Involvement of area MT in bimanual finger movements in left-handers: an fMRI study

The ease with which humans are able to perform symmetric movements of both hands has traditionally been attributed to the preference of the motor system to activate homologous muscles. Recently, we have shown in right-handers, however, that bimanual index finger adduction and abduction movements in incongruous hand orientations (one palm down/other up) preferentially engaged parietal perception-associated brain areas. Here, we used functional magnetic resonance imaging to investigate the influence of hand orientation in left-handers on cerebral activation during bimanual index finger movements. Performance in incongruous orientation of either hand yielded activations involving right and left motor cortex, supplementary motor area in right superior frontal gyrus (SMA and pre-SMA), bilateral premotor cortex, prefrontal cortex, bilateral somatosensory cortex and anterior parietal cortex along the intraparietal sulcus. In addition, the occipito-temporal cortex corresponding to human area MT (hMT) in either hemisphere was activated in relation to bimanual index finger movements in the incongruous hand orientation as compared with the same movements in the congruous hand orientation or with simply viewing the pacing stimuli. Comparison with the same movement condition in right-handed subjects from a former study support these hMT activations exclusively for left-handed subjects. These results suggest that left-handers use visual motion imagery in guiding incongruous bimanual finger movements.     

Reduced recruitment of motor association areas during bimanual coordination in concert pianists

Bimanual motor coordination is essential for piano playing. The functional neuronal substrate for high‐level bimanual performance achieved by professional pianists is unclear. We compared professional pianists to musically naïve controls while carrying out in‐phase (mirror) and anti‐phase (parallel) bimanual sequential finger movements during functional magnetic resonance imaging (fMRI). This task corresponds to bimanually playing scales practiced daily by pianists from the beginning of piano playing. Musicians and controls showed significantly different functional activation patterns. When comparing performance of parallel movements to rest, musically naïve controls showed stronger activations than did pianists within a network including anterior cingulate cortex, right dorsal premotor cortex, both cerebellar hemispheres, and right basal ganglia. The direct comparison of bimanual parallel to mirror movements between both groups revealed stronger signal increases in controls within mesial premotor cortex (SMA), bilateral cerebellar hemispheres and vermis, bilateral prefrontal cortex, left ventral premotor cortex, right anterior insula, and right basal ganglia. These findings suggest increased efficiency of cortical and subcortical systems for bimanual movement control in musicians. This may be fundamental to achieve high‐level motor skills allowing the musician to focus on artistic aspects of musical performance. Hum. Brain Mapping 22:206–215, 2004. © 2004 Wiley‐Liss, Inc.     

Cortical and cerebellar activity of the human brain during imagined and executed unimanual and bimanual action sequences: a functional MRI study

The neural (blood oxygenation level dependent) correlates of executed and imagined finger sequences, both unimanual and bimanual, were studied in adult right-handed volunteers using functional magnetic resonance imaging (fMRI) of the entire brain. The finger to thumb opposition tasks each consisted of three conditions, two unimanual and one bimanual. Each experimental condition consisted of overt movement of the fingers in a prescribed sequence and imagery of the same task. An intricate network consisting of sensorimotor cortex, supplementary motor area (SMA), superior parietal lobule and cerebellum was identified when the tasks involved both planning and execution. During imagery alone, however, cerebellar activity was largely absent. This apparent decoupling of sensorimotor cortical and cerebellar areas during imagined movement sequences, suggests that cortico-cerebellar loops are engaged only when action sequences are both intended and realized. In line with recent models of motor control, the cerebellum may monitor cortical output and feed back corrective information to the motor cortex primarily during actual, not imagined, movements. Although parietal cortex activation occurred during both execution and imagery tasks, it was most consistently present during bimanual action sequences. The engagement of the superior parietal lobule appears to be related to the increased attention and memory resources associated, in the present instance, with coordinating difficult bimanual sequences.     

Functional anatomy of human procedural learning determined with regional cerebral blood flow and PET.

The functional anatomy of motor skill acquisition was investigated in six normal human subjects who learned to perform a pursuit rotor task with their dominant right hand during serial positron emission tomography (PET) imaging of relative cerebral blood flow (relCBF). The effect of motor execution, rather than learning, was identified by a comparison of four motor performance scans with two control scans (eye movements only). Motor execution was associated with activation of a distributed network involving cortical, striatonigral, and cerebellar sites. Second, the effect of early motor learning was examined. Performance improved from 17% to 66% mean time on target across the four PET scans obtained during pursuit rotor performance. Across the same scans, significant longitudinal increases of relCBF were located in the left primary motor cortex, the left supplementary motor area, and the left pulvinar thalamus. The results demonstrate that changes of regional cerebral activity associated with early learning of skilled movements occur in sites that are a subset of a more widely distributed network that is active during motor execution.     

