Executive abilities for the planning of sequential motor actions performed under time and space constraints: a visuo-spatial tapping task

In a constantly changing environment, executive abilities allow us to organize sensory information of multiple sources and to adapt to diverse situations while at the same time inhibiting inappropriate behaviors. Research on the executive functions (EFs) have historical roots on neuropsychology, with the description of frontal patients that were showing disruptions in organizing their daily behaviors independently of any impairment in long-memory, language or general intelligence. A wide range of neuropsychological tools is used today to evaluate executive abilities: Tower of London for planning, go-no-go for inhibition, etc. However, the classical tasks often present methodological limitations and they lack of correspondence between process and behavior. Furthermore, the field lacks of a compelling theory that make links between the EFs themselves. The present PhD work was an attempt to propose a novel task to assess the EFs in the place of the classical batteries of neuropsychological tasks. After offering an overview of the EF literature and presenting simple motor tasks that seem to target similar EFs to those described in neuropsychology (CH1), I present the spatial-tapping task as a challenging paradigm to understand the relationships between the different EFs (CH2), and its potential to be used in clinical settings (CH3). Then I show how a similar approach can be used to investigate how EFs intervene in the control of more complex motor sequences, e.g. bi-manual tasks (CH4). Overall, the results presented here support an embodied perspective of cognition with mental organization reflecting the way one plans motor sequences for adaptive behavior

Spontaneous Motor Tempo is the Easiest Pace to Act Upon for Both the Emergent and the Predictive Timing Modes

AbstractSpontaneous Motor Tempo (SMT) is a self-paced regular series of movements that correspond to the preferred and natural pace to act upon. SMT is naturally observed within daily activities such as in hand clapping and walking. In experimental settings, SMT is evaluated using synchronization finger-tapping paradigms and has been estimated to correspond to time intervals of 600ms (Fraisse, 1982). More recently, subjects have been instructed to tap at the most comfortable rate, and the SMT was found to be a little faster, with a mean SMT comprised between 450 and 500ms of time intervals (Collyer et al., 1994; Moelants, 2002). Studies using whole body movements have also determined SMT between 100-130 bpm (500-600ms) both during daily activities (MacDougall & Moore, 2005) and when walking in synchrony to music (Styns, van Noorden, Moelants, & Leman, 2007). Nevertheless, the most striking aspect of these findings is the variability reported, with ranges going from 190 to 950ms of time intervals within a given group of healthy individuals.In the present work, the objective was not to determine a global mean SMT for a group but to work at the individual level. More specifically, we questioned what the functional role of SMT might be in the production of sequences of motor actions. After developing an application on Android telephone, we measured SMT in a group of healthy young adults throughout a period of a three of weeks and tested the hypotheses that (1) the SMT is different but characteristic of a given individual and that (2) SMT corresponds to the time window in which movements are performed the best.Thirty young adults aged from 20 to 28 years participated in the experiment. They all downloaded on their telephone the SPONT application and were required to measure their SMT at 10 am for 3 consecutive days, during a two-week period. During the third week, they were invited to come to the laboratory and they were randomly assigned to either a cycling session or a finger tapping session that lasted 30minutes each. At the start of the session, all individuals sat silently for 5minutes in silence before performing a 2-minute trial of cycling or of tapping at their “preferred and most comfortable pace”. This pace was used to set the metronome frequency that was used during the remaining of the experimental session.Both groups performed a sensori-motor synchronization and continuation task with the explicit instruction to perform movements in synchrony with a regular tone sequence and to continue even when the metronome stopped. The metronome was generated by a program written in Matlab and was played through speakers. All tones had the same pitch (640Hz) and the same duration (100ms). For the cycling group, participants were seated on a stationary bike of which the saddle was adjusted to the height of the participant. The bike was set so that the strength applied on the pedal was minimal. A passive reflective marker was located on the right pedal of the bike and its position was recorded through a Qualisys 3D motion capture system at a sampling frequency of 200Hz. For the finger-tapping group, the task was to tap six visual targets one after the other, which were presented on a touch screen (EloTouch). In both tasks, the regular pacing of the metronome was manipulated for each individual to be ±500, ±400, ±300, ±200, ±100ms or equal to each individual's SMT.Resultsshowed that the group SMT was 520ms with differences ranging from 235 and 832ms of SMT. These SMTs remained consistent for all individuals throughout the 6 measured sessions. The lab-based task confirmed the preferred tempo for all subjects especially in the finger-tapping task. During the synchronization-continuation task, participants were able to perform the task correctly without apparent difficulty. Subjects however reported that the “easiest” tempi to follow were those close to their own SMT. When measuring the inter-response intervals and the asynchrony during the synchronization task, results revealed an inverted U-shape with a minimal error and variance close to each individual's SMT. The fact that timing was both performed with the highest accuracy and the greatest stability within the SMT interval was observed both in the cycling and in the finger- tapping tasks. Finally, the analysis of the continuation data showed that especially for the extreme tempi (i.e., very slow and very fast) participants drifted towards their natural SMT.Overall, the reported results confirm previous findings of best performances close to SMT (Styns et al., 2007) but go further by showing that this finding is true both in cyclic movements (that are thought to use emergent timing processes) and in sequential rhythmic movements (that are thought to use predictive timing processes). An interpretation of how spontaneous tempo and the two modes of timing can be considered within a unique theoretical framework may be considered in reference to the cognitive model of executive functions by Miake et al. (2000)

