Measuring gait speed to better identify prodromal dementia

Abstract Slow gait speed has been shown to predict incident dementia and cognitive decline in older individuals. We aimed to summarize the evidence concerning the association of slow gait speed with cognitive decline and dementia, and discuss the possible shared pathways leading to cognitive and motor impairments, under the unifying hypothesis that body and mind are intimately connected. This is a scoping review supported by a systematic search of the literature, performed on PubMed and Web of Science. Longitudinal studies providing information on the role of gait speed in the prediction of cognitive decline and dementia in cognitively intact people and in those with initial cognitive impairment were eligible. Of 39 studies selected, including overall 57,456 participants, 33 reported a significant association between gait speed and cognitive outcomes, including dementia. Neurodegenerative pathology and cerebrovascular burden may damage cerebral areas involved in both cognitive functions and motor control. At the same time, systemic conditions, characterized by higher cardiorespiratory, and metabolic and inflammatory burden, can affect a number of organs and systems involved in motor functions, including the brain, having ultimately an impact on cognition. The interplay of body and mind seems relevant during the development of cognitive decline and dementia. The measurement of gait speed may improve the detection of prodromal dementia and cognitive impairment in individuals with and without initial cognitive deficits. The potential applicability of such a measure in both clinical and research settings points at the importance of expanding our knowledge about the common underlying mechanisms of cognitive and motor decline

Il ruolo dell’osservazione delle azioni nel recupero e nell’acquisizione delle abilità motorie

L’osservazione delle azioni è in grado di evocare nel sistema motorio dell’osservatore un’attività comparabile a quella associata all’esecuzione della stessa azione. Tale capacità d trasformare la rappresentazione sensoriale delle azioni altrui nella propria rappresentazione motoria concernente la medesima azione – i.e. meccanismo specchio – gioca un ruolo fondamentale nella comprensione delle azioni e nell’apprendimento motorio tramite imitazione. L’osservazione delle azioni è in grado di favorire l’accesso al sistema motorio anche quando sussistono deficit motori agli arti, favorendo i processi di riorganizzazione corticale motoria e migliorando le abilità d’esecuzione del movimento. Sulla base di questo principio, un approccio riabilitativo basato sull’osservazione delle azioni (Action Observation Treatment – AOT) si è dimostrato efficace nel migliorare le funzioni motorie in diverse patologie neurologiche. Lo scopo di questa tesi è quello di discutere il ruolo dell’osservazione delle azioni nel favorire il recupero e il perfezionamento delle abilità motorie. La prima parte della tesi riporta uno studio clinico pilota che ha dimostrato l’efficacia della AOT nel miglioramento delle funzioni motorie dell’arto superiore nei bambini affetti da paralisi cerebrale infantile. Questo studio presenta due principali elementi innovativi. Il primo consiste nella somministrazione e nel monitoraggio da remoto del trattamento, in modo da permettere l’implementazione delle sessioni riabilitative direttamente a casa del bambino. Il secondo è l’introduzione dell’interazione remota fra bambini partecipanti come fattore attivo di trattamento. La differenza di abilità manuali fra pari è risultata essere associata all’efficacia del trattamento, indicando che è preferibile per il bambino osservare un compagno con abilità superiori alle proprie al fine di incrementare le probabilità di miglioramento. Questo studio apre l’AOT tradizionale a nuovi scenari, in cui i bambini possono simultaneamente essere beneficiari ed erogatori all’interno del processo di apprendimento motorio. La seconda parte della tesi ha lo scopo di esplorare i substrati neurofisiologici dell’apprendimento motorio delle azioni tramite la loro osservazione attraverso uno studio di Stimolazione Magnetica Transcranica (TMS). In relazione alla recente interruzione delle attività sperimentali conseguente alla pandemia, questa parte della tesi richiederà un tempo aggiuntivo per essere ultimata. Pertanto, è stata richiesta una proroga semestrale per la consegna finale della tesi.The observation of an action is able to trigger in the observer’s motor system an activity similar to that evoked by the correspondent action execution. Such a capacity to transform the sensory representations of other’s actions into one’s own motor representation concerning the same action – i.e. mirror mechanism – plays a key role in action understanding and imitation-driven motor learning. Action observation is able to access the cortical motor system even when limb motor function is impaired, favoring cortical reorganization and ultimately affecting motor abilities in action execution. On this basis, a rehabilitative approach grounded on action observation (i.e. Action Observation Treatment – AOT) have proven effective in improving motor function in several neurological disorders. The aim of the thesis is to discuss the role of action observation in driving the recovery and the perfectioning of motor abilities. The first part of the thesis reports a clinical pilot study demonstrating the effectiveness of AOT for the improvement of upper limb motor function in children with cerebral palsy. This study presents two main elements of novelty. The first is the remote treatment delivery and monitoring, allowing the implementation of rehabilitative sessions at patient’s own home. The second is the introduction of child-to-child remote interaction as driving-factor of motor improvement. In particular, child-to-child difference in hand motor ability is linked to improvement, suggesting that it is preferable for a child to observe a leading peer with superior motor skills to his own. This study extends traditional AOT approaches to novel social-enriched scenarios by which children could simultaneously be both recipient and leader within the motor learning process. The second part of the thesis aim to investigate the neurophysiological substrates of observational learning in healthy subjects, by means of a Transcranial Magnetic Stimulation study (TMS). Since the recent interruption of the experimental activities due to the pandemic, this part needs additional time to be completed. Thus, a six-months extension for the completion of the thesis has been requested

