Motor Imagery as a Function of Disease Severity in Multiple Sclerosis: An fMRI Study

The multidimensional assessment of body representation and interoception in multiple sclerosis

BACKGROUND

The mental representation of the body (or body representation, BR) derives from the processing of multiple sensory and motor inputs and plays a crucial role in guiding our actions and in how we perceive our body. Fundamental inputs for BR construction come also from the interoceptive systems which refer to the whole bidirectional processes between the brain and the body. People with Multiple sclerosis (MS) show an abnormal multisensory integration which may compromise BR and interoception integrity. However, no study has evaluated possible deficits on distinct and dissociable dimensions of body representation (i.e., action-oriented, aBR; and a nonaction-oriented body representation, NaBR) and interoception (i.e., interoceptive accuracy, interoceptive sensibility, and interoceptive awareness) in MS.

OBJECTIVE

In the present study, we aimed to determine whether participants with MS present changes in BR and interoceptive dimensions.

METHODS

We performed comparison analyses on tasks and questionnaires tapping all BR and interoceptive dimensions between 36 people with relapsing-remitting MS (RRMS) and 42 healthy controls, and between 23 people with progressive MS (PMS) and 33 healthy controls.

RESULTS

Overall, patients with MS exhibited lower interoceptive accuracy than matched controls. The RRMS group also showed higher visceral interoceptive sensibility levels. No differences were found in BR accuracy measures, but the PMS reported longer response times when performing the aBR task.

CONCLUSION

These findings open a new issue on the role of inner-signal monitoring in the body symptomatology of MS and highlight the need for an accurate BR and interoceptive assessment in a clinical setting.

Motor imagery ability in baseball players with throwing yips

The motor imagery ability is closely related to an individual's motor performance in sports. However, whether motor imagery ability is diminished in athletes with yips, in whom motor performance is impaired, is unclear. Therefore, this cross-sectional study aimed to determine whether general motor imagery ability or vividness of motor imagery specific to throwing motion is impaired in baseball players with throwing yips. The study enrolled 114 college baseball players. They were classified into three groups: 33 players in the yips group, 26 in the recovered group (previously had yips symptoms but had resolved them), and 55 in the control group. They answered the revised version of the vividness of movement imagery questionnaire (VMIQ-2), which assesses general motor imagery ability. Furthermore, they completed a questionnaire that assesses both positive and negative motor imagery vividness specific to baseball throwing. In the former, they responded to their ability to vividly imagine accurately throwing a controlled ball, whereas in the latter, they responded to the vividness of their experience of negative motor imagery associated with baseball throwing, specifically the image of a wild throw. No significant difference in the VMIQ-2 was found among the three groups. While no significant difference in the vividness of positive motor imagery for ball throwing was found in either first-person visual or kinesthetic perspectives among the three groups, the yips group exhibited significantly higher vividness of negative motor imagery than the control group in both perspectives. These results indicate that negative motor imagery specific to baseball throwing may be associated with symptoms of yips. Therefore, interventions addressing psychological aspects, such as anxiety, which are potential causes of the generation of negative motor imagery, may be necessary to alleviate the symptoms of yips.

Early MS Identification Using Non-linear Functional Connectivity and Graph-theoretic Measures of Cognitive Task-fMRI Data

Introduction

Functional neuroimaging has developed a fundamental ground for understanding the physical basis of the brain. Recent studies have extracted invaluable information from the underlying substrate of the brain. However, cognitive deficiency has insufficiently been assessed by researchers in multiple sclerosis (MS). Therefore, extracting the brain network differences among relapsing-remitting MS (RRMS) patients and healthy controls as biomarkers of cognitive task functional magnetic resonance imaging (fMRI) data and evaluating such biomarkers using machine learning were the aims of this study.

Methods

In order to activate cognitive functions of the brain, blood-oxygen-level-dependent (BOLD) data were collected throughout the application of a cognitive task. Accordingly, a nonlinear-based brain network was established using kernel mutual information based on the automated anatomical labeling atlas (AAL). Subsequently, a statistical test was carried out to determine the variation in brain network measures between the two groups on binary adjacency matrices. We also found the prominent graph features by merging the Wilcoxon rank-sum test with the Fisher score as a hybrid feature selection method.

Results

The results of the classification performance measures showed that the construction of a brain network using a new nonlinear connectivity measure in task-fMRI performs better than the linear connectivity measures in terms of classification. The Wilcoxon rank-sum test also demonstrated a superior result for clinical applications.

