Simulated actions in the first and in the third person perspectives share common representations

Development and feasibility of first- and third-person motor imagery for people with stroke living in the community

BACKGROUND

Impairment of arm movement occurs in up to 85% of people post-stroke, affecting daily living activities, and quality of life. Mental imagery effectively enhances hand and daily function in people with stroke. Imagery can be performed when people imagine themselves completing the movement or imagine another person doing it. However, there is no report on the specific use of first-person and third-person imagery in stroke rehabilitation.

AIMS

To develop and assess the feasibility of the First-Person Mental Imagery (FPMI) and the Third-Person Mental Imagery (TPMI) programs to address the hand function of people with stroke living in the community.

METHODS

This study comprises phase 1-development of the FPMI and TPMI programs, and phase 2-pilot-testing of the intervention programs. The two programs were developed from existing literature and reviewed by an expert panel. Six participants with stroke, living in the community, participated in the pilot-testing of the FPMI and TPMI programs for 2 weeks. Feedback collected included the suitability of the eligibility criteria, therapist's and participant's adherence to intervention and instructions, appropriateness of the outcome measures, and completion of the intervention sessions within the specified time.

RESULTS

The FPMI and TPMI programs were developed based on previously established programs and included 12 hand tasks. The participants completed four 45-min sessions in 2 weeks. The treating therapist adhered to the program protocol and completed all the steps within the specified time frame. All hand tasks were suitable for adults with stroke. Participants followed the instructions given and engaged in imagery. The outcome measures selected were appropriate for the participants. Both programs showed a positive trend towards improvement in participants' upper extremity and hand function and self-perceived performance in activities of daily living.

CONCLUSIONS

The study provides preliminary evidence that these programs and outcome measures are feasible for implementation with adults with stroke living in the community. This study outlines a realistic plan for future trials in relation to participant recruitment, training of therapists on the intervention delivery, and the use of outcome measures.

TRIAL REGISTRATION

Title: Effectiveness of first-person and third-person motor imagery in relearning daily hand tasks for people with chronic stroke: a randomised controlled trial.

REGISTRATION NO

SLCTR/2017/031. Date registered: 22nd September 2017.

Motor Imagery: How to Assess, Improve Its Performance, and Apply It for Psychosis Diagnostics

With this review, we summarize the state-of-the-art of scientific studies in the field of motor imagery (MI) and motor execution (ME). We composed the brain map and description that correlate different brain areas with the type of movements it is responsible for. That gives a more complete and systematic picture of human brain functionality in the case of ME and MI. We systematized the most popular methods for assessing the quality of MI performance and discussed their advantages and disadvantages. We also reviewed the main directions for the use of transcranial magnetic stimulation (TMS) in MI research and considered the principal effects of TMS on MI performance. In addition, we discuss the main applications of MI, emphasizing its use in the diagnostics of various neurodegenerative disorders and psychoses. Finally, we discuss the research gap and possible improvements for further research in the field.

The neural correlates of biomechanical constraints in hand laterality judgment task performed from other person's perspective: A near-infrared spectroscopy study

Previous studies, mainly using a first-person perspective (1PP), have shown that the judgments of the hand laterality judgment (HLJ) task are dependent on biomechanical constraints (BC). Specifically, differing reaction times (RT) for hand pictures rotated medially or laterally around the mid sagittal plane are attributed to the BC effect on motor imagery. In contrast, we investigated whether the HLJ task is also subject to BC when performed from a third-person perspective (3PP) as well as 1PP using near-infrared spectroscopy (NIRS) to measure the brain activity of prefrontal cortex (PFC) in right-handed participants assigned to 1PP or 3PP groups. The 1PP group judged whether a presented hand was their own left or right hand, and the 3PP group whether it was the other’s left or right hand. Using their HLJ task error rates, the 1PP and 3PP groups were subdivided into an Error Group (EG) and No Error Group (NEG). For the 1PP group, both EG and NEG showed a significant Hand Laterality × Orientation interaction for RT, indicating the BC effect on motor imagery. For the 3PP group, however, neither EG nor NEG showed the interaction, even though EG showed a significantly longer RT than NEG. These results suggest that the 3PP EG appropriately followed the 3PP task instruction, while the NEG might have taken 1PP. However, the 3PP EG NIRS profile of left PFC showed a significant Hand Laterality × Orientation interaction, while the 1PP EG did not. More noteworthy is that the left PFC activation of EG showed an interaction between the 1PP and 3PP groups when the left hand was presented. Furthermore, in the NEG, the PFC activation was not influenced by the BC in either the 1PP or 3PP condition. These results indicate that BC interferes with the HLJ task performed from the 1PP and 3PP.

