or long delay, or after a single fixed delay. During variable delays, running and licking became anticipatory, and medial prefrontal local field potentials and single neurons showed ramping and reward-locked activity patterns aligned to expected reward time. Switching to a fixed delay rapidly sharpened behavioral anticipation and temporal coding. Optogenetic activation of cerebellar Purkinje cells selectively perturbed these dynamics and biased behavior around the earliest possible reward time. These results identify a cerebello-prefrontal circuit that encodes implicit temporal predictions on the sub-second scale.

neuroscience↗

bioRxiv2025

Subthreshold violations of trajectory predictions are sensitive to TMS of Cerebellum CRUS I/II

Temporal prediction can help to follow a trajectory. In case of an error, the prediction can be adjusted. However, processing the error and adjusting the prediction can take time. What happens immediately after a prediction error, and can the processing of the prediction be modulated? We use a newly found illusion based on moving squares and requiring trajectory regularity to be elicited. We examined the conscious consequences of a sub-threshold manipulation of the square trajectories, and transcranial magnetic stimulation (TMS) on the cerebellum (right CRUS I/II) to study the modulation of the processing of the trajectory manipulations. The TMS was a typical intermittent theta-burst stimulation, but only one sequence of around 3 minutes, compared with a placebo stimulation. The trajectory manipulation had a reliable effect on the illusion, even though the illusion emerged within less than 100 ms after the trajectory manipulation. The results suggest that the prediction is temporarily stopped after the trajectory change. The illusion was accompanied by EEG signals whose amplitude was modulated by TMS on the cerebellum, at least in those participants who received verum TMS after having performed the task three times. Those EEG signals resembled a late LPP (Late Positive Potential). As LPP spontaneously decreased over time, the results suggest the effect of TMS may represent a reinstation of the EEG consequences of the prediction error, i.e., a modulation of its significance.

neuroscience↗