Cortical activations during paced finger-tapping applying visual and auditory pacing stimuli

Dance of two brains: Interval subdivision in alternated condition enhances resistance to interference by others

The accomplishment of interpersonal sensorimotor synchronization is a challenging endeavor because it requires the achievement of a balance between accurate temporal control within individuals and smooth communication between them. This raises a critical question: How does the brain comprehend and process the perceptual information of others to guarantee accurate temporal control of action goals in a social context? A joint synchronization - continuation tapping task was conducted together with varying relative phases (0°/180°) and intervals of tempos (400 ms/800 ms/1600 ms) while neural data was collected using fNIRS (functional near-infrared spectroscopy). Individuals showed better behavioral performance and greater interpersonal brain synchronization(IBS) in the left dorsolateral prefrontal cortex at alternated condition (180° relative phase) compared to symmetric condition (0° relative phase), suggesting that the individual can better maintain behavioral performance and show improved IBS when the partner taps between the individual's gaps. Meanwhile, in most levels of alternated condition, IBS is inversely proportional to interference from partner, implying the counteraction of IBS against interference from others. In addition, when the interval of tempo was 1600 ms, behavioral performance showed a sharp decline, accompanied by a decrease in IBS, reflecting that IBS in SMS reflects effective information exchange between individuals rather than ineffective interference with each other. This study provides insight into the mechanisms underlying sensorimotor synchronization between individuals.

Perceptual coupling in human dyads: Kinematics does not affect interpersonal synchronization

The minimal, essential condition for individuals to interact is that they exchange information via at least one sensory channel. Once informational coupling is established, it enables basic forms of coordinated behavior to spontaneously emerge from the interaction. Our previous study revealed different coordination dynamics in dyads engaged in a joint finger-tapping task based on visual versus auditory coupling. This observation led us to propose the 'modality-dependent hypothesis', which posits that coordination dynamics are influenced by the sensory modality mediating informational coupling. However, recognizing that different modalities have inherent differences in accessing spatiotemporal features of perceived movement, we formulated the alternative 'kinematic hypothesis'. This hypothesis posits that differences in dynamics would vanish given equivalent kinematic information across modalities. The study involved forty (N = 40) participants, grouped into twenty (N = 20) dyads, who engaged in a joint finger-tapping task. This task was conducted under varying conditions of visual and auditory coupling, with manipulations in the access to kinematic information, categorized as discrete and continuous. Contrary to our initial predictions, the results strongly supported the 'modality-dependent hypothesis'. We observed that visual and auditory coupling consistently yielded distinct attractor dynamics, regardless of the access to kinematic information. Furthermore, all conditions of auditory coupling resulted in higher levels of synchronization than their visual counterparts. These findings suggest that the differences in interpersonal synchronization are predominantly influenced by the sensory modality, rather than the continuity of kinematic information. Our study highlights the significance of sensorimotor interactions in interpersonal synchronization and addresses the potential of sonification strategies in supporting motor training and rehabilitation.

Audiovisual integration of rhythm in musicians and dancers

Music training is associated with better beat processing in the auditory modality. However, it is unknown how rhythmic training that emphasizes visual rhythms, such as dance training, might affect beat processing, nor whether training effects in general are modality specific. Here we examined how music and dance training interacted with modality during audiovisual integration and synchronization to auditory and visual isochronous sequences. In two experiments, musicians, dancers, and controls completed an audiovisual integration task and an audiovisual target-distractor synchronization task using dynamic visual stimuli (a bouncing figure). The groups performed similarly on the audiovisual integration tasks (Experiments 1 and 2). However, in the finger-tapping synchronization task (Experiment 1), musicians were more influenced by auditory distractors when synchronizing to visual sequences, while dancers were more influenced by visual distractors when synchronizing to auditory sequences. When participants synchronized with whole-body movements instead of finger-tapping (Experiment 2), all groups were more influenced by the visual distractor than the auditory distractor. Taken together, this study highlights how training is associated with audiovisual processing, and how different types of visual rhythmic stimuli and different movements alter beat perception and production outcome measures. Implications for the modality appropriateness hypothesis are discussed.

Embodying Time in the Brain: A Multi-Dimensional Neuroimaging Meta-Analysis of 95 Duration Processing Studies

Time is an omnipresent aspect of almost everything we experience internally or in the external world. The experience of time occurs through such an extensive set of contextual factors that, after decades of research, a unified understanding of its neural substrates is still elusive. In this study, following the recent best-practice guidelines, we conducted a coordinate-based meta-analysis of 95 carefully-selected neuroimaging papers of duration processing. We categorized the included papers into 14 classes of temporal features according to six categorical dimensions. Then, using the activation likelihood estimation (ALE) technique we investigated the convergent activation patterns of each class with a cluster-level family-wise error correction at p < 0.05. The regions most consistently activated across the various timing contexts were the pre-SMA and bilateral insula, consistent with an embodied theory of timing in which abstract representations of duration are rooted in sensorimotor and interoceptive experience, respectively. Moreover, class-specific patterns of activation could be roughly divided according to whether participants were timing auditory sequential stimuli, which additionally activated the dorsal striatum and SMA-proper, or visual single interval stimuli, which additionally activated the right middle frontal and inferior parietal cortices. We conclude that temporal cognition is so entangled with our everyday experience that timing stereotypically common combinations of stimulus characteristics reactivates the sensorimotor systems with which they were first experienced.

Motor Processing in Children With Cochlear Implants as Assessed by Functional Near-Infrared Spectroscopy

Auditory-motor and visual-motor networks are often coupled in daily activities, such as when listening to music and dancing; but these networks are known to be highly malleable as a function of sensory input. Thus, congenital deafness may modify neural activities within the connections between the motor, auditory, and visual cortices. Here, we investigated whether the cortical responses of children with cochlear implants (CI) to a simple and repetitive motor task would differ from that of children with typical hearing (TH) and we sought to understand whether this response related to their language development. Participants were 75 school-aged children, including 50 with CI (with varying language abilities) and 25 controls with TH. We used functional near-infrared spectroscopy (fNIRS) to record cortical responses over the whole brain, as children squeezed the back triggers of a joystick that vibrated or not with the squeeze. Motor cortex activity was reflected by an increase in oxygenated hemoglobin concentration (HbO) and a decrease in deoxygenated hemoglobin concentration (HbR) in all children, irrespective of their hearing status. Unexpectedly, the visual cortex (supposedly an irrelevant region) was deactivated in this task, particularly for children with CI who had good language skills when compared to those with CI who had language delays. Presence or absence of vibrotactile feedback made no difference in cortical activation. These findings support the potential of fNIRS to examine cognitive functions related to language in children with CI.

The superior colliculus motor region does not respond to finger tapping movements in humans

Electrophysiological studies in macaques and functional neuroimaging in humans revealed a motor region in the superior colliculus (SC) for upper limb reaching movements. Connectivity studies in macaques reported direct connections between this SC motor region and cortical premotor arm, hand, and finger regions. These findings motivated us to investigate if the human SC is also involved in sequential finger tapping movements. We analyzed fMRI task data of 130 subjects executing finger tapping from the Human Connectome Project. While we found strong signals in the SC for visual cues, we found no signals related to simple finger tapping. In subsequent experimental measurements, we searched for responses in the SC corresponding to complex above simple finger tapping sequences. We observed expected signal increases in cortical motor and premotor regions for complex compared to simple finger tapping, but no signal increases in the motor region of the SC. Despite evidence for direct anatomical connections of the SC motor region and cortical premotor hand and finger areas in macaques, our results suggest that the SC is not involved in simple or complex finger tapping in humans.

Measurements of the lateral cerebellar hemispheres using near-infrared spectroscopy through comparison between autism spectrum disorder and typical development

The cerebellum plays a vital role in cognition, communication with the cerebral cortex, and fine motor coordination. Near-infrared spectroscopy (NIRS) is a portable, less restrictive, and noninvasive functional brain imaging method that can capture brain activity during movements by measuring the relative oxyhemoglobin (oxy-Hb) concentrations in the blood. However, the feasibility of using NIRS to measure cerebellar activity requires discussion. We compared NIRS responses between areas assumed to be the cerebellum and the occipital lobe during a fine motor task (tying a bow knot) and a visual task. Our results showed that the oxy-Hb concentration increased more in the occipital lobe than in the cerebellum during the visual task (p =.034). In contrast, during the fine motor task, the oxy-Hb concentration decreased in the occipital lobe but increased significantly in the cerebellum, indicating a notable difference (p =.015). These findings suggest that we successfully captured cerebellar activity associated with processing, particularly fine motor coordination. Moreover, the observed responses did not differ between individuals with autism spectrum disorder and those with typical development. Our study demonstrates the meaningful utility of NIRS as a method for measuring cerebellar activity during movements.

