Biology subjects

Nozaradan, S.

Publications and source records attributed to Nozaradan, S..

9 recordsLinked to original sources

bioRxiv2026

Neural categorisation of rhythm in human newborns

Music is ubiquitous across cultures, and humans engage in social interactions through music from early in life. A cornerstone of these interactions is rhythm categorisation, allowing the sheer diversity of rhythmic inputs to be mapped onto internal rhythm categories. The pervasiveness of certain rhythm categories across cultures suggests that rhythm categorisation may be partially rooted in neurobiological predispositions constraining the internal representations of rhythm. However, this view appears to conflict with the diversity of music practices across cultures, which points to a role of experience in rhythm categorisation. To assess the relative contributions of neurobiological predispositions and experience, we tested 0- to 3-day-old newborns, capitalising on their minimal postnatal experience with music. Using electroencephalography (EEG), we recorded, in newborns and adults, brain responses to drum sounds whose pattern of relative interval duration ranged from isochronous to long-short rhythms (1:1 - 2:1 interval ratio). Results indicate significant categorisation in newborns's neural responses, with a representational structure that correlate with those of adults, yet with a greater degree of differentiation across rhythms. These findings reveal neurobiological predispositions enabling rhythm categorisation to be present at birth and further shaped across the lifespan, highlighting the evolutionary roots and plasticity supporting this human cultural practice.

neuroscience↗

bioRxiv2026

Intracerebral recordings in humans reveal gradual emergence of musical beat representation across the dorsal auditory pathway

When experiencing music, humans readily perceive and move along with a periodic beat. This ability has been proposed to rely on an enhanced representation of the beat periodicity in brain activity. However, whether this beat representation is achieved in sensory areas or whether it involves associative brain regions remains debated. Here, we addressed this question using intracerebral depth electrodes implanted in 13 human individuals to record local field potentials directly inside the brain. Participants were presented with an acoustic rhythm known to induce perception of a consistent beat across Western adults. The rhythmic stimulus elicited significant responses in a number of areas, especially superior temporal, parietal and frontal cortices located along the dorsal auditory pathway. Notably, these regions, including the primary auditory cortex but also frontal motor regions, showed significantly enhanced beat periodicity as compared to a biomimetic model of subcortical auditory processing. This beat representation was further sharpened in the inferior parietal lobe, indicating that this associative region may play a key role in the mapping between rhythmic inputs and perceptual templates of beat, in line with its posited function as a sensory-motor interface. Together, these findings provide direct evidence for a gradual transformation of rhythmic sensory input into an abstract representation of beat periodicity. This process appears to rely on the dorsal auditory pathway as a functional network supporting the categorization of rhythmic stimuli into behaviorally relevant timing templates that may be experienced as the beat.

neuroscience↗

bioRxiv2026

Beyond Onset Timing: Longer Sound Envelope Duration Enhances Neural Representation of the Musical Beat

Musical rhythm is often experienced with a periodic beat, serving as a temporal reference for coordination with the rhythm. Thus far, models of beat processing have mainly relied on representing sensory inputs as patterns of onset timing, with limited consideration of other sensory features. Here, we challenge this view by showing that the internal representation of beat is affected by other temporal features of the stimulus beyond onset timing alone. We recorded electroencephalography (EEG) while participants listened to rhythmic sequences designed to elicit a beat. Across conditions, we manipulated the duration of the tones conveying the rhythms, while keeping all other parameters identical, including overall intensity, speed, and rhythmic pattern structure. Crucially, the beat periodicity was enhanced in neural activity with increased sound duration, even though the beat periodicity was not prominent in the acoustic features, thus ruling out basic sensory confounds. These results demonstrate the preferential role of longer sound durations in fostering temporal scaffolding processes that integrate fast rhythmic inputs into behavior-relevant internal structures such as the beat. More generally, our findings are compatible with a holistic processing account whereby a range of features beyond onset timing may be integrated into a neural representation of rhythm. Graphical Abstract: Fig. 2EEG was recorded while listeners heard rhythmic sequences eliciting a beat. Sound duration (sonic duty cycle) was varied across four conditions while speed, pattern, and intensity stayed constant. Beat-related EEG responses increased with longer sounds, and were enhanced in all conditions compared to auditory nerve model envelopes, which did not show prominent energy at the beat periodicity, ruling out sensory confounds. Results support holistic rhythm processing beyond onset timing alone. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/721298v1_fig2.gif" ALT="Figure 2"> View larger version (27K): org.highwire.dtl.DTLVardef@10a0599org.highwire.dtl.DTLVardef@f5a95forg.highwire.dtl.DTLVardef@42d1ceorg.highwire.dtl.DTLVardef@dc58a7_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 2.C_FLOATNO EEG and auditory nerve model output analysis based on magnitude spectrum and autocorrelation. Each row represents a duty cycle condition. The two columns on the left represent the magnitude spectrum-based analysis. The first column represents the group-level averaged magnitude spectra at a pool of fronto-central electrodes, across conditions. Beat-related frequencies are shown in red, and beat-unrelated frequencies are shown in blue. Scalp topographies of the neural activity measured at the average magnitudes of beat-related (in red circle) and unrelated (in blue circle) frequencies are represented as insets. The second column represents the normalized magnitude spectra obtained from the auditory nerve model output for each duty cycle sequence. The two columns on the right represent the autocorrelation-based analysis (for visualization purposes, only a subset of lags from 0 to 2.4 s corresponding to the pattern duration is shown). The first column represents the group-level averaged autocorrelation function measured from the same pool of fronto-central electrodes, across conditions. Beat-related lags are shown in red, and beat-unrelated lags are shown in blue. The second column represents the autocorrelation function of the auditory nerve model output for each duty cycle sequence. C_FIG