Neural feedback strategies to improve grasping coordination in neuromusculoskeletal prostheses

Conventional prosthetic arms suffer from poor controllability and lack of sensory feedback. Owing to the absence of tactile sensory information, prosthetic users must rely on incidental visual and auditory cues. In this study, we investigated the effect of providing tactile perception on motor coordination during routine grasping and grasping under uncertainty. Three transhumeral amputees were implanted with an osseointegrated percutaneous implant system for direct skeletal attachment and bidirectional communication with implanted neuromuscular electrodes. This neuromusculoskeletal prosthesis is a novel concept of artificial limb replacement that allows to extract control signals from electrodes implanted on viable muscle tissue, and to stimulate severed afferent nerve fibers to provide somatosensory feedback. Subjects received tactile feedback using three biologically inspired stimulation paradigms while performing a pick and lift test. The grasped object was instrumented to record grasping and lifting forces and its weight was either constant or unexpectedly changed in between trials. The results were also compared to the no-feedback control condition. Our findings confirm, in line with the neuroscientific literature, that somatosensory feedback is necessary for motor coordination during grasping. Our results also indicate that feedback is more relevant under uncertainty, and its effectiveness can be influenced by the selected neuromodulation paradigm and arguably also the prior experience of the prosthesis user

Capacités exécutives pour la planification de séquences d'actions motrices réalisées sous contraintes spatiales et temporelles : une tâche de tapping visuo-spatial

In a constant changing environment, executive abilities allow us to organize sensory information of multiple sources and to adapt to diverse stuations while at the same time inhibiting inappropriate behaviors. research on the executive functions (EFS) have historical roots on neuropsychology, with the description of frontal patients that were showing disruptions in organizing their daily behaviors independently of any impairment in memory, language or general intelligence. A wide range of neuropsychological tools is used today to evaluate executive abilities : tower of London for planning, go-no-go for inhibition, etc. However, the classical tasks often present methodological limitations and they lack of correpondence between process and behavior. Furthermore, the field lacks of a compelling theory that make links between the EFS themselves. The present PHD work was an attempt to propose a novel task to assess the EFS in the place of the classical batteries of neuropsychological tasks. After offering an overview of the EF literature and presenting simple motor tasks that seem to target similar EFS than those described in neuropsychology (Ch1), I present the spatial-tapping task as a challenging paradigm to understand the relationships between the different EFS (Ch2), and its potential to be used in clinical settings (Ch3). The I present how a similar approach can be used to investigate how EFS intervenes in the control of more complex motor sequences, E.G. bi-manual tasks (Ch4). Overall, the results presented here support an emboided perspective of cognition with mental organization reflecting the way one plans motor sequences for adaptive behavior.Dans un environnement en constant changement, les fonctions exécutives (FRE) nous permettent d'organiser l'information en provenance de sources multiples, de s'adapter à des situations sociales complexes et d'inhiber les comportements inappropriés. Les recherches sur le fonctionnement exécutif ont été initiées en neuropsychologie, après avoir observé chez des patients frontaux, des difficultés à organiser leurs comportements quotidiens sans pour autant présenter de difficultés de langage ou de mémoire. Un grand nombre de tests neuropsychologiques sont disponibles afin d'évaluer les FE. Cependant, ces tests sont souvent critiqués pour leur complexité et leur manque de validité de construction. Le champ des FE manque en réalité de modèles théoriques précis qui permettraient de décrire ces fonctions et leurs potentielles interactions pour le contrôle des comportements complexes. En conséquence, les tâches sont souvent construites de manière intuitive, dans le présent travail de thèse, après revue d'un état de l'art sur les FE (Ch1), je propose une nouvelle tâche, le spatial-tapping, qui pourrait être utilisée en remplacement des tâches classiques complexes (Ch2). Je promeus également le potentiel de cette tâche à être utilisée dans des contextes cliniques (Ch3). Je présente finalement comment les analyses réalisées pour le spatial-tapping afin d'étudier les FE peuvent être transférées à des situations motrices plus complexes, comme la coordination bi-manuelle (Ch4). En conclusion, les résultats présentés dans ce travail de thèse sont en faveur de l'idée selon laquelle notre organisation mentale reflète la manière dont on organise nos mouvements