Beyond Broca: neural architecture and evolution of a dual motor speech coordination system

Classical neural architecture models of speech production propose a single system centred on Broca's area coordinating all the vocal articulators from lips to larynx. Modern evidence has challenged both the idea that Broca's area is involved in motor speech coordination and that there is only one coordination network. Drawing on a wide range of evidence, here we propose a dual speech coordination model in which laryngeal control of pitch-related aspects of prosody and song are coordinated by a hierarchically organized dorsolateral system while supralaryngeal articulation at the phonetic/syllabic level is coordinated by a more ventral system posterior to Broca's area. We argue further that these two speech production subsystems have distinguishable evolutionary histories and discuss the implications for models of language evolution.

Emergent and planned interpersonal synchronization are both sensitive to 'tempo aftereffect contagion'

Interpersonal synchronization is fundamental for motor coordination during social interactions. Discerning emergent (entrainment) from planned synchronization represents a non-trivial issue in visually bonded individuals acting together, as well as assessing whether inter-individual differences, e.g., in autistic traits, modulate both types of synchronization. In a visuomotor finger-tapping task, two participants replicated a target tempo either synchronizing ('joint' condition) or not ('non-interactive' condition, 'non-int') with each other. One participant was exposed ('induced') to tempo aftereffect (a medium tempo seems faster or slower after exposure to slower or faster inducing tempi), but not the other participant ('not induced'); thus they had different timing perceptions of the same target. We assessed to what degree emergent and/or planned synchronization affected dyads by analyzing inter-tap-intervals, synchronization indexes, and cross-correlation coefficients. Results revealed a 'tempo aftereffect contagion': inter-tap-intervals of both induced and not-induced participants showed aftereffect in both the joint and non-int conditions. Moreover, aftereffects did not correlate across conditions suggesting they might be due to (at least in part) different processes, but the propensity for tempo aftereffect contagion correlated with individuals' autistic traits only in the non-int condition. Finally, participants co-adjusted their tapping more in the joint condition than in the non-int one, as confirmed by higher synchronization indexes and the mutual adaptation pattern of cross-correlation coefficients. Altogether, these results show the subtle interplay between emergent and planned interpersonal synchronization mechanisms that act on a millisecond timescale independently from synching or not with the partner.

Brain networks for temporal adaptation, anticipation, and sensory-motor integration in rhythmic human behavior

Human interaction often requires the precise yet flexible interpersonal coordination of rhythmic behavior, as in group music making. The present fMRI study investigates the functional brain networks that may facilitate such behavior by enabling temporal adaptation (error correction), prediction, and the monitoring and integration of information about 'self' and the external environment. Participants were required to synchronize finger taps with computer-controlled auditory sequences that were presented either at a globally steady tempo with local adaptations to the participants' tap timing (Virtual Partner task) or with gradual tempo accelerations and decelerations but without adaptation (Tempo Change task). Connectome-based predictive modelling was used to examine patterns of brain functional connectivity related to individual differences in behavioral performance and parameter estimates from the adaptation and anticipation model (ADAM) of sensorimotor synchronization for these two tasks under conditions of varying cognitive load. Results revealed distinct but overlapping brain networks associated with ADAM-derived estimates of temporal adaptation, anticipation, and the integration of self-controlled and externally controlled processes across task conditions. The partial overlap between ADAM networks suggests common hub regions that modulate functional connectivity within and between the brain's resting-state networks and additional sensory-motor regions and subcortical structures in a manner reflecting coordination skill. Such network reconfiguration might facilitate sensorimotor synchronization by enabling shifts in focus on internal and external information, and, in social contexts requiring interpersonal coordination, variations in the degree of simultaneous integration and segregation of these information sources in internal models that support self, other, and joint action planning and prediction.

Mental arithmetic modulates temporal variabilities of finger-tapping tasks in a tempo-dependent manner

Background

Several psychiatric diseases impair temporal processing. Temporal processing is thought to be based on two domains: supra-second intervals and sub-second intervals. Studies show that temporal processing in sub-second intervals is mainly an automated process. However, the brain functions involved in temporal processing at each time scale remain unclear. We hypothesized that temporal processing in supra-second intervals requires several brain areas, such as the ventrolateral prefrontal cortex, intraparietal sulcus (IPS), and inferior parietal lobe, corresponding to various cognitions in a time scale-dependent manner. We focused on a dual-task paradigm (DTP) involving simultaneous performance of cognitive and motor tasks, which is an effective method for screening psychomotor functions; we then designed a DTP comprising finger tapping at various tempi as the temporal processing task and two cognitive tasks (mental arithmetic and reading) that might affect temporal processing. We hoped to determine whether task-dependent interferences on temporal processing in supra-second intervals differed depending on the cognitive tasks involved.

Methods

The study included 30 participants with no history of neuromuscular disorders. Participants were asked to perform a DTP involving right index finger tapping at varying tempi (0.33, 0.5, 1, 2, 3, and 4 s inter-tapping intervals). Cognitive tasks comprised mental arithmetic (MA) involving three-digit addition, mental reading (MR) of three- to four-digit numbers, and a control (CTL) task without any cognitive loading. For comparison between tasks, we calculated the SDs of the inter-tapping intervals. Participants' MA abilities in the three-digit addition task were evaluated.

Results

The MA and MR tasks significantly increased the SDs of the inter-tapping intervals compared to those of the CTL task in 2-3 s and 3-4 s for the MA and MR tasks, respectively. Furthermore, SD peaks in the finger-tapping tasks involving MA were normalized by those in the CTL task, which were moderately correlated with the participants' MA ability (r = 0.462, P = 0.010).

Discussion

Our results established that DTP involving the temporal coordination of finger-tapping and cognitive tasks increased temporal variability in a task- and tempo-dependent manner. Based on the behavioral aspects, we believe that these modulations of temporal variability might result from the interaction between finger function, arithmetic processing, and temporal processing, especially during the "pre-semantic period". Our findings may help in understanding the temporal processing deficits in various disorders such as dementia, Parkinson's disease, and autism.

Musical abilities in children with developmental cerebellar anomalies

Developmental Cerebellar Anomalies (DCA) are rare diseases (e.g., Joubert syndrome) that affect various motor and non-motor functions during childhood. The present study examined whether music perception and production are affected in children with DCA. Sixteen children with DCA and 37 healthy matched control children were tested with the Montreal Battery for Evaluation of Musical Abilities (MBEMA) to assess musical perception. Musical production was assessed using two singing tasks: a pitch-matching task and a melodic reproduction task. Mixed model analyses showed that children with DCA were impaired on the MBEMA rhythm perception subtest, whereas there was no difference between the two groups on the melodic perception subtest. Children with DCA were also impaired in the melodic reproduction task. In both groups, singing performance was positively correlated with rhythmic and melodic perception scores, and a strong correlation was found between singing ability and oro-bucco-facial praxis in children with DCA. Overall, children with DCA showed impairments in both music perception and production, although heterogeneity in cerebellar patient’s profiles was highlighted by individual analyses. These results confirm the role of the cerebellum in rhythm processing as well as in the vocal sensorimotor loop in a developmental perspective. Rhythmic deficits in cerebellar patients are discussed in light of recent work on predictive timing networks including the cerebellum. Our results open innovative remediation perspectives aiming at improving perceptual and/or production musical abilities while considering the heterogeneity of patients’ clinical profiles to design music-based therapies.

