Rhythm and beat perception in motor areas of the brain

When we listen to rhythm, we often move spontaneously to the beat. This movement may result from processing of the beat by motor areas. Previous studies have shown that several motor areas respond when attending to rhythms. Here we investigate whether specific motor regions respond to beat in rhythm. We predicted that the basal ganglia and supplementary motor area (SMA) would respond in the presence of a regular beat. To establish what rhythm properties induce a beat, we asked subjects to reproduce different types of rhythmic sequences. Improved reproduction was observed for one rhythm type, which had integer ratio relationships between its intervals and regular perceptual accents. A subsequent functional magnetic resonance imaging study found that these rhythms also elicited higher activity in the basal ganglia and SMA. This finding was consistent across different levels of musical training, although musicians showed activation increases unrelated to rhythm type in the premotor cortex, cerebellum, and SMAs (pre-SMA and SMA). We conclude that, in addition to their role in movement production, the basal ganglia and SMAs may mediate beat perception.     

Inhibitory stimulation of the ventral premotor cortex temporarily interferes with musical beat rate preference

Behavioral studies suggest that preference for a beat rate (tempo) in auditory sequences is tightly linked to the motor system. However, from a neuroscientific perspective the contribution of motor‐related brain regions to tempo preference in the auditory domain remains unclear. A recent fMRI study (Kornysheva et al. [ 2010 ]: Hum Brain Mapp 31:48‐64) revealed that the activity increase in the left ventral premotor cortex (PMv) is associated with the preference for a tempo of a musical rhythm. The activity increase correlated with how strongly the subjects preferred a tempo. Despite this evidence, it remains uncertain whether an interference with activity in the left PMv affects tempo preference strength. Consequently, we conducted an offline repetitive transcranial magnetic stimulation (rTMS) study, in which the cortical excitability in the left PMv was temporarily reduced. As hypothesized, 0.9 Hz rTMS over the left PMv temporarily affected individual tempo preference strength depending on the individual strength of tempo preference in the control session. Moreover, PMv stimulation temporarily interfered with the stability of individual tempo preference strength within and across sessions. These effects were specific to the preference for tempo in contrast to the preference for timbre, bound to the first half of the experiment following PMv stimulation and could not be explained by an impairment of tempo recognition. Our results corroborate preceding fMRI findings and suggest that activity in the left PMv is part of a network that affects the strength of beat rate preference. Hum Brain Mapp, 2011. © 2010 Wiley‐Liss, Inc.     

Playing piano in the mind--an fMRI study on music imagery and performance in pianists

Reading of musical notes and playing piano is a very complex motor task which requires years of practice. In addition to motor skills, rapid and effective visuomotor transformation as well as processing of the different components of music like pitch, rhythm and musical texture are involved. The aim of the present study was the investigation of the cortical network which mediates music performance compared to music imagery in 12 music academy students playing the right hand part of a Bartok piece using functional magnetic resonance imaging (fMRI). In both conditions, fMRI activations of a bilateral frontoparietal network comprising the premotor areas, the precuneus and the medial part of Brodmann Area 40 were found. During music performance but not during imagery the contralateral primary motor cortex and posterior parietal cortex (PPC) bilaterally was active. This reflects the role of primary motor cortex for motor execution but not imagery and the higher visuomotor integration requirements during music performance compared to simulation. The notion that the same areas are involved in visuomotor transformation/motor planning and music processing emphasizes the multimodal properties of cortical areas involved in music and motor imagery in musicians.     