Acquisition of a new bimanual coordination pattern modulates the cerebral activations elicited by an intrinsic pattern: an fMRI study

Intensive practice of a new complex motor skill results in progressive improvement of performance. This induces neuroplastic changes, reflecting the transition from attention-demanding to more automatic performance throughout the learning. In the present fMRI study, learning-related cerebral activation changes during the acquisition of a new complex bimanual coordination pattern were examined, i.e., the 90 degrees out-of-phase pattern (90Phi). Furthermore, we investigated whether practice of this new pattern influenced the neural correlates associated with performance of a preferred intrinsic pattern. Twelve young healthy subjects were intensively trained on the 90Phi task, and underwent two fMRI scanning sessions in early (PRE) and late (POST) learning. Scanning sessions included performance of the trained 90Phi pattern, as well as the nontrained intrinsic in-phase pattern (InPhi). Kinematics registered during training and scanning experiments showed that the new 90Phi pattern was acquired successfully, resulting in learning-related brain activation changes. Activation decreases were observed in the right prefrontal cortex (DLPFC and dorsal premotor), in the right middle temporal and occipital cortices and in the posterior cerebellum. Conversely, increases were found in the basal ganglia and hippocampus. Interestingly, activity elicited by the InPhi task also evidenced within-subjects PRE/POST differences (although kinematics InPhi performance was equivalent in both sessions). In particular, the learning-related decreases found for the 90Phi pattern in the cerebellum, the occipital and temporal gyri were similarly observed for the intrinsic InPhi pattern. Moreover, InPhi performance induced PRE/POST increases of activity in the left superior frontal gyrus. Our fMRI results suggest that intensive practice of a new complex coordination pattern impacted, at least temporarily, on the neural correlates of preferred intrinsic coordination patterns. Additional neural recruitment might reflect increased mental effort to prevent negative transfer from the learned mode onto the intrinsic coordination mode.     

Functional networks in motor sequence learning: abnormal topographies in Parkinson's disease

We examined the neural circuitry underlying the explicit learning of motor sequences in normal subjects and patients with early stage Parkinson's disease (PD) using 15O-water (H2 15O) positron emission tomography (PET) and network analysis. All subjects were scanned while learning motor sequences in a task emphasizing explicit learning, and during a kinematically controlled motor execution reference task. Because different brain networks are thought to subserve target acquisition and retrieval during motor sequence learning, we used separate behavioral indices to quantify these aspects of learning during the PET experiments. In the normal cohort, network analysis of the PET data revealed a significant covariance pattern associated with acquisition performance. This topography was characterized by activations in the left dorsolateral prefrontal cortex (PFdl), rostral supplementary motor area (preSMA), anterior cingulate cortex, and in the left caudate/putamen. A second independent covariance pattern was associated with retrieval performance. This topography was characterized by bilateral activations in the premotor cortex (PMC), and in the right precuneus and posterior parietal cortex. The normal learning-related topographies failed to predict acquisition performance in PD patients and predicted retrieval performance less accurately in the controls. A separate network analysis was performed to identify discrete learning-related topographies in the PD cohort. In PD patients, acquisition performance was associated with a covariance pattern characterized by activations in the left PFdl, ventral prefrontal, and rostral premotor regions, but not in the striatum. Retrieval performance in PD patients was associated with a covariance pattern characterized by activations in the right PFdl, and bilaterally in the PMC, posterior parietal cortex, and precuneus. These results suggest that in early stage PD sequence learning networks are associated with additional cortical activation compensating for abnormalities in basal ganglia function.     

The cerebellar second homunculus remains silent during passive bimanual movements

In a previous study, we showed that the second homunculus in lobule VIII of the cerebellum is activated during bilateral out-of-phase index finger-thumb opposition, implying a role in motor coordination. However, several recent studies indicate that the cerebellum could be more actively involved in sensory information processing during movement. Therefore, as lobule VIII activation could involve either a motor or a proprioceptive component, these two components must be distinguished and their relative contribution must be determined. Using functional imaging, we studied cerebellar activation of the same region during passively induced index finger-thumb opposition of both hands in in-phase and out-of-phase modes, thereby excluding the voluntary movement component. No significant activation was detected in lobule VIII. Intense activation of lobule VIII, obtained during active, out-of-phase bimanual movements, therefore does not involve a significant sensory component related to direct proprioceptive feedback. This result is strongly in favour of the specific recruitment of lobule VIII during out-of-phase movements related more to complex motor timing than to sensory function.     

