Motor Planning Research Articles

Grasp context-dependent uncertainty alters the relative contribution of anticipatory and feedback-based mechanisms in object manipulation

Predictive control within dexterous object manipulation while allowing for the choice of contact points has been shown to employ a predominantly feedback-based force modulation. The anticipation is thought to be facilitated through the internal representation of the object dynamics being integrated and updated on a trial-to-trial basis with the feedback of contact locations on the object. This is as opposed to the classically studied memory representation-based fingertip force control for grasping with pre-selected contact locations. We designed a study to examine this grasp context-dependent asymmetry in sensorimotor integration by introducing binary uncertainty about the grasp type before movement initiation within the framework of motor planning. An inverted T-shaped instrumented object was presented to 24 participants as the manipulandum, and they were asked to reach, grasp, and lift it while minimising the peak roll. We dissociated the planning and the execution phases by pseudo-randomly manipulating the availability of visual contact cues on the object after movement onset. We analysed both derived as well as direct kinetic and kinematic measures of the grasp during the loading phase to understand the anticipatory coordination. Our findings suggest that uncertainty about the grasp context during movement preparation resulted in a shift towards feedback-based mechanisms for grasp force modulation despite the persistence of visual cues.

Research on the Cognitive Orientation to daily Occupational Performance Approach: A Bibliometric Review.

The Cognitive Orientation to daily Occupational Performance (CO-OP) is an evidence-based intervention approach that has significantly increased in popularity over the past two decades. However, how the research literature on this topic is patterned is still unknown, so it is difficult to identify potential areas for research and clinical interest. To analyze the literature published on the CO-OP approach to provide a detailed and structured analysis of the publication patterns. All literature related to CO-OP included in the Web of Science database through June 15, 2024. All published studies related to CO-OP were included in the bibliometric analysis, which was conducted on the raw data retrieved from the Web of Science database using the Bibliometrix R package. The annual growth rate in CO-OP research has been 0.8%, significantly increasing from 2015 onward. Most of the research has been published in occupational therapy and rehabilitation journals by English-speaking research teams, and its scope has expanded from developmental coordination disorder to a wide range of health conditions. In addition, two main lines of research have emerged: one focusing on understanding the underlying cognitive processes involved in CO-OP and the other focusing on its clinical effectiveness. Research on CO-OP has significantly increased over the past decade, and it currently encompasses a wide range of areas. This analysis may facilitate the advancement of research on and the clinical practical application of CO-OP. Plain-Language Summary: The Cognitive Orientation to daily Occupational Performance (CO-OP) is an evidence-based intervention approach that has significantly increased in popularity over the past two decades. Occupational therapists use it to improve the occupational performance of both children and adults with movement difficulties. However, it is unknown how the research literature on this topic is patterned, so it is difficult to identify potential areas for research and clinical interest. This study found that scientific literature on CO-OP has significantly increased in the past decade and that its scope has expanded from developmental coordination disorder to a wider range of health conditions, such as cerebral palsy. Moreover, research is now focused on two main questions: What are the underlying cognitive processes involved during intervention, and how effective is the CO-OP approach? These findings can be used to further improve occupational performance and participation among occupational therapy clients who struggle with motor performance and planning.

Exploring temporal congruence in motor imagery and movement execution in non-specific chronic low back pain

Chronic non-specific low back pain (NSCLBP) is linked to sensorimotor dysfunctions and altered motor planning, likely due to neuroplastic changes. Motor imagery (MI) and movement execution share neural pathways, but the relationship between imagined and executed movements in NSCLBP patients remains underexplored. This study aimed to assess the temporal congruence between imagined and executed movements in NSCLBP sufferers, with secondary goals of investigating group differences in movement chronometry, psychological well-being, and disability, as well as possible correlations among these factors. Fifty-six participants, including 28 NSCLBP patients and 28 asymptomatic subjects (AS), performed lumbar flexion and Timed Up and Go (TUG) tasks. NSCLBP patients showed significant temporal incongruence in both tasks, executing movements more slowly than imagined, whereas AS displayed incongruence only in the TUG task. NSCLBP patients also took longer to imagine and execute lumbar flexion movements compared to AS, with correlations observed between execution delays, higher disability, and greater fear of movement. The findings highlight a lack of temporal congruence in NSCLBP patients, especially in lumbar flexion, emphasizing the complex relationship between chronic pain, motor ability, and psychological factors. These results suggest that integrated treatment approaches addressing cognitive and emotional aspects are crucial for managing NSCLBP.

