Is the coupled control of hand and mouth postures precursor of reciprocal relations between gestures and words?

Post-surgery Rehabilitative Intervention Based on Imitation Therapy and Mouth-Hand Motor Synergies Provides Better Outcomes in Smile Production in Children and Adults With Long Term Facial Paralysis

Rehabilitation after free gracilis muscle transfer (smile surgery, SS) is crucial for a functional recovery of the smiling skill, mitigating social and psychological problems resulting from facial paralysis. We compared two post-SS rehabilitation treatments: the traditional based on teeth clenching exercises and the FIT-SAT (facial imitation and synergistic activity treatment). FIT-SAT, based on observation/imitation therapy and on hand-mouth motor synergies would facilitate neuronal activity in the facial motor cortex avoiding unwanted contractions of the jaw, implementing muscle control. We measured the smile symmetry on 30 patients, half of whom after SS underwent traditional treatment (control group, CG meanage = 20 ± 9) while the other half FIT-SAT (experimental group, EG meanage= 21 ± 14). We compared pictures of participants while holding two postures: maximum and gentle smile. The former corresponds to the maximal muscle contraction, whereas the latter is strongly linked to the control of muscle strength during voluntary movements. No differences were observed between the two groups in the maximum smile, whereas in the gentle smile the EG obtained a better symmetry than the CG. These results support the efficacy of FIT-SAT in modulating the smile allowing patients to adapt their smile to the various social contexts, aspect which is crucial during reciprocal interactions.

A New Neurorehabilitative Postsurgery Intervention for Facial Palsy Based on Smile Observation and Hand-Mouth Motor Synergies

Objective

To perform a preliminary test of a new rehabilitation treatment (FIT-SAT), based on mirror mechanisms, for gracile muscles after smile surgery.

Method

A pre- and postsurgery longitudinal design was adopted to study the efficacy of FIT-SAT. Four patients with bilateral facial nerve paralysis (Moebius syndrome) were included. They underwent two surgeries with free muscle transfers, one year apart from each other. The side of the face first operated on was rehabilitated with the traditional treatment, while the second side was rehabilitated with FIT-SAT. The FIT-SAT treatment includes video clips of an actor performing a unilateral or a bilateral smile to be imitated (FIT condition). In addition to this, while smiling, the participants close their hand in order to exploit the overlapped cortical motor representation of the hand and the mouth, which may facilitate the synergistic activity of the two effectors during the early phases of recruitment of the transplanted muscles (SAT). The treatment was also aimed at avoiding undesired movements such as teeth grinding. Discussion. Results support FIT-SAT as a viable alternative for smile rehabilitation after free muscle transfer. We propose that the treatment potentiates the effect of smile observation by activating the same neural structures responsible for the execution of the smile and therefore by facilitating its production. Closing of the hand induces cortical recruitment of hand motor neurons, recruiting the transplanted muscles, and reducing the risk of associating other unwanted movements such as teeth clenching to the smile movements.

Language, Gesture, and Emotional Communication: An Embodied View of Social Interaction

Spoken language is an innate ability of the human being and represents the most widespread mode of social communication. The ability to share concepts, intentions and feelings, and also to respond to what others are feeling/saying is crucial during social interactions. A growing body of evidence suggests that language evolved from manual gestures, gradually incorporating motor acts with vocal elements. In this evolutionary context, the human mirror mechanism (MM) would permit the passage from “doing something” to “communicating it to someone else.” In this perspective, the MM would mediate semantic processes being involved in both the execution and in the understanding of messages expressed by words or gestures. Thus, the recognition of action related words would activate somatosensory regions, reflecting the semantic grounding of these symbols in action information. Here, the role of the sensorimotor cortex and in general of the human MM on both language perception and understanding is addressed, focusing on recent studies on the integration between symbolic gestures and speech. We conclude documenting some evidence about MM in coding also the emotional aspects conveyed by manual, facial and body signals during communication, and how they act in concert with language to modulate other’s message comprehension and behavior, in line with an “embodied” and integrated view of social interaction.

