Translating novel findings of perceptual-motor codes into the neuro-rehabilitation of movement disorders

The bidirectional flow of perceptual and motor information has recently proven useful as rehabilitative tool for re-building motor memories. We analyzed how the visual-motor approach has been successfully applied in neurorehabilitation, leading to surprisingly rapid and effective improvements in action execution. We proposed that the contribution of multiple sensory channels during treatment enables individuals to predict and optimize motor behavior, having a greater effect than visual input alone. We explored how the state-of-the-art neuroscience techniques show direct evidence that employment of visual-motor approach leads to increased motor cortex excitability and synaptic and cortical map plasticity. This super-additive response to multimodal stimulation may maximize neural plasticity, potentiating the effect of conventional treatment, and will be a valuable approach when it comes to advances in innovative methodologies

Functional Connectivity of the Inferior Frontal Gyrus in Autism Spectrum Disorders

ABSTRACT The American Speech-Language-Hearing Association defines Autism Spectrum Disorder (ASD) as a “neurodevelopmental disorder characterized by deficits in social communication and social interaction” which is heavily impacts language abilities. There is an abundance of research on the neurological aspects of the disorder, which appear to have major differences of activation and functionality when compared to typically developing peers. Specifically, in the left inferior frontal gyrus (IFG), a key language region of the brain, functional connectivity levels tend to be significantly less in ASD groups. This study recognizes these trends and aims to expand the research by locating specific functional connections and relationships between the three regions of the left IFG (pars opercularis, pars triangularis, and pars orbitalis) and other locations of the brain that could impact language. By using functional magnetic resonance images, we ran a voxel-wise analysis between the three regions of the left IFG and each individual voxel throughout the brain. As we expected, there was significantly less functional connectivity in the ASD groups. However, the decreased functional connectivity was only in the pars orbitalis and not the pars opercularis or pars triangularis. This information could improve the knowledge of the neurological pathways of language processes in ASD

Action Observation for Neurorehabilitation in Apraxia

Neurorehabilitation and brain stimulation studies of post-stroke patients suggest that action-observation effects can lead to rapid improvements in the recovery of motor functions and long-term motor cortical reorganization. Apraxia is a clinically important disorder characterized by marked impairment in representing and performing skillful movements [gestures], which limits many daily activities and impedes independent functioning. Recent clinical research has revealed errors of visuo-motor integration in patients with apraxia. This paper presents a rehabilitative perspective focusing on the possibility of action observation as a therapeutic treatment for patients with apraxia. This perspective also outlines impacts on neurorehabilitation and brain repair following the reinforcement of the perceptual-motor coupling. To date, interventions based primarily on action observation in apraxia have not been undertaken

Causative role of left aIPS in coding shared goals during human-avatar complementary joint actions

Successful motor interactions require agents to anticipate what a partner is doing in order to predictively adjust their own movements. Although the neural underpinnings of the ability to predict others' action goals have been well explored during passive action observation, no study has yet clarified any critical neural substrate supporting interpersonal coordination during active, non-imitative (complementary) interactions. Here, we combine non-invasive inhibitory brain stimulation (continuous Theta Burst Stimulation) with a novel human-avatar interaction task to investigate a causal role for higher-order motor cortical regions in supporting the ability to predict and adapt to others' actions. We demonstrate that inhibition of left anterior intraparietal sulcus (aIPS), but not ventral premotor cortex, selectively impaired individuals' performance during complementary interactions. Thus, in addition to coding observed and executed action goals, aIPS is crucial in coding 'shared goals', that is, integrating predictions about one's and others' complementary actions

ERP Modulation during Observation of Abstract Paintings by Franz Kline

The aim of this study was to test the involvement of sensorimotor cortical circuits during the beholding of the static consequences of hand gestures devoid of any meaning.In order to verify this hypothesis we performed an EEG experiment presenting to participants images of abstract works of art with marked traces of brushstrokes. The EEG data were analyzed by using Event Related Potentials (ERPs). We aimed to demonstrate a direct involvement of sensorimotor cortical circuits during the beholding of these selected works of abstract art. The stimuli consisted of three different abstract black and white paintings by Franz Kline. Results verified our experimental hypothesis showing the activation of premotor and motor cortical areas during stimuli observation. In addition, abstract works of art observation elicited the activation of reward-related orbitofrontal areas, and cognitive categorization-related prefrontal areas. The cortical sensorimotor activation is a fundamental neurophysiological demonstration of the direct involvement of the cortical motor system in perception of static meaningless images belonging to abstract art. These results support the role of embodied simulation of artist’s gestures in the perception of works of art

High-Frequency Repetitive Transcranial Magnetic Stimulation Applied to the Parietal Cortex for Low-Functioning Children With Autism Spectrum Disorder: A Case Series