Conclusion

We believe that non-linear connectivity measures, like KMI, outperform linear connectivity measures, like correlation coefficient in finding the biomarkers of MS disease according to classification performance metrics.

Highlights

The performance of some brain regions (the hippocampus, parahippocampus, cuneus, pallidum, and two segments of the cerebellum) is different between healthy and MS people.Non-linear connectivity measures, such as Kernel mutual information, perform better than linear connectivity measures, such as correlation coefficient, in finding the biomarkers of MS disease.

Plain Language Summary

Multiple sclerosis (MS) can disrupt the function of the central nervous system. The function of brain network is impaired in these patients. In this study, we evaluated the change in brain network based on a non-linear connectivity measure using cognitive task-based fMRI data between MS patients and healthy controls. We used Kernel mutual information (KMI) and designed a graph network based on the results of connectivity analysis. The the paced auditory serial addition test was used to activate cognitive functions of the brain. The classification was employed for the results using different decision tree -based technique and support vector machine. KMI can be considered a valid measure of connectivity over linear measures, like the correlation coefficient. KMI does not have the drawbacks of mutual information technique. However, further studies should be implemented on brain data of MS patients to draw more definite conclusions.

Motor imagery has a priming effect on motor execution in people with multiple sclerosis

Priming is a learning process that refers to behavioral changes caused by previous exposure to a similar stimulus. Motor imagery (MI), which involves the mental rehearsal of action representations in working memory without engaging in actual execution, could be a strategy for priming the motor system. This study investigates whether MI primes action execution in Multiple Sclerosis (MS). Here, 17 people with MS (PwMS) and 19 healthy subjects (HS), all right-handed and good imaginers, performed as accurately and quickly as possible, with a pencil, actual or mental pointing movements between targets of small (1.0 × 1.0 cm) or large (1.5 × 1.5 cm) size. In actual trials, they completed five pointing cycles between the left and right targets, whereas in mental trials, the first 4 cycles were imagined while the fifth was actually executed. The fifth cycle was introduced to assess the MI priming effect on actual execution. All conditions, presented randomly, were performed with both dominant (i.e., right) and non-dominant arms. Analysis of the duration of the first 4 cycles in both actual and mental trials confirmed previous findings, showing isochrony in HS with both arms and significantly faster mental than actual movements (anisochrony) in PwMS (p < 0.01) [time (s); HS right: actual: 4.23 ± 0.15, mental: 4.36 ± 0.16; left: actual: 4.32 ± 0.15, mental: 4.43 ± 0.18; PwMS right: actual: 5.85 ± 0.16, mental: 5.99 ± 0.21; left: actual: 6.68 ± 0.20, mental: 5.94 ± 0.23]; anisochrony in PwMS was present when the task was performed with the non-dominant arm. Of note, temporal analysis of the fifth actual cycle showed no differences between actual and mental trials for HS with both arms, whereas in PwMS the fifth actual cycle was significantly faster after the four actual cycles for the non-dominant arm (p < 0.05) [time (s); HS right: actual: 1.03 ± 0.04, mental: 1.03 ± 0.03; left: actual: 1.08 ± 0.04, mental: 1.05 ± 0.03; PwMS right: actual: 1.48 ± 0.04, mental: 1.48 ± 0.06; left: actual: 1.66 ± 0.05, mental: 1.48 ± 0.06]. These results seem to suggest that a few mental repetitions of an action might be sufficient to exert a priming effect on the actual execution of the same action in PwMS. This would indicate further investigation of the potential use of MI as a new motor-cognitive tool for MS neurorehabilitation.

Transcranial Magnetic Stimulation of the Dorsolateral Prefrontal Cortex Increases Posterior Theta Rhythm and Reduces Latency of Motor Imagery

Experiments show activation of the left dorsolateral prefrontal cortex (DLPFC) in motor imagery (MI) tasks, but its functional role requires further investigation. Here, we address this issue by applying repetitive transcranial magnetic stimulation (rTMS) to the left DLPFC and evaluating its effect on brain activity and the latency of MI response. This is a randomized, sham-controlled EEG study. Participants were randomly assigned to receive sham (15 subjects) or real high-frequency rTMS (15 subjects). We performed EEG sensor-level, source-level, and connectivity analyses to evaluate the rTMS effects. We revealed that excitatory stimulation of the left DLPFC increases theta-band power in the right precuneus (PrecuneusR) via the functional connectivity between them. The precuneus theta-band power negatively correlates with the latency of the MI response, so the rTMS speeds up the responses in 50% of participants. We suppose that posterior theta-band power reflects attention modulation of sensory processing; therefore, high power may indicate attentive processing and cause faster responses.