Learning-related fMRI activation associated with a rotational visuo-motor transformation

The unique ability to learn transformed or altered visuo-motor relationships during motor learning (visuo-motor transformation learning) has engaged researchers for over a century. Compared to other forms of motor learning (e.g., sequence learning), little is known about plasticity in the cortical and/or subcortical systems involved. We used fMRI to isolate region-specific activation changes during the learning of a visuo-motor (joystick) task under a simple transformation (90 degree rotation of visual feedback). Distributed brain systems were engaged in the learning process. In particular, we found evidence of a learning-dependent transition from early activation of the posterior parietal cortex to later distributed cortico-subcortical-cerebellar responses (in the temporal and occipital cortices, basal ganglia, cerebellum and thalamus). The role of the posterior parietal cortex may relate specifically to the acquisition of the transformation, while that of the fusiform and superior temporal gyri may reflect higher level visual and visuo-spatial processing underlying consolidation. Learning-related increases in cerebellar responses are consistent with its proposed role in the acquisition of internal models of the motor apparatus. These learning-related changes suggest a role for interacting neural systems involving the co-operation of cortico-cortico, cortico-cerebellar and cortico-basal ganglia loops during visuo-motor transformation learning.     

A pianist's recovery from stroke

OBJECTIVE: To determine alternative neural pathways for restitution of piano playing after right hemispheric infarction causing left arm and hand paralysis. DESIGN: Case report testing coordinated bimanual skills using structured motor skills tests and neuroimaging. SETTING: A professional pianist sustained a lacunar infarction in the posterior limb of his right internal capsule, which resulted in left hemiparesis with immobilized left-hand and -finger movements persisting for 13 weeks. After 6 months, he had recovered bimanual coordinated piano skills by "ignoring" his left hand while concentrating or discussing subjects other than music while playing. PATIENT: A 63-year-old, male professional pianist. INTERVENTION: Detailed neurological examination including computed cranial tomography, functional magnetic resonance imaging, and positron emission tomography. RESULTS: Functional magnetic resonance imaging activation patterns correlated with rapid movements of fingers in each hand separately and together demonstrating that subcortical and cerebellar pathways were activated during skilled motor function of his left hand. Contralateral cerebral and cerebellar activation occurred with both left- and right-hand movements. During tapping of the left fingers, there was bilateral cerebellar, parietal, and left premotor strip and left thalamic activation. CONCLUSION: Patterns of activation relate to task performance and they are not similar to subjects engaged in simpler tasks such as finger opposition.     

Nigrostriatal dopamine system and motor lateralization

The mechanism by which most people favor use of the right hand remains unknown. It has been proposed that asymmetries in the nigrostriatal dopamine system may be related to motor lateralization in humans. We explored this hypothesis in vivo by using [18F]fluorodopa positron emission tomography. Whereas the degree of right hand preference was found to correlate with left putamen dominance as assessed by asymmetry in fluorodopa uptake (K(i)), right caudate dominance was positively correlated with the level of performance during simultaneous bimanual movements in right-handed normal subjects. In addition, right-handed patients with Parkinson's disease with higher right than left caudate K(i) performed much better in bimanual movement tests than those in whom the K(i) value of the left caudate was higher than that of the right. These findings support the notion that the nigrostriatal dopaminergic system may play a role in motor lateralization, and suggest a functional model for bimanual movements. We propose that the skill for performing simultaneous bilateral hand movements in right-handed subjects might depend upon both the activation (through the dominant left putamen circuitry) of the left supplementary motor area (SMA), and the inhibition (through the right caudate circuitry) of motor programs stored in the right SMA.     

