Distinct contribution of the striatum and cerebellum to motor learning

The Contributions of Pitch, Loudness, and Rate Control to Speech Naturalness in Cerebellar Ataxia

PURPOSE

The goal of this study was to determine the relationship between the perceptual measure of speech naturalness and objective measures of pitch, loudness, and rate control as a potential tool for assessment of ataxic dysarthria.

METHOD

Twenty-seven participants with ataxia and 29 age- and sex-matched control participants completed the pitch glide and loudness step tasks drawn from the Frenchay Dysarthria Assessment-Second Edition (FDA-2) in addition to speech diadochokinetic (DDK) tasks. First, group differences were compared for pitch variability in the pitch glide task, loudness variability in the loudness step task, and syllable duration and speech rate in the DDK task. Then, these acoustic measures were compared with previously collected ratings of speech naturalness by speech-language pathology graduate students.

RESULTS

Robust group differences were measured for pitch variability and both DDK syllable duration and speech rate, indicating that the ataxia group had greater pitch variability, longer DDK syllable duration, and slower DDK speech rate than the control group. No group differences were measured for loudness variability. There were robust relationships between speech naturalness and pitch variability, DDK syllable duration, and DDK speech rate, but not for loudness variability.

CONCLUSIONS

Objective acoustic measures of pitch variability in the FDA-2 pitch glide task and syllable duration and speech rate in the DDK task can be used to validate perceptual measures of speech naturalness. Overall, speech-language pathologists can incorporate both perceptual measures of speech naturalness and acoustic measures of pitch variability and DDK performance for a comprehensive evaluation of ataxic dysarthria.

Intact procedural memory and impaired auditory statistical learning in adults with dyslexia

Developmental dyslexia is a reading disorder that is associated with atypical brain function. One neuropsychological theory posits that dyslexia reflects a deficit in the procedural memory system, which supports implicit learning, or the acquisition of knowledge without conscious awareness or intention. This study investigated various forms of procedural learning in adults with dyslexia and typically-reading adults. Adults with dyslexia exhibited typical skill learning on mirror tracing and rotary pursuit tasks that have been well-established as reflecting purely procedural memory and dependent on basal ganglia and cerebellar structures. They also exhibited typical statistical learning for visual material, but impaired statistical learning for auditory material. Auditory statistical learning proficiency correlated positively with single-word reading performance across all participants and within the group with dyslexia, linking a major difficulty in dyslexia with impaired auditory statistical learning. These findings dissociate multiple forms of procedural memory that are intact in dyslexia from a specific impairment in auditory statistical learning that is associated with reading difficulty.

Age-related differences in resting-state functional connectivity from childhood to adolescence

The human brain is active at rest, and spontaneous fluctuations in functional MRI BOLD signals reveal an intrinsic functional architecture. During childhood and adolescence, functional networks undergo varying patterns of maturation, and measures of functional connectivity within and between networks differ as a function of age. However, many aspects of these developmental patterns (e.g. trajectory shape and directionality) remain unresolved. In the present study, we characterised age-related differences in within- and between-network resting-state functional connectivity (rsFC) and integration (i.e. participation coefficient, PC) in a large cross-sectional sample of children and adolescents (n = 628) aged 8-21 years from the Lifespan Human Connectome Project in Development. We found evidence for both linear and non-linear differences in cortical, subcortical, and cerebellar rsFC, as well as integration, that varied by age. Additionally, we found that sex moderated the relationship between age and putamen integration where males displayed significant age-related increases in putamen PC compared with females. Taken together, these results provide evidence for complex, non-linear differences in some brain systems during development.

Induction of BDNF Expression in Layer II/III and Layer V Neurons of the Motor Cortex Is Essential for Motor Learning

Motor learning depends on synaptic plasticity between corticostriatal projections and striatal medium spiny neurons. Retrograde tracing from the dorsolateral striatum reveals that both layer II/III and V neurons in the motor cortex express BDNF as a potential regulator of plasticity in corticostriatal projections in male and female mice. The number of these BDNF-expressing cortical neurons and levels of BDNF protein are highest in juvenile mice when adult motor patterns are shaped, while BDNF levels in the adult are low. When mice are trained by physical exercise in the adult, BDNF expression in motor cortex is reinduced, especially in layer II/III projection neurons. Reduced expression of cortical BDNF in 3-month-old mice results in impaired motor learning while space memory is preserved. These findings suggest that activity regulates BDNF expression differentially in layers II/III and V striatal afferents from motor cortex and that cortical BDNF is essential for motor learning.

SIGNIFICANCE STATEMENT Motor learning in mice depends on corticostriatal BDNF supply, and regulation of BDNF expression during motor learning is highest in corticostriatal projection neurons in cortical layer II/III.

Procedural Learning Improves Cognition in Multiple Sclerosis

Background:

Multiple sclerosis (MS) is considered a neurodegenerative disease and an inflammatory demyelinating neuropathology in young population. Procedural memory has been poorly investigated in MS.

Objective:

We assessed whether the MS group was able to develop a motor-cognitive skill, using a procedural task (PLSC) developed in our laboratory, applying a manual and serial reaction time (RT) paradigm to semantic categorization.

Methods:

We evaluated 26 MS patients and 26 socio-demographic matched control participants using the PLSC task.

Results:

Using non-parametric statistical analyses, we observed a significant improvement of semantic categorization RTs with practice (p = 0.002), even with new verbal material to categorize in MS patients (p = 0.006), despite their motor and executive moderate deficits. This same profile of semantic procedural learning in MS was observed in previous studies carried out with Alzheimer’s and Parkinson’s diseases. Moreover, the visual-motor RTs remained stable or slightly improved over the five blocks in both groups, as well as in the AD groups of previous studies. The MS group showed longer visual-motor reaction times than those of the control group (p < 0.042), except in motor initiation aspect (p = 0.064). Both groups showed no significant differences for any type of error. Additionally, disability level and cognitive performances were not associated with the ratio of semantic procedural learning.

Conclusion:

The present results support the notion that MS patients may be capable of acquiring semantic skill, despite their motor disabilities and executive troubles. This work also addresses the possibilities to improve motor-cognitive skill RTs in neurodegenerative diseases.

Differentiating Boys with ADHD from Those with Typical Development Based on Whole-Brain Functional Connections Using a Machine Learning Approach

PURPOSE

In recent years, machine learning techniques have received increasing attention as a promising approach to differentiating patients from healthy subjects. Therefore, some resting-state functional magnetic resonance neuroimaging (R-fMRI) studies have used interregional functional connections as discriminative features. The aim of this study was to investigate ADHD-related spatially distributed discriminative features derived from whole-brain resting-state functional connectivity patterns using machine learning.