Effects of pitch range on singing accuracy training

Recent theory and data suggest that inaccurate ( poor-pitch or poor) singing may be based on impoverished sensorimotor mapping between auditory perceptual representations and motor plans. One of the symptoms of poor singing is a restriction of vocal pitch range during pitch matching tasks that is not reducible to physical vocal limitations. We here test the hypothesis that remediation of poor singing may be best achieved by incorporating a wide pitch range during training. Two treatment groups underwent singing training using a procedure found to be effective in recent research. One group matched pitches from a wider range of one octave, whereas the other matched pitches from a narrower range of seven semitones (a perfect fifth). A third group completed visual imagery tasks for the same period of time and served as a control group. All three groups completed the Seattle Singing Accuracy Protocol (SSAP) before and after training, with all phases completed in a single session. The only significant improvement was found in the wide-range training group, for matching of single pitches from the SSAP, rather than four-note melodies. Results thus offer partial support for the hypothesis and suggest that successful remediation of singing accuracy may benefit from adopting a wide range of pitches.

Attention Deficit/Hyperactivity Disorder and Motor Planning Difficulties: A Confirmatory Study on the Overlap Between Neurodevelopmental Disorders

Attention deficit/hyperactivity disorder (ADHD) and developmental coordination disorder (DCD) represent two frequent neurodevelopmental disorders, which may be comorbid or have common characteristics with each other. The aim of the present study was to explore the presence of DCD or motor planning difficulties in children with behavioral disorders and/or ADHD, as already stated in the literature. Motor abilities were assessed in a sample of children which underwent a comprehensive neuropsychological evaluation. A total of 43 children were included in the study and were subdivided in three groups: those with ADHD and DCD, those with DCD, and those with ADHD but also presenting motor-praxic difficulties. The first group obtained clinical scores at the considered tests, with worse performances in the balance area; in the second and third groups lower scores were observed in the manual dexterity and balance, with more homogeneous profiles. Overall, 27.3% of ADHD subjects received a diagnosis of DCD as well, whereas 31.8% showed documented motor-praxic difficulties. Our results confirmed an increased prevalence of DCD or general motor difficulties in children with ADHD compared to the general population. Further research should investigate whether a poorer motor performance assessed by standardized tests could be either due to a comorbid neurodevelopmental condition or a direct consequence of the pivotal symptomatology of the disorder.

Individualized functional magnetic resonance imaging neuromodulation enhances visuospatial perception: a proof-of-concept study.

This proof-of-concept study uses individualized functional magnetic resonance imaging neuromodulation (iNM) to explore the mechanisms that enhance BOLD signals in visuospatial perception (VP) networks that are crucial for navigation. Healthy participants (n = 8) performed a VP up- and down-direction discrimination task at full and subthreshold coherence through peripheral vision, and superimposed direction through visual imagery (VI) at central space under iNM and control conditions. iNM targets individualized anatomical and functional middle- and medial-superior temporal (MST) networks that control VP. We found that iNM engaged selective exteroceptive and interoceptive attention (SEIA) and motor planning (MP) networks. Specifically, iNM increased overall: (i) area under the curve of the BOLD magnitude: 100% in VP (but decreased for weak coherences), 21-47% in VI, 26-59% in MP and 48-76% in SEIA through encoding; and (ii) classification performance for each direction, coherence and network through decoding, predicting stimuli from brain maps. Our findings, derived from encoding and decoding models, suggest that mechanisms induced by iNM are causally linked in enhancing visuospatial networks and demonstrate iNM as a feasibility treatment for low-vision patients with cortical blindness or visuospatial impairments that precede cognitive decline.This article is part of the theme issue 'Neurofeedback: new territories and neurocognitive mechanisms of endogenous neuromodulation'.

Efficient Coding in Motor Planning.

