Biology subjects

Shalev, N.

Publications and source records attributed to Shalev, N..

5 recordsLinked to original sources

bioRxiv2026

Prediction Is Preserved but Long-Timescale Benefits Are Reduced in ADHD

Attention-deficit/hyperactivity disorder (ADHD) has been associated with atypical temporal processing across multiple cognitive domains. However, most evidence derives from simplified paradigms that isolate timing from spatial behaviour. Here, we examine how temporal prediction operates within a continuous, dynamic visual environment. Using the Dynamic Visual Search (DVS) task, we embedded spatiotemporal regularities into a sustained stream of visual events, allowing observers to implicitly learn and anticipate predictable targets. Continuous mouse tracking provided a fine-grained measure of action planning beyond discrete reaction time and accuracy metrics. Young adults diagnosed with ADHD (N=40) were compared to matched neurotypical controls (N=38). Both groups benefited from target predictability and reduced distractor load, indicating intact early spatiotemporal learning in ADHD. Across the duration of the task, however, the groups diverged. Neurotypical participants showed progressive increases in behavioural benefits from prediction, accompanied by increasingly direct and efficient mouse trajectories. In contrast, individuals with ADHD reached a plateau in prediction benefits midway through the experiment. Their performance remained stable, with minimal evidence of resource depletion, but did not show further optimisation based on learned regularities. These findings suggest that while prediction formation is preserved in ADHD, its progressive utilisation across longer timescales is attenuated. Rather than reflecting a primary deficit in learning or sustained attention, ADHD may involve altered long-timescale integration or weighting of predictive information in dynamic environments.

neuroscience↗

bioRxiv2025

Feel the Beat: The Impact of Rhythms on Dynamic Visual Search

Rhythms are everywhere - we encounter them daily within our environment and produce them regularly through our movements, speech and sensory systems. In both cognitive and clinical contexts, external rhythms have been shown to enhance performance when they are aligned with, predict, or entrain stimuli onsets or relevant moments in time. In this study, we aimed to understand the impact of external and internal rhythms on performance in a task devoid of rhythmic temporal structure. We thus investigated the differential impact of auditory beats (1-, 2-, 5-Hz, or no beat) on detection in a non-rhythmic, dynamic search task requiring the continuous deployment of attention. We additionally assessed whether the influence of auditory beats on detection was modulated by individuals rhythmic preferences as measured by their spontaneous motor tempo. Overall, we found that auditory rhythms enhanced visual task performance, even in the absence of rhythmic structure within the measured task, improving both detection accuracy and response speed. This enhancement was tempo-dependent, with the strongest facilitation observed at 2 Hz. The magnitude of the observed benefits varied with individuals spontaneous motor tempo, such that participants with slower SMTs exhibited the greatest performance benefits due to the presence of auditory rhythms. We propose that rhythmic stimulation may serve as a powerful scaffold for sustained performance in the context of dynamic and temporally unpredictable environments.

neuroscience↗

bioRxiv2022

Rhythmic Modulation of Visual Discrimination is Dependent on Individuals' Spontaneous Motor Tempo

Rhythmic structure in our daily experience originates from various sources. It is generated endogenously and observed in spontaneous fluctuations in behaviour and performance. It can also arise exogenously from everyday stimuli, such as speech, motion and music. Here we examined how individual differences in spontaneous motor rhythms affect the tendency to use external rhythmic structure to guide perception. To measure individual differences in spontaneous rhythms of performance we utilized a spontaneous tapping task. To measure individual differences in perceptual rhythmic modulation we designed a visual discrimination task in which targets can appear either in-phase or out-of-phase with a preceding rhythmic stream of visual stimuli. We manipulated the tempo of the visual stream over different experimental blocks (0.77 Hz, 1.4 Hz, 2 Hz). We found that visual rhythmic stimulation modulates discrimination performance. The modulation was dependent on the tempo of stimulation, with maximal perceptual benefits for the slowest tempo of stimulation (0.77 Hz). Most importantly, the strength of modulation was also affected by individuals spontaneous motor tempo. Specifically, individuals with slower spontaneous tempi showed greater rhythmic modulation compared to individuals with faster spontaneous tempi. This discovery suggests that different tempi affect the cognitive system with varying levels of efficiency, and that self-generated rhythms impact our ability to utilize rhythmic structure in the environment for guiding perception and performance.

neuroscience↗

bioRxiv2021

Right fronto-parietal networks mediate the neurocognitive benefits of enriched environments.

Exposure to enriched environments (EE) throughout a lifetime, providing so called reserve, protects against cognitive decline in later years. It has been hypothesised that high levels of alertness necessitated by EE might strengthen the right fronto-parietal networks (FPN) to facilitate this neurocognitive resilience. We have previously shown that EE offset age-related deficits in selective attention by preserving grey matter within right fronto-parietal regions. Here, using neurite orientation dispersion and density imaging (NODDI), we examined the relationship between EE, microstructural properties of fronto-parietal white matter association pathways (three branches of the superior longitudinal fasciculus, SLF), structural brain health (atrophy), and attention (alertness, orienting and executive control) in a group of older adults. We show that EE is associated with a lower orientation dispersion index (ODI) within the right SLF1 which in turn mediates the relationship between EE and alertness, as well as grey- and white-matter atrophy. This suggests that EE may induce white matter plasticity (and prevent age-related dispersion of axons) within the right FPN to facilitate the preservation of neurocognitive health in later years.

neuroscience↗

bioRxiv2020

Eyes wide open: regulation of arousal by temporal expectations

To perform a task continuously over an extended period of time, it is necessary to maintain an adequate level of arousal. In cognitive research, traditional studies have used repetitive, monotonous tasks to learn about the dynamics of arousal in tasks that require sustained vigilance, such as driving or monitoring a factory line. To date, studies have rarely considered whether observers use task-embedded regularities in such continuous contexts to anticipate events and regulate arousal accordingly. In the current study, we explored whether arousal is an adaptive process that reacts to temporal stimulus predictability. Across two experiments, we used pupillometry as a proxy measure of arousal in human observers performing continuous tasks. Within the tasks, we manipulated the temporal predictability of relevant events by presenting stimuli either in a fixed rhythm or at varied intervals. Temporal predictability led to the lowering of tonic levels of arousal. Trial-wise temporal structures led to short-scale changes in pupil size related to temporal anticipation. Accordingly, we suggest that arousal is sensitive to varying levels of temporal predictability and dynamically adapts to task demands to bring about performance benefits as well as energetic efficiencies overall. Statement of RelevancePeople often have to sustain focus and high levels of performance on extended and non-stimulating tasks (e.g., driving, sowing, monitoring data acquisition). A critical factor to the success (or failure) in sustained performance is arousal - the energetic state of the cognitive system. Here we used pupil dilation as a proxy to study levels of arousal during sustained performance on monotonous tasks. We reveal that arousal is dynamically regulated to support performance according to an important fundamental property of any task: its temporal structure. When the timing of task-relevant events is predictable, arousal levels fluctuate accordingly, saving energy overall while also optimally guiding performance. Our study and findings add ecological validity to the study of temporal expectations, by moving investigations beyond typical trial-by-trial designs. They also carry significant implications for clinical studies relying on sustained performance tasks.

neuroscience↗