Carlotta Lega

Bodily rhythms are increasingly recognized as active organizers of brain function. Respiration, in particular, rhythmically modulates cortical excitability, perceptual sensitivity, memory, and action well beyond its homeostatic role. Whether breathing also shapes the brain's representation and generation of time, however, remains poorly understood. Here, we asked whether respiratory phase modulates two complementary domains of human timing, temporal perception and temporal production. Across two experiments in healthy adults (N = 40 each), respiration was continuously recorded and instantaneous respiratory phase reconstructed using Hilbert-transform-based analyses. In Experiment 1, participants performed an auditory temporal bisection task, judging intervals as “short” or “long” relative to previously learned anchors. Stimulus presentation was prospectively triggered at different phases of the respiratory cycle. Temporal judgments varied systematically with respiratory phase, particularly for perceptually ambiguous intervals: identical durations were judged as longer around peak inhalation/early expiration and shorter near peak exhalation. This modulation was specific to respiratory phase during stimulus presentation and was absent when phase was measured at the subsequent manual response, supporting a perceptual rather than response-related locus. In Experiment 2, participants synchronized finger taps to auditory metronomes at three tempi (75, 100, and 125 bpm) and subsequently continued tapping at the same tempo without external pacing. During self-paced continuation, the respiratory phases associated with slowest tapping clustered consistently across participants, particularly at the slowest tempo, with shorter inter-tap intervals occurring around inspiration. No corresponding respiratory modulation emerged during externally paced synchronization. Together, these findings suggest that respiration rhythmically shapes both perceived and self-generated time, consistent with a transient acceleration of internal timing around inspiration. Thus, the brain’s sense of time may fluctuate with each breath, suggesting that temporal processing is dynamically embedded within the ongoing physiological rhythms of the body.

Humans can flexibly extract a regular beat from complex rhythmic auditory patterns, as often occurs in music. Contemporary models of beat perception suggest that the premotor cortex (PMC) and the supplementary motor area (SMA) are integral to this process. However, how these motor planning regions actively contribute to beat perception, along with any potential hemispheric specialization, remains open questions. Therefore, following the validation of stimuli in a behavioral experiment (Experiment I, N = 29, 12 males, mean age = 23.8 ± 0.7 years), we employed transcranial magnetic stimulation (TMS) to test the causal contribution of these regions to beat perception. In Experiment II (N = 40, 16 males, mean age = 23.2 ± 2.37 years), we applied online repetitive TMS (rTMS) over a defined grid encompassing the right rostral and caudal dPMC, SMA, and pre‐SMA, and a sham control location. Results showed that stimulation of the caudal portion of right dPMC selectively affected beat perception compared to all other regions. In Experiment III (preregistered, N = 42, 17 males, mean age = 23.5 ± 2.61 years), we tested the lateralization of this contribution by applying rTMS over right and left caudal dPMC. Our results showed that only stimulation over right, but not left, dPMC modulated beat perception. Finally, across all three experiments, individual differences in musical reward predicted beat perception sensitivity. Together, these results support the causal role of the right dPMC in generating internal action predictions and perceptual expectations regarding ongoing sequential events, in line with recent models emphasizing the role of the dorsal auditory stream in beat‐based temporal perception. These findings offer valuable insights into the functional organization of the premotor cortex, contributing to a deeper understanding of the neural mechanisms involved in human rhythm perception.

Introduction: Music making is a process by which humans across cultures come together to create patterns of sounds that are aesthetically pleasing. What remains unclear is how this aesthetic outcome affects the sensorimotor interaction between participants.Method: Here we approach this question using an interpersonal sensorimotor synchronization paradigm to test whether the quality of a jointly created chord (consonant vs. dissonant) affects movement coordination. We recruited non-musician participants in dyads to perform a dyadic synchronization-continuation task (dSCT): on each trial, participants first synchronized their movements to a metronome (synchronization phase) and then continued tapping together at the same tempo without the metronome (continuation phase). Each tap yielded a note and participants heard both their own and that of their partner, thus creating a chord that was varied to be either consonant (Perf5 or Maj6) or dissonant (Min2 or Maj2). For each trial, participants also rated the pleasure they felt in creating the sounds together. Additionally, they completed questionnaires about social closeness to the other participant, musical reward sensitivity and musical training.Results: Results showed that participants' taps were closer in time when they jointly created consonant (high pleasure) vs. dissonant (low pleasure) chords, and that pleasure experienced by the dyad in each trial predicted interpersonal synchronization. However, consonance did not affect individual synchronization with the metronome or individual tapping when the metronome was discontinued. The effect of consonance on synchronization was greater in dyads who reported feeling less close prior to the task.Discussion: Together, these results highlight the role of consonance in shaping the temporal coordination of our actions with others. More broadly, this work shows that the aesthetic outcome of what we create together affects joint behaviors.