Neural Mechanisms of Rhythm Perception: Current Findings and Future Perspectives

Perception of temporal patterns is fundamental to normal hearing, speech, motor control, and music. Certain types of pattern understanding are unique to humans, such as musical rhythm. Although human responses to musical rhythm are universal, there is much we do not understand about how rhythm is processed in the brain. Here, I consider findings from research into basic timing mechanisms and models through to the neuroscience of rhythm and meter. A network of neural areas, including motor regions, is regularly implicated in basic timing as well as processing of musical rhythm. However, fractionating the specific roles of individual areas in this network has remained a challenge. Distinctions in activity patterns appear between “automatic” and “cognitively controlled” timing processes, but the perception of musical rhythm requires features of both automatic and controlled processes. In addition, many experimental manipulations rely on participants directing their attention toward or away from certain stimulus features, and measuring corresponding differences in neural activity. Many temporal features, however, are implicitly processed whether attended to or not, making it difficult to create controlled baseline conditions for experimental comparisons. The variety of stimuli, paradigms, and definitions can further complicate comparisons across domains or methodologies. Despite these challenges, the high level of interest and multitude of methodological approaches from different cognitive domains (including music, language, and motor learning) have yielded new insights and hold promise for future progress.     

Abnormal phasic activity in saliency network,motor areas,and basal ganglia in Parkinson's disease during rhythm perception

Behavioral studies indicate that persons with Parkinson's disease have complexity dependent problems with the discrimination of auditory rhythms. Furthermore, neuroimaging studies show that rhythm processing activates many brain areas that overlap with areas affected by Parkinson's disease (PD). This study sought to investigate the neural correlates of rhythm processing in PD and healthy controls, with a particular focus on rhythmic complexity. We further aimed to investigate differences in brain activation during initial phases of rhythm processing. Functional magnetic resonance imaging was used to scan 15 persons with Parkinson's disease and 15 healthy controls while they listened to musical rhythms with two different levels of complexity. Rhythmic complexity had no significant effect on brain activations, but patients and controls showed differences in areas related to temporal auditory processing, notably bilateral planum temporale and inferior parietal lobule. We found indications of a particular sequential or phasic activation pattern of brain activity, where activity in caudate nucleus in the basal ganglia was time‐displaced by activation in the saliency network—comprised of anterior cingulate cortex and bilateral anterior insula—and cortical and subcortical motor areas, during the initial phases of listening to rhythms. We relate our findings to core PD pathology, and discuss the overall, rhythm processing related hyperactivity in PD as a possible dysfunction in specific basal ganglia mechanisms, and the phasic activation pattern in PD as a reflection of a lack of preparatory activation of task‐relevant brain networks for rhythm processing in PD.     

Moving on time: brain network for auditory-motor synchronization is modulated by rhythm complexity and musical training

Much is known about the motor system and its role in simple movement execution. However, little is understood about the neural systems underlying auditory-motor integration in the context of musical rhythm, or the enhanced ability of musicians to execute precisely timed sequences. Using functional magnetic resonance imaging, we investigated how performance and neural activity were modulated as musicians and nonmusicians tapped in synchrony with progressively more complex and less metrically structured auditory rhythms. A functionally connected network was implicated in extracting higher-order features of a rhythm's temporal structure, with the dorsal premotor cortex mediating these auditory-motor interactions. In contrast to past studies, musicians recruited the prefrontal cortex to a greater degree than nonmusicians, whereas secondary motor regions were recruited to the same extent. We argue that the superior ability of musicians to deconstruct and organize a rhythm's temporal structure relates to the greater involvement of the prefrontal cortex mediating working memory.     

Computer aided music therapy evaluation: Testing the Music Therapy Logbook prototype 1 system

Research indicates that music therapists are likely to make use of computer software, designed to measure changes in the way a patient and therapist make use of music in music therapy sessions. A proof of concept study investigated whether music analysis algorithms (designed to retrieve information from commercial music recordings) can be adapted to meet the needs of music therapists. Computational music analysis techniques were applied to multi-track audio recordings of simulated sessions, then to recordings of individual music therapy sessions; these were recorded by a music therapist as part of her ongoing practice with patients with acquired brain injury.The music therapist wanted to evaluate two hypotheses: one, whether changes in her tempo were affecting the tempo of a patient's play on acoustic percussion instruments, and two, whether her musical interventions were helping the patient reduce habituated, rhythmic patterning. Automatic diagrams were generated that gave a quick overview of the instrumental activity contained within each session: when, and for how long each instrument was played. From these, computational analysis was applied to musical areas of specific interest. The results of the interdisciplinary team work, audio recording tests, computer analysis tests, and music therapy field tests are presented and discussed.     

