Motor Imagery of Walking in People Living with and without Multiple Sclerosis: A Cross-Sectional Comparison of Mental Chronometry

Motor imagery represents the ability to simulate anticipated movements mentally prior to their actual execution and has been proposed as a tool to assess both individuals’ perception of task difficulty as well as their perception of their own abilities. People with multiple sclerosis (pwMS) often present with motor and cognitive dysfunction, which may negatively affect motor imagery. In this cross-sectional study, we explored differences in motor imagery of walking performance between pwMS (n = 20, age = 57.1 (SD = 8.6) years, 55% female) and age- and sex-matched healthy controls (n = 20, age = 58.1 (SD = 7.0) years, 60% female). Participants underwent mental chronometry assessments, a subset of motor imagery, which evaluated the difference between imagined and actual walking times across four walking tasks of increasing difficulty (i.e., large/narrow-width walkway with/without obstacles). Raw and absolute mental chronometry (A-MC) measures were recorded in single- (ST) and dual-task (DT) conditions. In ST conditions, pwMS had higher A-MC scores across all walking conditions (p ≤ 0.031, η2 ≥ 0.119), indicating lower motor imagery ability compared to healthy controls. During DT, all participants tended to underestimate their walking ability (3.38 ± 6.72 to 5.63 ± 9.17 s). However, after physical practice, pwMS were less able to adjust their imagined walking performance compared to healthy controls. In pwMS, A-MC scores were correlated with measures of balance confidence (ρ = −0.629, p < 0.01) and the self-reported expanded disability status scale (ρ = 0.747, p < 0.01). While the current study revealed that pwMS have lower motor imagery of walking performance compared to healthy individuals, further work is necessary to examine how the disassociation between mental chronometry and actual performance relates to quality of life and well-being.

Mental chronometry in big noisy data

Temporal measures (latencies) in the event-related potentials of the EEG (ERPs) are a valuable tool for mental chronometry. In large scale studies with a multitude of single EEG-based tasks the quality of latency measures often suffers from high and low frequency noise due to low trial counts (because of compressed tasks) and the missing opportunity of visual inspection. In the present study, we systematically evaluated two different approaches to latency estimation (peak latencies and fractional area latencies) with respect to their data quality and the application of noise reduction by jackknifing methods. Additionally, we tested the recently introduced method of Standardized Measurement Error (SME) to prune the dataset. We demonstrate that fractional area latency in pruned and jackknifed data may amplify within-subjects effect sizes by the factor ten in the analyzed data set. Between-subjects effects were less affected by the applied procedure, but remained stable regardless of procedure.

Assessment of reliability and validity of the mental chronometry task based on the box and block test in multiple sclerosis patients

Objectives: Motor imagery (MI) is the visualization of action without its overt performance. One of the measures of explicit MI is mental chronometry which has been applied to multiple sclerosis (MS) patients; nonetheless, the reliability and validity of this tool has been never confirmed. Therefore, the present study aimed to assess the reliability and validity of mental chronometry in MS patients. Methods: A number of 60 MS patients who met the inclusion criteria were included in the present study via the census method. Thereafter, 20 MS patients were tested via mental chronometry based on the box and block test, as well as kinesthetic and visual imagery questionnaire-20 (KVIQ-20) in two sessions with a 10-day interval. Intra-class correlation coefficients (ICCs) were calculated to determine the test-retest reliability of mental chronometry. Pearson’s correlation analysis was used to evaluate criterion validity with the KVIQ-20. Results: The test-retest reliability for the mental chronometry was good (ICCs: visual analogue scale=0.88, mean execution and motor imagery absolute difference= 0.75, imagery duration=0.91, and execution duration=0.97). Moreover, the concurrent validity between the visual analogue scale of mental chronometry and KVIQ-20 was good. Conclusion: As evidenced by the results of the present study, the mental chronometry based on box and block is a reliable and valid tool for the assessment of motor imagery in MS patients.

Transcranial Magnetic Stimulation and the Understanding of Behavior

The development of the use of transcranial magnetic stimulation (TMS) in the study of psychological functions has entered a new phase of sophistication. This is largely due to an increasing physiological knowledge of its effects and to its being used in combination with other experimental techniques. This review presents the current state of our understanding of the mechanisms of TMS in the context of designing and interpreting psychological experiments. We discuss the major conceptual advances in behavioral studies using TMS. There are meaningful physiological and technical achievements to review, as well as a wealth of new perceptual and cognitive experiments. In doing so we summarize the different uses and challenges of TMS in mental chronometry, perception, awareness, learning, and memory.

Effects of a single mental chronometry training session in subacute stroke patients – a randomized controlled trial