Numerical Affordance Influences Action Execution: A Kinematic Study of Finger Movement

Humans represent symbolic numbers as oriented from left to right: the mental number line (MNL). Up to now, scientific studies have mainly investigated the MNL by means of response times. However, the existing knowledge on the MNL can be advantaged by studies on motor patterns while responding to a number. Cognitive representations, in fact, cannot be fully understood without considering their impact on actions. Here we investigated whether a motor response can be influenced by number processing. Participants seated in front of a little soccer goal. On each trial they were visually presented with a numerical (2, 5, 8) or a non-numerical ($) stimulus. They were instructed to kick a small ball with their right index toward a frontal soccer goal as soon as a stimulus appeared on a screen. However, they had to refrain from kicking when number five was presented (no-go signal). Our main finding is that performing a kicking action after observation of the larger digit proved to be more efficient: the trajectory path was shorter and lower on the surface, velocity peak was anticipated. The smaller number, instead, specifically altered the temporal and spatial aspects of trajectories, leading to more prolonged left deviations. This is the first experimental demonstration that the reaching component of a movement is influenced by number magnitude. Since this paradigm does not require any verbal skill and non-symbolic stimuli (array of dots) can be used, it could be fruitfully adopted to evaluate number abilities in children and even preschoolers. Notably, this is a self-motivating and engaging task, which might help children to get involved and to reduce potential arousal connected to institutional paper-and-pencil examinations.

Tongue protrusions modify the syntax of skilled reaching for food by the mouse: Evidence for flexibility in action selection and shared hand/mouth central modulation of action

Skilled reaching for food by the laboratory mouse has the appearance of an action pattern with a distinctive syntax in which ten submovements occur in an orderly sequence. A mouse locates the food by Sniffing, Lifts, Aims, Advances, and Shapes the hand to Pronate it over a food target that it Grasps, Retracts, and Withdraws to Release to its mouth for eating. The structure of the individual actions in the chain are useful for the study of the mouse motor system and contribute to the use of the mouse as a model of human neurological conditions. The present study describes tongue protrusions that modify the syntax of reaching by occurring at the point of the reaching action at which the hand is at the Aim position. Tongue protrusions were not related to reaching success and were not influenced by training. Tongue protrusions were more likely to occur in the presence of a food target than with reaches made when food was absent. There were vast individual differences; some mice always make tongue protrusions while other mice never make tongue protrusions. That the syntax of reaching can be altered by the insertion of a surrogate (co-occurring) movement adds to a growing body of evidence that skilled reaching is assembled from a number of relatively independent actions, each with its own sensorimotor control that are subject to central modulation. That tongue and hand reaching movements can co-occur suggests a privileged relation between neural mechanisms that control movements of the tongue and hand.

A proposal for new neurorehabilitative intervention on Moebius Syndrome patients after 'smile surgery'. Proof of concept based on mirror neuron system properties and hand-mouth synergistic activity

Studies of the last twenty years on the motor and premotor cortices of primates demonstrated that the motor system is involved in the control and initiation of movements, and in higher cognitive processes, such as action understanding, imitation, and empathy. Mirror neurons are only one example of such theoretical shift. Their properties demonstrate that motor and sensory processing are coupled in the brain. Such knowledge has been also central for designing new neurorehabilitative therapies for patients suffering from brain injuries and consequent motor deficits. Moebius Syndrome patients, for example, are incapable of moving their facial muscles, which are fundamental for affective communication. These patients face an important challenge after having undergone a corrective surgery: reanimating the transplanted muscles to achieve a voluntarily control of smiling. We propose two new complementary rehabilitative approaches on MBS patients based on observation/imitation therapy (Facial Imitation Therapy, FIT) and on hand-mouth motor synergies (Synergistic Activity Therapy, SAT). Preliminary results show that our intervention protocol is a promising approach for neurorehabilitation of patients with facial palsy.

The Effects of Meaning and Emotional Content of a Sentence on the Kinematics of a Successive Motor Sequence Mimiking the Feeding of a Conspecific

Aim: Do the emotional content and meaning of sentences affect the kinematics of successive motor sequences?

Material and Methods: Participants observed video-clips of an actor pronouncing sentences expressing positive or negative emotions and meanings (related to happiness or anger in Experiment 1 and food admiration or food disgust in Experiment 2). Then, they reached-to-grasp and placed a sugar lump on the actor’s mouth. Participants acted in response to sentences whose content could convey (1) emotion (i.e., face expression and prosody) and meaning, (2) meaning alone, or (3) emotion alone. Within each condition, the kinematic effects of sentences expressing positive and negative emotions were compared. Stimuli (positive for food admiration and negative for food disgust), conveyed either by emotion or meaning affected similarly the kinematics of both grasp and reach.