Differences in sensorimotor integration mechanisms have been observed between people who stutter (PWS) and controls who do not. Delayed auditory feedback (DAF) introduces timing discrepancies between perception and action, disrupting sequence production in verbal and non-verbal domains. While DAF consistently enhances speech fluency in PWS, its impact on non-verbal sensorimotor synchronization abilities remains unexplored. A total of 11 PWS and 13 matched controls completed five tasks: (1) unpaced tapping; (2) synchronization-continuation task (SCT) without auditory feedback; (3) SCT with DAF, with instruction either to align the sound in time with the metronome; or (4) to ignore the sound and align their physical tap to the metronome. Additionally, we measured participants’ sensitivity to detecting delayed feedback using a (5) delay discrimination task. Results showed that DAF significantly affected performance in controls as a function of delay duration, despite being irrelevant to the task. Conversely, PWS performance remained stable across delays. When auditory feedback was absent, no differences were found between PWS and controls. Moreover, PWS were less able to detect delays in speech and tapping tasks. These findings show subtle differences in non-verbal sensorimotor performance between PWS and controls, specifically when action–perception loops are disrupted by delays, contributing to models of sensorimotor integration in stuttering.

Psychophysical observations indicate that the spatial profile of visuospatial attention includes a central enhancement around the attentional focus, encircled by a narrow zone of reduced excitability in the immediate surround. This inhibitory ring optimally amplifies relevant target information, likely stemming from top-down frontoparietal recurrent activity modulating early visual cortex activations. However, the mechanisms through which neural suppression gives rise to the surrounding attenuation and any potential hemispheric specialization remain unclear. We used transcranial magnetic stimulation to evaluate the role of two regions of the dorsal attention network in the center-surround profile: the frontal eye field and the intraparietal sulcus. Participants performed a psychophysical task that mapped the entire spatial attentional profile, while transcranial magnetic stimulation was delivered either to intraparietal sulcus or frontal eye field on the right (Experiment 1) and left (Experiment 2) hemisphere. Results showed that stimulation of right frontal eye field and right intraparietal sulcus significantly changed the center-surround profile, by widening the inhibitory ring around the attentional focus. The stimulation on the left frontal eye field, but not left intraparietal sulcus, induced a general decrease in performance but did not alter the center-surround profile. Results point to a pivotal role of the right dorsal attention network in orchestrating inhibitory spatial mechanisms required to limit interference by surrounding distractors.

In recent years, the use of implicit mechanisms based on statistical learning (SL) has emerged as a strong factor in biasing visuospatial attention, so that target selection is improved at frequently attended locations and distractor filtering is facilitated at frequently suppressed locations. Although these mechanisms have been consistently described in younger adults, similar evidence in healthy aging is scarce. Therefore, we studied the learning and persistence of SL of target selection and distractor suppression in younger and older adults in visual search tasks where the frequency of target (Experiment 1) or distractor (Experiment 2) was biased across spatial locations. The results show that SL of target selection was preserved in the older adults so, similar to their younger counterparts, they showed a strong and persistent advantage in target selection at locations more frequently attended. However, unlike young adults, they did not benefit from implicit SL of distractor suppression, so that distractor interference was maintained throughout the experiment independently of the contingencies associated with distractor locations. Taken together, these results provide novel evidence of distinct developmental patterns for SL of task-relevant and task-irrelevant visual information, likely reflecting differences in the implementation of proactive suppression attentional mechanisms between younger and older adults. Public Significance StatementHumans can use regularities in visual scenes to improve performance in finding relevant objects (targets) and inhibiting responses to irrelevant objects (distractors). The present study demonstrates that older adults can learn and exploit target-related but not distractor-related spatial regularities. This finding sheds further light on how the ability to use prior experience to guide attention may change in aging, with potential consequences for daily activities characterized by irrelevant distractors (e.g., driving).