Reproducible Inter-Personal Brain Coupling Measurements in Hyperscanning Settings With functional Near Infra-Red Spectroscopy

Despite a huge advancement in neuroimaging techniques and growing importance of inter-personal brain research, few studies assess the most appropriate computational methods to measure brain-brain coupling. Here, we focus on the signal processing methods to detect brain-coupling in dyads. From a public dataset of functional Near Infra-Red Spectroscopy signals (N=24 dyads), we derived a synthetic control condition by randomization, we investigated the effectiveness of four most used signal similarity metrics: Cross Correlation, Mutual Information, Wavelet Coherence and Dynamic Time Warping. We also accounted for temporal variations between signals by allowing for misalignments up to a maximum lag. Starting from the observed effect sizes, computed in terms of Cohen's d, the power analysis indicated that a high sample size ([Formula: see text]) would be required to detect significant brain-coupling. We therefore discuss the need for specialized statistical approaches and propose bootstrap as an alternative method to avoid over-penalizing the results. In our settings, and based on bootstrap analyses, Cross Correlation and Dynamic Time Warping outperform Mutual Information and Wavelet Coherence for all considered maximum lags, with reproducible results. These results highlight the need to set specific guidelines as the high degree of customization of the signal processing procedures prevents the comparability between studies, their reproducibility and, ultimately, undermines the possibility of extracting new knowledge.

With No Attention Specifically Directed to It, Rhythmic Sound Does Not Automatically Facilitate Visual Task Performance

In a century where humans and machines—powered by artificial intelligence or not—increasingly work together, it is of interest to understand human processing of multi-sensory stimuli in relation to attention and working memory. This paper explores whether and when supporting visual information with rhythmic auditory stimuli can optimize multi-sensory information processing. In turn, this can make the interaction between humans or between machines and humans more engaging, rewarding and activating. For this purpose a novel working memory paradigm was developed where participants are presented with a series of five target digits randomly interchanged with five distractor digits. Their goal is to remember the target digits and recall them orally. Depending on the condition support is provided by audio and/or rhythm. It is expected that the sound will lead to a better performance. It is also expected that this effect of sound is different in case of rhythmic and non-rhythmic sound. Last but not least, some variability is expected across participants. To make correct conclusions, the data of the experiment was statistically analyzed in a classic way, but also predictive models were developed in order to predict outcomes based on a range of input variables related to the experiment and the participant. The effect of auditory support could be confirmed, but no difference was observed between rhythmic and non-rhythmic sounds. Overall performance was indeed affected by individual differences, such as visual dominance or perceived task difficulty. Surprisingly a music education did not significantly affect the performance and even tended toward a negative effect. To better understand the underlying processes of attention, also brain activation data, e.g., by means of electroencephalography (EEG), should be recorded. This approach can be subject to a future work.

Anodal Transcranial Direct Current Stimulation (atDCS) of the Primary Motor Cortex (M1) Facilitates Nonconscious Error Correction of Negative Phase Shifts

Accurate motor timing requires the temporally precise coupling between sensory input and motor output including the adjustment of movements with respect to changes in the environment. Such error correction has been related to a cerebello-thalamo-cortical network. At least partially distinct networks for the correction of perceived (i.e., conscious) as compared to nonperceived (i.e., nonconscious) errors have been suggested. While the cerebellum, the premotor, and the prefrontal cortex seem to be involved in conscious error correction, the network subserving nonconscious error correction is less clear. The present study is aimed at investigating the functional contribution of the primary motor cortex (M1) for both types of error correction in the temporal domain. To this end, anodal transcranial direct current stimulation (atDCS) was applied to the left M1 in a group of 18 healthy young volunteers during a resting period of 10 minutes. Sensorimotor synchronization as well as error correction of the right index finger was tested immediately prior to and after atDCS. Sham stimulation served as control condition. To induce error correction, nonconscious and conscious temporal step-changes were interspersed in a sequence of an isochronous auditory pacing signal in either direction (i.e., negative or positive) yielding either shorter or longer intervals. Prior to atDCS, faster error correction in conscious as compared to nonconscious trials was observed replicating previous findings. atDCS facilitated nonconscious error correction, but only in trials with negative step-changes yielding shorter intervals. In contrast to this, neither tapping speed nor synchronization performance with respect to the isochronous pacing signal was significantly modulated by atDCS. The data suggest M1 as part of a network distinctively contributing to the correction of nonconscious negative step-changes going beyond sensorimotor synchronization.

Auditory perception dominates in motor rhythm reproduction

It is commonly agreed that vision is more sensitive to spatial information, while audition is more sensitive to temporal information. When both visual and auditory information are available simultaneously, the modality appropriateness hypothesis predicts that, depending on the task, the most appropriate (i.e., reliable) modality dominates perception. While previous research mainly focused on discrepant information from different sensory inputs to scrutinize the modality appropriateness hypothesis, the current study aimed at investigating the modality appropriateness hypothesis when multimodal information was provided in a nondiscrepant and simultaneous manner. To this end, participants performed a temporal rhythm reproduction task for which the auditory modality is known to be the most appropriate. The experiment comprised an auditory (i.e., beeps), a visual (i.e., flashing dots), and an audiovisual condition (i.e., beeps and dots simultaneously). Moreover, constant as well as variable interstimulus intervals were implemented. Results revealed higher accuracy and lower variability in the auditory condition for both interstimulus interval types when compared to the visual condition. More importantly, there were no differences between the auditory and the audiovisual condition across both interstimulus interval types. This indicates that the auditory modality dominated multimodal perception in the task, whereas the visual modality was disregarded and hence did not add to reproduction performance.

Exploring the role of the left DLPFC in fatigue during unresisted rhythmic movements

Understanding central fatigue during motor activities is important in neuroscience and different medical fields. The central mechanisms of motor fatigue are known in depth for isometric muscle contractions; however, current knowledge about rhythmic movements and central fatigue is rather scarce. In this study, we explored the role of an executive area (left dorsolateral prefrontal cortex [DLPFC]) in fatigue development during rhythmic movement execution, finger tapping (FT) at the maximal rate, and fatigue after effects on the stability of rhythmic patterns. Participants (n = 19) performed six sets of unresisted FT (with a 3 min rest in‐between). Each set included four interleaved 30 s repetitions of self‐selected (two repetitions) and maximal rate FT (two repetitions) without rest in‐between. Left DLPFC involvement in the task was perturbed by transcranial static magnetic stimulation (tSMS) in two sessions (one real and one sham). Moreover, half of the self‐selected FT repetitions were performed concurrently with a demanding cognitive task, the Stroop test. Compared with sham stimulation, real tSMS stimulation prevented waning in tapping frequency at the maximal rate without affecting perceived levels of fatigue. Participants' engagement in the Stroop test just prior to maximal FT reduced the movement amplitude during this mode of execution. Movement variability at self‐selected rates increased during Stroop execution, especially under fatigue previously induced by maximal FT. Our results indicate cognitive‐motor interactions and a prominent role of the prefrontal cortex in fatigue and the motor control of simple repetitive movement patterns. We suggest the need to approach motor fatigue including cognitive perspectives.

We show the fundamental role of executive areas in fatigue caused by very simple repetitive movements. Fatigue developed less during the maximal frequency of movement production, while the left DLPFC received magnetic stimulation (in right‐handers). The role of cognitive‐motor interaction in fine motor control was also clear when participants engaged in cognitive tasks. At the clinical level, our work reinforces the need to treat fatigue from a comprehensive perspective.

Sensorimotor Synchronization in Healthy Aging and Neurocognitive Disorders

Sensorimotor synchronization (SMS), the coordination of physical actions in time with a rhythmic sequence, is a skill that is necessary not only for keeping the beat when making music, but in a wide variety of interpersonal contexts. Being able to attend to temporal regularities in the environment is a prerequisite for event prediction, which lies at the heart of many cognitive and social operations. It is therefore of value to assess and potentially stimulate SMS abilities, particularly in aging and neurocognitive disorders (NCDs), to understand intra-individual communication in the later stages of life, and to devise effective music-based interventions. While a bulk of research exists about SMS and movement-based interventions in Parkinson's disease, a lot less is known about other types of neurodegenerative disorders, such as Alzheimer's disease, vascular dementia, or frontotemporal dementia. In this review, we outline the brain and cognitive mechanisms involved in SMS with auditory stimuli, and how they might be subject to change in healthy and pathological aging. Globally, SMS with isochronous sounds is a relatively well-preserved skill in old adulthood and in patients with NCDs. At the same time, natural tapping speed decreases with age. Furthermore, especially when synchronizing to sequences at slow tempi, regularity and precision might be lower in older adults, and even more so in people with NCDs, presumably due to the fact that this process relies on attention and working memory resources that depend on the prefrontal cortex and parietal areas. Finally, we point out that the effect of the severity and etiology of NCDs on sensorimotor abilities is still unclear: More research is needed with moderate and severe NCD, comparing different etiologies, and using complex auditory signals, such as music.