Results: In Experiment 1, the kinematics did not vary between positive and negative sentences either when the content was expressed by both emotion and meaning, or meaning alone. In contrast, in the case of sole emotion, sentences with positive valence made faster the approach of the conspecific. In Experiment 2, the valence of emotions (positive for food admiration and negative for food disgust) affected the kinematics of both grasp and reach, independently of the modality.

Discussion: The lack of an effect of meaning in Experiment 1 could be due to the weak relevance of sentence meaning with respect to the motor sequence goal (feeding). Experiment 2 demonstrated that, indeed, this was the case, because when the meaning and the consequent emotion were related to the sequence goal, they affected the kinematics. In contrast, the sole emotion activated approach or avoidance toward the actor according to positive and negative valence. The data suggest a behavioral dissociation between effects of emotion and meaning.

Options to enhance recovery from aphasia by means of non-invasive brain stimulation and action observation therapy

Aphasia is a highly disabling language disorder usually caused by a left-lateralized brain damage. Even if traditional linguistic-based therapies have been proved to induce an adequate clinical improvement, a large percentage of patients are left with some degree of language impairments. Therefore, new approaches to common speech therapies are urgently needed in order to maximize the recovery from aphasia. The recent application of non-invasive neurostimulation techniques to language rehabilitation has already provided promising results particularly for the recovery of word-retrieval deficits in chronic stroke aphasic patients. Positive outcomes also come from action observation therapy. Indeed, some very recent studies have shown that the observation and/or execution of gestures positively influences language recovery especially for words related to human actions. This article gives an overview of the most important results achieved using these two approaches and discusses how the application of these treatments might potentiate aphasia recovery.

Concatenation of observed grasp phases with observer's distal movements: a behavioural and TMS study

The present study aimed at determining how actions executed by two conspecifics can be coordinated with each other, or more specifically, how the observation of different phases of a reaching-grasping action is temporary related to the execution of a movement of the observer. Participants observed postures of initial finger opening, maximal finger aperture, and final finger closing of grasp after observation of an initial hand posture. Then, they opened or closed their right thumb and index finger (experiments 1, 2 and 3). Response times decreased, whereas acceleration and velocity of actual finger movements increased when observing the two late phases of grasp. In addition, the results ruled out the possibility that this effect was due to salience of the visual stimulus when the hand was close to the target and confirmed an effect of even hand postures in addition to hand apparent motion due to the succession of initial hand posture and grasp phase. In experiments 4 and 5, the observation of grasp phases modulated even foot movements and pronunciation of syllables. Finally, in experiment 6, transcranial magnetic stimulation applied to primary motor cortex 300 ms post-stimulus induced an increase in hand motor evoked potentials of opponens pollicis muscle when observing the two late phases of grasp. These data suggest that the observation of grasp phases induced simulation which was stronger during observation of finger closing. This produced shorter response times, greater acceleration and velocity of the successive movement. In general, our data suggest best concatenation between two movements (one observed and the other executed) when the observed (and simulated) movement was to be accomplished. The mechanism joining the observation of a conspecific's action with our own movement may be precursor of social functions. It may be at the basis for interactions between conspecifics, and related to communication between individuals.

Effect of action verbs on the performance of a complex movement

The interaction between language and motor action has been approached by studying the effect of action verbs, kinaesthetic imagery and mental subtraction upon the performance of a complex movement, the squat vertical jump (SVJ). The time of flight gave the value of the height of the SVJ and was measured with an Optojump® and a Myotest® apparatuses. The results obtained by the effects of the cognitive stimuli showed a statistically significant improvement of the SVJ performance after either loudly or silently pronouncing, hearing or reading the verb saute (jump in French language). Action verbs specific for other motor actions (pince = pinch, lèche = lick) or non-specific (bouge = move) showed no or little effect. A meaningless verb for the French subjects (tiáo = jump in Chinese) showed no effect as did rêve (dream), tombe (fall) and stop. The verb gagne (win) improved significantly the SVJ height, as did its antonym perds (lose) suggesting a possible influence of affects in the subjects' performance. The effect of the specific action verb jump upon the heights of SVJ was similar to that obtained after kinaesthetic imagery and after mental subtraction of two digits numbers from three digits ones; possibly, in the latter, because of the intervention of language in calculus. It appears that the effects of the specific action verb jump did seem effective but not totally exclusive for the enhancement of the SVJ performance. The results imply an interaction among language and motor brain areas in the performance of a complex movement resulting in a clear specificity of the corresponding action verb. The effect upon performance may probably be influenced by the subjects' intention, increased attention and emotion produced by cognitive stimuli among which action verbs.