Motor-related Potentials Research Articles

N°150 – Subject specific scalp EEG simulations during resting state, motor related potentials and interictal activity using a human brain computational model

N°150 – Subject specific scalp EEG simulations during resting state, motor related potentials and interictal activity using a human brain computational model

Measurement of excitation-contraction coupling time in critical illness myopathy

ObjectiveThis study aimed to develop a simple and reliable technique to assess excitation-contraction (E-C) coupling for early diagnosis of critical illness myopathy (CIM). MethodsWe prospectively performed clinical and electrophysiological examinations on patients admitted to intensive care unit (ICU). In addition to full neurological examinations and routine nerve conduction study, motor related potential (MRP) was recorded using an accelerometer attached to the base of hallux after tibial nerve stimulation, and E-C coupling time (ECCT) was measured from the latency difference between soleus compound muscle action potential (CMAP) and MRP. ResultsOf 41 patients evaluated, 25 met the criteria for ICU-acquired weakness, 23 of whom had CIM. The time to the first electrophysiological examination (time to first test) correlated negatively with CMAP and with MRP. Conversely, a positive correlation was observed between the time to first test and ECCT. E-C coupling impairment occurred in most of our patients with CIM by the third day of ICU admission, and prolonged ECCT could be the earliest detectable abnormality. ConclusionsThe ECCT measurement is an easy and reliable technique to detect reduced muscle membrane excitability in the early stage of CIM. SignificanceThe ECCT measured by our method using an accelerometer may be a parameter that predicts the development of CIM.

Influence of User Tasks on EEG-based Classification Performance in a Hazard Detection Paradigm.

Attention-based brain-computer interface (BCI) paradigms offer a way to exert control, but also to provide insight into a user's perception and judgment of the environment. For a sufficient classification performance, user engagement and motivation are critical aspects. Consequently, many paradigms require the user to perform an auxiliary task, such as mentally counting subsets of stimuli or pressing a button when encountering them. In this work, we compare two user tasks, mental counting and button-presses, in a hazard detection paradigm in driving videos. We find that binary classification performance of events based on the electroencephalogram as well as user preference are higher for button presses. Amplitudes of evoked responses are higher for the counting task-an observation which holds even after projecting out motor-related potentials during the data preprocessing. Our results indicate that the choice of button-presses can be a preferable choice in such BCIs based on prediction performance as well as user preference.

Cognitive and motor event-related potentials in Tourette syndrome and tic disorders: A systematic review

ObjectivesTourette syndrome (TS) patients face various cognitive and motor impairments. Event-related potentials (ERP) constitute an effective way to investigate the neural correlates of those functional impairments. Various components have been assessed among TS patients, with a wide variety of paradigms. This systematic review aimed to evaluate the portrait of ERP components in TS patients, and to understand the factors leading to discrepancies across studies. MethodsA literature search was performed in Embase, PsycINFO, Pubmed, and Web of Science, to identify studies that conducted ERP experiments among TS patients. Of the 372 unique records identified, 47 met inclusion criteria and were included in our systematic review. ResultsVarious ERP particularities were reported among included studies. Many discrepancies exist, but impairments in motor-related potentials and contingent negative variation seem constant across studies. Divergent findings point toward a possibly reduced P3b during oddball tasks. ConclusionsERPs offer an insightful investigation into the cognitive and motor functions of TS patients. Future studies should always control for confounding factors such as comorbidity, age, or medication status. SignificanceThis is the first systematic review of ERP in TS patients. Motor-related and slow cortical potentials could constitute electrophysiological markers of TS.

3D visualization of movements can amplify motor cortex activation during subsequent motor imagery.

