Damage to fronto-parietal networks impairs motor imagery ability after stroke : a voxel-based lesion symptom mapping study

Background: mental practice with motor imagery has been shown to promote motor skill acquisition in healthy subjects and patients. Although lesions of the common motor imagery and motor execution neural network are expected to impair motor imagery ability, functional equivalence appears to be at least partially preserved in stroke patients.Aim: to identify brain regions that are mandatory for preserved motor imagery ability after stroke.Method: thirty-seven patients with hemiplegia after a first time stroke participated. Motor imagery ability was measured using a Motor Imagery questionnaire and temporal congruence test. A voxelwise lesion symptom mapping approach was used to identify neural correlates of motor imagery in this cohort within the first year post-stroke.Results: poor motor imagery vividness was associated with lesions in the left putamen, left ventral premotor cortex and long association fibres linking parieto-occipital regions with the dorsolateral premotor and prefrontal areas. Poor temporal congruence was otherwise linked to lesions in the more rostrally located white matter of the superior corona radiata. Conclusion: This voxel-based lesion symptom mapping study confirms the association between white matter tract lesions and impaired motor imagery ability, thus emphasizing the importance of an intact fronto-parietal network for motor imagery. Our results further highlight the crucial role of the basal ganglia and premotor cortex when performing motor imagery tasks

Narrow Window Feature Extraction for EEG-Motor Imagery Classification using k-NN and Voting Scheme

Achieving consistent accuracy still big challenge in EEG based Motor Imagery classification since the nature of EEG signal is non-stationary, intra-subject and inter-subject dependent. To address this problems, we propose the feature extraction scheme employing statistical measurements in narrow window with channel instantiation approach. In this study, k-Nearest Neighbor is used and a voting scheme as final decision where the most detection in certain class will be a winner. In this channel instantiation scheme, where EEG channel become instance or record, seventeen EEG channels with motor related activity is used to reduce from 118 channels. We investigate five narrow windows combination in the proposed methods, i.e.: one, two, three, four and five windows. BCI competition III Dataset IVa is used to evaluate our proposed methods. Experimental results show that one window with all channel and a combination of five windows with reduced channel outperform all prior research with highest accuracy and lowest standard deviation. This results indicate that our proposed methods achieve consistent accuracy and promising for reliable BCI systems

Magnetoencephalography in Stroke Recovery and Rehabilitation

Magnetoencephalography (MEG) is a non-invasive neurophysiological technique used to study the cerebral cortex. Currently, MEG is mainly used clinically to localize epileptic foci and eloquent brain areas in order to avoid damage during neurosurgery. MEG might, however, also be of help in monitoring stroke recovery and rehabilitation. This review focuses on experimental use of MEG in neurorehabilitation. MEG has been employed to detect early modifications in neuroplasticity and connectivity, but there is insufficient evidence as to whether these methods are sensitive enough to be used as a clinical diagnostic test. MEG has also been exploited to derive the relationship between brain activity and movement kinematics for a motor-based brain-computer interface. In the current body of experimental research, MEG appears to be a powerful tool in neurorehabilitation, but it is necessary to produce new data to confirm its clinical utility

Komunikacja w grupie pacjentów z zaburzeniami świadomości – wnioskiz projektu InteRDoCTor