neuroscience↗

bioRxiv2024

Repetition of Rhythmic Patterns Fosters Neural Representation of Musical Meter

Music often entails perception of periodic pulses (hereafter meter) which serve as an internal temporal reference to coordinate movements to music. Crucially, meter perception arises even when the musical rhythm only weakly cues meter periodicities (i.e., syncopated rhythms). However, syncopated rhythms are often looped in music, suggesting that repetition of rhythmic patterns may facilitate meter perception by providing periodic cues at a slower, supra-second timescale. Here, we tested this hypothesis by recording separately electroencephalographic (EEG) and behavioral responses (finger tapping) while participants listened to different syncopated rhythmic sequences. These sequences either consisted of a repeated pattern (repetition of 4.8 and 9.6-s patterns) or were generated without repetition. EEG responses showed overall periodization of the rhythmic input, at periodicities corresponding to those expressed as the meter in behavioral responses, and in contrast with the weak cues to these periodicities in the rhythmic inputs. Most importantly, pattern repetition strengthened this neural representation of the meter, demonstrating that supra-second periodicities in the rhythmic input further enhance sub-second periodicities in neural activity. These findings thus highlight the multiscale nature of temporal processes at stake in processing musical rhythm, and, more generally, complex rhythmic inputs involved in interpersonal interaction and communication.

neuroscience↗

bioRxiv2024

Behavior-relevant periodized neural representation of acoustic but not tactile rhythm in humans

Music makes people move. This human propensity to coordinate movement with the rhythm of music requires multiscale temporal integration, allowing fast sensory events composing rhythmic input to be mapped onto slower internal templates such as periodic beats. Relatedly, beat perception has been shown to involve a selective enhancement of the beat periodicities in the neural response to rhythm. However, the extent to which this ability to move to the beat, and the related periodized neural representation, are shared across the senses beyond audition remains unknown. Here we addressed this question using acoustic and tactile rhythms, while recording separately the electroencephalography (EEG) responses and finger tapping to these rhythms in healthy volunteers. Consistent with previous studies, EEG responses to the acoustic rhythm featured significant enhancement of the beat, and this periodized neural representation was specifically concentrated within a low-frequency range below 15 Hz. In contrast, the same rhythm conveyed with tactile inputs elicited responses over a broader frequency range, up to 25Hz, with no significant periodization, and resulted in less stable tapping. Together, these findings indicate that low-frequency neural activity preferentially supports behavior-relevant internal representation of rhythmic input. However, this neural representation is not necessarily shared across the senses, as well as the ability to move to the beat, corroborating multimodal differences in beat perception. This low-frequency neural representation may thus reflect a process of multiscale temporal integration allowing the auditory system to go beyond mere tracking of onset timing and support higher-level internal representation and motor entrainment to rhythm. Significance statementIntegrating the fast sensory events composing music into slower temporal units is a cornerstone of beat perception and social interaction through music. The current study shows that this ability critically relies on brain activity concentrated in a lower frequency range - below the recurrence of sensory events - in response to acoustic rhythm. In contrast, when the rhythm is conveyed through touch, brain responses comparatively exhibit higher frequency activity corresponding to the faithful tracking of each individual events of the tactile rhythm. Most importantly, these auditory-specific slow fluctuations feature a periodization of rhythmic inputs, compatible with behavior. This higher-level neural processing of rhythmic input could thus reflect internal representations of the beat that are not necessarily shared across sensory modalities, in line with the concept of auditory dominance in temporal event perception and motor entrainment to rhythm. The current study thus opens a promising avenue to gain fundamental knowledge on high-level multimodal perception and motor entrainment processes specific to humans.

neuroscience↗

bioRxiv2024

Revealing rhythm categorization in human brain activity

Humans across cultures show an outstanding capacity to perceive, learn, and produce musical rhythms. These skills rely on mapping the infinite space of possible rhythmic sensory inputs onto a finite set of internal rhythm categories. What are the brain processes underlying rhythm categorization? We used electroencephalography (EEG) to measure brain activity as human participants listened to a continuum of rhythmic sequences characterized by repeating patterns of two inter-onset intervals. Using frequency and representational similarity analyses, we show that brain activity does not merely track the temporal structure of rhythmic inputs, but, instead, automatically produces categorical representation of rhythms. Surprisingly, despite this automaticity, these rhythm categories do not arise in the earliest stages of the ascending auditory pathway, but show strong similarity between implicit neural and overt behavioral responses. Together, these results and methodological advances constitute a critical step towards understanding the biological roots and diversity of musical behaviors across cultures.