Background Motor imagery training might be helpful in stroke rehabilitation. This study explored if a single session of motor imagery (MI) training induces performance changes in mental chronometry (MC), motor execution, or changes of motor excitability. Methods Subacute stroke patients (n = 33) participated in two training sessions. The order was randomized. One training consisted of a mental chronometry task, the other training was a hand identification task, each lasting 30 min. Before and after the training session, the Box and Block Test (BBT) was fully executed and also performed as a mental version which served as a measure of MC. A subgroup analysis based on the presence of sensory deficits was performed. Patients were allocated to three groups (no sensory deficits, moderate sensory deficits, severe sensory deficits). Motor excitability was measured by transcranial magnetic stimulation (TMS) pre and post training. Amplitudes of motor evoked potentials at rest and during pre-innervation as well as the duration of cortical silent period were measured in the affected and the non-affected hand. Results Pre-post differences of MC showed an improved MC after the MI training, whereas MC was worse after the hand identification training. Motor execution of the BBT was significantly improved after mental chronometry training but not after hand identification task training. Patients with severe sensory deficits performed significantly inferior in BBT execution and MC abilities prior to the training session compared to patients without sensory deficits or with moderate sensory deficits. However, pre-post differences of MC were similar in the 3 groups. TMS results were not different between pre and post training but showed significant differences between affected and unaffected side. Conclusion Even a single training session can modulate MC abilities and BBT motor execution in a task-specific way. Severe sensory deficits are associated with poorer motor performance and poorer MC ability, but do not have a negative impact on training-associated changes of mental chronometry. Studies with longer treatment periods should explore if the observed changes can further be expanded. Trial registration DRKS, DRKS00020355, registered March 9th, 2020, retrospectively registered

Sensorized Assessment of Dynamic Locomotor Imagery in People with Stroke and Healthy Subjects

Dynamic motor imagery (dMI) is a motor imagery task associated with movements partially mimicking those mentally represented. As well as conventional motor imagery, dMI has been typically assessed by mental chronometry tasks. In this paper, an instrumented approach was proposed for quantifying the correspondence between upper and lower limb oscillatory movements performed on the spot during the dMI of walking vs. during actual walking. Magneto-inertial measurement units were used to measure limb swinging in three different groups: young adults, older adults and stroke patients. Participants were tested in four experimental conditions: (i) simple limb swinging; (ii) limb swinging while imagining to walk (dMI-task); (iii) mental chronometry task, without any movement (pure MI); (iv) actual level walking at comfortable speed. Limb swinging was characterized in terms of the angular velocity, frequency of oscillations and sinusoidal waveform. The dMI was effective at reproducing upper limb oscillations more similar to those occurring during walking for all the three groups, but some exceptions occurred for lower limbs. This finding could be related to the sensory feedback, stretch reflexes and ground reaction forces occurring for lower limbs and not for upper limbs during walking. In conclusion, the instrumented approach through wearable motion devices adds significant information to the current dMI approach, further supporting their applications in neurorehabilitation for monitoring imagery training protocols in patients with stroke.

A Different Point of View: The Evaluation of Motor Imagery Perspectives in Patients With Sensorimotor Impairments in A Longitudinal Study

BackgroundMotor imagery (MI) has been successfully applied in neurological rehabilitation. Little is known about the spontaneous selection of the MI perspectives in patients with sensorimotor impairments. What MI perspective is selected: internal (first- person view), or external (third-person view)? The aim was to evaluate the MI perspective preference in patients after stroke (STR), with Multiple Sclerosis (MS) or Parkinson’s disease (PD).MethodsIn a longitudinal study including four measurement sessions over two weeks, MI ability and MI perspective preference in both visual and kinaesthetic imagery modalities were assessed using the Kinaesthetic and Visual Imagery Questionnaire including 20 items (KVIQ-20), mental rotation, and mental chronometry. Additionally, patients' activity level was assessed. Descriptive statistical analyses were performed regarding different age- (≤44, 45-63, 64≤) and activity levels (inactive, partially active, active), and KVIQ-20 movement classifications (axial, proximal, distal, upper and lower limb).ResultsIn total, 55 in- and outpatients (25 SRT, 25 MS, 5 PD; 25 females; mean age 58±14 years) were included. At the first measurement session, the mean mental rotation score was 27±4.1 out of 32. For mental chronometry, a congruency ratio of 1.0±0.3 was determined. The KVIQ-20 scores for the visual and kinaesthetic subscales were 62.4±16.2 and 58.2±17.2. The internal MI perspective was favoured in 66.5% on the visual subscale and in 72.7% on the kinaesthetic subscale. The external perspective was preferred in 30.3% on the visual subscale and in 26.5% on the kinaesthetic subscale. Over the four measurement sessions, patients became more consistent in their MI perspective selection. MI perspective changes occurred mainly during imagination of shoulder, arm and neck movements. During imagination of foot and finger movements their MI perspective was more constant. Results showed a tendency to use an external perspective in patients older than 64 years and in patients with a descreasing physical activity level. Axial and proximal movements were commonly imagined using the external perspective. ConclusionIt is recommended to evaluate the spontaneous MI perspective selection to design patient-specific MI training interventions. Distal movements (foot, finger) may be an indicator when evaluating the consistency of the MI perspective in patients with sensorimotor impairments. Trial registrationThis is a research project involving persons other than a clinical trial according to the Human Research Act other than clinical (non-clinical trial). Registered: EKNZ 2015-172, 19. Mai 2015

Electrophysiology

One important method that can be applied for gaining an understanding of the implementation of aesthetics in the brain is that of electrophysiology. Cognitive electrophysiology, in particular, allows the identification of components in a mental processing architecture. The present chapter reviews findings in the neurocognitive psychology of aesthetics, or neuroaesthetics, that have been obtained with the method of event-related brain potentials (ERPs), as derived from the human electroencephalogram (EEG). The cognitive-perceptual bases, as well as affective sub-stages of aesthetic processing have been investigated, and those are described here. The ERP method allows for the identification of mental processing modes in cognitive and aesthetic processing. It also provides an assessment of the mental chronometry of cognitive and affective stages in aesthetic appreciation. As the work described here shows, distinct processes in the brain are engaged in aesthetic judgments.