1,720,980 research outputs found
Space in action: motor aspects of peripersonal space representation
No full textSpazio in azione: aspetti motori della rappresentazione dello spazio peripersonal
Machine learning for exploring neurophysiological functionality in multiple sclerosis based on trigeminal and hand blink reflexes
No full textBrainstem dysfunctions are very common in Multiple Sclerosis (MS) and are a critical predictive factor for future disability. Brainstem functionality can be explored with blink reflexes, subcortical responses consisting in a blink following a peripheral stimulation. Some reflexes are already employed in clinical practice, such as Trigeminal Blink Reflex (TBR). Here we propose for the first time in MS the exploration of Hand Blink Reflex (HBR), which size is modulated by the proximity of the stimulated hand to the face, reflecting the extension of the peripersonal space. The aim of this work is to test whether Machine Learning (ML) techniques could be used in combination with neurophysiological measurements such as TBR and HBR to improve their clinical information and potentially favour the early detection of brainstem dysfunctionality. HBR and TBR were recorded from a group of People with MS (PwMS) with Relapsing-Remitting form and from a healthy control group. Two AdaBoost classifiers were trained with TBR and HBR features each, for a binary classification task between PwMS and Controls. Both classifiers were able to identify PwMS with an accuracy comparable and even higher than clinicians. Our results indicate that ML techniques could represent a tool for clinicians for investigating brainstem functionality in MS. Also, HBR could be promising when applied in clinical practice, providing additional information about the integrity of brainstem circuits potentially favouring early diagnosis
Motor sequence learning and intermanual transfer with a phantom limb
No full textAmputees with phantom limb sometimes report vivid experiences of moving their phantom. Is phantom movement only "imaginary", or, instead, it has physiological properties comparable to those pertaining to real movements? To answer this question, we took advantage of the intermanual transfer of sequence learning, occurring when one hand motor skills improve after training with the other hand. Ten healthy controls and two upper-limb amputees (with and without phantom-movement) were recruited. They were asked to perform with the right (intact) hand a fingers-thumb opposition sequence either in Naïve condition or after an active (Real condition) or a mental (Imagery condition) training with the left (phantom) hand. In healthy controls, the results showed different effects after active training (i.e., faster movement duration (MD) with stable accuracy) and after mental training (i.e., increased accuracy with stable MD). Opposite results between moving-phantom case and static-phantom case were found. In the Real condition, after an "active" training with her phantom hand, the moving-phantom case showed a faster performance of the intact hand. This transfer effect was not different from that found in healthy controls, actually performing the active training with an existing hand (Real condition), but, crucially, it was significantly different from both Imagery and Naïve conditions of controls. Contrariwise, in the static phantom case, the performance during the Real condition was significantly different from the Real condition of healthy controls and it was not significantly different from their Imagery and Naïve conditions. Importantly, a significant difference was found when the transfer effect in Real condition was compared between the two phantom cases. Taken together, these findings provide the first evidence that a phantom limb can learn motor skills and transfer them to the intact limb
Motor training and the combination of action observation and peripheral nerve stimulation reciprocally interfere with the plastic changes induced in primary motor cortex excitability
No full textAO-PNS is a stimulation protocol combining action observation (AO) and peripheral nerve stimulation (PNS) to induce plasticity in the primary motor cortex (M1) (increased excitability). Another method to increase M1 excitability is motor training. The combination of two protocols, which individually induce long-term potentiation (LTP)-like plasticity in overlapping neural circuits, results in a transitory occlusion or reverse of this phenomenon. This study aimed to understand the neurophysiological mechanisms underlying AO-PNS by testing whether AO-PNS and motor training induced LTP-like plasticity in, at least partially, overlapping neural networks. One group of participants practiced a motor training (finger opposition movements) followed by AO-PNS, whereas another group performed the two protocols in reverse order. Motor performance was evaluated by means of a sensor-engineered glove and transcranial magnetic stimulation was used to assess M1 excitability before and after each conditioning protocol. Motor training increased movement frequency, suggesting the occurrence of motor learning in both groups. When applied on first, both motor training and AO-PNS significantly increased the motor-evoked potential (MEP), but occluded the increase of cortical excitability expected after the following protocol, leading to a significant decrease of MEP amplitude. These results suggest that motor training and AO-PNS act on partially overlapping neuronal networks, which include M1, and that AO-PNS might be able to induce LTP-like plasticity in a similar way to overt movement execution. This candidates AO-PNS as methodology potentially useful when planning rehabilitative interventions on patients who cannot voluntarily move
Wearing a Mask Shapes Interpersonal Space during COVID-19 Pandemic
Full text linkSocial distancing norms have been promoted after the COVID-19 pandemic. In this work, we tested interpersonal space (IPS) in 107 subjects through a reaching-comfort distance estimation task. In the main experiment, subjects had to estimate the comfort and reach space between an avatar wearing or not wearing a face mask. We found that IPS was greater between avatars not wearing a mask with respect to stimuli with the mask on, while reaching space was not modulated. IPS increment in the NoMask condition with respect to the Mask condition correlated with anxiety traits, as shown with the State-Trait Anxiety Inventory, rather than with transient aspects related to the pandemic situation. In the control experiment, the avatars with a mask were removed to further explore the conditioning effect provided by the presence of the facial protection in the main experiment. We found a significant difference comparing this condition with the same condition of the main experiment, namely, the distances kept between avatars not wearing a mask in the main experiment were greater than those between the same stimuli in the control experiment. This showed a contextual adaptation of IPS when elements related to the actual pandemic situation were relevant. Additionally, no significant differences were found between the control experiment and the Mask condition of the main experiment, suggesting that participants had internalized social distancing norms and wearing a mask has become the new normal. Our results highlight the tendency of people in underestimating the risk of contagion when in the presence of someone wearing a mask
