Matti Itkonen

Proficient use of multiple fingers across both hands enables complex interactions with the world. Developing dexterity for delicate bimanual tasks can take weeks to years to master. This study examines whether a simple mechanical abstraction can enhance bimanual response times to visual stimuli using index fingers and thumbs. A plate placed over the buttons was introduced to shift task conceptualization—rather than pressing buttons, subjects rocked the plate over them. Following this mechanical augmentation, we observed improved bimanual performance in middle‐aged participants but no effect on unimanual actions. Conversely, younger adults showed no performance improvement. A control group of middle‐aged participants confirmed that the observed improvements resulted from the augmentation. We hypothesize that highly similar afferent sensory signals from the fingers of both hands alter the motor control strategy. This work provides a foundation for further research into the diverse mechanisms of multi‐fingered bimanual behavior in both abstract and practical contexts.

Proficient use of multiple fingers across both hands to manipulate objects empowers our daily interactions with the world. Gaining dexterity in performing delicate tasks with both hands can take weeks to years to master. The goal of this study is to understand if simple mechanical abstraction could improve performance on bimanual response time to visual stimuli, using index fingers and thumbs. A plate placed over the buttons was introduced to induce a new conceptualization of the task, where instead of pressing buttons, the subjects were rocking a plate over them. We observed improved performance in bimanual actions but not in unilateral actions. In the group of middle-aged individuals, synchronous bimanual responses were enhanced with the use of this mechanical augmentation. This effect remained even after removing the plate. Conversely, within a group of younger adults, there was no observed effect. We believe that highly similar afferent sensory signals from the fingers of both hands change the motor control strategy. This work lays the ground-work for further research into understanding the rich variety of multi-fingered bimanual behaviors in both abstract and practical settings. New & Noteworthy Mechanical coupling of hands improved bimanual choice response time in middle-aged participants, while young adult participants remained unaffected. The effect remained after removing the coupling.

Sit-to-stand (STS) motion is an important daily activity and many post-stroke patients have difficulty in performing the STS motion. Post-stroke patients who can perform STS independently, still utilize four muscle synergies (synchronized muscle activation) as seen in healthy people. In addition, temporal muscle synergy features can reflect motor impairment of post-stroke patients. However, it has been unclear whether post-stroke patients improve their STS movements in short-term rehabilitation and which muscle synergy features can estimate this improvement. Here, we demonstrate that temporal features of muscle synergies which contribute to body extension and balance maintenance can estimate the effect of short-term rehabilitation based on machine learning methods. By analyzing muscle synergies of post-stroke patients (n = 33) before and with the intervention of physical therapists, we found that about half of the patients who were severely impaired, improved activation timing of muscle synergy to raise the hip with the intervention. Additionally, we identified the temporal features that can estimate whether severely impaired post-stroke patients improve. We conclude that temporal features of muscle synergies can estimate the motor recovery in short-term rehabilitation of post-stroke patients. This finding may lead to new rehabilitation strategies for post-stroke patients that focus on improving activation timing of different muscle synergies.

A time-snap review – moments captured pictorially – means the creation of multi-layered observation. The enquiring gaze then extends beyond the present moment: to its existential roots. However, it is not a question of presenting an historical list, a collection of topics of various types and periods. Of course, understanding the present also requires knowledge of the people and events of the past. In this way it also becomes possible to study the recurring nature of existence. Can war-related travel also count as cultural travel? Is it possible to talk about war tourism? Presumably, in many countries the answer to this will be positive. It relates to the history of ideas and also to national sentiment. This kind of cultural education may be indoctrinating in character, with the goal of insinuating into people's minds the concept of the incomparable excellence of their own nationality. The spirit of the 2010s contains shades of indoctrination. Fortunately, alongside this struggle to impress, education for democracy is also present. Photographs and poetry are powerful media, helping us to create a nostalgia for being. Then, too, a longing for the past is awakened. It is here that a philosophy of yearning or wistfulness is needed, providing an exploratory tool for analyzing the nature of the individual and the community. Modernity needs philosophical poet-travellers. They are adept at loving the wisdom of travel.

Brain damage due to stroke often leaves survivors with lateral functional motor deficits. Bimanual rehabilitation of the paretic arm is an active field of research aimed at restoring normal functionality by making use of the complex neural bindings that exist between the arms. In search of an effective rehabilitation method, we introduced a group of post-stroke rehabilitation patients to a set of bimanual motion tasks with inter-manual coupling and phasing. The surface EMG profiles of the patients were compared in order to understand the effect of the motion conditions. The paretic arms of the patients were more strongly affected by the task conditions compared with the non-paretic arms. These results suggest that in-phase motion may activate neural circuits that trigger recovery. Coupling also had an effect on behavior, but the response of patients was divided between those whom coupling helped or hindered.

Background: Muscle synergies are now widely discussed as a method for evaluating the existence of redundant neural networks that can be activated to enhance stroke rehabilitation. However, this approach was initially conceived to study muscle coordination during learned motions in healthy individuals. After brain damage, there are several neural adaptations that contribute to the recovery of motor strength, with muscle coordination being one of them. In this study, a model is proposed that assesses motion based on surface electromyography (sEMG) according to two main factors closely related to the neural adaptations underlying motor recovery: (1) the correct coordination of the muscles involved in a particular motion and (2) the ability to tune the effective strength of each muscle through muscle fiber contractions. These two factors are hypothesized to be affected differently by brain damage. Therefore, their independent evaluation will play an important role in understanding the origin of stroke-related motor impairments. Results: The model proposed was validated by analyzing sEMG data from 18 stroke patients with different paralysis levels and 30 healthy subjects. While the factors necessary to describe motion were stable across heathy subjects, there was an increasing disassociation for stroke patients with severe motor impairment. Conclusions: The clear dissociation between the coordination of muscles and the tuning of their strength demonstrates the importance of evaluating these factors in order to choose appropriate rehabilitation therapies. The model described in this research provides an efficient approach to promptly evaluate these factors through the use of two intuitive indexes.