Learning of Sequential Finger Movements in Man: A Combined Kinematic and Positron Emission Tomography (PET) Study

The cerebral structures participating in learning of a manual skill were mapped with regional cerebral blood flow (rCBF) measurements and positron emission tomography in nine healthy volunteers. The task was a complicated right-hand finger movement sequence. The subjects were examined at three stages: during initial practice of the finger movement sequence, in an advanced stage of learning, and after they had learnt the finger movement sequence. Quantitative evaluation of video tapes and electromyographic records of the right forearm and hand muscles demonstrated that the finger movements significantly accelerated and became more regular. Significant mean rCBF increases were induced in the left motor hand area, the left premotor cortex, the left supplementary motor area, the left sensory hand area, the left supplementary sensory area and the right anterior lobe of the cerebellum. During the learning process significant depressions of the mean rCBF occurred bilaterally in the superior parietal lobule, the anterior parietal cortex and the pars triangularis of the right inferior frontal cortex. The mean rCBF increases in these structures during the initial stage of learning were related to somatosensory feedback processing and internal language for the guidance of the finger movements. These activations disappeared when the subjects had learnt the finger movement sequence. Conversely, the mean rCBF significantly rose during the course of learning in the midsector of the putamen and globus pallidus on the left side. It is suggested that during the learning phase of this movement sequence, the basal ganglia were critically involved in the establishment of the final motor programme.     

Activation of cortical and cerebellar motor areas during executed and imagined hand movements: an fMRI study.

Brain activation during executed (EM) and imagined movements (IM) of the right and left hand was studied in 10 healthy right-handed subjects using functional magnetic resonance imagining (fMRI). Low electromyographic (EMG) activity of the musculi flexor digitorum superficialis and high vividness of the imagined movements were trained prior to image acquisition. Regional cerebral activation was measured by fMRI during EM and IM and compared to resting conditions. Anatomically selected regions of interest (ROIs) were marked interactively over the entire brain. In each ROI activated pixels above a t value of 2.45 (p<0.01) were counted and analyzed. In all subjects the supplementary motor area (SMA), the premotor cortex (PMC), and the primary motor cortex (M1) showed significant activation during both EM and IM; the somatosensory cortex (S1) was significantly activated only during EM. Ipsilateral cerebellar activation was decreased during IM compared to EM. In the cerebellum, IM and EM differed in their foci of maximal activation: Highest ipsilateral activation of the cerebellum was observed in the anterior lobe (Larsell lobule H IV) during EM, whereas a lower maximum was found about 2-cm dorsolateral (Larsell lobule H VII) during IM. The prefrontal and parietal regions revealed no significant changes during both conditions. The results of cortical activity support the hypothesis that motor imagery and motor performance possess similar neural substrates. The differential activation in the cerebellum during EM and IM is in accordance with the assumption that the posterior cerebellum is involved in the inhibition of movement execution during imagination.     

Procedural learning in schizophrenia investigated with functional magnetic resonance imaging

A cerebral basis for the acquisition and retention of procedural knowledge in schizophrenia was examined with 1.5 T functional MRI during an embedded sequence Serial Reaction Time Task (SRTT) in 10 chronic medicated patients and 15 healthy controls. Comparable procedural learning was observed in both groups, suggesting that the impairment reported in previous schizophrenia samples may not be robust. Consistent with previous fMRI reports, procedural learning in the control group was associated with activity in the dorsal striatum, anterior cingulate, parietal cortex and frontal cortex. Greater procedural learning related activity was observed in the control relative to the schizophrenia group in the bilateral frontal, left parietal and bilateral caudate regions. Patients did not activate frontal or parietal areas while responding to the embedded sequence within the SRTT, but greater activation during procedural learning was observed relative to the control sample in the right anterior cingulate, left globus pallidus and the right superior temporal gyrus. Thus, despite comparable instantiation of procedural learning in schizophrenia, the cerebral activation associated with this cognitive skill was abnormal. The paucity of activity in bilateral frontal cortex, left parietal cortex and bilateral caudate nucleus may represent cerebral dysfunction associated with schizophrenia, whereas the hyperactivation of the right superior temporal gyrus, the right anterior cingulate cortex and the left globus pallidus may represent a compensatory cerebral action capable of facilitating near-normal task performance. The results are thus consistent with a neurodevelopmental pathology impinging on fronto-subcortical circuitry.     