PATIENTS AND METHODS

We measured the interregional functional connections of the R-fMRI data from 40 ADHD patients and 28 matched typically developing controls. Machine learning was used to discriminate ADHD patients from controls. Classification performance was assessed by permutation tests.

RESULTS

The results from the model with the highest classification accuracy showed that 85.3% of participants were correctly identified using leave-one-out cross-validation (LOOV) with support vector machine (SVM). The majority of the most discriminative functional connections were located within or between the cerebellum, default mode network (DMN) and frontoparietal regions. Approximately half of the most discriminative connections were associated with the cerebellum. The cerebellum, right superior orbitofrontal cortex, left olfactory cortex, left gyrus rectus, right superior temporal pole, right calcarine gyrus and bilateral inferior occipital cortex showed the highest discriminative power in classification. Regarding the brain-behaviour relationships, some functional connections between the cerebellum and DMN regions were significantly correlated with behavioural symptoms in ADHD (P < 0.05).

CONCLUSION

This study indicated that whole-brain resting-state functional connections might provide potential neuroimaging-based information for clinically assisting the diagnosis of ADHD.

Neocerebellar Crus I Abnormalities Associated with a Speech and Language Disorder Due to a Mutation in FOXP2

Bilateral volume reduction in the caudate nucleus has been established as a prominent brain abnormality associated with a FOXP2 mutation in affected members of the 'KE family', who present with developmental orofacial and verbal dyspraxia in conjunction with pervasive language deficits. Despite the gene's early and prominent expression in the cerebellum and the evidence for reciprocal cerebellum-basal ganglia connectivity, very little is known about cerebellar abnormalities in affected KE members. Using cerebellum-specific voxel-based morphometry (VBM) and volumetry, we provide converging evidence from subsets of affected KE members scanned at three time points for grey matter (GM) volume reduction bilaterally in neocerebellar lobule VIIa Crus I compared with unaffected members and unrelated controls. We also show that right Crus I volume correlates with left and total caudate nucleus volumes in affected KE members, and that right and total Crus I volumes predict the performance of affected members in non-word repetition and non-verbal orofacial praxis. Crus I also shows bilateral hypo-activation in functional MRI in the affected KE members relative to controls during non-word repetition. The association of Crus I with key aspects of the behavioural phenotype of this FOXP2 point mutation is consistent with recent evidence of cerebellar involvement in complex motor sequencing. For the first time, specific cerebello-basal ganglia loops are implicated in the execution of complex oromotor sequences needed for human speech.

Physical Exercise Enhances Neuroplasticity and Delays Alzheimer's Disease

Accumulating evidence indicates that exercise can improve learning and memory as well as attenuate neurodegeneration, including Alzheimer's disease (AD). In addition to improving neuroplasticity by altering the synaptic structure and function in various brain regions, exercise also modulates systems like angiogenesis and glial activation that are known to support neuroplasticity. Moreover, exercise helps to maintain a cerebral microenvironment that facilitates synaptic plasticity by enhancing the clearance of Aβ, one of the main culprits of AD pathogenesis. The purpose of this review is to highlight the positive impacts of exercise on promoting neuroplasticity. Possible mechanisms involved in exercise-modulated neuroplasticity are also discussed. Undoubtedly, more studies are needed to design an optimal personalized exercise protocol for enhancing brain function.

Resting-state brain network features associated with short-term skill learning ability in humans and the influence of N-methyl-d-aspartate receptor antagonism

Graph theoretical functional magnetic resonance imaging (fMRI) studies have demonstrated that brain networks reorganize significantly during motor skill acquisition, yet the associations between motor learning ability, brain network features, and the underlying biological mechanisms remain unclear. In the current study, we applied a visually guided sequential pinch force learning task and graph theoretical analyses to investigate the associations between short-term motor learning ability and resting-state brain network metrics in 60 healthy subjects. We further probed the test-retest reliability (n = 26) and potential effects of the N-methyl-d-aspartate (NMDA) antagonist ketamine (n = 19) in independent healthy volunteers. Our results show that the improvement of motor performance after short-term training was positively correlated with small-worldness (p = 0.032) and global efficiency (p = 0.025), whereas negatively correlated with characteristic path length (p = 0.014) and transitivity (p = 0.025). In addition, using network-based statistics (NBS), we identified a learning ability–associated (p = 0.037) and ketamine-susceptible (p = 0.027) cerebellar-cortical network with fair to good reliability (intraclass correlation coefficient [ICC] > 0.7) and higher functional connectivity in better learners. Our results provide new evidence for the association of intrinsic brain network features with motor learning and suggest a role of NMDA-related glutamatergic processes in learning-associated subnetworks.

Learning a new motor skill prompts immediate reconfigurations of distributed brain networks followed by adaptive changes in intrinsic brain circuits related to synaptic plasticity. Here, we identify global brain network properties and a cerebellar-cortical functional subnetwork that are both significantly associated with motor learning ability in a previously trained visuomotor task in humans. We further show that the associated functional subnetwork connectivity but not the global brain network properties are susceptible to ketamine. Our findings suggest a distinct functional role for learning-related global versus local network metrics and support the idea of a preferential susceptibility of learning-associated subnetworks to N-methyl-d-aspartate antagonist and plasticity-related consolidation effects.

Histone H2AX deficiency causes neurobehavioral deficits and impaired redox homeostasis

ATM drives DNA repair by phosphorylating the histone variant H2AX. While ATM mutations elicit prominent neurobehavioral phenotypes, neural roles for H2AX have been elusive. We report impaired motor learning and balance in H2AX-deficient mice. Mitigation of reactive oxygen species (ROS) with N-acetylcysteine (NAC) reverses the behavioral deficits. Mouse embryonic fibroblasts deficient for H2AX exhibit increased ROS production and failure to activate the antioxidant response pathway controlled by the transcription factor NRF2. The NRF2 targets GCLC and NQO1 are depleted in the striatum of H2AX knockouts, one of the regions most vulnerable to ROS-mediated damage. These findings establish a role for ROS in the behavioral deficits of H2AX knockout mice and reveal a physiologic function of H2AX in mediating influences of oxidative stress on NRF2-transcriptional targets and behavior.

H2AX is a histone variant with an essential function in DNA double-strand break repair and genome stability. Here, Weyemi and colleagues show that loss of neuronal H2AX leads to locomotor dysfunction and alteration in oxidative stress response.