TMS over dorsolateral prefrontal cortex affects the timing of motor imagery but not overt action: Further support for the motor-cognitive model

The Motor-Cognitive model suggests a functional dissociation between motor imagery and overt action, in contrast to the Functional Equivalence view of common processes between the two behaviours. According to the Motor-Cognitive model, motor imagery differs from overt action primarily through the use of executive resources to monitor and elaborate a motor image during execution, which can result in a lack of correspondence between motor imagery and its overt action counterpart. The present study examined the importance of executive resources in motor imagery by using TMS to impair the function of the dorsolateral prefrontal cortex while measuring the time to complete imagined versus overt actions. In two experiments, TMS over the dorsolateral prefrontal cortex slowed motor imagery but did not affect overt actions. TMS over the same region also interfered with performance of a mental calculation task, though it did not reliably affect less demanding cognitive tasks also thought to rely on executive functions. Taken together, these results were consistent with the Motor-Cognitive model but not with the idea of functional equivalence. The implications of these results for the theoretical understanding of motor imagery, and potential applications of the Motor-Cognitive model to the use of motor imagery in training and rehabilitation, are discussed.

Electroencephalographic Effective Connectivity Analysis of the Neural Networks during Gesture and Speech Production Planning in Young Adults

Gestures and speech, as linked communicative expressions, form an integrated system. Previous functional magnetic resonance imaging studies have suggested that neural networks for gesture and spoken word production share similar brain regions consisting of fronto-temporo-parietal brain regions. However, information flow within the neural network may dynamically change during the planning of two communicative expressions and also differ between them. To investigate dynamic information flow in the neural network during the planning of gesture and spoken word generation in this study, participants were presented with spatial images and were required to plan the generation of gestures or spoken words to represent the same spatial situations. The evoked potentials in response to spatial images were recorded to analyze the effective connectivity within the neural network. An independent component analysis of the evoked potentials indicated 12 clusters of independent components, the dipoles of which were located in the bilateral fronto-temporo-parietal brain regions and on the medial wall of the frontal and parietal lobes. Comparison of effective connectivity indicated that information flow from the right middle cingulate gyrus (MCG) to the left supplementary motor area (SMA) and from the left SMA to the left precentral area increased during gesture planning compared with that of word planning. Furthermore, information flow from the right MCG to the left superior frontal gyrus also increased during gesture planning compared with that of word planning. These results suggest that information flow to the brain regions for hand praxis is more strongly activated during gesture planning than during word planning.

Mental Practice and Manipulative Skills Training Among People With Multiple Sclerosis: A Pilot Study

IMPORTANCE

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that produces both motor and cognitive dysfunctions. Impairments in limb function as a result of MS cause a decline in the performance of activities of daily living (ADLs).

OBJECTIVE

To determine whether the use of mental practice (MP) or MP combined with training in motor manipulation skills (skills training) would improve gross and fine motor skills and treatment satisfaction among people with MS.

DESIGN

Pilot study with a duration of 3 mo plus 3-mo follow-up.

SETTING

Two MS associations.

PARTICIPANTS

Thirty-five patients diagnosed with MS of the relapsing-remitting and progressive secondary subtypes, ages 25 to 60 yr.

INTERVENTION

The participants were allocated to one of three groups according to their order of inclusion in the study: (1) MP, (2) MP + skills training, or (3) control group. The treatment protocol had a 6-wk duration and a total of 12 sessions. Outcomes and Measures: Blinded evaluators performed three assessments for each patient (pretreatment, posttreatment, and 3-mo follow-up) using the Nine-Hole Peg Test, Box and Block Test, ABILHAND, and Canadian Occupational Performance Measure (COPM).

RESULTS

We found no evidence of benefits in self-perceived performance of ADLs with respect to gross and fine motor skills; however, there was an improvement in perceived satisfaction and in the performance of activities, independent of the treatment received.

CONCLUSIONS AND RELEVANCE

Perceived ADL performance and satisfaction with performance increases among people with MS when they receive MP, MP + skills training, and conventional rehabilitation treatment. What This Article Adds: Mental practice combined with conventional treatment could contribute to patients perceiving improved performance of ADLs. Self-reported outcome measures, such as the COPM, could provide highly valuable information about occupation performance that may not match the objective evidence.