Poor synchronization to the beat may result from deficient auditory-motor mapping

Moving to the beat of music is natural and spontaneous for humans. Yet some individuals, so-called ‘beat deaf', may differ from the majority by being unable to synchronize their movements to musical beat. This condition was recently described in Mathieu (Phillips-Silver et al. (2011). Neuropsychologia, 49, 961–969), a beat-deaf individual, showing inaccurate motor synchronization to the beat accompanied by poor beat perception, with spared pitch processing. It has been suggested that beat deafness is the outcome of impoverished beat perception. Deficient synchronization to the beat, however, may also result from inaccurate mapping of the perceived beat to movement. To test this possibility, we asked 99 non-musicians to synchronize with musical and non-musical stimuli via hand tapping. Ten among them who revealed particularly poor synchronization were submitted to a thorough assessment of motor synchronization to various pacing stimuli and of beat perception. Four participants showed poor synchronization in absence of poor pitch perception; moreover, among them, two individuals were unable to synchronize to music, in spite of unimpaired detection of small durational deviations in musical and non-musical sequences, and normal rhythm discrimination. This mismatch of perception and action points toward disrupted auditory-motor mapping as the key impairment accounting for poor synchronization to the beat.     

Impairment of beat-based rhythm discrimination in Parkinson's disease

Humans often synchronize movements to the beat, indicating that motor areas may be involved in detecting or generating a beat. The basal ganglia have been shown to be preferentially activated by perception of rhythms with a regular beat (Grahn and Brett, 2007), but their necessity for beat-based rhythm processing has not been proven. Previous research has shown that Parkinson's disease (PD) patients are impaired in timing of isochronous intervals ( [Harrington et?al., 1998a] and [O'Boyle et?al., 1996]), but little work has tested more complex rhythms. In healthy volunteers, behavioural performance is better for rhythms with a beat than without a beat (Essens, 1986). We tested PD patients and controls on a rhythm discrimination task to determine if basal ganglia dysfunction results in an impairment of processing rhythms that have a beat. Unlike rhythm reproduction, discrimination has no motor requirements that are problematic for patients. Half the rhythms had a beat-based structure, and half did not. Subjects heard a rhythm twice and then indicated if a third presentation of the rhythm was the same or different. We predicted that PD patients would benefit less from beat structure than controls, resulting in a group by rhythm-type interaction, with reduced relative performance for the beat-based sequences in the PD group. Indeed this was the pattern of the results. In the control group, a significant advantage was observed for discrimination of rhythms with a beat compared to those without a beat. This advantage was greatly reduced in the PD group. Discrimination of beat-based rhythms was significantly impaired in PD patients compared to controls, whereas discrimination of non-beat-based rhythms did not differ significantly. This suggests that the basal ganglia are part of a system involved in detecting or generating an internal beat, and that this system is compromised in patients with Parkinson's disease.     

Assessment of musical processing in brain-damaged patients: implications for laterality of music

Reception and production aspects of musical ability were assessed in two studies of left cerebro-vascular accident (LCVA) and right cerebro-vascular accident (RCVA) patients and controls. Musical tasks included perception of rhythm and pitch variations in familiar and unfamiliar tunes; and production of a well-known song, three original melodies, and imitation of rhythm patterns. The only "laterality of music" effect to emerge in the first study was impaired ability in LVCA patients to correctly perceive rhythmic changes. In the second study LCVAs were poorer than the other two groups in the singing of novel melodies, and both lesioned groups were poorer than controls in singing a familiar tune and in tapping rhythms. Premorbid musical ability was significantly related to performance over all groups combined. The RCVA group showed an inconsistent pattern of performance. The LCVA group was consistently more impaired over all tasks but apart from the aforementioned effects this was nonsignificant. It is argued that laterality effects for music processing cannot be reliably established.     