Disrupted implicit motor sequence learning in schizophrenia and bipolar disorder revealed with ambidextrous Serial Reaction Time Task

BACKGROUND

Impairment of implicit motor sequence learning was shown in schizophrenia (SZ) and, most recently, in bipolar disorder (BD), and was connected to cerebellar abnormalities. The goal of this study was to compare implicit motor sequence learning in BD and SZ.

METHODS

We examined 33 patients with BD, 33 patients with SZ and 31 healthy controls with a use of ambidextrous Serial Reaction Time Task (SRTT), which allows exploring asymmetries in performance depending on the hand used.

RESULTS

BD and SZ patients presented impaired implicit motor sequence learning, although the pattern of their impairments was different. While BD patients showed no signs of implicit motor sequence learning for both hands, the SZ group presented some features of motor learning when performing with the right, but not with the left hand.

CONCLUSIONS

To our best knowledge this is the first study comparing implicit motor sequence learning in BD and SZ. We show that both diseases share impairments in this domain, however in the case of SZ this impairment differs dependently on the hand performing SRTT. We propose that implicit motor sequence learning impairments constitute an overlapping symptom in BD and SZ and suggest further neuroimaging studies to verify cerebellar underpinnings as its cause.

Viscoelasticity of subcortical gray matter structures

Viscoelastic mechanical properties of the brain assessed with magnetic resonance elastography (MRE) are sensitive measures of microstructural tissue health in neurodegenerative conditions. Recent efforts have targeted measurements localized to specific neuroanatomical regions differentially affected in disease. In this work, we present a method for measuring the viscoelasticity in subcortical gray matter (SGM) structures, including the amygdala, hippocampus, caudate, putamen, pallidum, and thalamus. The method is based on incorporating high spatial resolution MRE imaging (1.6 mm isotropic voxels) with a mechanical inversion scheme designed to improve local measures in pre-defined regions (soft prior regularization [SPR]). We find that in 21 healthy, young volunteers SGM structures differ from each other in viscoelasticity, quantified as the shear stiffness and damping ratio, but also differ from the global viscoelasticity of the cerebrum. Through repeated examinations on a single volunteer, we estimate the uncertainty to be between 3 and 7% for each SGM measure. Furthermore, we demonstrate that the use of specific methodological considerations-higher spatial resolution and SPR-both decrease uncertainty and increase sensitivity of the SGM measures. The proposed method allows for reliable MRE measures of SGM viscoelasticity for future studies of neurodegenerative conditions. Hum Brain Mapp 37:4221-4233, 2016. © 2016 Wiley Periodicals, Inc.

Learning to live without the cerebellum

The near-total absence of the cerebellum is a rare congenital condition with a wide phenotypic heterogeneity ranging from a severe to mild impairment of motor, cognitive, and behavioral functions. In this study, the case of a 48-year-old right-handed man with a near-total absence of the cerebellum was examined with the aim of understanding the long-term reorganization of a brain developed without a cerebellum. Clinical, neuropsychological evaluation and a neuroimaging study on a 3-T scanner were carried out. Both conventional structural diffusion tensor imaging (DTI) and functional (resting-state fMRI) data were acquired. A severe neuropsychomotor delay in infancy and adolescence involving motor skills, cognitive, and affective competencies was observed, which improved over the years. Conventional MRI findings confirmed the complete absence of the cerebellum. Analysis of DTI and resting-state fMRI data showed an impairment of the executive-control network, involving areas strongly connected with the cerebellum through the frontopontine fibers. The neuroimaging findings excluded the involvement of the extracerebellar structure. In conclusion, our data support the vascular genesis hypothesis for this rare pathology, consistent with an acquired embryonic cerebellar insult. This case also shows that it is possible to learn to live without the cerebellum over time.

Amplitude of low-frequency oscillations in Parkinson's disease: a 2-year longitudinal resting-state functional magnetic resonance imaging study

BACKGROUND

Neuroimaging studies have found that functional changes exist in patients with Parkinson's disease (PD). However, the majority of functional magnetic resonance imaging (fMRI) studies in patients with PD are task-related and cross-sectional. This study investigated the functional changes observed in patients with PD, at both baseline and after 2 years, using resting-state fMRI. It further investigated the relationship between whole-brain spontaneous neural activity of patients with PD and their clinical characteristics.

METHODS

Seventeen patients with PD underwent an MRI procedure at both baseline and after 2 years using resting-state fMRI that was derived from the same 3T MRI. In addition, 20 age- and sex-matched, healthy controls were examined using resting-state fMRI. The fractional amplitude of low-frequency fluctuation (fALFF) approach was used to analyze the fMRI data. Nonlinear registration was used to model within-subject changes over the scanning interval, as well as changes between the patients with PD and the healthy controls. A correlative analysis between the fALFF values and clinical characteristics was performed in the regions showing fALFF differences.

RESULTS

Compared to the control subjects, the patients with PD showed increased fALFF values in the left inferior temporal gyrus, right inferior parietal lobule (IPL) and right middle frontal gyrus. Compared to the baseline in the 2 years follow-up, the patients with PD presented with increased fALFF values in the right middle temporal gyrus and right middle occipital gyrus while also having decreased fALFF values in the right cerebellum, right thalamus, right striatum, left superior parietal lobule, left IPL, left precentral gyrus, and left postcentral gyrus (P < 0.01, after correction with AlphaSim). In addition, the fALFF values in the right cerebellum were positively correlated with the Unified PD Rating Scale (UPDRS) motor scores (r = 0.51, P < 0.05, uncorrected) and the change in the UPDRS motor score (r = 0.61, P < 0.05, uncorrected).

CONCLUSIONS

The baseline and longitudinal changes of the fALFF values in our study suggest that dysfunction in the brain may affect the regions related to cortico-striato-pallido-thalamic loops and cerebello-thalamo-cortical loops as the disease progresses and that alterations to the spontaneous neural activity of the cerebellum may also play an important role in the disease's progression in patients with PD.

Mirror reversal and visual rotation are learned and consolidated via separate mechanisms: recalibrating or learning de novo?