A Comparison of Movement Imagery Ability Self-Report and Imagery Use in a Motor Task: A Preliminary Investigation

The present study used the Movement Imagery Questionnaire (MIQ-3) to determine the relationship between self-report movement imagery ability and performance on a motor task requiring use of visual and kinesthetic imagery. Young adults were asked to view a number sequence of 4- and 5 digits, maintain the information over a 6 s delay (blank screen) using visual imagery maintenance, and complete the sequence by finger-tapping complementary numbers using motor (kinesthetic) imagery and actually executing movements. We predicted higher movement imagery ability scores would be associated with faster movement times, and imagery ability would be significantly related to the motor tasks. Correlation results indicated no significant differences between self-report and finger-tapping scores, suggesting that in the context of the motor tasks used here, performance was independent of movement imagery ability. Discussion of this preliminary study focuses on the role of visual working memory in the motor task used here and its lack of assessment using the MIQ-3 and other current self-reports.

Effect of imagery perspective on occupational performance after stroke: a randomized controlled trial

OBJECTIVE

This preliminary study sought to determine whether the imagery perspective used during mental practice (MP) differentially influenced performance outcomes after stroke.

METHOD

Nineteen participants with unilateral subacute stroke (9 men and 10 women, ages 28-77) were randomly allocated to one of three groups. All groups received 30-min occupational therapy sessions 2×/wk for 6 wk. Experimental groups received MP training in functional tasks using either an internal or an external perspective; the control group received relaxation imagery training. Participants were pre- and posttested using the Fugl-Meyer Motor Assessment (FMA), the Jebsen-Taylor Test of Hand Function (JTTHF), and the Canadian Occupational Performance Measure (COPM).

RESULTS

At posttest, the internal and external experimental groups showed statistically similar improvements on the FMA and JTTHF (p < .05). All groups improved on the COPM (p < .05).

CONCLUSION

MP combined with occupational therapy improves upper-extremity recovery after stroke. MP does not appear to enhance self-perception of performance. This preliminary study suggests that imagery perspective may not be an important variable in MP interventions.

Virtual reality versus conventional treatment of reaching ability in chronic stroke: clinical feasibility study

INTRODUCTION

The objective of this study was to evaluate the potential of exercises performed in a 2D video-capture virtual reality (VR) training environment to improve upper limb motor ability in stroke patients compared to those performed in conventional therapy.

METHODS

A small sample randomized control trial, in an outpatient rehabilitation center with 12 patients with chronic stroke, aged 33-80 years, who were randomly allocated to video-capture VR therapy and conventional therapy groups. All patients participated in four clinical evaluation sessions (pre-test 1, pre-test 2, post-test, follow-up) and nine 45-minute intervention sessions over a 3-week period. Main outcomes assessed were Body Structure and Function (impairment: Fugl-Meyer Assessment [FMA]; Composite Spasticity Index [CSI]; Reaching Performance Scale for Stroke), Activity (Box and Blocks; Wolf Motor Function Test [WMFT]), and Participation (Motor Activity Log) levels of the International Classification of Functioning.

RESULTS

Improvements occurred in both groups, but more patients in the VR group improved upper limb clinical impairment (FMA, CSI) and activity scores (WMFT) and improvements occurred earlier. Patients in the VR group also reported satisfaction with the novel treatment.

CONCLUSIONS

The modest advantage of VR over conventional training supports further investigation of the effect of video-capture VR or VR combined with conventional therapy in larger-scale randomized, more intense controlled studies.

Perspective-taking in blindness: electrophysiological evidence of altered action representations

It is well established that the mental simulation of actions involves visual and/or somatomotor representations of those imagined actions. To investigate whether the total absence of vision affects the brain activity associated with the retrieval of motor representations, we recorded the readiness potential (RP), a marker of motor preparation preceding the execution, as well as the motor imagery of the right middle-finger extension in the first-person (1P; imagining oneself performing the movement) and in the third-person (3P; imagining the experimenter performing the movement) modes in 19 sighted and 10 congenitally blind subjects. Our main result was found for the single RP slope values at the Cz channel (likely corresponding to the supplementary motor area). No difference in RP slope was found between 1P and 3P in the sighted group, suggesting that similar motor preparation networks are recruited to simulate our own and other people's actions in spite of explicit instructions to perform the task in 1P or 3P. Conversely, reduced RP slopes in 3P compared with 1P found in the blind group indicated that they might have used an alternative, nonmotor strategy to perform the task in 3P. Moreover, movement imagery ability, assessed both by means of mental chronometry and a modified version of the Movement Imagery Questionnaire-Revised, indicated that blind and sighted individuals had similar motor imagery performance. Taken together, these results suggest that complete visual loss early in life modifies the brain networks that associate with others' action representations.