Testing the co-existence of two timing strategies for motor control in a unique task: The synchronisation spatial-tapping task

The control of rhythmic action sequences may involve two distinct timing strategies, i.e., event-based and emergent timing, which are usually revealed through finger-tapping and circle-drawing tasks, respectively. There is a lively debate concerning the possibility of coexistence of the two modes of timing for the execution of a single task. If one considers emergent timing as simply an absence of explicit representation of a time interval, then by definition, the two modes of timing cannot coexist. However, if one considers that emergent timing engages control of another motor parameter, e.g., a control of movement through space rather than time, then the possibility of coexistence needs to be reassessed. In the present study, we designed a hybrid of finger-tapping and circle-drawing tasks for which the demands for space and time control were present at the same time in order to reassess the coexistence hypothesis. Seventy-eight participants performed a spatial-tapping task in which finger taps were to be produced in synchrony with a regular metronome to 6 visual targets presented around a virtual circle. The metronome set ten distinct tempi (1100-300 ms). Using autocorrelation analyses on timing variables, we show that motor timing was event-based at slow tempi and emergent at faster tempi. Through an analysis of the trajectory, we confirm that an increase in the spatial control of movement took place congruently with a switch from event-based to emergent timing modes. At these fast tempi, timing and spatial errors were correlated but only at the specific target location for which a dynamical anchor point was revealed. Hence, we conclude that the coding of emergent timing has a spatial nature from which emerge timing regularities. This spatio-temporal strategy insures the performance of sequential motor actions when cognitive effort is too high for the use of pure event-based timing strategies

Experience-driven remodeling of S1 digit representation in awake monkeys: the challenge of comparing active and passive touch

International audienceMany studies have compared active and passive touch to understand how motor action shapes touch perception. Current views emphasize the difficulties in making such a comparison and promote investigating how motor strategies enable the filtering out of sensory inputs to reshape touch perception. Cybulska-Klosowicz et al. (Cybulska-Klosowicz A, Tremblay F, Jiang W, Bourgeon S, Meftah E-M, Chapman CE. J Neurophysiol 123: 1072–1089, 2020) suggest that primary somatosensory (S1) cortical remodeling of digit representation occurs during active touch. Here, alternative interpretations are proposed, and the relevance of studying multidigit scanning is emphasized

Nouveautés en Neurosciences : ressentir le toucher sans être touché

La microstimulation électrique de nerfs périphériques va nous permettre de ressentir le toucher sans être touché directement sur la peau. Le système tactile est donc activé de manière artificielle, rendant possible son étude fondamentale, et ouvrant ainsi la voie de la réhabilitation clinique

The spatial-tapping task to reveal the coexistence of event-based and emergent timing for the control of rhythmic sequences