Changes in brain activation patterns according to cross-training effect in serial reaction time task An functional MRI study

Cross-training is a phenomenon related to motor learning, where motor performance of the untrained limb shows improvement in strength and skill execution following unilateral training of the homologous contralateral limb. We used functional MRI to investigate whether motor performance of the untrained limb could be improved using a serial reaction time task according to motor sequential learning of the trained limb, and whether these skill acquisitions led to changes in brain activation patterns. We recruited 20 right-handed healthy subjects, who were randomly allocated into training and control groups. The training group was trained in performance of a serial reaction time task using their non-dominant left hand, 40 minutes per day, for 10 days, over a period of 2 weeks. The control group did not receive training. Measurements of response time and percentile of response accuracy were performed twice during pre- and post-training, while brain functional MRI was scanned during performance of the serial reaction time task using the untrained right hand. In the training group, prominent changes in response time and percentile of response accuracy were observed in both the untrained right hand and the trained left hand between pre- and post-training. The control group showed no significant changes in the untrained hand between pre- and post-training. In the training group, the activated volume of the cortical areas related to motor function (i.e., primary motor cortex, premotor area, posterior parietal cortex) showed a gradual decrease, and enhanced cerebellar activation of the vermis and the newly activated ipsilateral dentate nucleus were observed during performance of the serial reaction time task using the untrained right hand, accompanied by the cross-motor learning effect. However, no significant changes were observed in the control group. Our findings indicate that motor skills learned over the 2-week training using the trained limb were transferred to the opposite homologous limb, and motor skill acquisition of the untrained limb led to changes in brain activation patterns in the cerebral cortex and cerebellum.     

Functional MRI of motor sequence acquisition: effects of learning stage and performance

Neural networks of motor control are well understood and the motor domain therefore lends itself to the study of learning. Neuroimaging of motor learning has demonstrated fronto-parietal, subcortical, and cerebellar involvement. However, there is conflicting evidence on the specific functional contributions of individual regions and their relative importance for early and advanced stages of learning. Using functional MRI (fMRI), we examined hemodynamic effects in seven right-handed men during brief episodes of explicit learning of novel six-digit sequences (experiments 1 and 2) and during prolonged learning of an eight-digit sequence (experiment 3), all performed with the dominant hand. Brief episodes of new learning were predominantly associated with bilateral activations in premotor and supplementary motor areas, superior and inferior parietal cortices, and anterior cerebellum. In experiment 2, which included a control condition matched for complexity of motor execution, we also found unexpectedly strong activation in the bilateral inferior frontal lobes. In experiment 3, analysis of task by learning stage interactions showed greater involvement of the bilateral superior parietal lobes, the right middle frontal gyrus, and the left caudate nucleus during early stages, whereas left occipito-temporal and superior frontal cortex as well as the bilateral parahippocampal region were more activated during late learning stages. Analysis of task by performance interactions (based on each subject's response times and accuracy during each scan) showed effects in bilateral fronto-polar, right hippocampal, and anterior cerebellar regions associated with high levels of performance, as well as inverse effects in bilateral occipito-parietal regions. We conclude that superior parietal and occipital regions are most intensely involved in visually driven explicit digit sequence learning during early stages and low performance, whereas later stages of acquisition and higher levels of performance are characterized by stronger recruitment of prefrontal and mediotemporal regions.     

Side of lesion influences bilateral activation in chronic, post-stroke hemiparesis.

OBJECTIVE: To determine how stroke lesion side and ipsilateral motor pathways influence motor performance in bimanual tasks. METHODS: Stroke subjects and age-matched controls participated in two data collection sessions: (1) motor behavior was examined during a movement task performed in unimanual, bimanual symmetric, and bimanual asymmetric conditions and (2) transcranial magnetic stimulation was used to examine the excitability of ipsilateral and contralateral motor pathways during isometric unilateral and bilateral muscle activation. RESULTS: Subjects with left hemiparesis and controls demonstrated a performance differential between symmetric and asymmetric motor tasks compared to subjects with right hemiparesis. Contralateral motor pathway excitability decreased and ipsilateral pathway excitability increased during bilateral compared to unilateral activation in control subjects and in the non-affected arm of stroke subjects. Responses in the affected arm were similar to controls in subjects with left hemiparesis but not right. CONCLUSIONS: Changes in motor pathway excitability during bilateral activation may promote more stable performance of symmetric movements. In individuals with hemiparesis, the side of lesion influences neural and behavioral aspects of bimanual tasks. Those with injuries to the right hemisphere exhibit coupling that is more similar to age-matched controls. SIGNIFICANCE: The efficacy of bilateral training interventions may be different between people with lesions in the left and right hemispheres.     