Motor learning tasks are often classified into adaptation tasks, which involve the recalibration of an existing control policy (the mapping that determines both feedforward and feedback commands), and skill-learning tasks, requiring the acquisition of new control policies. We show here that this distinction also applies to two different visuomotor transformations during reaching in humans: Mirror-reversal (left-right reversal over a mid-sagittal axis) of visual feedback versus rotation of visual feedback around the movement origin. During mirror-reversal learning, correct movement initiation (feedforward commands) and online corrections (feedback responses) were only generated at longer latencies. The earliest responses were directed into a nonmirrored direction, even after two training sessions. In contrast, for visual rotation learning, no dependency of directional error on reaction time emerged, and fast feedback responses to visual displacements of the cursor were immediately adapted. These results suggest that the motor system acquires a new control policy for mirror reversal, which initially requires extra processing time, while it recalibrates an existing control policy for visual rotations, exploiting established fast computational processes. Importantly, memory for visual rotation decayed between sessions, whereas memory for mirror reversals showed offline gains, leading to better performance at the beginning of the second session than in the end of the first. With shifts in time-accuracy tradeoff and offline gains, mirror-reversal learning shares common features with other skill-learning tasks. We suggest that different neuronal mechanisms underlie the recalibration of an existing versus acquisition of a new control policy and that offline gains between sessions are a characteristic of latter.

GABA and 5-HT chitosan nanoparticles decrease striatal neuronal degeneration and motor deficits during liver injury

The metabolic alterations resulted from hepatic injury and cell loss lead to synaptic defects and neurodegeneration that undoubtedly contribute motor deficits. In the present study, GABA and 5-HT chitosan nanoparticles mediated liver cell proliferation influenced by growth factor and cytokines and neuronal survival in corpus striatum of partially hepatectomised rats was evaluated. Liver cell proliferation was initiated and progressed by the combined effect of increased expression of growth factor, insulin like growth factor-1 and decreased expressions of cytokines, tumor necrosis factor-α and Akt-1. This was confirmed by the extent of incorporation of thymidine analogue, BrdU, in the DNA of rapidly dividing cells. Inappropriate influx of compounds to corpus striatum resulting from incomplete metabolism elevated GABAB and 5-HT2A neurotransmissions compared to those treated with nanoparticles. This directly influenced cyclic AMP response element binding protein, glial cell derived neurotrophic factor and brain derived neurotrophic factor in the corpus striatum that facilitate neurogenesis, neuronal survival, development, differentiation and neuroprotection. Motor deficits due to liver injury followed striatal neuronal damage were scored by grid walk and rotarod studies, which confirmed the regain of motor activity by GABA and 5-HT chitosan nanoparticle treatment. The present study revealed the therapeutic significance of GABA and 5-HT chitosan nanoparticles in liver based diseases and related striatal neuronal damage that influenced by GABA and 5-HT.

Delineating the cortico-striatal-cerebellar network in implicit motor sequence learning

Theoretical models and experimental evidence suggest that cortico-striatal-cerebellar networks play a crucial role in mediating motor sequence learning. However, how these different regions interact in order to mediate learning is less clear. In the present fMRI study, we used dynamic causal modeling to investigate effective connectivity within the cortico-striatal-cerebellar network while subjects performed a serial reaction time task. Using Bayesian model selection and family wise inference, we show that the cortico-cerebellar loop had higher model evidence than the cortico-striatal loop during motor learning. We observed significant negative modulatory effects on the connections from M1 to cerebellum bilaterally during learning. The results suggest that M1 causes the observed decrease in activity in the cerebellum as learning progresses. The current study stresses the significant role that the cerebellum plays in motor learning as previously suggested by fMRI studies in healthy subjects as well as behavioral studies in patients with cerebellar dysfunction. These results provide important insight into the neural mechanisms underlying motor learning.

Age- and gender-related metabonomic alterations in striatum and cerebellar cortex in rats

In order to identify the neurochemical alterations in motor associated subcortical nuclei, and enhance our understanding of neurophysiology of progressive reduction in fine motor control with aging, the metabolic changes in striatum and cerebellar cortex in SD rats along with aging were investigated using a metabonomic approach based on high resolution "magic angle spinning" 1H-NMR spectroscopy and partial least squares-discriminant analysis. It was found that there were increased myo-inositol and lactate, and decreased taurine in these two brain regions of old rats. The above changes may be a marker for alterations of neuronal cells, which reduce fine motor control. Besides, some of the metabolites are gender-related and region-specific. Old female rats had decreased glutamate and increased creatine in striatum, while old male rats had increased choline in striatum, and increased GABA in cerebellar cortex, respectively. However, further analyses showed that most of the metabolites in male rats were not distinctively different with those of female ones except choline, which was in a relative lower level in striatum of male rats. All this results suggest that energy metabolism is an important indication of age-related change, which is not only in male, but also in female rats.

Superior working memory and behavioural habituation but diminished psychomotor coordination in mice lacking the ecto-5'-nucleotidase (CD73) gene

Adenosine is an important neuromodulator in the central nervous system involved in the regulation of wakefulness, sleep, learning and memory, fear and anxiety as well as motor functions. Extracellular adenosine is synthesized by the cell-surface ectoenzyme ecto-5'-nucleotidase (CD73) from 5'-adenosine monophosphate. While CD73 is widely expressed throughout the mammalian brain, its specific role for behaviour is poorly understood. We examined spatial working memory, emotional responses, motor coordination and motor learning as well as behavioural habituation in mice with a targeted deletion of CD73. CD73 knockout (CD73-/-) mice exhibit enhanced spatial working memory in the Y-maze and enhanced long-term behavioural habituation in the open field. Furthermore, impaired psychomotor coordination on the accelerating rotarod was found in CD73-/- mice. No changes in motor learning and/or anxiety-like behaviour were evident in CD73-/- mice. Our data provide evidence for a role of CD73 in the regulation of learning and memory and psychomotor coordination. Our results might be important for the evaluation of adenosine neuromodulators as possible treatments to ameliorate cognitive and motor deficits associated with neurodegenerative diseases.

Cognitive dysfunction with aging and the role of inflammation

As the average lifespan continues to climb because of advances in medical care, there is a greater need to understand the factors that contribute to quality of life in the elderly. The capacity to live independently is highly significant in this regard, but is compromised by cognitive dysfunction. Aging is associated with decreases in cognitive function, including impairments in episodic memory and executive functioning. The prefrontal cortex appears to be particularly vulnerable to the effects of advancing age. Although the mechanism of age-related cognitive decline is not yet known, age-related inflammatory changes are likely to play a role. New insights from preclinical and clinical research may give rise to novel therapeutics which may have efficacy in slowing or preventing cognitive decline with advancing age.