Assessment of musical processing in brain-damaged patients: Implications for laterality of music

Abstract

Reception and production aspects of musical ability were assessed in two studies of left cerebro-vascular accident (LCVA) and right cerebro-vascular accident (RCVA) patients and controls. Musical tasks included perception of rhythm and pitch variations in familiar and unfamiliar tunes; and production of a well-known song, three original melodies, and imitation of rhythm patterns. The only “laterality of music” effect to emerge in the first study was impaired ability in LVCA patients to correctly perceive rhythmic changes. In the second study LCVAs were poorer than the other two groups in the singing of novel melodies, and both lesioned groups were poorer than controls in singing a familiar tune and in tapping rhythms. Premorbid musical ability was significantly related to performance over all groups combined. The RCVA group showed an inconsistent pattern of performance. The LCVA group was consistently more impaired over all tasks but apart from the aforementioned effects this was nonsignificant. It is argued that laterality effects for music processing cannot be reliably established.     

Rhythm evokes action: Early processing of metric deviances in expressive music by experts and laymen revealed by ERP source imaging

To examine how musical expertise tunes the brain to subtle metric anomalies in an ecological musical context, we presented piano compositions ending on standard and deviant cadences (endings) to expert pianists and musical laymen, while high‐density EEG was recorded. Temporal expectancies were manipulated by substituting standard “masculine” cadences at metrically strong positions with deviant, metrically unaccented, “feminine” cadences. Experts detected metrically deviant cadences better than laymen. Analyses of event‐related potentials demonstrated that an early P3a‐like component (～ 150–300 ms), elicited by musical closure, was significantly enhanced at frontal and parietal electrodes in response to deviant endings in experts, whereas a reduced response to deviance occurred in laymen. Putative neuronal sources contributing to the modulation of this component were localized in a network of brain regions including bilateral supplementary motor areas, middle and posterior cingulate cortex, precuneus, associative visual areas, as well as in the right amygdala and insula. In all these regions, experts showed enhanced responses to metric deviance. Later effects demonstrated enhanced activations within the same brain network, as well as higher processing speed for experts. These results suggest that early brain responses to metric deviance in experts may rely on motor representations mediated by the supplementary motor area and motor cingulate regions, in addition to areas involved in self‐referential imagery and relevance detection. Such motor representations could play a role in temporal sensory prediction evolved from musical training and suggests that rhythm evokes action more strongly in highly trained instrumentalists. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.     

Rhythmic priming enhances the phonological processing of speech

While natural speech does not possess the same degree of temporal regularity found in music, there is recent evidence to suggest that temporal regularity enhances speech processing. The aim of this experiment was to examine whether speech processing would be enhanced by the prior presentation of a rhythmical prime. We recorded electrophysiological (EEG) and behavioural (reaction time) data while participants listened to nonsense words preceded by a simple rhythm. Results showed that speech processing was enhanced by the temporal expectations generated by the prime. Interestingly, beat and metrical structure of the prime had an effect on different ERP components elicited by the following word (N100, P300). These results indicate that using a musical-like rhythmic prime matched to the prosodic features of speech enhances phonological processing of spoken words and thus reveal a cross-domain effect of musical rhythm on the processing of speech rhythm.     