Bimanual recoupling by visual cueing in callosal disconnection

The cerebral control of bimanual movements is not completely understood. We investigated a 59-year-old, right-handed man who presented with an acute bimanual coordination deficit. Magnetic resonance imaging showed a lesion involving the entire corpus callosum, which was found on stereotactic biopsy to be an ischemic infarct. Paired-pulse transcranial magnetic stimulation indicated that the patient had a lack of interhemispheric inhibition, while intracortical inhibition in motor cortex of either side was normal. Functional magnetic resonance imaging showed activation of the left SMA, the bilateral motor cortex and anterior cerebellum during spontaneous bimanual thumb-index oppositions, which were uncoupled as evident from simultaneous electromyographic recordings. In contrast, when the bimanual thumb-index oppositions were cued by a visual stimulus, the movements of both hands were tightly correlated. This synchronized activity was accompanied by additional activations bilateral in lateral occipital cortex, dorsal premotor cortex and cerebellum. The data suggest that the visually cued movements of both hands were recoupled by action of a bihemispheric motor network.     

Right motor neglect associated with dynamic aphasia, loss of drive and amnesia: case report and cerebral blood flow study.

A 30-year-old right-handed man had right motor neglect, amnesia, aphasia and loss of drive following bilateral thalamic and subthalamic infarctions. Serial resting cerebral blood flow (CBF) measurements with either Xenon 133 inhalation or positron emission tomography at 1, 8 and 10 months post-onset showed a widespread and long-lasting low CBF in the cortex. An additional CBF measurement, during motor tasks, showed a marked interhemispheric asymmetry in the pattern of activation: whereas left hand movement resulted in a CBF increase in contralateral superior rolandic and prerolandic areas, no significant regional CBF changes were seen during right hand movement, despite recovery from motor neglect. This loss of CBF increase in cortical motor and premotor areas during voluntary movement of the previously neglected side points to a disruption of cortico-subcortical pathways subserving motor activation. The pathophysiology of aphasia, loss of drive and amnesia as well as their relationships to motor neglect, may also be discussed on the basis of thalamo-cortical disconnections.     

Bimanual Recoupling by Visual Cueing in Callosal Disconnection

Abstract

The cerebral control of bimanual movements is not completely understood. We investigated a 59-year-old, right-handed man who presented with an acute bimanual coordination deficit. Magnetic resonance imaging showed a lesion involving the entire corpus callosum, which was found on stereotactic biopsy to be an ischemic infarct. Paired-pulse transcranial magnetic stimulation indicated that the patient had a lack of interhemispheric inhibition, while intracortical inhibition in motor cortex of either side was normal. Functional magnetic resonance imaging showed activation of the left SMA, the bilateral motor cortex and anterior cerebellum during spontaneous bimanual thumb-index oppositions, which were uncoupled as evident from simultaneous electromyographic recordings. In contrast, when the bimanual thumb-index oppositions were cued by a visual stimulus, the movements of both hands were tightly correlated. This synchronized activity was accompanied by additional activations bilateral in lateral occipital cortex, dorsal premotor cortex and cerebellum. The data suggest that the visually cued movements of both hands were recoupled by action of a bihemispheric motor network.     

Distinct cortico-cerebellar activations in rhythmic auditory motor synchronization

We investigated the role of the cerebellum in differential aspects of temporal control of rhythmic auditory motor synchronization using positron emission tomography (PET). Subjects tapped with their right index finger to metronome tones at a mean frequency of .8 Hz during 5 conditions: (1) an isochronous rhythm condition, (2) random changes in interval durations, and while the duration of rhythmic intervals was continuously time-modulated following a cosine-wave function at (3) 3%, (4) 7%, and (5) 20% of base interval. Anterior lobe cerebellar neuronal populations showed similar motor-associated activity across all conditions regardless of rhythmic time structure in vermal and hemispheric parts ipsilateral to the movements. Neuronal populations in bilateral anterior posterior lobe, especially in the simple lobule, increased their activity stepwise with each increase in tempo modulation from a steady beat. Neuronal populations in other parts of the posterior lobe showed an increase of activity only during the 20% condition, which involved conscious monitoring of rhythmic pattern synchronization, especially on the left side contralateral to the movements. Differential cerebellar activation patterns correspond to those in contralateral primary (primary sensorimotor), ipsilateral secondary (inferior parietal close to the intraparietal sulcus) and bilateral tertiary (dorsolateral prefrontal cortex) sensorimotor areas of the cerebral cortex, suggesting that distinct functional cortico-cerebellar circuits subserve differential aspects of rhythmic synchronization in regard to rhythmic motor control, conscious and subconscious response to temporal structure, and conscious monitoring of rhythmic pattern tracking.