A paramount challenge for the brain is to precisely model the world and control behavior within the confines of limited encoding capacities. Efficient coding theory posits a unified framework for understanding how neural systems enhance encoding accuracy by tuning to environmental statistics. While this theory has been thoroughly explored within the perceptual realm, it is less clear how efficient coding applies to the motor system. Here, we probe the core principles of efficient coding theory through center-out reaching tasks. Our results reveal novel sequential effects in motor planning. Specifically, current movements are biased in a direction opposite to recent movements, and movement variance increases with the angular divergence between successive actions. These effects are modulated by the variability within the motor system: a larger repulsive bias is observed when movements are performed with the nondominant hand compared to the dominant hand, and in individuals exhibiting higher motor variance compared to those with lower variance. These behavioral findings align with the predictions of an efficient coding model, suggesting that the motor system rapidly adapts to the context to enhance accuracy in motor planning.

Neural effects of multisensory dance training in Parkinson's disease: evidence from a longitudinal neuroimaging single case study.

Dance is associated with beneficial outcomes in motor and non-motor domains in Parkinson's disease (PD) and regular participation may help delay symptom progression in mild PD. However, little is known about the neurobiological mechanisms of dance interventions for PD. The present case study explored potential neuroplastic changes in a 69-year-old male with mild PD participating in regular dance classes over 29 weeks. Functional MRI was performed at four timepoints (pre-training, 11 weeks, 18 weeks, 29 weeks), where the individual imagined a dance choreography while listening to the corresponding music. Neural activity was compared between dance-imagery and fixation blocks at each timepoint. Analysis of functionally defined regions revealed significant blood-oxygen-level-dependent (BOLD) signal activation in the supplementary motor area, right and left superior temporal gyri and left and right insula, with modulation of these regions observed over the training period except for the left insula. The results suggest the potential for dance to induce neuroplastic changes in people with PD in regions associated with motor planning and learning, auditory processing, rhythm, emotion, and multisensory integration. The findings are consistent with dance being a multimodal therapeutic activity that could provide long-term benefits for people with PD.

Spike-based computational primitives to reproduce neural dynamics in the parietal cortex during motor preparation

Abstract Biologically plausible spiking neural network models of sensory cortices can be instrumental in understanding and validating their principles of computation.
 Models based on Cortical Computational Primitives (CCPs), such as Hebbian plasticity and Winner-Take-All (WTA) networks, have already been successful in this approach.
 However, the specific nature and roles of CCPs in sensorimotor cortices during cognitive tasks are yet to be fully deciphered.
 The evolution of motor intention in the Posterior Parietal Cortex (PPC) before arm-reaching movements is a well-suited cognitive process to assess the effectiveness of different CCPs.
 To this end, we propose a biologically plausible model composed of heterogeneous spiking neurons which implements and combines multiple CCPs, such as multi-timescale learning and soft WTA modules.
 By training the model to replicate the dynamics of in-vivo recordings from non-human primates, we show how it is effective in generating meaningful representations from unbalanced input data, and in faithfully reproducing the transition from motor planning to action selection.
 Our findings elucidate the importance of distributing spike-based plasticity across multi-timescales, and provide an explanation for the role of different CCPs in models of frontoparietal cortical networks for performing multisensory integration to efficiently inform action execution.

Connectivity of Fronto-Temporal Regions in Syntactic Structure Building During Speaking and Listening.

The neural infrastructure for sentence production and comprehension has been found to be mostly shared. The same regions are engaged during speaking and listening, with some differences in how strongly they activate depending on modality. In this study, we investigated how modality affects the connectivity between regions previously found to be involved in syntactic processing across modalities. We determined how constituent size and modality affected the connectivity of the pars triangularis of the left inferior frontal gyrus (LIFG) and of the left posterior temporal lobe (LPTL) with the pars opercularis of the LIFG, the left anterior temporal lobe (LATL), and the rest of the brain. We found that constituent size reliably increased the connectivity across these frontal and temporal ROIs. Connectivity between the two LIFG regions and the LPTL was enhanced as a function of constituent size in both modalities, and it was upregulated in production possibly because of linearization and motor planning in the frontal cortex. The connectivity of both ROIs with the LATL was lower and only enhanced for larger constituent sizes, suggesting a contributing role of the LATL in sentence processing in both modalities. These results thus show that the connectivity among fronto-temporal regions is upregulated for syntactic structure building in both sentence production and comprehension, providing further evidence for accounts of shared neural resources for sentence-level processing across modalities.