Background: Repetitive transcranial magnetic stimulation (rTMS) is a safe and efficacious technique to stimulate specific areas of cortical dysfunction in several neuropsychiatric diseases; however, it is not known whether high-frequency rTMS (HF-rTMS) over the left inferior parietal lobule, in low functioning children with autism spectrum disorder (ASD), improves core symptoms.Method: Eleven low-functioning children with ASD completed two separate HF-rTMS treatment courses, 6 weeks apart. Each treatment course involved five 5-s trains at 20 Hz, with 10-min inter-train intervals, on left inferior parietal lobule each consecutive weekday for a 3-week period (15 treatments per course). Subjects were assessed at five time points: immediately before and after the first HF-rTMS course, immediately before and after the second HF-rTMS course, and 6 weeks after the second rTMS treatment course. Treatment effectiveness was evaluated using the Verbal Behavior Assessment Scale (VerBAS) and Autism Treatment Evaluation Checklist (ATEC). The latter test consists of four subtest scales: Language, Sociability, Sensory, and Behavior. In addition, daily treatment logbooks completed by parents were considered as one of the outcome measures.Results: Participants showed a significant reduction in language- and social-related symptoms measured by ATEC from pretreatment to the 6-week follow-up after the second treatment course. Moreover, some possible improvements in imitation and cognition were reported by caregivers.Conclusions: Our findings suggest that HF-rTMS over the left parietal cortex might improve core deficits in low-functioning children with ASD

Neural representations for multi-context visuomotor adaptation and the impact of common representation on multi-task performance: a multivariate decoding approach

The human brain's remarkable motor adaptability stems from the formation of context representations and the use of a common context representation (e.g., an invariant task structure across task contexts) derived from structural learning. However, direct evaluation of context representations and structural learning in sensorimotor tasks remains limited. This study aimed to rigorously distinguish neural representations of visual, movement, and context levels crucial for multi-context visuomotor adaptation and investigate the association between representation commonality across task contexts and adaptation performance using multivariate decoding analysis with fMRI data. Here, we focused on three distinct task contexts, two of which share a rotation structure (i.e., visuomotor rotation contexts with −90° and +90° rotations, in which the mouse cursor's movement was rotated 90 degrees counterclockwise and clockwise relative to the hand-movement direction, respectively) and the remaining one does not (i.e., mirror-reversal context where the horizontal movement of the computer mouse was inverted). This study found that visual representations (i.e., visual direction) were decoded in the occipital area, while movement representations (i.e., hand-movement direction) were decoded across various visuomotor-related regions. These findings are consistent with prior research and the widely recognized roles of those areas. Task-context representations (i.e., either −90° rotation, +90° rotation, or mirror-reversal) were also distinguishable in various brain regions. Notably, these regions largely overlapped with those encoding visual and movement representations. This overlap suggests a potential intricate dependency of encoding visual and movement directions on the context information. Moreover, we discovered that higher task performance is associated with task-context representation commonality, as evidenced by negative correlations between task performance and task-context-decoding accuracy in various brain regions, potentially supporting structural learning. Importantly, despite limited similarities between tasks (e.g., rotation and mirror-reversal contexts), such association was still observed, suggesting an efficient mechanism in the brain that extracts commonalities from different task contexts (such as visuomotor rotations or mirror-reversal) at multiple structural levels, from high-level abstractions to lower-level details. In summary, while illuminating the intricate interplay between visuomotor processing and context information, our study highlights the efficiency of learning mechanisms, thereby paving the way for future exploration of the brain's versatile motor ability

Distortion of Visuo-Motor Temporal Integration in Apraxia: Evidence From Delayed Visual Feedback Detection Tasks and Voxel-Based Lesion-Symptom Mapping

Limb apraxia is a higher brain dysfunction that typically occurs after left hemispheric stroke and its cause cannot be explained by sensory disturbance or motor paralysis. The comparison of motor signals and visual feedback to generate errors, i.e., visuo-motor integration, is important in motor control and motor learning, which may be impaired in apraxia. However, in apraxia after stroke, it is unknown whether there is a specific deficit in visuo-motor temporal integration compared to visuo-tactile and visuo-proprioceptive temporal integration. We examined the precision of visuo-motor temporal integration and sensory-sensory (visuo-tactile and visuo-proprioception) temporal integration in apraxia after stroke by using a delayed visual feedback detection task with three different conditions (tactile, passive movement, and active movement). The delay detection threshold and the probability curve for delay detection obtained in this task were quantitative indicators of the respective temporal integration functions. In addition, we performed subtraction and voxel-based lesion-symptom mapping to identify the brain lesions responsible for apraxia and deficits in visuo-motor temporal integration. The behavioral experiments showed that the delay detection threshold was extended and that the probability curve for delay detection was less steep in apraxic patients compared to controls (pseudo-apraxic patients and unaffected patients), only for the active movement condition, and not for the tactile and passive movement conditions. Furthermore, the severity of apraxia was significantly correlated with the delay detection threshold and the steepness of the probability curve in the active movement condition. These results indicated that multisensory (i.e., visual, tactile, and proprioception) feedback was normally temporally integrated, but motor prediction and visual feedback were not correctly temporally integrated in apraxic patients. That is, apraxic patients had difficulties with visuo-motor temporal integration. Lesion analyses revealed that both apraxia and the distortion of visuo-motor temporal integration were associated with lesions in the fronto-parietal motor network, including the left inferior parietal lobule and left inferior frontal gyrus. We suppose that damage to the left inferior fronto-parietal network could cause deficits in motor prediction for visuo-motor temporal integration, but not for sensory-sensory (visuo-tactile and visuo-proprioception) temporal integration, leading to the distortion of visuo-motor temporal integration in patients with apraxia