The Music of Silence: Part I: Responses to Musical Imagery Encode Melodic Expectations and Acoustics

Musical imagery is the voluntary internal hearing of music in the mind without the need for physical action or external stimulation. Numerous studies have already revealed brain areas activated during imagery. However, it remains unclear to what extent imagined music responses preserve the detailed temporal dynamics of the acoustic stimulus envelope and, crucially, whether melodic expectations play any role in modulating responses to imagined music, as they prominently do during listening. These modulations are important as they reflect aspects of the human musical experience, such as its acquisition, engagement, and enjoyment. This study explored the nature of these modulations in imagined music based on EEG recordings from 21 professional musicians (6 females and 15 males). Regression analyses were conducted to demonstrate that imagined neural signals can be predicted accurately, similarly to the listening task, and were sufficiently robust to allow for accurate identification of the imagined musical piece from the EEG. In doing so, our results indicate that imagery and listening tasks elicited an overlapping but distinctive topography of neural responses to sound acoustics, which is in line with previous fMRI literature. Melodic expectation, however, evoked very similar frontal spatial activation in both conditions, suggesting that they are supported by the same underlying mechanisms. Finally, neural responses induced by imagery exhibited a specific transformation from the listening condition, which primarily included a relative delay and a polarity inversion of the response. This transformation demonstrates the top-down predictive nature of the expectation mechanisms arising during both listening and imagery.SIGNIFICANCE STATEMENT It is well known that the human brain is activated during musical imagery: the act of voluntarily hearing music in our mind without external stimulation. It is unclear, however, what the temporal dynamics of this activation are, as well as what musical features are precisely encoded in the neural signals. This study uses an experimental paradigm with high temporal precision to record and analyze the cortical activity during musical imagery. This study reveals that neural signals encode music acoustics and melodic expectations during both listening and imagery. Crucially, it is also found that a simple mapping based on a time-shift and a polarity inversion could robustly describe the relationship between listening and imagery signals.

The influence of auditory rhythms on the speed of inferred motion

The present research explored the influence of isochronous auditory rhythms on the timing of movement-related prediction in two experiments. In both experiments, participants observed a moving disc that was visible for a predetermined period before disappearing behind a small, medium, or large occluded area for the remainder of its movement. In Experiment 1, the disc was visible for 1 s. During this period, participants were exposed to either a fast or slow auditory rhythm, or they heard nothing. They were instructed to press a key to indicate when they believed the moving disc had reached a specified location on the other side of the occluded area. The procedure measured the (signed) error in participants' estimate of the time it would take for a moving object to contact a stationary one. The principal results of Experiment 1 were main effects of the rate of the auditory rhythm and of the size of the occlusion on participants' judgments. In Experiment 2, the period of visibility was varied with size of the occlusion area to keep the total movement time constant for all three levels of occlusion. The results replicated the main effect of rhythm found in Experiment 1 and showed a small, significant interaction, but indicated no main effect of occlusion size. Overall, the results indicate that exposure to fast isochronous auditory rhythms during an interval of inferred motion can influence the imagined rate of such motion and suggest a possible role of an internal rhythmicity in the maintenance of temporally accurate dynamic mental representations.

What Behavioral Abilities Emerged at Key Milestones in Human Brain Evolution? 13 Hypotheses on the 600-Million-Year Phylogenetic History of Human Intelligence

This paper presents 13 hypotheses regarding the specific behavioral abilities that emerged at key milestones during the 600-million-year phylogenetic history from early bilaterians to extant humans. The behavioral, intellectual, and cognitive faculties of humans are complex and varied: we have abilities as diverse as map-based navigation, theory of mind, counterfactual learning, episodic memory, and language. But these faculties, which emerge from the complex human brain, are likely to have evolved from simpler prototypes in the simpler brains of our ancestors. Understanding the order in which behavioral abilities evolved can shed light on how and why our brains evolved. To propose these hypotheses, I review the available data from comparative psychology and evolutionary neuroscience.

ADGRL3, FGF1 and DRD4: Linkage and Association with Working Memory and Perceptual Organization Candidate Endophenotypes in ADHD

Attention deficit hyperactivity disorder (ADHD) is a highly heritable neurobehavioral disorder that affects children worldwide, with detrimental long-term consequences in affected individuals. ADHD-affected patients display visual-motor and visuospatial abilities and skills that depart from those exhibited by non-affected individuals and struggle with perceptual organization, which might partially explain impulsive responses. Endophenotypes (quantifiable or dimensional constructs that are closely related to the root cause of the disease) might provide a more powerful and objective framework for dissecting the underlying neurobiology of ADHD than that of categories offered by the syndromic classification. In here, we explore the potential presence of the linkage and association of single-nucleotide polymorphisms (SNPs), harbored in genes implicated in the etiology of ADHD (ADGRL3, DRD4, and FGF1), with cognitive endophenotypes related to working memory and perceptual organization in 113 nuclear families. These families were ascertained from a geographical area of the Caribbean coast, in the north of Colombia, where the community is characterized by its ethnic diversity and differential gene pool. We found a significant association and linkage of markers ADGRL3-rs1565902, DRD4-rs916457 and FGF1-rs2282794 to neuropsychological tasks outlining working memory and perceptual organization such as performance in the digits forward and backward, arithmetic, similarities, the completion of figures and the assembly of objects. Our results provide strong support to understand ADHD as a combination of working memory and perceptual organization deficits and highlight the importance of the genetic background shaping the neurobiology, clinical complexity, and physiopathology of ADHD. Further, this study supplements new information regarding an ethnically diverse community with a vast African American contribution, where ADHD studies are scarce.

Modality-specific frequency band activity during neural entrainment to auditory and visual rhythms

Rhythm perception depends on the ability to predict the onset of rhythmic events. Previous studies indicate beta band modulation is involved in predicting the onset of auditory rhythmic events (Fujioka et al., 2009, 2012; Snyder & Large, 2005). We sought to determine if similar processes are recruited for prediction of visual rhythms by investigating whether beta band activity plays a role in a modality-dependent manner for rhythm perception. We looked at electroencephalography time-frequency neural correlates of prediction using an omission paradigm with auditory and visual rhythms. By using omissions, we can separate out predictive timing activity from stimulus-driven activity. We hypothesized that there would be modality-independent markers of rhythm prediction in induced beta band oscillatory activity, and our results support this hypothesis. We find induced and evoked predictive timing in both auditory and visual modalities. Additionally, we performed an exploratory-independent components-based spatial clustering analysis, and describe all resulting clusters. This analysis reveals that there may be overlapping networks of predictive beta activity based on common activation in the parietal and right frontal regions, auditory-specific predictive beta in bilateral sensorimotor regions, and visually specific predictive beta in midline central, and bilateral temporal/parietal regions. This analysis also shows evoked predictive beta activity in the left sensorimotor region specific to auditory rhythms and implicates modality-dependent networks for auditory and visual rhythm perception.