Thanks to recent advances in health care an increased number of patients may recover from  severe brain injuries, but some of them are still assessed as non-responsive. Reliance on behavioural measures in communication with DoC patients seems be too prone to errors. There is need for solutions providing more objective attempts of bidirectional communication (intentional questions/commands and adequate related responses) in patients with DoC using significant processed by the patient stimuli and novel technologies (EEG-, fMRI-, BCI-based, etc.) based on recent scientific and clinical evidences. Such communication may be fulfilled even in the absence of behavior.This article aims at assessment the extent to which current possibilities in the area of devices for extended communication has been exploited, including own experiences within InteRDoCTor project.Dzięki najnowszym osiągnięciom w opiece zdrowotnej coraz większa liczba pacjentów może powrócić do zdrowia z poważnych urazów mózgu, lecz część z nich jest ciągle diagnozowana jako niereagujący na bodźce. Poleganie jedy-nie na miarach behawioralnych w komunikacji z pacjentami z zaburzeniami świadomości wydaje się zbyt podatne na błędy. Istnieje zapotrzebowanie na rozwiązania zapewniające bardziej obiektywne próby komunikacji dwukierunkowej (celowe pytania/polecenia i odpowiadające im reakcje)u pacjentów z zaburzeniami świadomości, z wykorzystaniem bodźców znaczących dla pacjenta i przetwarzanych przez niego oraz nowych technologii (opartych na EEG, fMRI, BCI, itd.) w oparciu o najnowsze dowody naukowe i kliniczne. Ww. komunikacja może być realizowana nawet w przypadku braku obserwowalnych zmian zachowania pacjenta.Artykuł ma na celu ocenę, w jakim zakresie wykorzystuje się możliwości w tym obszarze, w tym w oparciu o doświadczenia własne z projektu InteRDoCTor

Communication in patients with disorders of consciousness – lessons learned From InteRDoCTor project

Thanks to recent advances in health care an increased number of patients may recover from  severe brain injuries, but some of them are still assessed as non-responsive. Reliance on behavioural measures in communication with DoC patients seems be too prone to errors. There is need for solutions providing more objective attempts of bidirectional communication (intentional questions/commands and adequate related responses) in patients with DoC using significant processed by the patient stimuli and novel technologies (EEG-, fMRI-, BCI-based, etc.) based on recent scientific and clinical evidences. Such communication may be fulfilled even in the absence of behavior. This article aims at assessment the extent to which current possibilities in the area of devices for extended communication has been exploited, including own experiences within InteRDoCTor project.Dzięki najnowszym osiągnięciom w opiece zdrowotnej coraz większa liczba pacjentów może powrócić do zdrowia z poważnych urazów mózgu, lecz część z nich jest ciągle diagnozowana jako niereagujący na bodźce. Poleganie jedy-nie na miarach behawioralnych w komunikacji z pacjentami z zaburzeniami świadomości wydaje się zbyt podatne na błędy. Istnieje zapotrzebowanie na rozwiązania zapewniające bardziej obiektywne próby komunikacji dwukierunkowej (celowe pytania/polecenia i odpowiadające im reakcje)u pacjentów z zaburzeniami świadomości, z wykorzystaniem bodźców znaczących dla pacjenta i przetwarzanych przez niego oraz nowych technologii (opartych na EEG, fMRI, BCI, itd.) w oparciu o najnowsze dowody naukowe i kliniczne. Ww. komunikacja może być realizowana nawet w przypadku braku obserwowalnych zmian zachowania pacjenta. Artykuł ma na celu ocenę, w jakim zakresie wykorzystuje się możliwości w tym obszarze, w tym w oparciu o doświadczenia własne z projektu InteRDoCTor

Adaptive Motor Imagery: A Multimodal Study of Immobilization-Induced Brain Plasticity.

The consequences of losing the ability to move a limb are traumatic. One approach that examines the impact of pathological limb nonuse on the brain involves temporary immobilization of a healthy limb. Here, we investigated immobilization-induced plasticity in the motor imagery (MI) circuitry during hand immobilization. We assessed these changes with a multimodal paradigm, using functional magnetic resonance imaging (fMRI) to measure neural activation, magnetoencephalography (MEG) to track neuronal oscillatory dynamics, and transcranial magnetic stimulation (TMS) to assess corticospinal excitability. fMRI results show a significant decrease in neural activation for MI of the constrained hand, localized to sensorimotor areas contralateral to the immobilized hand. MEG results show a significant decrease in beta desynchronization and faster resynchronization in sensorimotor areas contralateral to the immobilized hand. TMS results show a significant increase in resting motor threshold in motor cortex contralateral to the constrained hand, suggesting a decrease in corticospinal excitability in the projections to the constrained hand. These results demonstrate a direct and rapid effect of immobilization on MI processes of the constrained hand, suggesting that limb nonuse may not only affect motor execution, as evidenced by previous studies, but also MI. These findings have important implications for the effectiveness of therapeutic approaches that use MI as a rehabilitation tool to ameliorate the negative effects of limb nonuse