Neuro-cognitive and social components of dyadic motor interactions revealed by the kinematics of a joint-grasping task

This thesis describes a PhD project is based on the notion that we live our whole life dipped into an interactive social environment where we observe and act together with others and where our behavior is influenced by first sight impressions, social categorizations and stereotypes which automatically and unavoidably arise during interactions. Nevertheless, the bidirectional impact of interpersonal coding on dyadic motor interactions has never been directly investigated. Moreover, the neurocognitive bases of social interaction are still poorly understood. In particular, in every-day dyadic encounters we usually interact with others in non-imitative fashions (Sebanz et al. 2006), challenging the hypothesis of a direct matching between action observation and action execution within one system (“common coding approach”, Prinz 1997), which is instead supported by neurophysiological data on the so called “mirror neurons”(Rizzolatti and Sinigaglia 2010) which fire both during action execution and observation of similar actions performed by others. Suggestion is made that what characterizes joint action is the presence of a common goal (i.e. the “shared” goal, Butterfill 2012) which organizes individuals’ behaviour and channel simulative processes. During her PhD, Lucia Sacheli developed a novel interactive scenario able to investigate face-to-face dyadic interactions within a naturalistic and yet controlled experimental environment, with the aim to build a more coherent model of the role of simulative mechanisms during social interaction and on the role of socio-emotional variables in modulating these processes. This scenario required pairs of participants to reciprocally coordinate their reach-to-grasp movements and perform on-line mutual adjustments in time and space in order to fulfill a common (motor) goal. So far, she demonstrated by means of kinematic data analysis that simulation of the partner’s movement is task-dependent (Sacheli et al. 2013) and modulated by the interpersonal relationship linking co-agents (Sacheli et al. 2012) and by social stereotypes as ethnic biases (Sacheli et al. under review). Moreover, she used the same scenario to investigate the different contribution of the parietal and frontal nodes of the fronto-parietal “mirror” network during joint-action by means of Transcranial Magnetic Stimulation combined with analysis of kinematics

Neuro-cognitive and social components of dyadic motor interactions revealed by the kinematics of a joint-grasping task

This thesis describes a PhD project is based on the notion that we live our whole life dipped into an interactive social environment where we observe and act together with others and where our behavior is influenced by first sight impressions, social categorizations and stereotypes which automatically and unavoidably arise during interactions. Nevertheless, the bidirectional impact of interpersonal coding on dyadic motor interactions has never been directly investigated. Moreover, the neurocognitive bases of social interaction are still poorly understood. In particular, in every-day dyadic encounters we usually interact with others in non-imitative fashions (Sebanz et al. 2006), challenging the hypothesis of a direct matching between action observation and action execution within one system (“common coding approach”, Prinz 1997), which is instead supported by neurophysiological data on the so called “mirror neurons”(Rizzolatti and Sinigaglia 2010) which fire both during action execution and observation of similar actions performed by others. Suggestion is made that what characterizes joint action is the presence of a common goal (i.e. the “shared” goal, Butterfill 2012) which organizes individuals’ behaviour and channel simulative processes. During her PhD, Lucia Sacheli developed a novel interactive scenario able to investigate face-to-face dyadic interactions within a naturalistic and yet controlled experimental environment, with the aim to build a more coherent model of the role of simulative mechanisms during social interaction and on the role of socio-emotional variables in modulating these processes. This scenario required pairs of participants to reciprocally coordinate their reach-to-grasp movements and perform on-line mutual adjustments in time and space in order to fulfill a common (motor) goal. So far, she demonstrated by means of kinematic data analysis that simulation of the partner’s movement is task-dependent (Sacheli et al. 2013) and modulated by the interpersonal relationship linking co-agents (Sacheli et al. 2012) and by social stereotypes as ethnic biases (Sacheli et al. under review). Moreover, she used the same scenario to investigate the different contribution of the parietal and frontal nodes of the fronto-parietal “mirror” network during joint-action by means of Transcranial Magnetic Stimulation combined with analysis of kinematics