Cognitive and Motor Therapy After Stroke Is Not Superior to Motor and Cognitive Therapy Alone to Improve Cognitive and Motor Outcomes: New Insights From a Meta-analysis.

OBJECTIVE: To evaluate whether cognitive and motor therapy (CMT) is more effective than no therapy, motor therapy, or cognitive therapy on motor and/or cognitive outcomes after stroke. Additionally, this study evaluates whether effects are lasting and which CMT approach is most effective. DATA SOURCES: AMED, EMBASE, MEDLINE/PubMed, and PsycINFO databases were searched in October 2022. STUDY SELECTION: Twenty-six studies fulfilled the inclusion criteria: randomized controlled trials published in peer-reviewed journals since 2010 that investigated adults with stroke, delivered CMT, and included at least 1 motor, cognitive, or cognitive-motor outcome. Two CMT approaches exist: CMT dual-task ("classical" dual-task where the secondary cognitive task has a distinct goal) and CMT integrated (where cognitive components of the task are integrated into the motor task). DATA EXTRACTION: Data on study design, participant characteristics, interventions, outcome measures (cognitive/motor/cognitive-motor), results and statistical analysis were extracted. Multilevel random effects meta-analysis was conducted. DATA SYNTHESIS: CMT demonstrated positive effects compared with no therapy on motor outcomes (g=0.49; 95% confidence interval [CI], 0.10, 0.88) and cognitive-motor outcomes (g=0.29; 95% CI, 0.03, 0.54). CMT showed no significant effects compared with motor therapy on motor, cognitive, and cognitive-motor outcomes. A small positive effect of CMT compared with cognitive therapy on cognitive outcomes (g=0.18; 95% CI, 0.01, 0.36) was found. CMT demonstrated no follow-up effect compared with motor therapy (g=0.07; 95% CI, -0.04, 0.18). Comparison of CMT dual-task and integrated revealed no significant difference for motor (F1,141=0.80; P=.371) or cognitive outcomes (F1,72=0.61, P=.439). CONCLUSIONS: CMT was not superior to monotherapies in improved outcomes after stroke. CMT approaches were equally effective, suggesting that training that enlists a cognitive load per se may benefit outcomes.

Reaction time coupling in a joint stimulus-response task: A matter of functional actions or likable agents?

Shaping one owns actions by observing others' actions is driven by the deep-rooted mechanism of perception-action coupling. It typically occurs automatically, expressed as for example the unintentional synchronization of reaction times in interactive games. Theories on perception-action coupling highlight its benefits such as the joint coordination of actions to cooperatively perform tasks properly, the learning of novel actions from others, and the bonding with likable others. However, such functional aspects and how they shape perception-action coupling have never been compared quantitatively. Here we tested a total of hundred-fifteen participants that played a stimulus-response task while, in parallel, they observed videos of agents that played the exact same task several milliseconds in advance. We compared to what degree the reaction times of actions of agents, who varied their behavior in terms of functionality and likability in preceding prisoner dilemma games and quizzes, shape the reaction times of human test participants. To manipulate functionality and likability, we varied the predictability of cooperative behavior and correctness of actions of agents, respectively, resulting in likable (cooperative), dislikable (uncooperative), functional (correct actions), and dysfunctional (incorrect actions) agents. The results of three experiments showed that the participants' reaction times correlated most with the reaction times of agents that expressed functional behavior. However, the likability of agents had no effects on reaction time correlations. These findings suggest that, at least in the current computer task, participants are more likely to adopt the timing of actions from people that perform correct actions than from people that they like.

Limb apparent motion perception: Modification by tDCS, and clinically or experimentally altered bodily states.

Limb apparent motion perception (LAMP) refers to the illusory visual perception of a moving limb upon observing two rapidly alternating photographs depicting the same limb in two different postures. Fast stimulus onset asynchronies (SOAs) induce the more visually guided perception of physically impossible movements. Slow SOAs induce the perception of physically possible movements. According to the motor theory of LAMP, the latter perception depends upon the observer's sensorimotor representations. Here, we tested this theory in two independent studies by performing a central (study 1) and peripheral (study 2) manipulation of the body's sensorimotor states during two LAMP tasks. In the first sham-controlled transcranial direct current stimulation between-subject designed study, we observed that the dampening of left sensorimotor cortex activity through cathodal stimulation biased LAMP towards the more visually guided perception of physically impossible movements for stimulus pairs at slow SOAs. In the second, online within-subject designed study, we tested three participant groups twice: (1) individuals with an acquired lower limb amputation, either while wearing or not wearing their prosthesis (2) individuals with body integrity dysphoria (i.e., with a desire for amputation of a healthy leg) while sitting in a regular position or binding up the undesired leg (to simulate the desired amputation); (3) able-bodied individuals while sitting in a normal position or sitting on one of their legs. We found that the momentary sensorimotor state crucially impacted LAMP in individuals with an amputation and able-bodied participants, but not in BID individuals. Taken together, the results of these two studies substantiate the motor theory of LAMP.