Musical memory in a patient with severe anterograde amnesia

The ability to play a musical instrument represents a unique procedural skill that can be remarkably resilient to disruptions in declarative memory. For example, musicians with severe anterograde amnesia have demonstrated preserved ability to play musical instruments. However, the question of whether amnesic musicians can learn how to play new musical material despite severe memory impairment has not been thoroughly investigated. We capitalized on a rare opportunity to address this question. Patient S.Z., an amateur musician (tenor saxophone), has extensive bilateral damage to his medial temporal lobes following herpes simplex encephalitis, resulting in a severe anterograde amnesia. We tested S.Z.'s capacity to learn new unfamiliar songs by sight-reading following three months of biweekly practices. Performances were recorded and were then evaluated by a professional saxophonist. S.Z. demonstrated significant improvement in his ability to read and play new music, despite his inability to recognize any of the songs at a declarative level. The results suggest that it is possible to learn certain aspects of new music without the assistance of declarative memory.

Age related differences in the neural substrates of motor sequence learning after interleaved and repetitive practice

Practice of tasks in an interleaved order generally induces superior retention compared to practicing in a repetitive order. Younger and older adults practiced serial reaction time tasks that were arranged in a repeated or an interleaved order on 2 successive days. Retention was tested on Day 5. For both groups, reaction times in the interleaved condition were slower than the repetitive condition during practice, but the reverse was true during retention on Day 5. After interleaved practice, changes in M1 excitability measured by paired-pulse TMS were greater than after repetitive practice, and this effect was more pronounced in older adults. Moreover, the increased M1 excitability correlated with the benefit of interleaved practice. BOLD signal was also increased for interleaved compared to repetitive practice in both groups. However, the pattern of correlations between increased BOLD during practice and subsequent benefit of the interleaved condition differed by group. In younger adults, dorsolateral-prefrontal activity during practice was related to this benefit, while in older adults, activation in sensorimotor regions and rostral prefrontal cortex during practice correlated with the benefit of interleaving on retention. Older adults may engage compensatory mechanisms during interleaved practice such as increasing sensorimotor recruitment which in turn benefits learning.

Interleaved practice enhances skill learning and the functional connectivity of fronto-parietal networks

Practice of tasks in an interleaved order generally induces superior learning compared with practicing in a repetitive order, a phenomenon known as the contextual-interference (CI) effect. Increased neural activity during interleaved over repetitive practice has been associated with the beneficial effects of CI. Here, we used psychophysiological interaction (PPI) analysis to investigate whether the neural connectivity of the dorsal premotor (PM) and the dorsolateral prefrontal (DLPFC) cortices changes when motor sequences are acquired through interleaved practice. Sixteen adults practiced a serial reaction time task where a set of three 4-element sequences were arranged in a repetitive or in an interleaved order on 2 successive days. On Day 5, participants were tested with practiced sequences to evaluate retention. A within-subjects design was used so that participants practiced sequences in the other condition (repetitive or interleaved) 2-4 weeks later. Functional magnetic resonance images were acquired during practice and retention. On Day 2 of practice, there was greater inter-regional functional connectivity in the interleaved compared with the repetitive condition for both PM-seeded and DLPFC-seeded connectivity. The increased functional connectivity between both seeded regions and sensorimotor cortical areas correlated with the benefit of interleaved practice during later retention. During retention, a significant PPI effect was found in DLPFC-seeded connectivity, with increased DLPFC-supplementary motor area connectivity correlated with the benefits of interleaved practice. These data suggest that interleaved practice benefits learning by enhancing coordination of sensorimotor cortical regions, and superior performance of sequences learned under CI is characterized by increased functional connectivity in frontal cortex.

Elephants have relatively the largest cerebellum size of mammals

The current study used MR imaging to determine the volume of the cerebellum and its component parts in the brain of three adult male African elephants (Loxodonta africana) and compared this with published data from Asian elephants and other mammalian species including odontocete cetaceans, primates, chiropterans, insectivores, carnivores, and artiodactyls. The cerebellum of the adult elephant has a volume of ∼925 mL (average of both African and Asian species). Allometric analysis indicates that the elephant has the largest relative cerebellum size of all mammals studied to date. In addition, both odontocete cetaceans and microchiropterans appear to have large relative cerebellar sizes. The vermal and hemispheric components of the African elephant cerebellum are both large relative to other mammals of similar brain size, however, for odontocete cetaceans the vermal component is small and the hemispheric component is large. These volumetric observations are related to life-histories and anatomies of the species investigated. The current study provides context for one aspect of the elephant brain in the broader picture of mammalian brain evolution.

Plastic changes in striatal fast-spiking interneurons following hemicerebellectomy and environmental enrichment

Recent findings suggest marked interconnections between the cerebellum and striatum, thus challenging the classical view of their segregated operation in motor control. Therefore, this study was aimed at further investigating this issue by analyzing the effects of hemicerebellectomy (HCb) on density and dendritic length of striatal fast-spiking interneurons (FSi). First, we analyzed the plastic rearrangements of striatal FSi morphology in hemicerebellectomized animals reared in standard conditions. Then, since environmental enrichment (EE) induces structural changes in experimental models of brain disease, we evaluated FSi morphology in lesioned animals exposed to an enriched environment after HCb. Although HCb did not affect FSi density, it progressively shrank dendritic branching of striatal FSi of both sides. These plastic changes, already evident 15 days after the cerebellar ablation, became very marked 30 days after the lesion. Such a relevant effect was completely abolished by postoperative enrichment. EE not only counteracted shrinkage of FSi dendritic arborization but also provoked a progressive increase in dendritic length which surpassed that of the controls as the enrichment period lengthened. These data confirm that the cerebellum and striatum are more interconnected than previously retained. Furthermore, cerebellar damage likely evokes a striatal response through cortical mediation. The EE probably modifies HCb-induced plastic changes in the striatum by increasing the efficiency of the cortical circuitry. This is the first study describing the morphological rearrangement of striatal FSi following a cerebellar lesion; it provides the basis for further studies aimed at investigating the mechanisms underlying cerebello-striatal "talking."