Comparing different motion correction approaches for resting-state functional connectivity analysis with functional near-infrared spectroscopy data
Full text linkSignificance: Motion artifacts are a notorious challenge in the functional near-infrared spectroscopy (fNIRS) field. However, little is known about how to deal with them in resting-state data. Aim: We assessed the impact of motion artifact correction approaches on assessing functional connectivity, using semi-simulated datasets with different percentages and types of motion artifact contamination. Approach: Thirty-five healthy adults underwent a 15-min resting-state acquisition. Semi-simulated datasets were generated by adding spike-like and/or baseline-shift motion artifacts to the real dataset. Fifteen pipelines, employing various correction approaches, were applied to each dataset, and the group correlation matrix was computed. Three metrics were used to test the performance of each approach. Results: When motion artifact contamination was low, various correction approaches were effective. However, with increased contamination, only a few pipelines were reliable. For datasets mostly free of baseline-shift artifacts, discarding contaminated frames after pre-processing was optimal. Conversely, when both spike and baseline-shift artifacts were present, discarding contaminated frames before pre-processing yielded the best results. Conclusions: This study emphasizes the need for customized motion correction approaches as the effectiveness varies with the specific type and amount of motion artifacts present
Sensorimotor expertise influences perceptual weight judgments during observation of a sport-specific gesture
No full textThis study aimed to investigate the role of sensorimotor expertise in evaluating relative weight of a lifted object during the observation of a sport-specific gesture, namely the deadlift. Fifty-six participants, assigned to three groups according to their experience in weight lifting, powerlifters, CrossFit & REG; practitioners and naive participants (controls), performed a perceptual weight judgments task. Participants observed videos showing a powerlifter executing a deadlift at the 80%, 90% and 100% of 1 repetition maximum (1RM) and answered a question about the weight of the lifted object. Participants' response accuracy and variability were evaluated. Findings showed that powerlifters were more accurate than controls. No differences appeared between powerlifter and CrossFit & REG; practitioners, and between CrossFit & REG; practitioners and controls. Response variability was similar in the three groups. These findings suggest that a fine sensorimotor expertise specific for the observed gesture is crucial to detect the weight of the object displayed in the observed movement, since it might allow detecting small changes in the observed movement kinematics, which we speculate are at the basis of the object weight recognition
This racket is not mine: The influence of the tool-use on peripersonal space
No full textThe aim of the present study was to test whether the peripersonal space (PPS), defined as the portion of the space immediately surrounding the body, is modulated by the long-term motor experience with a specific tool in a sportsmen population. To this end, we evaluated, by means of a multisensory integration paradigm, how tennis players and novices to the sport of tennis perceived the PPS while holding a tennis racket. Going deeply, in the case of the athletes, we tested the effect of their personal racket, i.e., the one they regularly use during their sport activities, compared to a common one. When handling one of these objects or nothing, participants were requested to verbally respond to a tactile stimulus administered at the right wrist while hearing a task-irrelevant sound emitted by a speaker positioned either near to the hand (Near) or far from it (Far). Reaction time to a tactile stimulus associated with the Far sound were higher than those associated with the Near sound when tennis players and novices held the common racket, whereas this difference disappeared when the athletes handled the personal tennis racket. These results suggest that the tool daily used during sport activity is stably embodied in the peripersonal space of tennis players
Time-of-day influences resting-state functional cortical connectivity
Full text linkTime-of-day is rarely considered during experimental protocols investigating motor behavior and neural activity. The goal of this work was to investigate differences in functional cortical connectivity at rest linked to the time of the day using functional Near-Infrared Spectroscopy (fNIRS). Since resting-state brain is shown to be a succession of cognitive, emotional, perceptual, and motor processes that can be both conscious and nonconscious, we studied self-generated thought with the goal to help in understanding brain dynamics. We used the New-York Cognition Questionnaire (NYC-Q) for retrospective introspection to explore a possible relationship between the ongoing experience and the brain at resting-state to gather information about the overall ongoing experience of subjects. We found differences in resting-state functional connectivity in the inter-hemispheric parietal cortices, which was significantly greater in the morning than in the afternoon, whilst the intra-hemispheric fronto-parietal functional connectivity was significantly greater in the afternoon than in the morning. When we administered the NYC-Q we found that the score of the question 27 ("during RS acquisition my thoughts were like a television program or film") was significantly greater in the afternoon with respect to the morning. High scores in question 27 point to a form of thought based on imagery. It is conceivable to think that the unique relationship found between NYC-Q question 27 and the fronto-parietal functional connectivity might be related to a mental imagery process during resting-state in the afternoon
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