Maternal cortisol concentration is associated with reduced brain activation to infant cry and more intrusive parenting behavior

Previous research indicates that maternal cortisol function and maternal brain response to infant are each in turn related to variations in parenting behavior. However, little is known about how maternal cortisol and maternal brain function are associated, thus studying these two mechanisms together may improve our understanding of how maternal cortisol assessed during interactions with own infant is associated with brain response to infant cry. First-time mothers (N = 59) of infants aged 3–4 months old were recruited to participate. Mothers’ cortisol concentration was measured during a naturalistic interaction with their infant and their behavior was coded for two parenting behaviors-- maternal sensitivity and non-intrusiveness. In an fMRI session, mothers listened to their own infant and a control infant crying. Higher cortisol concentration was associated with more intrusive behavior. We found greater cortisol concentration was further associated with decreased activation in the brain to infant cry in the right precentral gyrus, the left culmen extending into the left inferior temporal gyrus and fusiform, two clusters in the superior temporal gyrus, and in the medial frontal gyrus. We also found that lower activation in these regions was associated with more intrusive maternal behavior. These data demonstrate the associations between maternal cortisol concentration and reduced brain activation to infant cry in both motor planning and auditory processing regions in predicting intrusive parenting behavior.

Exploring vowel errors produced in nonword repetition in children with speech and language disorders.

Accurate nonword repetition (NWR) is contingent on many underlying skills, including encoding, memory and motor planning and programming. Though vowel errors are frequently associated with childhood apraxia of speech (CAS), several recent studies have found that children with developmental language disorder (DLD) produce high rates of vowel errors in NWR tasks. This retrospective analysis explored whether the overall frequency and types of vowel errors produced in NWR distinguish children with DLD, children with CAS, children with speech sound disorder (SSD) and children with typical development (TD). We present data for 24 children (six per DLD, CAS, SSD and TD groups), ranging in age from 50-92 months. Children with DLD, CAS and SSD showed similar articulation scores and children with DLD and children with CAS showed similar expressive language scores. Total vowel errors, total monophthong errors, monophthong substitutions, diphthongization errors, total diphthong errors, diphthong substitutions and diphthong reduction errors were calculated by syllable length and group. Repeated measures analyses of variance were used to examine group differences. Children with DLD and children with CAS produced a higher frequency of total vowel errors compared to children with TD. Children with DLD produced more total monophthong errors than children with TD. Children with DLD and children with CAS produced more total diphthong errors than children with TD. For children with DLD, these were characterised by diphthong substitutions. For children with CAS, these were characterised by diphthong substitutions and diphthong reduction errors. For all measures, error rates in children with SSD did not significantly differ from any of the other three groups. Preliminary evidence indicates that children with DLD and children with CAS both show high rates of vowel errors in NWR tasks and weaknesses in encoding and memory. For children with CAS, additional motor planning difficulties are associated with an increased likelihood to reduce diphthongs. Children with SSD show more mild processing difficulties than children with DLD and children with CAS, though they do not perform as well as TD peers. Future work should replicate and further specify the processing weaknesses that affect vowel accuracy in NWR tasks in a larger sample. What is already known on the subject Nonword repetition (NWR) tasks are often included in diagnostic batteries to identify children with developmental language disorder (DLD). Poor performance on these tasks have historically been attributed to phonological working memory deficits in children with DLD. However, repeating nonwords relies on a number of underlying processing skills and many of these skills are affected to varying degrees in children with speech and language disorders. An in-depth analysis of vowel errors has the potential to reveal the shared as well as specific underlying processing weaknesses in children with DLD, children with childhood apraxia of speech (CAS) and children with speech sound disorder (SSD). What this paper adds to existing knowledge We found that children with DLD and children with CAS show low vowel competence compared to children with typical development. A nuanced examination of vowel error types further revealed that children with DLD and children with CAS show weaknesses in encoding and memory. Motor planning and programming weaknesses were unique to CAS. Children with SSD show more mild processing deficits and their performance did not significantly differ from any of the other three groups. What are the clinical implications of this work? Examining the types of vowel errors produced by children with DLD, children with CAS and children with SSD in NWR allows us to further specify the underlying processing weaknesses that differentiate these three groups. This research informs theoretical accounts of language processing in children with different types of speech and language disorders and has the potential to improve the diagnostic utility of NWR tasks.