Spatial constraints and cognitive fatigue affect motor imagery of walking in people with multiple sclerosis

Motor imagery (MI) is the mental simulation of an action without any overt motor execution. Interestingly, a temporal coupling between durations of real and imagined movements, i.e., the so-called isochrony principle, has been demonstrated in healthy adults. On the contrary, anisochrony has frequently been reported in elderly subjects or those with neurological disease such as Parkinson disease or multiple sclerosis (MS). Here, we tested whether people with MS (PwMS) may have impaired MI when they imagined themselves walking on paths with different widths. When required to mentally simulate a walking movement along a constrained pathway, PwMS tended to overestimate mental movement duration with respect to actual movement duration. Interestingly, in line with previous evidence, cognitive fatigue was found to play a role in the MI of PwMS. These results suggest that investigating the relationship between cognitive fatigue and MI performances could be key to shedding new light on the motor representation of PwMS and providing critical insights into effective and tailored rehabilitative treatments.

Influence of RehaCom Therapy on the Improvement of Manual Skills in Multiple Sclerosis Subjects

Objective

To assess the influence of cognitive therapy, in combination with cognitive software, on manual dexterity in individuals with multiple sclerosis (MS).

Methods

The Nine-Hole Peg Test (NHPT) was used to establish the eligibility of individuals with MS for testing and to assess their upper limb performance. In addition to standard upper limb rehabilitation, 20 participants received RehaCom-based visual-motor therapy, administered three times a week in 20-minute routines.

Results

A significant relationship was found between the use of manual therapy that utilized the cognitive function platform and the improvement of the non-dominant hand (p=0.037). Compared to controls, the experimental group scored higher on the NHPT, when using the dominant hand (p=0.007). All members of the experimental group, aged ≤60 years, needed considerably less time to do the NHPT with the dominant hand (p=0.008).

Conclusion

Application of manual therapy using the cognitive function platform improves performance of the hand. However, further research is needed to analyze the correlation between cognitive function and motor performance in patients with MS.

Two-year dynamic functional network connectivity in clinically isolated syndrome

Background:

The features of functional network connectivity reorganization at the earliest stages of MS have not been investigated yet.

Objective:

To combine static and dynamic analysis of resting state (RS) functional connectivity (FC) to identify mechanisms of clinical dysfunction and recovery occurring in clinically isolated syndrome (CIS) patients.

Methods:

RS functional magnetic resonance imaging (fMRI) and clinical data were prospectively acquired from 50 CIS patients and 13 healthy controls (HC) at baseline, month 12 and month 24. Between-group differences and longitudinal evolution of network FC were analysed across 41 functionally relevant networks.

Results:

At follow-up, 47 patients developed MS. Disability remained stable (and relatively low). CIS and HC exhibited two recurring RS FC states (states 1 and 2, showing low and high internetwork connectivity, respectively). At baseline, patients showed reduced state 2 connectivity strength in the default-mode and cerebellar networks, and no differences in global dynamism versus HC. A selective FC reduction in networks affected by the clinical attack was also detected. At follow-up, increased state 2 connectivity strength and global connectivity dynamism was observed in patients versus HC.

Conclusion:

Longitudinal FC modifications occurring relatively early in the course of multiple sclerosis may represent a protective mechanism contributing to preserve clinical function over time.

The Role of fMRI in the Assessment of Neuroplasticity in MS: A Systematic Review

Neuroplasticity, which is the ability of the brain to adapt to internal and external environmental changes, physiologically occurs during growth and in response to damage. The brain's response to damage is of particular interest in multiple sclerosis, a chronic disease characterized by inflammatory and neurodegenerative damage to the central nervous system. Functional MRI (fMRI) is a tool that allows functional changes related to the disease and to its evolution to be studied in vivo. Several studies have shown that abnormal brain recruitment during the execution of a task starts in the early phases of multiple sclerosis. The increased functional activation during a specific task observed has been interpreted mainly as a mechanism of adaptive plasticity designed to contrast the increase in tissue damage. More recent fMRI studies, which have focused on the activity of brain regions at rest, have yielded nonunivocal results, suggesting that changes in functional brain connections represent mechanisms of either adaptive or maladaptive plasticity. The few longitudinal studies available to date on disease evolution have also yielded discrepant results that are likely to depend on the clinical features considered and the length of the follow-up. Lastly, fMRI has been used in interventional studies to investigate plastic changes induced by pharmacological therapy or rehabilitation, though whether such changes represent a surrogate of neuroplasticity remains unclear. The aim of this paper is to systematically review the existing literature in order to provide an overall description of both the neuroplastic process itself and the evolution in the use of fMRI techniques as a means of assessing neuroplasticity. The quantitative and qualitative approach adopted here ensures an objective analysis of published, peer-reviewed research and yields an overview of up-to-date knowledge.