International audienceThe control of rhythmic motor sequences may involve two distinct timing processes, i.e. event-based and emergent timing. Event-based timing refers to the mode of action control in which the task goal is to maintain timing accuracy (Wing & Kristofferson, 1973a, 1973b), while in emergent processes, the timing emerges from the dynamics of control of the spatial trajectory (Robertson et al., 1999; Turvey, 1977). These timing modes have been revealed through finger tapping and circle drawing tasks, respectively (Zelaznik, Spencer, & Doffin, 2000; Zelaznik, Spencer, & Ivry, 2002). In the present study, we used a hybrid-pointing task in order to assess whether the two modes could co-exist within a unique movement, as suggested by Repp & Steinman (2010). Sixty-eight participants performed a spatial-tapping task in which they were instructed to produce discrete tapping actions around a circular trajectory, across nine distinct tempi (1100 to 300 ms of inter-onset-interval). Autocorrelation functions (AC) of the inter-response-intervals were calculated up to ten lags to reveal series dependencies. Significant negative AC-1 were revealed at tempi ≥ 700 ms, suggesting that the timing was event-based at these tempi, and significant positive AC-6 were revealed at tempi ≤ 500 ms, suggesting that the timing was emergent at these slow tempi. Furthermore, an analysis of the spatial errors indicated that the timing errors were the smallest between 1100 to 900 ms of IOI, intermediate between 800 to 600 ms of IOI, and the largest between 500 to 300 ms of IOI, pattern that follows the index of difficulty of the task. Finally, between 600 to 300 ms of IOI the endpoint distributions were significantly more oriented in function of the tangent to the circle, with the emergence of an anchor point in the spatial trajectory, suggesting that the task goal at faster tempi was to smooth the tapping actions within a global circular pattern rather than maintaining timing accuracy per se (see Roerdink, Ophoff, Peper, & Beek, 2008 for descriptions of the anchoring phenomenon). Overall, our results suggest that for sequential motor control, two different timing modes can be used in function of task constraints. Autocorrelation analyses suggest that event coding is used at slower tempi (≥ 900 ms), and that an emergent timing mode is used at faster tempi (≤ 500 ms). For intermediate tempi, the temporal pressure was higher and the control was maintained event-based between 800 to 700 ms of IOI, with however a significant decrease in subjects’ performances. A combination of modes was revealed around 600 ms of IOI. Hence, we conclude that our results argue in favour of the coexistence of the two timing within the same motor sequence as a balance, with one mode taking over when timing is the priority (event-coding at slow tempi) and the other being dominant when the spatial aspect of the task is set as the priority (emergent-coding at fast tempi)

Cognitive Benefits of Physical Activity Increased when Producing Rhythmic Actions

International audienceThe changes in human cognitive performance that take place after an acute session of physical activity (PA) have attracted much attention in later years. A variety of exercise protocols have reported that cognitive performance is facilitated after the cessation of exercise regardless of the exercise regimen (Chang et al., 2012) and more specifically, response execution and inhibition (reaction times) are shortened (e.g., Colcombe et al., 2003; Joyce et al., 2009). Nevertheless, less clear-cut results have been reported when considering the higher cognitive functions like action planning (Chang et al., 2011). In the present study, we predict that the absence of findings is primarily due to the fact that cyclic movements only have been used (cycling, walking, running). Considering the fact that motor planning requires the capacity to anticipate action consequences and determine the timed requirements to achieve sub-goals, we posit that significant impact of PA on the higher cognitive functions will be observed especially when using sequential activities that require the predictive timing of motor actions.Thirty-six young sedentary adults participated in the study. They were randomly assigned to a cycling, dancing, and reading group. Participants performed 4 sessions of 30 minutes of activity, on four separate days. The groups were matched for age and sex. A neuropsychological test battery was used at inclusion, and after each session to test for cognitive performance changes including the Tower of London and the Spatial-Tapping tests to assess motor planning and motor timing capacities more specifically. Results revealed a significant cognitive improvement in those individuals engaged in PA compared with the control group. The benefits on cognitive flexibility and inhibition capacities were greater in the dancing compared to the cycling group. More importantly, planning and timing abilities were observed in the dancing group only.We confirmed the cognitive and psychological benefits of a PA in healthy subjects. The benefits on motor planning and timing are most important when sequential activities are performed, probably due to the necessity during such activities to produce series of movements through space and time. These findings open the possibility of using sequential physical activities as new cognitive stimulation programs for improving timing capacities in clinical populations