A repetitive movement practice by motor imagery (MI) can influence motor cortical excitability in the electroencephalogram (EEG). This study investigated if a realistic visualization in 3D of upper and lower limb movements can amplify motor related potentials during subsequent MI. We hypothesized that a richer sensory visualization might be more effective during instrumental conditioning, resulting in a more pronounced event related desynchronization (ERD) of the upper alpha band (10–12 Hz) over the sensorimotor cortices thereby potentially improving MI based brain-computer interface (BCI) protocols for motor rehabilitation. The results show a strong increase of the characteristic patterns of ERD of the upper alpha band components for left and right limb MI present over the sensorimotor areas in both visualization conditions. Overall, significant differences were observed as a function of visualization modality (VM; 2D vs. 3D). The largest upper alpha band power decrease was obtained during MI after a 3-dimensional visualization. In total in 12 out of 20 tasks the end-user of the 3D visualization group showed an enhanced upper alpha ERD relative to 2D VM group, with statistical significance in nine tasks.With a realistic visualization of the limb movements, we tried to increase motor cortex activation during subsequent MI. The feedback and the feedback environment should be inherently motivating and relevant for the learner and should have an appeal of novelty, real-world relevance or aesthetic value (Ryan and Deci, 2000; Merrill, 2007). Realistic visual feedback, consistent with the participant’s MI, might be helpful for accomplishing successful MI and the use of such feedback may assist in making BCI a more natural interface for MI based BCI rehabilitation.

2D vs 3D visualization modalities and their effects on motor related potentials

2D vs 3D visualization modalities and their effects on motor related potentials

Response-Related Potentials during Semantic Priming: The Effect of a Speeded Button Response Task on ERPs

This study examines the influence of a button response task on the event-related potential (ERP) in a semantic priming experiment. Of particular interest is the N400 component. In many semantic priming studies, subjects are asked to respond to a stimulus as fast and accurately as possible by pressing a button. Response time (RT) is recorded in parallel with an electroencephalogram (EEG) for ERP analysis. In this case, the response occurs in the time window used for ERP analysis and response-related components may overlap with stimulus-locked ones such as the N400. This has led to a recommendation against such a design, although the issue has not been explored in depth. Since studies keep being published that disregard this issue, a more detailed examination of influence of response-related potentials on the ERP is needed. Two experiments were performed in which subjects pressed one of two buttons with their dominant hand in response to word-pairs with varying association strength (AS), indicating a personal judgement of association between the two words. In the first experiment, subjects were instructed to respond as fast and accurately as possible. In the second experiment, subjects delayed their button response to enforce a one second interval between the onset of the target word and the button response. Results show that in the first experiment a P3 component and motor-related potentials (MRPs) overlap with the N400 component, which can cause a misinterpretation of the latter. In order to study the N400 component, the button response should be delayed to avoid contamination of the ERP with response-related components.

Neural correlates of non-verbal social interactions: A dual-EEG study

Successful non-verbal social interaction between human beings requires dynamic and efficient encoding of others′ gestures. Our study aimed at identifying neural markers of social interaction and goal variations in a non-verbal task. For this, we recorded simultaneously the electroencephalogram from two participants (dual-EEG), an actor and an observer, and their arm/hand kinematics in a real face-to-face paradigm. The observer watched “biological actions” performed by the human actor and “non-biological actions” performed by a robot. All actions occurred within an interactive or non-interactive context depending on whether the observer had to perform a complementary action or not (e.g., the actor presents a saucer and the observer either places the corresponding cup or does nothing). We analysed the EEG signals of both participants (i.e., beta (~20Hz) oscillations as an index of cortical motor activity and motor related potentials (MRPs)). We identified markers of social interactions by synchronising EEG to the onset of the actor′s movement. Movement kinematics did not differ in the two context conditions and the MRPs of the actor were similar in the two conditions. For the observer, however, an observation-related MRP was measured in all conditions but was more negative in the interactive context over fronto-central electrodes. Moreover, this feature was specific to biological actions. Concurrently, the suppression of beta oscillations was observed in the actor's EEG and the observer's EEG rapidly after the onset of the actor's movement. Critically, this suppression was stronger in the interactive than in the non-interactive context despite the fact that movement kinematics did not differ in the two context conditions. For the observer, this modulation was observed independently of whether the actor was a human or a robot. Our results suggest that acting in a social context induced analogous modulations of motor and sensorimotor regions in observer and actor. Sharing a common goal during an interaction seems thus to evoke a common representation of the global action that includes both actor and observer movements.