Motor imagery entails task-set inhibition

Motor imagery requires the covert execution of a movement without any overt motor output. Previous studies indicated that motor imagery results in the prolonged inhibition of motor commands. In the present study, we investigated whether motor imagery also leads to the inhibition of more abstract task representations. To do so, we investigated the effect of motor imagery onn- 2 repetition costs, which offer an index of the extent to which task representations are inhibited. Participants switched among three tasks and among two response modes: overt and covert responding (i.e., motor imagery).N- 2 repetition costs were present when the current trial required an overt response but absent when the current trial required a covert response. Furthermore,n- 2 repetition costs were more pronounced when trialn- 1 required a covert response rather than an overt response. This pattern of results suggests that motor imagery also leads to the inhibition of abstract task representations. We discuss our findings in view of current conceptualizations of motor imagery and argue that the inhibitory mechanism entailed by motor imagery targets more than motor commands alone. Finally, we also relate our findings to the mechanisms underlying the inhibition of task representations

Parietal/premotor lesions effects on visuomotor cognition in neuro-oncology patients: A multimodal study

Background: Assessing prior to surgery the functionality of brain areas exposed near the tumor requires a multimodal approach that combines the use of neuropsychological testing and fMRI tasks. Paradigms based on motor imagery, which corresponds to the ability to mentally evoke a movement, in the absence of actual action execution, can be used to test sensorimotor areas and the functionality of mental motor representations. Methods: The most commonly used paradigm is the Limb Laterality Recognition Task (LLRT), requiring judgments about whether a limb belongs to the left or right side of the body. The group studied included 38 patients with high-grade (N = 21), low-grade (N = 11) gliomas and meningiomas (N = 6) in areas anterior (N = 21) and posterior (N = 17) to the central sulcus. Patients before surgery underwent neuropsychological assessment and fMRI. They performed the LLRT as an fMRI task. Accuracy, and neuroimaging data were collected and combined in a multimodal study. Structural MRI data analyses were performed by subtracting the overlap of volumes of interest (VOIs) plotted on lesions from the impaired patient group vs the overlap of VOIs from the spared group. The fMRI analyses were performed comparing the impaired patients and spared group. Results: In general, patients were within normal limits on many neuropsychological screening tests. Compared with the control group, 17/38 patients had significantly different performance. The subtraction between the VOIs overlay of the impaired patients' group vs. the VOIs overlay of the spared group revealed that the areas maximally involved by lesions in the impaired patients' group were the right postcentral gyrus, right inferior parietal lobe, right supramarginal gyrus, right precentral gyrus, paracentral lobule, left postcentral gyrus, right superior parietal lobe, left inferior parietal lobe, and left superior and middle frontal gyrus. Analysis of the fMRI data showed which of these areas contributes to a correct LLRT performance. The task (vs. rest) in the group comparison (spared vs. impaired patients) activated a cluster in the left inferior parietal lobe. Conclusion: Underlying the altered performance at LLRT in patients with lesions to the parietal and premotor areas of the right and left hemispheres is a difference in activation of the left inferior parietal lobe. This region is involved in visuomotor processes and those related to motor attention, movement selection, and motor planning

Combined action observation and motor imagery therapy: a novel method for post-stroke motor rehabilitation

Cerebral vascular accidents (strokes) are a leading cause of motor deficiency in millions of people worldwide. While a complex range of biological systems is affected following a stroke, in this paper we focus primarily on impairments of the motor system and the recovery of motor skills. We briefly review research that has assessed two types of mental practice, which are currently recommended in stroke rehabilitation. Namely, action observation (AO) therapy and motor imagery (MI) training. We highlight the strengths and limitations in both techniques, before making the case for combined action observation and motor imagery (AO + MI) therapy as a potentially more effective method. This is based on a growing body of multimodal brain imaging research showing advantages for combined AO + MI instructions over the two separate methods of AO and MI. Finally, we offer a series of suggestions and considerations for how combined AO + MI therapy could be employed in neurorehabilitation