Decreased cholinergic receptor expression in the striatum: motor function deficit in hypoglycemic and diabetic rats

Hypoglycemic brain injury is a common and serious complication of insulin therapy associated with diabetes. This study evaluated the effect of insulin-induced hypoglycemia and STZ-induced diabetes on striatal cholinergic receptors and enzyme expression and on motor function. Cholinergic enzymes: AChE and ChAT gene expression, radioreceptor binding assay and immunohistochemistry of muscarinic M1, M3 receptors and α7nAChR were carried out. Motor performance on grid walk test was analysed. AChE and ChAT expression significantly downregulated in hypoglycemic and diabetic rats. Total muscarinic and Muscarinic M3 receptor binding decreased in hypoglycemic rats compared to diabetic rats whereas muscarinic M1 receptor binding increased in hypoglycemic rats compared to diabetic rats. Real-time PCR analysis and confocal imaging of muscarinic M1, M3 receptors confirmed the changes in muscarinic receptor binding in hypoglycemic and diabetic rats. In hypoglycemic rats, α7nAChR expression significantly up regulated compared to diabetic rats. Grid walk test demonstrated the impairment in motor function and coordination in hypoglycemic and hyperglycemic rats. Neurochemical changes along with the behavioral data implicate a role for impaired striatal cholinergic receptor function inducing motor function deficit induced by hypo and hyperglycemia. Hypoglycemia exacerbated the neurobehavioral deficit in diabetes which has clinical significance in the treatment of diabetes.

The role of the basal ganglia in learning and memory: insight from Parkinson's disease

It has long been known that memory is not a single process. Rather, there are different kinds of memory that are supported by distinct neural systems. This idea stemmed from early findings of dissociable patterns of memory impairments in patients with selective damage to different brain regions. These studies highlighted the role of the basal ganglia in non-declarative memory, such as procedural or habit learning, contrasting it with the known role of the medial temporal lobes in declarative memory. In recent years, major advances across multiple areas of neuroscience have revealed an important role for the basal ganglia in motivation and decision making. These findings have led to new discoveries about the role of the basal ganglia in learning and highlighted the essential role of dopamine in specific forms of learning. Here we review these recent advances with an emphasis on novel discoveries from studies of learning in patients with Parkinson's disease. We discuss how these findings promote the development of current theories away from accounts that emphasize the verbalizability of the contents of memory and towards a focus on the specific computations carried out by distinct brain regions. Finally, we discuss new challenges that arise in the face of accumulating evidence for dynamic and interconnected memory systems that jointly contribute to learning.

Implicit procedural learning in fragile X and Down syndrome

BACKGROUND

Procedural learning refers to rule-based motor skill learning and storage. It involves the cerebellum, striatum and motor areas of the frontal lobe network. Fragile X syndrome, which has been linked with anatomical abnormalities within the striatum, may result in implicit procedural learning deficit.

METHODS

To address this issue, a serial reaction time (RT) task including six blocks of trials was performed by 14 individuals with fragile X syndrome, 12 individuals with Down syndrome and 12 mental age-matched control subjects. The first (B1) and fifth (B5) blocks were random whereas the others (B2, B3, B4 and B6) consisted of a repeated 10-step sequence. Results were analysed by Kruskal-Wallis one-way analysis of variance and Wilcoxon signed-rank test.

RESULTS

For patients with fragile X syndrome, the RT was highly suggestive of preserved implicit learning as a significant difference was observed between blocks B5 and B6 (P = 0.009). However, the difference of RT between B4 and B5 did not reach significance, possibly due to a subgroup of individuals who did not learn. In contrast, in the Down syndrome group, RT decreased significantly between B4 and B5 (W = 2; P = 0.003) but not between the last ordered block (B6) and the last random block (B5), suggesting a weakness in procedural learning which was sensitive to the interfering random block.

CONCLUSION

implicit learning is variable in genetic syndromes and therefore relatively independent of general intellectual capacities. The results are discussed together with previous reports.

Motor sequence learning performance in Parkinson's disease patients depends on the stage of disease

It is still unclear, whether patients with Parkinson's disease (PD) are impaired in the incidental learning of different motor sequences in short succession, although such a deficit might greatly impact their daily life. The aim of this study was thus to clarify the relation between disease parameters of PD and incidental motor learning of two different sequences in short succession. Results revealed that the PD patients were able to acquire two sequences in short succession but needed more time than healthy subjects. However, both the severity of axial manifestations, as assessed on a subsection of the Unified Parkinson's Disease Rating Scale III (UPDRS III) and the Hoehn and Yahr score, and the levodopa-equivalent dose (LED) were negatively correlated with the sequence learning performance. These findings indicate that, although PD patients are able to learn two sequences in short succession, they need more time and their overall sequence learning performance is strongly correlated with the stage of disease.

Task-specific contribution of the human striatum to perceptual-motor skill learning

Acquisition of new perceptual-motor skills depends on multiple brain areas, including the striatum. However, the specific contribution of each structure to this type of learning is still poorly understood. Focusing on the striatum, we proposed (a) to replicate the finding of impaired rotary pursuit (RP) and preserved mirror tracing (MT) in Huntington's disease (HD); and (b) to further explore this putative learning dissociation with other human models of striatal dysfunction (i.e., Parkinson's disease and focal vascular damage) and two new paradigms (i.e., Geometric Figures, GF, and Control Stick, CS) of skill learning. Regardless of the etiology, participants with damage to the striatum showed impaired learning of visuomotor tracking skills (i.e., RP and GF), whereas the ability to learn skills that require motor adaptation (i.e., MT and CS) was not affected. These results suggest a task-specific involvement of the striatum in the early stages of skill learning.

Effective connectivity of neural networks in automatic movements in Parkinson's disease

Patients with Parkinson's disease (PD) have difficulty in performing learned movements automatically. The neural mechanism of this deficiency remains unclear. In the current study, we used functional MRI (fMRI) and psychophysiological interaction (PPI) methods to investigate the changes in effective connectivity of the brain networks when movements become automatic in PD patients and age-matched normal controls. We found that during automaticity, the rostral supplementary motor area, cerebellum, and cingulate motor area had increased effective connectivity with brain networks in PD patients. In controls, in addition to these regions, the putamen also had automaticity-related strengthened interactions with brain networks. The dorsal lateral prefrontal cortex had more connectivity at the novel stage than in the automatic stage in normal subjects, but not in PD patients. The comparison of the PPI results between the groups showed that the rostral supplementary motor area, cerebellum, and cingulate motor area had significantly more increased effective connectivity with several regions in normal subjects than in PD. The changes of effective connectivity in some areas negatively correlated with the Unified Parkinson's Disease Rating Scale (UPDRS). Our findings show that some of the factors related to PD patients having difficulty achieving automaticity are less efficient neural coding of movement and failure to shift execution of automatic movements more subcortically. The changes of effective connectivity become more abnormal as the disorder progresses. In addition, in PD, the connections of the attentional networks are altered.