Motor resonance facilitates movement execution: an ERP and kinematic study

Action observation, simulation and execution share neural mechanisms that allow for a common motor representation. It is known that when these overlapping mechanisms are simultaneously activated by action observation and execution, motor performance is influenced by observation and vice versa. To understand the neural dynamics underlying this influence and to measure how variations in brain activity impact the precise kinematics of motor behavior, we coupled kinematics and electrophysiological recordings of participants while they performed and observed congruent or non-congruent actions or during action execution alone. We found that movement velocities and the trajectory deviations of the executed actions increased during the observation of congruent actions compared to the observation of non-congruent actions or action execution alone. This facilitation was also discernible in the motor-related potentials of the participants; the motor-related potentials were transiently more negative in the congruent condition around the onset of the executed movement, which occurred 300 ms after the onset of the observed movement. This facilitation seemed to depend not only on spatial congruency but also on the optimal temporal relationship of the observation and execution events.

Effects of aging on slowing of motor-response generation

The aim of the present study was to analyze different stages of central processing mechanisms during a choice reaction task and to evaluate their contribution to aging-related response slowing. Event-related potentials (ERPs) were recorded from two groups of subjects, young (mean 22 years) and older adults (mean 58 years), who performed a four-alternative choice-reaction task. The results showed the expected reaction time slowing in the older subjects. This behavioural slowing was not due to delays in stimulus processing (as reflected by latencies of early ERP components), or in response selection (as reflected by the onset of the lateralized readiness potential). Instead, this slowing was due to an alteration of movement-related components, particularly an amplitude enhancement and prolongation of the motor-related potential at the cortex contralateral to the responding hand. This alteration was reliable and of general nature since it was also found in a second study using a different choice-reaction task with a more direct stimulus–response relation. The results suggest that the overt response requires a higher activation level in older vs. young subjects; this extra-activation needs time and hence prolongs reaction time with aging.

Motor-response generation as a source of aging-related behavioural slowing in choice-reaction tasks

Objective To analyze the effects of stimulus–response (SR) processing modes on different central stages of sensorimotor processing in order to evaluate their contribution to aging-related behavioural slowing. Methods Components of stimulus- and response-related potentials (ERPs/RRPs) and lateralized readiness potentials (LRPs) were analyzed in two groups of young (mean 22.5 years) and older adults (mean 58.3 years) during an auditory and a visual four-choice-reaction task. Results (1) Reaction time (RT) depended on the SR type, indicating SR-specific differences in processing, which did not vary with age. (2) For each SR type, the RT increased with age. RT slowing was not accompanied by significant delays in early stimulus processing (as reflected by P1 and N1 latencies) nor in response selection (as reflected by the onset of stimulus-locked LRP), but resulted from a prolongation of contralateral motor activity during motor response execution indexed by earlier, longer durated and larger motor-related potentials in older adults. These aging effects were observed for each SR type. Conclusion In a four-choice-reaction task, (1) task complexity rather than differences in cognitive strategy or activation patterns subserving SR-specific processing leads to response slowing with aging and (2) the most plausible contributor to this slowing is the cortical response generation system.