Dynamics of Saccade Trajectory Modulation by Distractors: Neural Activity Patterns in the Frontal Eye Field.

The sudden appearance of a visual distractor shortly before saccade initiation can capture spatial attention and modulate the saccade trajectory in spite of the ongoing execution of the initial plan to shift gaze straight to the saccade target. To elucidate the neural correlates underlying these curved saccades, we recorded from single neurons in the frontal eye field (FEF) of two male rhesus monkeys shifting gaze to a target while a distractor with the same eccentricity appeared either left or right of the target at various delays after target presentation. We found that the population level of pre-saccadic activity of neurons representing the distractor location encoded the direction of the saccade trajectory. Stronger activity occurred when saccades curved toward the distractor, and weaker when saccades curved away. This relationship held whether the distractor was ipsilateral or contralateral to the recorded neurons. Meanwhile, visually responsive neurons showed asymmetrical patterns of excitatory responses that varied with the location of the distractor and the duration of distractor processing relating to attentional capture and distractor inhibition. During earlier distractor processing, neurons encoded curvature towards the distractor. During later distractor processing, neurons encoded curvature away from the distractor. This was observed when saccades curved away from distractors contralateral to the recording site and when saccades curved towards distractors ipsilateral to the recording site. These findings indicate that saccadic motor planning involves dynamic push-pull hemispheric interactions producing attraction or repulsion for potential but unselected saccade targets.Significant Statement This study not only advances our understanding of oculomotor function in dynamic environments but also has potential clinical relevance for diagnosing and understanding disorders characterized by abnormal saccade trajectories. Our research elucidates the neural mechanisms behind saccade trajectories that are not always linear due to the brain's integration of multiple visual cues and/or motor plans. By analyzing the frontal eye field (FEF) activity in rhesus monkeys, we found that saccade directionality and timing are influenced by the interaction between FEF visual neurons representing target and distractor stimuli. The FEF's role extends beyond a winner-takes-all approach, incorporating saccade vector averaging computations that produce curved saccades. Furthermore, ipsilateral visual neurons encode distractor suppression that drives curvature away from the distractor.

Alcohol exposure induces cortical activity change during quiescent state

Alcohol Use Disorder (AUD) is a significant global mental health issue that impacts both the central and peripheral systems, leading to widespread cognitive and motor dysfunctions. The primary motor cortex (M1) plays a critical role in motor planning, control, and execution, yet the effects of chronic alcohol exposure on M1 remain underexplored, particularly during quiescent states. This study investigates the functional changes in M1 due to chronic alcohol exposure using high-resolution Neuropixels electrode recordings in a mouse model. Our findings reveal alterations in neuronal firing mode, particularly in layer V, highlighting disruptions in the excitatory/inhibitory (E/I) balance. Despite similar overall firing rates, changes in firing interval distributions suggest altered temporal dynamics of neuronal activity due to alcohol exposure. These results align with existing literature on cortical disruptions caused by alcohol and provide new insights into the specific neuronal dynamics within M1, especially in quiescent states.