neuroscience↗

bioRxiv2024

Neural and behavioral dynamics of encoding, production and synchronization with external rhythms in subcortical lesion patients

Acting in and adapting to a dynamically changing environment necessitates precise encoding of the timing of unfolding sensory events in our environment, and to time of our own (re-)actions to them. Cerebellar (CE) and basal ganglia (BG) circuitries play fundamental and complementary roles in timing processes. While the CE seems to encode the precise timing of sensory events (when an event occurs), the BG engage in generating temporal predictions (when a next event occurs). However, their contributions are rarely investigated in combination, as it is generally difficult to record data from respective patient groups in parallel. Here we investigated the causal roles of CE and BG in sensory and sensorimotor timing processes. Healthy controls and patients with CE or BG lesions listened to isochronous auditory sequences while their EEG was recorded and later performed a tapping synchronization task. We assessed intra- and inter-individual variabilities, as well as group differences, using event-related responses, delta-band inter-trial phase-coherence and acceleration dynamics while tuning to the stimulation frequency (Sf). CE and BG lesions increased variability in ERP latency and reduced the coherence of delta-band activity. CE but not BG lesions further impacted the stability of delta-band oscillations while tuning to the Sf. These findings show a causal link between subcortical lesions and the capacity to encode and synchronize ongoing neural activity with temporal regularities in the acoustic environment, but do not fully dissociate the specific contributions of the BG and the CE to processing sound in isochronous contexts.

neuroscience↗

bioRxiv2020

Attention affects overall gain but not selective contrast at meter frequencies in the neural processing of rhythm

When listening to music, humans spontaneously perceive and synchronize movement to periodic pulses of meter. A growing body of evidence suggests that this widespread ability is related to neural processes that selectively enhance meter periodicities. However, to what extent these neural processes are affected by the attentional state of the listener remains largely unknown. Here, we recorded EEG while participants listened to auditory rhythms and detected small changes in tempo or pitch of the stimulus, or performed a visual task. The overall neural response to the auditory input decreased when participants attended the visual modality, indicating generally lower sensitivity to acoustic information. However, the selective contrast at meter periodicities did not differ across the three tasks. Moreover, this selective contrast could be trivially accounted for by biologically-plausible models of subcortical auditory processing, but only when meter periodicities were already prominent in the acoustic input. However, when meter periodicities were not prominent in the auditory input, the EEG responses could not be explained by low-level processing. This was also confirmed by early auditory responses that originate predominantly in early auditory areas and were recorded in the same EEG. The contrast at meter periodicities in these early responses was consistently smaller than in the EEG responses originating mainly from higher-level processing stages. Together, these results demonstrate that selective contrast at meter periodicities involves higher-level neural processes that may be engaged automatically, irrespective of behavioral context. This robust shaping of the neural representation of rhythm might thus contribute to spontaneous and effortless synchronization to musical meter in humans across cultures.

neuroscience↗

bioRxiv2019

Hysteresis in the selective synchronization of brain activity to musical rhythm

When listening to musical rhythm, people tend to spontaneously perceive and move along with a periodic pulse-like meter. Moreover, perception and entrainment to the meter show remarkable stability in the face of dynamically changing rhythmic structure of music, even when acoustic cues to meter frequencies are degraded in the rhythmic input. Here we show that this perceptual phenomenon is supported by a selective synchronization of endogenous brain activity to the perceived meter, and that this neural synchronization is significantly shaped by recent context, especially when the incoming input becomes increasingly ambiguous. We recorded the EEG while non-musician and musician participants listened to nonrepeating rhythmic sequences where acoustic cues to meter frequencies either gradually decreased (from regular to ambiguous) or increased (from ambiguous to regular). We observed that neural activity selectively synchronized to the perceived meter persisted longer when the sequence gradually changed from regular to ambiguous compared to the opposite, thus demonstrating hysteresis in the neural processing of a dynamically changing rhythmic stimulus. This dependence on recent context was weaker in the neural responses of musicians, who also showed greater ability to tap along with a regular meter irrespective of stimulus ambiguity, thus reflecting greater stability relative to current and recent stimulus in musicians. Together, these asymmetric context effects demonstrate how the relative contribution of incoming and prior signals is continuously weighted to shape neural selection of functionally-relevant features and guide perceptual organization of dynamic input.\n\nSignificance statementWhen listening to musical rhythm, people tend to spontaneously perceive and move along with a periodic pulse-like meter. Moreover, perception and entrainment to the meter seem to show remarkable stability in the face of dynamically changing rhythmic structure of music. Here we show that this is supported by a selective synchronization of brain activity at meter frequencies. This selective neural synchronization persists longer when a nonrepeating sequence gradually transforms from a regular to an ambiguous rhythm compared to the opposite. This asymmetric context effect suggests that the brain processes rhythm based on a flexible combination of sensory and endogenous information. Such continuously updated neural emphasis on meter periodicities might therefore guide robust perceptual organization of a dynamic rhythmic input.

neuroscience↗