Evaluation of different cortical source localization methods using simulated and experimental EEG data

Different cortical source localization methods have been developed to directly link the scalp potentials with the cortical activities. Up to now, these methods are the only possible solution to noninvasively investigate cortical activities with both high spatial and time resolutions. However, the application of these methods is hindered by the fact that they have not been rigorously evaluated nor compared. In this paper, the performances of several source localization methods (moving dipoles, minimum Lp norm, and low resolution tomography (LRT) with Lp norm, p equal to 1, 1.5, and 2) were evaluated by using simulated scalp EEG data, scalp somatosensory evoked potentials (SEPs), and upper limb motor-related potentials (MRPs) obtained on human subjects (all with 163 scalp electrodes). By using simulated EEG data, we first evaluated the source localization ability of the above methods quantitatively. Subsequently, the performance of the various methods was evaluated qualitatively by using experimental SEPs and MRPs. Our results show that the overall LRT Lp norm method with p equal to 1 has a better source localization ability than any of the other investigated methods and provides physiologically meaningful reconstruction results. Our evaluation results provide useful information for choosing cortical source localization approaches for future EEG/MEG studies.

Event- and Motor-Related Potentials During the Continuous Performance Task in Attention- Deficit/Hyperactivity Disorder

Abstract Contingent negative variation (CNV) and evoked potentials were recorded during the continuous performance test in 20 children (aged 7 to 12) with attention deficit/hyperactivity disorder (ADHD) and in 19 age-matched healthy children. A series of letters were displayed every 2.1 s and a button had to be pressed whenever the letter O was followed by an X. Children were also given neuropsychological tests and questionnaires assessing anxiety and depression. Unlike ADHD children, healthy children showed a more pronounced CNV after the cue - the letter O - than after the distractors. At Fz, CNV negativity was significantly correlated with IQ and executive function. Control children also exhibited a higher parietal N375 post S1 - likely to be associated with letter processing - and a higher N550 amplitude at Fz than ADHD children post S1 and S2; both groups showed a higher N550 amplitude whenever X followed non-O or O was followed by non-X. This component appears to be involved in decision-making processes regarding the initiation or inhibition of movement. ADHD children had a faster reaction time but made more errors of omission and commission. Results suggest that ADHD children show deficits in both stimulus processing and response execution.

Brain-computer interface research at the Neil Squire Foundation.

The ultimate goal of our research is to utilize voluntary motor-related potentials recorded from the scalp in a direct Brain Computer Interface for asynchronous control applications. This type of interface will allow an individual with a high-level impairment to have effective and sophisticated control of devices such as wheelchairs, robotic assistive appliances, computers, and neural prostheses.

The Simon effect and its reversal studied with event-related potentials

The Simon effect (slower RT when stimulus and response locations do not match, stimulus location being irrelevant) and its reversal, were investigated using P300 latency and motor-related potentials. Stimuli were one of two colors, and response keys were two buttons with color labels that changed randomly in every trial. Depending on the stimulus-response (S-R) mapping instructions, subjects pressed the same-color key or the alternate-color key. Behavioral measures showed a Simon effect in same- and a reverse Simon effect in alternate-color mapping contradicting the display-control arrangement correspondence and the S-S compatibility, as explanations for the reverse Simon effect. P300 latencies followed the same pattern as RT, i.e. they were influenced by the S-R mapping, suggesting that this measure does not index the duration of the stimulus evaluation, but response selection processes. The motor-related potentials demonstrated response activation based on stimulus location, also supporting response-interference interpretations of the Simon effect.

Possibilités et limites des potentiels évoqués pour l'analyse des états de veille et des processus d'attention sélective: Revue des données récentes

The aim of this paper was to briefly review the use of normal human Event Related Potentials (ERP) in the evaluation of processes of diffuse and selective attention. The reviewed results from recent experiments concern the exogeneous components of the evoked potential (in particular N120-P200), the endogeneous components N200-P300, P600 (or the so called "Emitted Potentials"), the motor related potentials and the CNV. The behavioural correlates of each of these components, as well as their relationships with the various stages of information processing during perceptivo-motor tasks implying decision making, were emphasized. As a conclusion, the psychiatric applications of this type of electrophysiological research was discussed; moreover the need of its development in the field of neuro-psychology was underlined.