Difficulties in perceptual–motor coordination of reaching behavior in children with autism spectrum disorder

Increased risk of injury from collisions with objects is an important issue in children with autism spectrum disorder (ASD). The purpose of the present study was to examine whether impaired perceptual–motor coordination may underlie the high frequency of collisions. Specifically, we hypothesized that collisions are likely to occur frequently in children with ASD due to their difficulty with body-related spatial perception and their inadequate motor planning, due to their detail-focused processing style, i.e., a tendency to focus attention on specific details rather than on the overall context. To evaluate impairment of perceptual–motor coordination in children with ASD, an original action selection task was developed to assess (a) body-related spatial perception and (b) predictive attentional properties for planning the subsequent movements based on the measures of hand movement and gaze behavior. Twenty-six children (13 diagnosed as ASD and 13 with typical development [TD]) completed the task, and their parents completed a questionnaire regarding their child's susceptibility to injury. Results showed that children with ASD displayed inaccurate body-related spatial perception and inadequate motor planning under conditions that induced their detail-focused processing style. In addition, analyses of gaze behavior reflected the characteristics of a detail-focused processing in children with ASD. This was correlated with the severity of ASD and the measure of motor planning. The present findings suggest that difficulty with perceptual–motor coordination, resulting in part from the detail-focused processing style, might contribute to susceptibility to injury in children with ASD. We consider that our evaluation of the difficulty with perceptual–motor of individuals with ASD provides a framework for understanding their high rate of collision-related injuries and could inform strategies for preventing these injuries.

Subthalamic nucleus neurons encode syllable sequence and phonetic characteristics during speech.

Speech is a complex behavior that can be used to study unique contributions of the basal ganglia to motor control in the human brain. Computational models suggest that the basal ganglia encode either the phonetic content or the sequence of speech elements. To explore this question, we investigated the relationship between phoneme and sequence features of a spoken syllable triplet and the firing rate of subthalamic nucleus (STN) neurons recorded during the implantation of deep brain stimulation (DBS) electrodes in individuals with Parkinson's disease. Patients repeated aloud a random sequence of three consonant-vowel (CV) syllables in response to audio cues. Single-unit extracellular potentials were sampled from the sensorimotor STN; a total of 227 unit recordings were obtained from the left STN of 25 subjects (4 females). Of these, 113 (50%) units showed significant task-related increased firing and 53 (23%) showed decreased firing (t test relative to inter-trial period baseline, P < 0.05). Linear regression analysis revealed that both populations of STN neurons encode phoneme and sequence features of produced speech. Maximal phoneme encoding occurred at the time of phoneme production, suggesting efference copy- or sensory-related processing, rather than speech motor planning (-50 ms and +175 ms relative to CV transition for consonant and vowel encoding, respectively). These findings demonstrate that involvement of the basal ganglia in speaking includes separate single unit representations of speech sequencing and phoneme selection in the STN.NEW & NOTEWORTHY Speech is a unique human behavior that requires dynamic execution of precisely timed and coordinated movements, resulting in intelligible vocalizations. Here, we demonstrate that activity of individual neurons in the subthalamic nucleus (STN) of the basal ganglia encode syllable sequence order and phoneme identity during a speech production task. These findings advance our understanding of neural substrates of human speech and shed light on potential involvement of the STN in complex human behaviors.

A geometrical solution underlies general neural principle for serial ordering

A general mathematical description of how the brain sequentially encodes knowledge remains elusive. We propose a linear solution for serial learning tasks, based on the concept of mixed selectivity in high-dimensional neural state spaces. In our framework, neural representations of items in a sequence are projected along a “geometric” mental line learned through classical conditioning. The model successfully solves serial position tasks and explains behaviors observed in humans and animals during transitive inference tasks amidst noisy sensory input and stochastic neural activity. This approach extends to recurrent neural networks performing motor decision tasks, where the same geometric mental line correlates with motor plans and modulates network activity according to the symbolic distance between items. Serial ordering is thus predicted to emerge as a monotonic mapping between sensory input and behavioral output, highlighting a possible pivotal role for motor-related associative cortices in transitive inference tasks.