Beta‐band oscillations during passive listening to metronome sounds reflect improved timing representation after short‐term musical training in healthy older adults

Sub‐second time intervals in musical rhythms provide predictive cues about future events to performers and listeners through an internalized representation of timing. While the acuity of automatic, sub‐second timing as well as cognitively controlled, supra‐second timing declines with ageing, musical experts are less affected. This study investigated the influence of piano training on temporal processing abilities in older adults using behavioural and neuronal correlates. We hypothesized that neuroplastic changes in beta networks, caused by training in sensorimotor coordination with timing processing, can be assessed even in the absence of movement. Behavioural performance of internal timing stability was assessed with synchronization–continuation finger‐tapping paradigms. Magnetoencephalography (MEG) was recorded from older adults before and after one month of one‐on‐one training. For neural measures of automatic timing processing, we focused on beta oscillations (13–30 Hz) during passive listening to metronome beats. Periodic beta‐band modulations in older adults before training were similar to previous findings in young listeners at a beat interval of 800 ms. After training, behavioural performance for continuation tapping was improved and accompanied by an increased range of beat‐induced beta modulation, compared to participants who did not receive training. Beta changes were observed in the caudate, auditory, sensorimotor and premotor cortices, parietal lobe, cerebellum and medial prefrontal cortex, suggesting that increased resources are involved in timing processing and goal‐oriented monitoring as well as reward‐based sensorimotor learning.     

Making mirrors: premotor cortex stimulation enhances mirror and counter-mirror motor facilitation

Mirror neurons fire during both the performance of an action and the observation of the same action being performed by another. These neurons have been recorded in ventral premotor and inferior parietal cortex in the macaque, but human brain imaging studies suggest that areas responding to the observation and performance of actions are more widespread. We used paired-pulse TMS to test whether dorsal as well as ventral premotor cortex is involved in producing mirror motor facilitation effects. Stimulation of premotor cortex enhanced mirror motor facilitation and also enhanced the effects of counter-mirror training. No differences were found between the two premotor areas. These results support an associative account of mirror neuron properties, whereby multiple regions that process both sensory and motor information have the potential to contribute to mirror effects.     

Inter‐subject synchronization of brain responses during natural music listening

Music is a cultural universal and a rich part of the human experience. However, little is known about common brain systems that support the processing and integration of extended, naturalistic ‘real‐world’ music stimuli. We examined this question by presenting extended excerpts of symphonic music, and two pseudomusical stimuli in which the temporal and spectral structure of the Natural Music condition were disrupted, to non‐musician participants undergoing functional brain imaging and analysing synchronized spatiotemporal activity patterns between listeners. We found that music synchronizes brain responses across listeners in bilateral auditory midbrain and thalamus, primary auditory and auditory association cortex, right‐lateralized structures in frontal and parietal cortex, and motor planning regions of the brain. These effects were greater for natural music compared to the pseudo‐musical control conditions. Remarkably, inter‐subject synchronization in the inferior colliculus and medial geniculate nucleus was also greater for the natural music condition, indicating that synchronization at these early stages of auditory processing is not simply driven by spectro‐temporal features of the stimulus. Increased synchronization during music listening was also evident in a right‐hemisphere fronto‐parietal attention network and bilateral cortical regions involved in motor planning. While these brain structures have previously been implicated in various aspects of musical processing, our results are the first to show that these regions track structural elements of a musical stimulus over extended time periods lasting minutes. Our results show that a hierarchical distributed network is synchronized between individuals during the processing of extended musical sequences, and provide new insight into the temporal integration of complex and biologically salient auditory sequences.     

Effects of apnea on motor and cardiac rhythms

Usually, spontaneous rhythm of movements is studied through tasks involving an increase in heart rate (HR) such as physical exercises, locomotion or mental tasks. This experiment, instead, checks whether spontaneous rhythm is influenced by HR deceleration provoked by a voluntary apnea. The performances in a motor spontaneous tempo (MST) task performed for 3 min were compared to the same finger-tapping task performed in apnea. The results show a systematic adjustment period at the beginning of each trial in order to achieve a stable MST. More interestingly, HR and MST decreased simultaneously during apnea conditions and the finger-taps occur most frequently around the ventricular systole. Assuming that apnea increases arousal level, this parallelism between cardiac and motor rhythms is in contradiction with the sympathetic hypothesis that suggested that MST is mainly influenced by arousal.     