Discovering affordances that determine the spatial structure of reach-to-grasp movements

Extensive research has identified the affordances used to guide actions, as originally conceived by Gibson (Perceiving, acting, and knowing: towards an ecological psychology. Erlbaum, Hillsdale, 1977; The ecological approach to visual perception. Erlbaum, Hillsdale, 1979/1986). We sought to discover the object affordance properties that determine the spatial structure of reach-to-grasp movements--movements that entail both collision avoidance and targeting. First, we constructed objects that presented a significant collision hazard and varied properties relevant to targeting, namely, object width and size of contact surface. Participants reached-to-grasp objects at three speeds (slow, normal, and fast). In Experiment 1, we explored a "stop" task where participants grasped the objects without moving them. In Experiment 2, we studied "fly-through" movements where the objects were lifted. We discovered the object affordance properties that produced covariance in the spatial structure of reaches-to-grasp. Maximum grasp aperture (MGA) reflected affordances determined by collision avoidance. Terminal grasp aperture (TGA)--when the hand stops moving but prior to finger contact--reflected affordances relevant to targeting accuracy. A model with a single free parameter predicted the prehensile spatial structure and provided a functional affordance-based account of that structure. In Experiment 3, we investigated a "slam" task where participants reached-to-grasp flat rectangular objects on a tabletop. The affordance structure of this task was found to eliminate the collision risk and thus reduced safety margins in MGA and TGA to zero for larger objects. The results emphasize the role of affordances in determining the structure and scaling of reach-to-grasp actions. Finally, we report evidence supporting the opposition vector as an appropriate unit of analysis in the study of grasping and a unit of action that maps directly to affordance properties.

Motor imagery: if you can't do it, you won't think it

Since long, motor imagery has been recognized as a method for studying motor representations. In the last few years, important advances regarding the use of motor imagery have been made. In particular, issues concerning the functional equivalence between imagery and action have been addressed, and how equivalence affects the use of imagery to study motor representations. In this paper, we review recent findings in order to highlight the current state of knowledge about motor imagery and its relation to motor action. Three topics are discussed: (i) the imagery perspective, (ii) task complexity, and (iii) the importance of physical experience. It is shown how theses factors are closely related and how previous studies may have underestimated to what extent these factors affect the interpretation of results. Practical implications for imagery interventions are considered. It is concluded that if you cannot perform an action physically, you cannot imagine it in a way that is necessary for a high degree of functional equivalence.

Non-linear EEG synchronization during observation: effects of instructions and expertise

The aim of this study was to examine the effects of instructions and expertise upon neuronal changes during observation of sequential finger movements. Professional pianists and musically naïve subjects observed these movements with the aim of either replicating or recognizing them at a later stage. A non-linear measure of functional coupling was used to investigate EEG activity. In the 10-13 Hz frequency band and in musically naïve subjects, functional coupling during observation for replica was greater within central and neighboring areas than during observation for recognition. An opposite pattern was found in the 4-8 Hz frequency band. In the 10-13 Hz band and in areas including the parietal cortex, functional coupling in musically naïve subjects was greater compared to professional pianists under observation for replica. Results are discussed in the light of recent findings from the cognitive and behavioral neuroscience literature.

Simulation modifies prehension: evidence for a conjoined representation of the graspable features of an object and the action of grasping it

Movement formulas, engrams, kinesthetic images and internal models of the body in action are notions derived mostly from clinical observations of brain-damaged subjects. They also suggest that the prehensile geometry of an object is integrated in the neural circuits and includes the object's graspable characteristics as well as its semantic properties. In order to determine whether there is a conjoined representation of the graspable characteristics of an object in relation to the actual grasping, it is necessary to separate the graspable (low-level) from the semantic (high-level) properties of the object. Right-handed subjects were asked to grasp and lift a smooth 300-g cylinder with one hand, before and after judging the level of difficulty of a “grasping for pouring” action, involving a smaller cylinder and using the opposite hand. The results showed that simulated grasps with the right hand exert a direct influence on actual motor acts with the left hand. These observations add to the evidence that there is a conjoined representation of the graspable characteristics of the object and the biomechanical constraints of the arm.