Effectiveness of an object moving depending on its orientation in the environment: a kinematic analysis of motor planning and execution

Background. Grasping objects with the hand is one of the most common movements in everyday life. It requires training involving the cognitive processes of goal selection and motor planning.Aim. To investigate the effect of object rotation on motor planning using an experiment where participants moved abstract objects that sometimes required rotation, and movement was assessed using a kinematic analysis system. We hypothesized that reaction times and movements would be longer for tasks with rotation.Materials and methods. Sixteen subjects participated in the study (11 females and 5 males), mean age – 23.375 ± 2.277 years. Participants were required to perform a task of moving 4 abstract objects onto corresponding platforms with their right hand, while periodically rotating the object by 90°, 180°, or 270°. The motion tracking system monitored the movement of trackers located on the subject’s right thumb and index finger, on the subject’s right wrist, and on the object and the subject’s special glasses.Results. To assess the effect of object rotation on motor planning, the data were grouped according to the angle of rotation. A one-factor analysis of variance with repeated measures was used. The results showed statistically significant differences:total movement time as a function of turning angle: F(3.45) = 5.014, p = 0.004;time to reach the grasping target: F(3.45) = 61.79, p = 0.001;object motion time: F(3.45) = 14.641, p = 0.001;time to reach maximum capture aperture: F(3.45) = 8.559, p = 0.001.Conclusion. Overall, our results support the hypothesis that object rotation during movement affects both the preparation and execution of the movement itself. The planning and executing the movement with the object rotated 180° was easier and faster than with 90° and 270° rotations. The testing allows distinguishing the stages of planning and preparation of the movement from the execution of the movement itself. Using this approach in patients with central nervous system lesions helps to assess and monitor the state of motor function, which is important for monitoring the recovery process.

Brain-wide dynamics linking sensation to action during decision-making.

Perceptual decisions rely on learned associations between sensory evidence and appropriate actions, involving the filtering and integration of relevant inputs to prepare and execute timely responses1,2. Despite the distributed nature of task-relevant representations3-10, it remains unclear how transformations between sensory input, evidence integration, motor planning and execution are orchestrated across brain areas and dimensions of neural activity. Here we addressed this question by recording brain-wide neural activity in mice learning to report changes in ambiguous visual input. After learning, evidence integration emerged across most brain areas in sparse neural populations that drive movement-preparatory activity. Visual responses evolved from transient activations in sensory areas to sustained representations in frontal-motor cortex, thalamus, basal ganglia, midbrain and cerebellum, enabling parallel evidence accumulation. In areas that accumulate evidence, shared population activity patterns encode visual evidence and movement preparation, distinct from movement-execution dynamics. Activity in movement-preparatory subspace is driven by neurons integrating evidence, which collapses at movement onset, allowing the integration process to reset. Across premotor regions, evidence-integration timescales were independent of intrinsic regional dynamics, and thus depended on task experience. In summary, learning aligns evidence accumulation to action preparation in activity dynamics across dozens of brain regions. This leads to highly distributed and parallelized sensorimotor transformations during decision-making. Our work unifies concepts from decision-making and motor control fields into a brain-wide framework for understanding how sensory evidence controls actions.

Neural correlates of bradykinesia in Parkinson’s disease: a kinematic and functional MRI study

Bradykinesia is defined as a “complex” of motor alterations including decreased movement amplitude and/or speed and tendency to reduce them with movement repetition (sequence effect). This study aimed at investigating the neural and kinematic correlates of bradykinesia during hand-tapping in people with Parkinson’s disease (pwPD) relative to healthy controls. Twenty-five pwPD and 25 age- and sex-matched healthy controls underwent brain functional MRI (fMRI) during a hand-tapping task: subjects alternatively opened and closed their right hand as fully and quickly as possible. Hand-tapping kinematic parameters were objectively measured during the fMRI task using an optical fibre glove. During the fMRI task, pwPD showed reduced hand-tapping amplitude (hypokinesia) and a greater sequence effect. PwPD relative to healthy controls showed a reduced activity of fronto-parietal areas, middle cingulum/supplementary motor area (SMA), parahippocampus, pallidum/thalamus and motor cerebellar areas. Moreover, pwPD showed an increased activity of brain cognitive areas such as superior temporal gyrus, posterior cingulum, and cerebellum crus I. The decreased activity of cerebellum IV–V–VI, vermis IV–V, inferior frontal gyrus, and cingulum/SMA correlated with hypokinesia and with the sequence effect. Interestingly, a reduced activity of areas involved in motor planning and timing correlated both with hypokinesia and with the sequence effect in pwPD. This study has the major strength of collecting objective motor parameters and brain activity simultaneously, providing a unique opportunity to investigate the neural correlates of the “bradykinesia complex”.