The Myelin Content of the Human Precentral Hand Knob Reflects Interindividual Differences in Manual Motor Control at the Physiological and Behavioral Level

The primary motor cortex hand area (M1_HAND) and adjacent dorsal premotor cortex (PMd) form the so-called motor hand knob in the precentral gyrus. M1_HAND and PMd are critical for dexterous hand use and are densely interconnected via corticocortical axons, lacking a sharp demarcating border. In 24 young right-handed volunteers, we performed multimodal mapping to delineate the relationship between structure and function in the right motor hand knob. Quantitative structural magnetic resonance imaging (MRI) at 3 tesla yielded regional R1 maps as a proxy of cortical myelin content. Participants also underwent functional MRI (fMRI). We mapped task-related activation and temporal precision, while they performed a visuomotor synchronization task requiring visually cued abduction movements with the left index or little finger. We also performed sulcus-aligned transcranial magnetic stimulation of the motor hand knob to localize the optimal site (hotspot) for evoking a motor evoked potential (MEP) in two intrinsic hand muscles. Individual motor hotspot locations varied along the rostrocaudal axis. The more rostral the motor hotspot location in the precentral crown, the longer were corticomotor MEP latencies. “Hotspot rostrality” was associated with the regional myelin content in the precentral hand knob. Cortical myelin content also correlated positively with task-related activation of the precentral crown and temporal precision during the visuomotor synchronization task. Together, our results suggest a link among cortical myelination, the spatial cortical representation, and temporal precision of finger movements. We hypothesize that the myelination of cortical axons facilitates neuronal integration in PMd and M1_HAND and, hereby, promotes the precise timing of movements.

SIGNIFICANCE STATEMENT Here we used magnetic resonance imaging and transcranial magnetic stimulation of the precentral motor hand knob to test for a link among cortical myelin content, functional corticomotor representations, and manual motor control. A higher myelin content of the precentral motor hand knob was associated with more rostral corticomotor presentations, with stronger task-related activation and a higher precision of movement timing during a visuomotor synchronization task. We propose that a high precentral myelin content enables fast and precise neuronal integration in M1 (primary motor cortex) and dorsal premotor cortex, resulting in higher temporal precision during dexterous hand use. Our results identify the degree of myelination as an important structural feature of the neocortex that is tightly linked to the function and behavior supported by the cortical area.

The Differential Effects of Auditory and Visual Stimuli on Learning, Retention and Reactivation of a Perceptual-Motor Temporal Sequence in Children With Developmental Coordination Disorder

This study investigates the procedural learning, retention, and reactivation of temporal sensorimotor sequences in children with and without developmental coordination disorder (DCD). Twenty typically-developing (TD) children and 12 children with DCD took part in this study. The children were required to tap on a keyboard, synchronizing with auditory or visual stimuli presented as an isochronous temporal sequence, and practice non-isochronous temporal sequences to memorize them. Immediate and delayed retention of the audio-motor and visuo-motor non-isochronous sequences were tested by removing auditory or visual stimuli immediately after practice and after a delay of 2 h. A reactivation test involved reintroducing the auditory and visual stimuli after the delayed recall. Data were computed via circular analyses to obtain asynchrony, the stability of synchronization and errors (i.e., the number of supplementary taps). Firstly, an overall deficit in synchronization with both auditory and visual isochronous stimuli was observed in DCD children compared to TD children. During practice, further improvements (decrease in asynchrony and increase in stability) were found for the audio-motor non-isochronous sequence compared to the visuo-motor non-isochronous sequence in both TD children and children with DCD. However, a drastic increase in errors occurred in children with DCD during immediate retention as soon as the auditory stimuli were removed. Reintroducing auditory stimuli decreased errors in the audio-motor sequence for children with DCD. Such changes were not seen for the visuo-motor non-isochronous sequence, which was equally learned, retained and reactivated in DCD and TD children. All these results suggest that TD children benefit from both auditory and visual stimuli to memorize the sequence, whereas children with DCD seem to present a deficit in integrating an audio-motor sequence in their memory. The immediate effect of reactivation suggests a specific dependency on auditory information in DCD. Contrary to the audio-motor sequence, the visuo-motor sequence was both learned and retained in children with DCD. This suggests that visual stimuli could be the best information for memorizing a temporal sequence in DCD. All these results are discussed in terms of a specific audio-motor coupling deficit in DCD.

A Cortical Parcellation Based Analysis of Ventral Premotor Area Connectivity

Introduction. The ventral premotor area (VPM) plays a crucial role in executing various aspects of motor control. These include hand reaching, joint coordination, and direction of movement in space. While many studies discuss the VPM and its relationship to the rest of the motor network, there is minimal literature examining the connectivity of the VPM outside of the motor network. Using region-based fMRI studies, we built a neuroanatomical model to account for these extra-motor connections.Methods. Thirty region-based fMRI studies were used to generate an activation likelihood estimation (ALE) using BrainMap software. Cortical parcellations overlapping the ALE were used to construct a preliminary model of the VPM connections outside the motor network. Diffusion spectrum imaging (DSI)-based fiber tractography was performed to determine the connectivity between cortical parcellations in both hemispheres, and a laterality index (LI) was calculated with resultant tract volumes. The resulting connections were described using the cortical parcellation scheme developed by the Human Connectome Project (HCP).Results. Four cortical regions were found to comprise the VPM. These four regions included 6v, 4, 3b, and 3a. Across mapped brains, these areas showed consistent interconnections between each other. Additionally, ipsilateral connections to the primary motor cortex, supplementary motor area, and dorsal premotor cortex were demonstrated. Inter-hemispheric asymmetries were identified, especially with areas 1, 55b, and MI connecting to the ipsilateral VPM regions.Conclusion. We describe a preliminary cortical model for the underlying connectivity of the ventral premotor area. Future studies should further characterize the neuroanatomic underpinnings of this network for neurosurgical applications.

Oddball onset timing: Little evidence of early gating of oddball stimuli from tapping, reacting, and producing

Oddballs, rare or novel stimuli, appear to last longer than non-oddballs. This illusion is often attributed to the perceived time that an oddball occupies being longer than that of a non-oddball. However, it is also possible that oddball stimuli are perceived to onset earlier than non-oddballs; they are “gated” earlier in time and thus the perceived duration of those stimuli are longer. In the current article, we directly investigate this proposal by asking participants to react to, produce durations initiated with, and tap along to either oddball or standard stimuli. Tapping provided some support for earlier perceived onset of an oddball in the visual modality. However, both reaction time and duration production experiments provided evidence against an oddball being gated earlier than a standard stimulus. Contrarily, these experiments showed an oddball resulted in longer reaction times and productions, respectively. Taken together, these three experiments indicate it is unlikely that the expansion of time attributed to oddball presentation is purely due to the earlier gating of oddball stimuli. In fact, the first two experiments provide some evidence that the effect of an oddball must compensate for the later gating of these stimuli.

The influence of accuracy constraints on bimanual and unimanual sequence learning

An experiment was designed to determine whether accuracy constraints can influence how unimanual and bimanual motor sequences are produced and learned. The accuracy requirements of the task were manipulated using principles derived from Fitts' Law to create relatively low (ID = 3) and high (ID = 5) accuracy demands. Right-limb dominant participants (N = 28, age = 21.9 yrs; 15 females and 13 males) were required to produce unimanual left, unimanual right or bimanual movement sequences using elbow extension and flexion movements to hit a series of illuminated targets. The targets were illuminated in a repeating sequence of 16 elements. Participants performed 20 practice trials. Thirty minutes following the practice trials participants performed a retention test. Element duration (time interval between target hits) and segment harmonicity (hesitations/adjustments in movement pattern) were calculated. The results indicate longer element duration and lower harmonicity values (more adjustments) when the task required higher accuracy demands (ID = 5) compared to low accuracy demands (ID = 3). Element duration was shorter and harmonicity was higher at ID = 5 for both unimanual groups than the bimanual group. However, element duration was shorter and harmonicity was higher at ID = 3 for the bimanual group than for both unimanual groups. These results indicate that the accuracy demands of the task can influence both performance and learning of motor sequences and suggest differences between unimanual and bimanual motor sequence learning. It appears there is a bimanual advantage for tasks with lower accuracy demands whereas performance is more accurate with unimanual performance, regardless of limb, with higher accuracy demands. These results are consistent with recent research indicating that accuracy requirements change the control processes for bimanual performance differently than for unimanual tasks.

Brain activation patterns during visuomotor adaptation in motor experts and novices: An FDG PET study with unrestricted movements

BACKGROUND

Speed of performance improvements and the strength of memory consolidation in humans vary with movement expertise. Underlying neural mechanisms of behavioural differences between levels of movement expertise are so far unknown.

NEW METHOD

In this study, PET with [¹⁸F]fluorodeoxyglucose (FDG) was proposed as a powerful novel methodology to assess learning-related brain activity patterns during large non-restricted movements (ball throwing with a right hand). 24 male handball players ('Experts') and 24 male participants without handball experience ('Novices') performed visuomotor adaptations to prismatic glasses with or without strategic manoeuvres (i.e., explicit or implicit adaptation).