Speech skill learning of persons who stutter and fluent speakers under single and dual task conditions

Two studies compared the accuracy and efficiency of initiating oral reading of nonsense syllables by persons who stutter (PWS) and fluent speakers (PNS) over practise. Findings of Study One, comparing 12 PWS and 12 PNS, replicated previous findings of slow speech sequence initiation over practise by PWS relative to PNS. In Study Two, nine PWS and eight PNS practised reading syllable sequences under single, and then dual task conditions in which a colour recognition distracter task was introduced. The speech sequences of PWS were initiated significantly slower than those of PNS. Significant GroupxCondition interactions for reaction time and accuracy were interpreted to suggest that PNS, but not PWS, demonstrated the ability to switch between an attention-demanding movement strategy under dual task conditions and a relatively automatic (little attention required) movement strategy after practise under single task conditions.

Contributions of the basal ganglia and functionally related brain structures to motor learning

This review discusses the cerebral plasticity, and the role of the cortico-striatal system in particular, observed as one is learning or planning to execute a newly learned motor behavior up to when the skill is consolidated or has become highly automatized. A special emphasis is given to imaging work describing the neural substrate mediating motor sequence learning and motor adaptation paradigms. These results are then put into a plausible neurobiological model of motor skill learning, which proposes an integrated view of the brain plasticity mediating this form of memory at different stages of the acquisition process.

Neural evidence of a role for spatial response selection in the learning of spatial sequences

Despite over 20 years of behavioral research, considerable disagreement remains regarding the locus of the cognitive mechanisms (e.g., stimulus encoding, response selection or response production) responsible for the acquisition and expression of learned sequences. Functional neuroimaging may prove invaluable for resolving this controversy. The cortical mechanisms underlying spatial response selection (i.e., right dorsal prefrontal, dorsal premotor and superior parietal cortices) are well known. These regions as well as supplementary motor area, striatum and the hippocampus have also been implicated in sequence learning. This neural overlap lends support for the hypothesis that spatial response selection is involved in learning spatial sequences; however, these experimental factors have not been investigated in the same experiment so the extent of neural overlap is debatable. The present study investigates the role of spatial response selection in sequence learning during the performance of the serial reaction time task. We orthogonally manipulated spatial sequence learning and spatial response-selection difficulty to precisely identify the neural overlap of these cognitive systems. Results demonstrate near complete overlap in regions affected by the spatial response selection and spatial sequence learning manipulations. Only right dorsal prefrontal cortex was selectively influenced by the response selection difficulty manipulation. These findings emphasize the importance of spatial response selection for successful spatial sequence learning.

Modifications of the interactions in the motor networks when a movement becomes automatic

A crucial feature of the motor system is the ability to control some movements automatically. We have previously shown that all parts of the motor networks reduce their activity with automaticity, and, while this change may indicate increased efficiency in terms of neural processing, it is not clear how motor skill can be maintained after a reduction of neural activity. In the current study, we used functional MRI (fMRI) to investigate influences on the effective connectivity of the brain motor networks when movements become automatic. Subjects practiced a sequential movement until they could execute it automatically, and task-related brain fMRI activation was measured before and after they achieved automaticity. Using the psychophysiological interaction (PPI) method, we found that the cerebellum, cingulate motor area, supplementary motor area, and putamen had significantly greater connectivity, whereas the precuneus had less connectivity in the motor networks at the automatic stage. Our findings demonstrate that the importance of the attention networks decrease when movements become automatic. Moreover, the process of automaticity is accompanied by a strengthened interaction of central motor networks even though the magnitude of the activation is decreased. We speculate that this increase in connectivity reflects more efficient neural coding of movement at the automatic stage.

Adaptations of glutamatergic synapses in the striatum contribute to recovery from cerebellar damage

Recent findings proposed that the cerebellum and the striatum, key structures in motor control, are more interconnected than commonly believed, and that the cerebellum may influence striatal activity. In the present study, the possible changes of synaptic transmission in the striatum of hemicerebellectomized rats have been investigated. Neurophysiological recordings showed a significant facilitation of glutamate transmission in the contralateral striatum occurring early following hemicerebellectomy. This process of synaptic adaptation appears to be relevant for the compensation of cerebellar deficits. Accordingly, pharmacological blockade of glutamate N-methyl-d-aspartate (NMDA) receptors with MK-801 prevented the rearrangement of excitatory synapses in the striatum and interfered with the recovery from motor disturbances in rats with cerebellar lesions. Hemicerebellectomy also perturbed gamma-aminobutyric acid (GABA) transmission in contralateral but not ipsilateral striatum. The present findings advance the role of striatal excitatory transmission in the compensation of cerebellar deficits, providing support to the notion that adaptations of striatal function exert a role in the recovery of cerebellar symptoms.

Hybrid feature subset selection for the quantitative assessment of skills of stroke patients in activity of daily living tasks

Stroke patients have a decreased ability in performing activity of daily living (ADL) tasks such as in 'drinking a glass of water', 'turning a key', 'picking up a spoon', 'lifting a bag', 'reaching a bottle' and 'lifting and carrying a bottle'. These tasks can be quantified by measuring forces and torques exerted on the objects. However, the resulting force and torque time series represent information at a very low level of abstraction and don't inform clinicians what really distinguishes patients from normal controls in performing these tasks. We conduct an extensive quantitative analysis of these tasks and derive interesting features from the time signals that characterize the differences in behavior between patients and normal controls. We show that 'drinking a glass' and 'turning a key' are the most discriminative tasks; furthermore we show that the ability or disability to synchronize the thumb and the middle finger is one of the most important features.

Aging affects motor skill learning when the task requires inhibitory control

Few studies have examined the influence of aging on motor skill learning (MSL) tasks involving different skills and conditions. Two tasks, each including two different conditions (repeated and nonrepeated), were used: (a) the Mirror Tracing task, requiring the inhibition of an overlearned response and the learning of a new visuomotor association, and (b) the Pursuit Tracking task, mainly requiring the processing of visuospatial stimuli. We hypothesized that older participants would benefit as much as younger participants from the stimuli repetition and that they would exhibit a slower learning rate exclusively on the Mirror Tracing task. As expected, older and younger participants' MSL were not differentially affected by task conditions. They also showed a similar learning rate on the Pursuit Tracking task and a subgroup of older participants exhibited MSL difficulties on the Mirror Tracing task. Problems in the inhibitory control of competing motor memories could explain these age-related MSL difficulties.