Enhanced brainstem encoding predicts musicians' perceptual advantages with pitch

Important to Western tonal music is the relationship between pitches both within and between musical chords; melody and harmony are generated by combining pitches selected from the fixed hierarchical scales of music. It is of critical importance that musicians have the ability to detect and discriminate minute deviations in pitch in order to remain in tune with other members of their ensemble. Event-related potentials indicate that cortical mechanisms responsible for detecting mistuning and violations in pitch are more sensitive and accurate in musicians as compared with non-musicians. The aim of the present study was to address whether this superiority is also present at a subcortical stage of pitch processing. Brainstem frequency-following responses were recorded from musicians and non-musicians in response to tuned (i.e. major and minor) and detuned (± 4% difference in frequency) chordal arpeggios differing only in the pitch of their third. Results showed that musicians had faster neural synchronization and stronger brainstem encoding for defining characteristics of musical sequences regardless of whether they were in or out of tune. In contrast, non-musicians had relatively strong representation for major/minor chords but showed diminished responses for detuned chords. The close correspondence between the magnitude of brainstem responses and performance on two behavioral pitch discrimination tasks supports the idea that musicians' enhanced detection of chordal mistuning may be rooted at pre-attentive, sensory stages of processing. Findings suggest that perceptually salient aspects of musical pitch are not only represented at subcortical levels but that these representations are also enhanced by musical experience.     

Supplementary motor area and primary auditory cortex activation in an expert break-dancer during the kinesthetic motor imagery of dance to music

The current study used functional magnetic resonance imaging to examine the neural activity of an expert dancer with 35 years of break-dancing experience during the kinesthetic motor imagery (KMI) of dance accompanied by highly familiar and unfamiliar music. The goal of this study was to examine the effect of musical familiarity on neural activity underlying KMI within a highly experienced dancer. In order to investigate this in both primary sensory and motor planning cortical areas, we examined the effects of music familiarity on the primary auditory cortex [Heschl’s gyrus (HG)] and the supplementary motor area (SMA). Our findings reveal reduced HG activity and greater SMA activity during imagined dance to familiar music compared to unfamiliar music. We propose that one’s internal representations of dance moves are influenced by auditory stimuli and may be specific to a dance style and the music accompanying it.     

Chronic hyperammonemia alters the circadian rhythms of corticosteroid hormone levels and of motor activity in rats

Patients with liver cirrhosis may present hepatic encephalopathy with a wide range of neurological disturbances and alterations in sleep quality and in the sleep‐wake circadian rhythm. Hyperammonemia is a main contributor to the neurological alterations in hepatic encephalopathy. We have assessed, in an animal model of chronic hyperammonemia without liver failure, the effects of hyperammonemia per se on the circadian rhythms of motor activity, temperature, and plasma levels of adrenal corticosteroid hormones. Chronic hyperammonemia alters the circadian rhythms of locomotor activity and of cortisol and corticosterone levels in blood. Different types of motor activity are affected differentially. Hyperammonemia significantly alters the rhythm of spontaneous ambulatory activity, reducing strongly ambulatory counts and slightly average velocity during the night (the active phase) but not during the day, resulting in altered circadian rhythms. In contrast, hyperammonemia did not affect wheel running at all, indicating that it affects spontaneous but not voluntary activity. Vertical activity was affected only very slightly, indicating that hyperammonemia does not induce anxiety. Hyperammonemia abolished completely the circadian rhythm of corticosteroid hormones in plasma, completely eliminating the peaks of cortisol and corticosterone present in control rats at the start of the dark period. The data reported show that chronic hyperammonemia, similar to that present in patients with liver cirrhosis, alters the circadian rhythms of corticosteroid hormones and of motor activity. This suggests that hyperammonemia would be a relevant contributor to the alterations in corticosteroid hormones and in circadian rhythms in patients with liver cirrhosis. © 2009 Wiley‐Liss, Inc.