RESULTS

Regional changes in FDG uptake as a marker of neuronal activity, relative to a control condition, were assessed. Prismatic adaptation, in general, was associated with decreased occipital neuronal activity as a possible response to misleading visual information. In 'Experts', the adaptation was associated with altered neuronal activity in a network comprising the right parietal cortex and the left cerebellum. In 'Novices', implicit adaptation resulted in an activation of the middle frontal and inferior temporal gyrus.

COMPARISON WITH EXISTING METHODS

This study demonstrates the versatility of FDG PET for studying brain activations patterns in experimental settings with unrestricted movements that are not accessible by other techniques (e.g., fMRI or EEG).

CONCLUSIONS

Observed results are consistent with the involvement of different functional networks related to strategic manoeuvres and expertise levels. This strengthens the assumption of different mechanisms underlying behavioural changes associated with movement expertise. Furthermore, the present study underscores the value of FDG PET for studying brain activation patterns during unrestricted movements.

Temporal twilight zone and beyond: Timing mechanisms in consciously delayed actions

Precise timing is essential for many kinds of human behavior. When a fastest response is not required, movements are initiated at the appropriate time requiring an anticipatory temporal component. Temporal mechanisms for movements with such an anticipatory component are not yet sufficiently understood; in particular, it is not known whether on the operational level for delayed movements distinct time windows are used or whether anticipatory control is characterized by continuous temporal processing. With a modified reaction-time paradigm, we asked participants to act with predefined time delays between 400 and 5000 ms; after each individual trial, a numerical feedback was provided which allowed correction of the response time for each next trial. Visual stimuli (Experiment 1) and auditory stimuli (Experiment 2) were used. In the statistical analyses, piecewise linear models and exponential decay models for the response variability of different delay times were compared. These analyses favored piecewise linear models; a decreasing variability with increasing delay of voluntary controlled actions was observed up to ~1 s, followed by close to constant variability beyond this delay. We suggest that precise temporal control of voluntary delayed movements is reached only after a "temporal twilight zone" of ~1 s, which apparently marks a temporal border between two different timing mechanisms.

Processing of numerical representation of fingers depends on their location in space

Fingers can express quantities and thus contribute to the acquisition and manipulation of numbers as well as the development of arithmetical skills. As embodied entities, the processing of finger numerical configurations should, therefore, be facilitated when they match shared cultural representations and are presented close to the body. To investigate these issues, the present study investigated whether canonical finger configurations are processed faster than noncanonical configurations or spatially matched dot configurations, taking into account their location in the peripersonal or the extrapersonal space. Analysis of verbal responses to the enumeration of small and large numerosities showed that participants (N = 30) processed small numerosities faster than large ones and dots faster than finger configurations despite visuo-spatial matching. Canonical configurations were also processed faster than noncanonical configurations but for finger numerical stimuli only. Furthermore, the difference in response time between dots and fingers processing was greater when the stimuli were located in the peripersonal space than in the extrapersonal space. As a whole, the data suggest that, due to their motor nature, finger numerical configurations are not processed as simple visual stimuli but in relation to corporal and cultural counting habits, in agreement with the embodied framework of numerical cognition.

Tracking differential activation of primary and supplementary motor cortex across timing tasks: An fNIRS validation study

Functional near-infrared spectroscopy (fNIRS) provides an alternative to functional magnetic resonance imaging (fMRI) for assessing changes in cortical hemodynamics. To establish the utility of fNIRS for measuring differential recruitment of the motor network during the production of timing-based actions, we measured cortical hemodynamic responses in 10 healthy adults while they performed two versions of a finger-tapping task. The task, used in an earlier fMRI study (Jantzen et al., 2004), was designed to track the neural basis of different timing behaviors. Participants paced their tapping to a metronomic tone, then continued tapping at the established pace without the tone. Initial tapping was either synchronous or syncopated relative to the tone. This produced a 2 × 2 design: synchronous or syncopated tapping and pacing the tapping with or continuing without a tone. Accuracy of the timing of tapping was tracked while cortical hemodynamics were monitored using fNIRS. Hemodynamic responses were computed by canonical statistical analysis across trials in each of the four conditions. Task-induced brain activation resulted in significant increases in oxygenated hemoglobin concentration (oxy-Hb) in a broad region in and around the motor cortex. Overall, syncopated tapping was harder behaviorally and produced more cortical activation than synchronous tapping. Thus, we observed significant changes in oxy-Hb in direct relation to the complexity of the task.

Functional connectivity of supplementary motor area during finger-tapping in major depression

Psychomotor disturbance has been consistently regarded as an essential feature of depressive disorders. Studying objectively measurable motor behaviors like finger-tapping may help advance the diagnostic methods. Twenty-five patients with major depressive disorder (MDD) and 15 healthy participants underwent functional magnetic resonance imaging (fMRI) measurements while tapping their index fingers. The finger-tapping (FT) task was performed by the right hand (the tapping frequency varied between 1, 2 and 4 Hz) or both hands either in synchrony or alternation (the tapping frequency varied between 1 and 2 Hz). A mixed-model ANOVA was used for between- and within-group comparisons of the task accuracy and fMRI percent signal change in the supplementary motor area (SMA) during 26-second sequences of finger-tapping. Furthermore, using seed-based correlation analyses we compared the connectivity of the SMA between the two samples. At the behavioral level, no significant group differences in FT performance between the patient and control groups was observed. The mean fMRI percent signal change of the SMA was significantly elevated at higher levels of speed in both groups. In the MDD group, an increased connectivity of the left SMA with the bilateral cortical and cerebellar motor- and vision-related regions was found. Most importantly, a decreased connectivity between the SMA and the basal ganglia was found at frequencies of 4 Hz. Our findings support the contention that, in depression, brain connectivity measures during motor performance may reveal deviant neural processes that are potentially relevant to measurable (bio)markers for individual diagnosis and treatment.

The Neural Correlates of Time: A Meta-analysis of Neuroimaging Studies

During the last two decades, our inner sense of time has been repeatedly studied with the help of neuroimaging techniques. These investigations have suggested the specific involvement of different brain areas in temporal processing. At least two distinct neural systems are likely to play a role in measuring time: One is mainly constituted of subcortical structures and is supposed to be more related to the estimation of time intervals below the 1-sec range (subsecond timing tasks), and the other is mainly constituted of cortical areas and is supposed to be more related to the estimation of time intervals above the 1-sec range (suprasecond timing tasks). Tasks can then be performed in motor or nonmotor (perceptual) conditions, thus providing four different categories of time processing. Our meta-analytical investigation partly confirms the findings of previous meta-analytical works. Both sub- and suprasecond tasks recruit cortical and subcortical areas, but subcortical areas are more intensely activated in subsecond tasks than in suprasecond tasks, which instead receive more contributions from cortical activations. All the conditions, however, show strong activations in the SMA, whose rostral and caudal parts have an important role not only in the discrimination of different time intervals but also in relation to the nature of the task conditions. This area, along with the striatum (especially the putamen) and the claustrum, is supposed to be an essential node in the different networks engaged when the brain creates our sense of time.

Previous Musical Experience and Cortical Thickness Relate to the Beneficial Effect of Motor Synchronization on Auditory Function

Auditory processing can be enhanced by motor system activity. During auditory-motor synchronization, motor activity guides auditory attention and thus facilitates auditory processing through active sensing. Previous research on enhanced auditory processing through motor synchronization has been limited to easy tasks with simple stimulus material. Further, the mechanisms and brain regions underlying this synchronization are unclear. We investigated the effect of motor synchronization on auditory processing with naturalistic, musical auditory material in a discrimination task. We further assessed how previous musical training and cortical thickness of specific brain regions relate to different aspects of auditory-motor synchronization. We conducted an auditory-motor experiment in 139 adults. The task involved melody discrimination and beat tapping synchronization. Additionally, 68 participants underwent structural MRI. We found that individuals with better auditory-motor synchronization accuracy showed improved melody discrimination, and that melody discrimination was better in trials with higher tapping accuracy. However, melody discrimination was worse in the tapping than in the listening only condition. Longer previous musical training and thicker Heschl's gyri were associated with better melody discrimination and better tapping synchrony. Post hoc analyses furthermore pointed to a possible moderating role of frontal regions. Our results suggest that motor synchronization can enhance auditory discrimination abilities through active sensing, but that this beneficial effect can be counteracted by dual-task inference when the two tasks are too challenging. Moreover, prior experience and structural brain differences influence the extent to which an individual can benefit from motor synchronization in complex listening. This could inform future research directed at development of personalized training programs for hearing ability.