Sequence skill learning in persons who stutter: implications for cortico-striato-thalamo-cortical dysfunction

The basal ganglia and cortico-striato-thalamo-cortical connections are known to play a critical role in sequence skill learning and increasing automaticity over practice. The current paper reviews four studies comparing the sequence skill learning and the transition to automaticity of persons who stutter (PWS) and fluent speakers (PNS) over practice. Studies One and Two found PWS to have poor finger tap sequencing skill and nonsense syllable sequencing skill after practice, and on retention and transfer tests relative to PNS. Studies Three and Four found PWS to be significantly less accurate and/or significantly slower after practice on dual tasks requiring concurrent sequencing and colour recognition over practice relative to PNS. Evidence of PWS' deficits in sequence skill learning and automaticity development support the hypothesis that dysfunction in cortico-striato-thalamo-cortical connections may be one etiological component in the development and maintenance of stuttering.

EDUCATIONAL OBJECTIVES

As a result of this activity, the reader will: (1) be able to articulate the research regarding the basal ganglia system relating to sequence skill learning; (2) be able to summarize the research on stuttering with indications of sequence skill learning deficits; and (3) be able to discuss basal ganglia mechanisms with relevance for theory of stuttering.

Evidence for reduced cerebellar volumes in trichotillomania

BACKGROUND

Limited knowledge exists regarding the neurobiology of trichotillomania (TTM). Cerebellum (CBM) volumes were explored, given its role in complex, coordinated motor sequences.

METHODS

Morphometric magnetic resonance imaging (MRI) scans were obtained for 14 female subjects with DSM-IV diagnoses of TTM and 12 age-, education-, and gender-matched normal control (NC) participants. Parcellation was performed utilizing a recently developed methodology to measure subterritory volumes of the CBM. Regions were defined based on knowledge of the structural and functional subunits of the CBM.

RESULTS

As predicted, significant group differences were reported for CBM raw cortical volumes (p = .008) that survived correction for total brain volume (TBV; p = .037) and head circumference (HC; p = .011). A priori and post hoc group raw volume comparisons for CBM subterritories and functional clusters revealed many significant differences. However, most differences failed to withstand correction for total CBM volumes (TCV). Smaller volumes were consistently reported for the TTM versus NC cohorts. Total Massachusetts General Hospital Hair Pulling Scale (MGHHPS) scores were significantly inversely correlated with left primary sensorimotor cluster volumes (p = .008), with smaller volumes associated with more severe TTM symptoms.

CONCLUSIONS

These findings implicate the CBM in the neurobiology of TTM, with reduced subterritory volumes reported for the TTM versus NC groups.

Selective impairments in implicit learning in Parkinson's disease

The basal ganglia are thought to participate in implicit sequence learning. However, the exact nature of this role has been difficult to determine in light of the conflicting evidence on implicit learning in subjects with Parkinson's disease (PD). We examined the performance of PD subjects using a modified form of the serial reaction time task, which ensured that learning remained implicit. Subjects with predominantly right-sided symptoms were trained on a 12-element sequence using the right hand. Although there was no evidence of sequence learning on the basis of response time savings, the subjects showed knowledge of the sequence when performance was assessed in terms of the number of errors made. This effect transferred to the left (untrained) hand as well. Thus, these data demonstrate that PD patients are not impaired at implicitly learning sequential order, but rather at the translation of sequence knowledge into rapid motor performance. Furthermore, the results suggest that the basal ganglia are not essential for implicit sequence learning in PD.

Statistically rigorous human movement onset detection with the maximal information redundancy criterion

Stroke patients have a decreased ability in performing activity of daily living (ADL) tasks such as in "drinking a glass of water", "lifting a bag", "turning a key" and so on. Sensorimotor force and torque measurements from patients performing these standardized ADL tasks are hypothesized to give quantitative information about the recovery process. Parts of the force/torque measurements contain useful information, when related to the initiation of the movement during ADL tasks. Here we address the challenging problem of automatically extracting the movement initiation from these force/torque measurements. We will adopt a machine learning approach which relies on the statistically rigorous maximal information redundancy (MIR) criterion. This assumes that movement initiation parts of the signals are characterized by an increased redundancy in the signal. A thorough evaluation of the criterion shows that the accuracy of the criterion in movement onset detection is close to that of clinical experts.

Learning and retention of movement sequences in Parkinson's disease

The purpose of this study was to examine motor learning and retention given extensive practice in two fundamentally different movement sequences. One sequence was a memory-driven task (performing a series of whole body positions from memory) and the other a context-driven task (buttoning). Practice took place over 3 weeks, with performance measured weekly; retention was measured weekly for 3 weeks after practice. There were 7 people with Parkinson's disease (PD) and 7 age-matched neurologically healthy people who participated in this study. Both groups improved performance on both tasks with practice, with the majority of the change for the PD group occurring between 1 and 2 weeks of practice. Although those with PD did not necessarily perform as well as age-matched controls, they learned both sequences in a manner similar to age-matched controls, and exhibited retention across the 3-week retention interval. If people with PD are given sufficient practice they can learn and retain both memory-based and context-driven movement sequences as well as age-matched controls. The results provide support for maintaining physical activity and for intervention through movement therapy.

A functional MRI study of automatic movements in patients with Parkinson's disease

Patients with Parkinson's disease have great difficulty performing learned movements automatically. The neural contribution to the problem has not been identified. In the current study, we used functional magnetic resonance imaging (fMRI) to investigate the underlying neural mechanisms of movement automaticity in Parkinson's disease patients. Fifteen patients with Parkinson's disease were recruited. Three patients were finally excluded because they could not achieve automaticity. The remaining 12 patients were aged from 52 to 67 years, with a mean age of 61.2 years. Controls included 14 age-matched normal subjects. The subjects were asked to practise four tasks, including two self-initiated, self-paced sequences of finger movements with different complexity until they could perform the tasks automatically. Two dual tasks were used to evaluate automaticity. For dual tasks, subjects performed a visual letter-counting task simultaneously with the sequential movements. Twelve normal subjects performed all sequences automatically. All patients performed sequences correctly; 12 patients could perform the simpler sequence automatically; and only 3 patients could perform the more complex sequence automatically. fMRI results showed that for both groups, sequential movements activated similar brain regions before and after automaticity was achieved. No additional activity was observed in the automatic condition. In normal subjects, many areas had reduced activity at the automatic stage, whereas in patients, only the bilateral superior parietal lobes and left insular cortex were less activated. Patients had greater activity in the cerebellum, premotor area, parietal cortex, precuneus and prefrontal cortex compared with normal subjects while performing automatic movements. We conclude that Parkinson's disease patients can achieve automaticity after proper training, but with more difficulty. Our study is the first to demonstrate that patients with Parkinson's disease require more brain activity to compensate for basal ganglia dysfunction in order to perform automatic movements.