Electrocorticographic dissociation of alpha and beta rhythmic activity in the human sensorimotor system.

This study uses electrocorticography in humans to assess how alpha- and beta-band rhythms modulate excitability of the sensorimotor cortex during psychophysically-controlled movement imagery. Both rhythms displayed effector-specific modulations, tracked spectral markers of action potentials in the local neuronal population, and showed spatially systematic phase relationships (traveling waves). Yet, alpha- and beta-band rhythms differed in their anatomical and functional properties, were weakly correlated, and traveled along opposite directions across the sensorimotor cortex. Increased alpha-band power in the somatosensory cortex ipsilateral to the selected arm was associated with spatially-unspecific inhibition. Decreased beta-band power over contralateral motor cortex was associated with a focal shift from relative inhibition to excitation. These observations indicate the relevance of both inhibition and disinhibition mechanisms for precise spatiotemporal coordination of movement-related neuronal populations, and illustrate how those mechanisms are implemented through the substantially different neurophysiological properties of sensorimotor alpha- and beta-band rhythms.

Visual perception of the arm manipulates the experienced pleasantness of touch.

Touch, such as a caress, can be interpreted as very pleasant. The emotional valence assigned to touch is likely related to certain bottom-up factors, such as optimal activation of C-tactile (CT) afferents. It is however unclear if besides somatosensory input, contextual factors related to the own body also play a role in the perceived pleasantness of touch. To test this, we manipulated visual appearance of the participant's arm (veridical vision, no vision, pixelated moving statistic projected onto the arm (i.e. crawling skin)). We used slow velocity stroking (CT optimal stroking) with a soft brush to induce pleasant touch, and fast velocity stroking as a control condition. After each visual condition we asked participants (N=23) to rate the emotional valence of the stroking they felt. After slow velocity stroking ratings on perceived pleasantness (but not on perceived unpleasantness) were modulated by visual condition, with veridical vision of the arm resulting in higher pleasantness ratings than both no vision and pixelated vision. We conclude that contextual processes affect the perceived pleasantness of touch. These findings shed a new light on the underlying mechanisms of how humans experience pleasant touch and show that pleasant touch not solely dependents on bottom up information.

Modulation of somatosensory perception by motor intention.

The intention to execute a movement can modulate our perception of sensory events; however, theoretical accounts of these effects, and also empirical data, are often contradictory. We investigated how perception of a somatosensory stimulus differed according to whether it was delivered to a limb being prepared for movement or to a nonmoving limb. Our results demonstrate that individuals perceive a somatosensory stimulus delivered to the "moving" limb as occurring significantly later than when an identical stimulus is delivered to a "nonmoving" limb. Furthermore, human brain imaging (fMRI) analyses demonstrate that this modulation is accompanied by a significant decrease in BOLD signal in the right parietal operculum (SII) for stimuli delivered to the moving limb. These results indicate that during movement preparation a network of premotor brain areas may facilitate movement execution by attenuating the processing of behaviorally irrelevant signals within higher-order secondary somatosensory (SII) areas.

Prism adaptation influences perception but not attention: evidence from antisaccades.

Prism adaptation has been shown to successfully alleviate symptoms of hemispatial neglect, yet the underlying mechanism is still poorly understood. In this study, the antisaccade task was used to measure the effects of prism adaptation on spatial attention in healthy participants. Results indicated that prism adaptation did not influence the saccade latencies or antisaccade errors, both strong measures of attentional deployment, despite a successful prism adaptation procedure. In contrast to visual attention, prism adaptation evoked a perceptual bias in visual space as measured by the landmark task. We conclude that prism adaptation has a differential influence on visual attention and visual perception in healthy participants as measured by the tasks used.

Seeing, since childhood, without ventral stream: a behavioural study.

We report the case of a 30-year-old man (S.B.) who developed visual agnosia following a meningoencephalitis at the age of 3 years. MRI disclosed extensive bilateral lesions of the occipital temporal visual pathway (ventral stream) and lesions in the right dorsal pathway, sparing primary visual cortices. S.B. showed a severe visual recognition deficit (texture, colour, objects, faces and words), although movement and space perception were largely preserved. His remaining visual capacities illustrate the competence of an isolated dorsal system which essentially functions on the sole basis of magnocellular afferents (low spatial resolution, high sensitivity to low contrast and moving stimuli). Patient S.B. also shows remarkable visuomotor competences, despite his perceptual limitations. It is suggested that his perceptual capacities correspond to the visual processing limitations of the dorsal visual stream, which in this patient have become accessible to perceptual awareness.