Auditory entrainment of motor responses in older adults with and without Parkinson's disease: An MEG study

Medical therapies applied to Parkinson's disease (PD) have advanced tremendously since the 1960's based on advances in our understanding of the underlying neurophysiology. Behavioral therapies, such as rhythmic auditory stimulation (RAS), have been developed more recently and demonstrated efficacy. However, the neural mechanisms of RAS are only vaguely understood. In this study, we examined the neurophysiology of RAS using magnetoencephalography (MEG) in a sample of older adults with (21 people) and without PD (23 participants). All participants underwent high-density MEG during a beat-based cued tapping task with rhythmic and non-rhythmic patterns, and the resulting data were analyzed using a Bayesian image reconstruction method. Complex wavelet based time-frequency decomposition was used to compute inter-trial phase locking factor (PLF) to auditory stimuli for left and right signal space projection vectors. Tapping with a rhythm compared to a non-rhythmic sequence resulted in differential brain activity in each group: (i) a greater activation of temporal, motor and parietal areas was found in healthy adults; (ii) a greater reliance on parietal and frontal gyri was found in PD participants. During rhythmic tapping, older adults without PD had significantly stronger neural activity in bilateral frontal, supplementary and primary motor areas compared to those with PD. Conversely, older adults with PD exhibited significantly stronger activity in the bilateral parietal regions, as well as the rolandic operculum and bilateral supramarginal gyri, relative to their healthy peers. These data suggest that RAS mobilizes diverse oscillatory networks; Healthy controls may shift to frontal areas mobilization whereas PD patients rely on parietal areas to a greater extent, which may reflect frontal network dysfunction with compensation in PD, and could serve as specific regions of interest for further RAS studies.

Developmental Changes in Task-Induced Brain Deactivation in Humans Revealed by a Motor Task

Performing tasks activates relevant brain regions in adults while deactivating task-irrelevant regions. Here, using a well-controlled motor task, we explored how deactivation is shaped during typical human development and whether deactivation is related to task performance. Healthy right-handed children (8-11 years), adolescents (12-15 years), and young adults (20-24 years; 20 per group) underwent functional magnetic resonance imaging with their eyes closed while performing a repetitive button-press task with their right index finger in synchronization with a 1-Hz sound. Deactivation in the ipsilateral sensorimotor cortex (SM1), bilateral visual and auditory (cross-modal) areas, and bilateral default mode network (DMN) progressed with development. Specifically, ipsilateral SM1 and lateral occipital deactivation progressed prominently between childhood and adolescence, while medial occipital (including primary visual) and DMN deactivation progressed from adolescence to adulthood. In adults, greater cross-modal deactivation in the bilateral primary visual cortices was associated with higher button-press timing accuracy relative to the sound. The region-specific deactivation progression in a developmental period may underlie the gradual promotion of sensorimotor function segregation required in the task. Task-induced deactivation might have physiological significance regarding suppressed activity in task-irrelevant regions. Furthermore, cross-modal deactivation develops to benefit some aspects of task performance in adults.

Motor Timing in Tourette Syndrome: The Effect of Movement Lateralization and Bimanual Coordination

The study of motor timing informs on how temporal information integrates with motor acts. Cortico-basal ganglia and cortico-cerebellar circuits control this integration, whereas transcallosal interhemispheric connectivity modulates finely timed lateralized or bimanual actions. Motor timing abilities are under-explored in Tourette syndrome (TS). We adopted a synchronization-continuation task to investigate motor timing in sequential movements in TS patients. We studied 14 adult TS patients and 19 age-matched healthy volunteers. They were asked to tap in synchrony with a metronome cue (SYNC) and then, when the tone stopped, to keep tapping, maintaining the same rhythm (CONT). We tested both a sub-second and a supra-second inter-stimulus interval between the cues. Subjects randomly performed a single-hand task with the right hand and a bimanual task using both hands simultaneously wearing sensor-engineered gloves. We measured the temporal error and the interval reproduction accuracy index. We also performed MRI-based diffusion tensor imaging and probabilistic tractography of inter-hemispheric corpus callosum (CC) connections between supplementary motor areas (SMA) and the left SMA-putamen fiber tract. TS patients were less accurate than healthy individuals only on the single-hand version of the CONT task when asked to reproduce supra-second time interval. Supra-second time processing improved in TS patients in the bimanual task, with the performance of the right hand on the bimanual version of the CONT task being more accurate than that of the right hand on the single-hand version of the task. We detected a significantly higher fractional anisotropy (FA) in both SMA-SMA callosal and left-sided SMA-putamen fiber tracts in TS patients. In TS patients only, the structural organization of transcallosal connections between the SMAs and of the left SMA-putamen tract was higher when the motor timing accuracy of the right hand on the bimanual version of the task was lower. Abnormal timing performance for supra-second time processing is suggestive of a defective network inter-connecting the striatum, the dorsolateral prefrontal cortex and the SMA. An increase in accuracy on the bimanual version of the CONT task may be the result of compensatory processes linked to self-regulation of motor control, as witnessed by plastic rearrangement of inter-hemispheric and cortical-subcortical fiber tracts.

Motor Synchronization to Rhythmic Auditory Stimulation (RAS) Attenuates Dopaminergic Responses in Ventral Striatum in Young Healthy Adults: [11C]-(+)-PHNO PET Study

Auditory-motor entrainment using rhythmic auditory stimulation (RAS) has been shown to improve motor control in healthy persons and persons with neurologic motor disorders such as Parkinson's disease and stroke. Neuroimaging studies have shown the modulation of corticostriatal activity in response to RAS. However, the underlying neurochemical mechanisms for auditory-motor entrainment are unknown. The current study aimed to investigate RAS-induced dopamine (DA) responses in basal ganglia (BG) during finger tapping tasks combined with [11C]-(+)-PHNO-PET in eight right-handed young healthy participants. Each participant underwent two PET scans with and without RAS. Binding potential relative to the non-displaceable compartment (BPND) values were derived using the simplified reference tissue method. The task performance was measured using absolute tapping period error and its standard deviation. We found that the presence of RAS significantly improved the task performance compared to the absence of RAS, demonstrated by reductions in the absolute tapping period error (p = 0.007) and its variability (p = 0.006). We also found that (1) the presence of RAS reduced the BG BPND variability (p = 0.013) and (2) the absence of RAS resulted in a greater DA response in the left ventral striatum (VS) compared to the presence of RAS (p = 0.003), These suggest that the absence of external cueing may require more DA response in the left VS associated with more motivational and sustained attentional efforts to perform the task. Additionally, we demonstrated significant age effects on D2/3 R availability in BG: increasing age was associated with reduced D2/3 R availability in the left putamen without RAS (p = 0.026) as well as in the right VS with RAS (p = 0.02). This is the first study to demonstrate the relationships among RAS, DA response/D2/3 R availability, motor responses and age, providing the groundwork for future studies to explore mechanisms for auditory-motor entrainment in healthy elderly and patients with dopamine-based movement disorders.

Hierarchy of speech-driven spectrotemporal receptive fields in human auditory cortex

Existing data indicate that cortical speech processing is hierarchically organized. Numerous studies have shown that early auditory areas encode fine acoustic details while later areas encode abstracted speech patterns. However, it remains unclear precisely what speech information is encoded across these hierarchical levels. Estimation of speech-driven spectrotemporal receptive fields (STRFs) provides a means to explore cortical speech processing in terms of acoustic or linguistic information associated with characteristic spectrotemporal patterns. Here, we estimate STRFs from cortical responses to continuous speech in fMRI. Using a novel approach based on filtering randomly-selected spectrotemporal modulations (STMs) from aurally-presented sentences, STRFs were estimated for a group of listeners and categorized using a data-driven clustering algorithm. 'Behavioral STRFs' highlighting STMs crucial for speech recognition were derived from intelligibility judgments. Clustering revealed that STRFs in the supratemporal plane represented a broad range of STMs, while STRFs in the lateral temporal lobe represented circumscribed STM patterns important to intelligibility. Detailed analysis recovered a bilateral organization with posterior-lateral regions preferentially processing STMs associated with phonological information and anterior-lateral regions preferentially processing STMs associated with word- and phrase-level information. Regions in lateral Heschl's gyrus preferentially processed STMs associated with vocalic information (pitch).

Neural substrates of internally-based and externally-cued timing: An activation likelihood estimation (ALE) meta-analysis of fMRI studies

A dynamic interplay exists between Internally-Based (IBT) and Externally-Cued (ECT) time processing. While IBT processes support the self-generation of context-independent temporal representations, ECT mechanisms allow constructing temporal representations primarily derived from the structure of the sensory environment. We performed an activation likelihood estimation (ALE) meta-analysis on 177 fMRI experiments, from 79 articles, to identify brain areas involved in timing; two individual ALEs tested the hypothesis of a neural segregation between IBT and ECT. The general ALE highlighted a network involving supplementary motor area (SMA), intraparietal sulcus, inferior frontal gyrus (IFG), insula (INS) and basal ganglia. We found evidence of a partial dissociation between IBT and ECT. IBT relies on a subset of areas also involved in ECT, however ECT tasks activate SMA, right IFG, left precentral gyrus and INS in a significantly stronger way. Present results suggest that ECT involves the detection of environmental temporal regularities and their integration with the output of the IBT processing, to generate a representation of time which reflects the temporal metric of the environment.

Trajectory formation during sensorimotor synchronization and syncopation to auditory and visual metronomes

Previous work on sensorimotor synchronization has investigated the dynamics of finger tapping and how individual movement trajectories contribute to timing accuracy via asymmetry in movement velocities. The present study investigated sensorimotor synchronization (in-phase) and syncopation (anti-phase) to both an auditory metronome and a visual flashing light at multiple frequencies to understand how individual movement phases contribute to the variability of timekeeping and error correction in different sensory modalities and with different task constraints. Results demonstrate that the proportional time spent in both the upward phase of movement and the holding phase of movement (time spent on the surface of the table) remain relatively invariant across both stimulus modalities and across tapping styles (syncopation and synchronization), but changes with interval duration, increasing as interval duration increases. The time spent in the downward phase of movement did significantly differ across stimulus modality and tapping style, increasing during both visuomotor timing and syncopation, accompanied by a significant decrease in flexion velocity during syncopation. Extension velocity and flexion time were found to be the main contributors to differences between visual and auditory timing, while flexion velocity and flexion time were found to be the main contributors to differences between synchronization and syncopation. No correlations were found between asynchrony and the upward, downward, or holding phases of movement, suggesting the existence of multiple error correction strategies.

Sensorimotor Synchronization With Auditory and Visual Modalities: Behavioral and Neural Differences

It has long been known that the auditory system is better suited to guide temporally precise behaviors like sensorimotor synchronization (SMS) than the visual system. Although this phenomenon has been studied for many years, the underlying neural and computational mechanisms remain unclear. Growing consensus suggests the existence of multiple, interacting, context-dependent systems, and that reduced precision in visuo-motor timing might be due to the way experimental tasks have been conceived. Indeed, the appropriateness of the stimulus for a given task greatly influences timing performance. In this review, we examine timing differences for sensorimotor synchronization and error correction with auditory and visual sequences, to inspect the underlying neural mechanisms that contribute to modality differences in timing. The disparity between auditory and visual timing likely relates to differences in the processing specialization between auditory and visual modalities (temporal vs. spatial). We propose this difference could offer potential explanation for the differing temporal abilities between modalities. We also offer suggestions as to how these sensory systems interface with motor and timing systems.

Stop signals delay synchrony more for finger tapping than vocalization: a dual modality study of rhythmic synchronization in the stop signal task

BACKGROUND

A robust feature of sensorimotor synchronization (SMS) performance in finger tapping to an auditory pacing signal is the negative asynchrony of the tap with respect to the pacing signal. The Paillard-Fraisse hypothesis suggests that negative asynchrony is a result of inter-modal integration, in which the brain compares sensory information across two modalities (auditory and tactile). The current study compared the asynchronies of vocalizations and finger tapping in time to an auditory pacing signal. Our first hypothesis was that vocalizations have less negative asynchrony compared to finger tapping due to the requirement for sensory integration within only a single (auditory) modality (intra-modal integration). However, due to the different measurements for vocalizations and finger responses, interpreting the comparison between these two response modalities is problematic. To address this problem, we included stop signals in the synchronization task. The rationale for this manipulation was that stop signals would perturb synchronization more in the inter-modal compared to the intra-modal task. We hypothesized that the inclusion of stop signals induce proactive inhibition, which reduces negative asynchrony. We further hypothesized that any reduction in negative asynchrony occurs to a lesser degree for vocalization than for finger tapping.

METHOD

A total of 30 participants took part in this study. We compared SMS in a single sensory modality (vocalizations (or auditory) to auditory pacing signal) to a dual sensory modality (fingers (or tactile) to auditory pacing signal). The task was combined with a stop signal task in which stop signals were relevant in some blocks and irrelevant in others. Response-to-pacing signal asynchronies and stop signal reaction times were compared across modalities and across the two types of stop signal blocks.

RESULTS

In the blocks where stopping was irrelevant, we found that vocalization (-61.47 ms) was more synchronous with the auditory pacing signal compared to finger tapping (-128.29 ms). In the blocks where stopping was relevant, stop signals induced proactive inhibition, shifting the response times later. However, proactive inhibition (26.11 ms) was less evident for vocalizations compared to finger tapping (58.06 ms).

DISCUSSION

These results support the interpretation that relatively large negative asynchrony in finger tapping is a consequence of inter-modal integration, whereas smaller asynchrony is associated with intra-modal integration. This study also supports the interpretation that intra-modal integration is more sensitive to synchronization discrepancies compared to inter-modal integration.

Taking two to tango: fMRI analysis of improvised joint action with physical contact

Many forms of joint action involve physical coupling between the participants, such as when moving a sofa together or dancing a tango. We report the results of a novel two-person functional MRI study in which trained couple dancers engaged in bimanual contact with an experimenter standing next to the bore of the magnet, and in which the two alternated between being the leader and the follower of joint improvised movements. Leading showed a general pattern of self-orientation, being associated with brain areas involved in motor planning, navigation, sequencing, action monitoring, and error correction. In contrast, following showed a far more sensory, externally-oriented pattern, revealing areas involved in somatosensation, proprioception, motion tracking, social cognition, and outcome monitoring. We also had participants perform a "mutual" condition in which the movement patterns were pre-learned and the roles were symmetric, thereby minimizing any tendency toward either leading or following. The mutual condition showed greater activity in brain areas involved in mentalizing and social reward than did leading or following. Finally, the analysis of improvisation revealed the dual importance of motor-planning and working-memory areas. We discuss these results in terms of theories of both joint action and improvisation.

Synchronizing to auditory and tactile metronomes: a test of the auditory-motor enhancement hypothesis

Humans show a striking advantage for synchronizing movements with discretely timed auditory metronomes (e.g., clicking sounds) over temporally matched visual metronomes (e.g., flashing lights), suggesting enhanced auditory-motor coupling for rhythmic processing. Does the auditory advantage persist for other modalities (not just vision)? Here, nonmusicians finger tapped to the beat of auditory, tactile, and bimodal metronomes. Stimulus magnitude and rhythmic complexity were also manipulated. In conditions involving a large area of stimulation and simple rhythmic sequences, tactile synchronization closely matched auditory. Although this finding shows a limitation to the hypothesis of enhanced auditory-motor coupling for rhythmic processing, other findings clearly support it. First, there was a robust advantage with auditory information for synchronization with complex rhythm sequences; moreover, in complex sequences a measure of error correction was found only when auditory information was present. Second, higher order grouping was evident only when auditory information was present.