Catching the imposter in the brain: the case of Capgras delusion

Single case report about Capgras delusion

Telerehabilitation in response to constrained physical distance: an opportunity to rethink neurorehabilitative routines

Ensuring proper dosage of treatment and repetition over time is a major challenge in neurorehabilitation. However, a requirement of physical distancing to date compromises their achievement. While mostly associated to COVID-19, physical distancing is not only required in a pandemic scenario, but also advised for several clinical conditions (e.g. immunocompromised individuals) or forced for specific social contexts (e.g. people living in remote areas worldwide). All these contexts advocate for the implementation of alternative healthcare models. The objective of this perspective is to highlight the benefits of remote administration of rehabilitative treatment, namely telerehabilitation, in counteracting physical distancing barriers in neurorehabilitation. Sustaining boosters of treatment outcome, such as compliance, sustainability, as well as motivation, telerehabilitation may adapt to multiple neurological conditions, with the further advantage of a high potential for individualization to patient's or pathology's specificities. The effectiveness of telerehabilitation can be potentiated by several technologies available to date: virtual reality can recreate realistic environments in which patients may bodily operate, wearable sensors allow to quantitatively monitor the patient's performance, and signal processing may contribute to the prediction of long-term dynamics of patient recovery. Telerehabilitation might spark its advantages far beyond the mere limitation of physical distancing effects, mitigating criticalities of daily neurorehabilitative practice, and thus paving the way to the envision of mixed models of care, where hospital-based procedures are complementarily integrated with telerehabilitative ones

The Proactive Synergy Between Action Observation and Execution in the Acquisition of New Motor Skills

Motor learning can be defined as a process that leads to relatively permanent changes in motor behavior through repeated interactions with the environment. Different strategies can be adopted to achieve motor learning: movements can be overtly practiced leading to an amelioration of motor performance; alternatively, covert strategies (e.g., action observation) can promote neuroplastic changes in the motor system even in the absence of real movement execution. However, whether a training regularly alternating action observation and execution (i.e., Action Observation Training, AOT) may surpass the pure motor practice (MP) and observational learning (OL) remains to be established. To address this issue, we enrolled 54 subjects requiring them to learn tying nautical knots via one out of three types of training (AOT, MP, OL) with the scope to investigate which element mostly contributes to motor learning. We evaluated the overall improvement of each group, along with the predictive role that neuropsychological indexes exert on each treatment outcome. The AOT group exhibited the highest performance improvement (42%), indicating that the regular alternation between observation and execution biases participants toward a better performance. The reiteration of this sequence provides an incremental, adjunct value that super-adds onto the efficacy of motor practice or observational learning in isolation (42% > 25% + 10%, i.e., OL + MP). These findings extend the use of the AOT from clinical and rehabilitative contexts to daily routines requiring the learning and perfectioning of new motor skills such as sports training, music, and occupational activities requiring fine motor control

The value of corticospinal excitability and intracortical inhibition in predicting motor skill improvement driven by action observation

The observation of other's actions represents an essential element for the acquisition of motor skills. While action observation is known to induce changes in the excitability of the motor cortices, whether such modulations may explain the amount of motor improvement driven by action observation training (AOT) remains to be addressed. Using transcranial magnetic stimulation (TMS), we first assessed in 41 volunteers the effect of action observation on corticospinal excitability, intracortical inhibition, and transcallosal inhibition. Subsequently, half of the participants (AOT-group) were asked to observe and then execute a right-hand dexterity task, while the controls had to observe a no-action video before practicing the same task. AOT participants showed greater performance improvement relative to controls. More importantly, the amount of improvement in the AOT group was predicted by the amplitude of corticospinal modulation during action observation and, even more, by the amount of intracortical inhibition induced by action observation. These relations were specific for the AOT group, while the same patterns were not found in controls. Taken together, our findings demonstrate that the efficacy of AOT in promoting motor learning is rooted in the capacity of action observation to modulate the trainee's motor system excitability, especially its intracortical inhibition. Our study not only enriches the picture of the neurophysiological effects induced by action observation onto the observer's motor excitability, but linking them to the efficacy of AOT, it also paves the way for the development of models predicting the outcome of training procedures based on the observation of other's actions

Motor Cortical Plasticity to Training Started in Childhood: The Example of Piano Players.

Converging evidence suggest that motor training is associated with early and late changes of the cortical motor system. Transcranial magnetic stimulation (TMS) offers the possibility to study plastic rearrangements of the motor system in physiological and pathological conditions. We used TMS to characterize long-term changes in upper limb motor cortical representation and interhemispheric inhibition associated with bimanual skill training in pianists who started playing in an early age. Ipsilateral silent period (iSP) and cortical TMS mapping of hand muscles were obtained from 30 strictly right-handed subjects (16 pianists, 14 naïve controls), together with electromyographic recording of mirror movements (MMs) to voluntary hand movements. In controls, motor cortical representation of hand muscles was larger on the dominant (DH) than on the non-dominant hemisphere (NDH). On the contrary, pianists showed symmetric cortical output maps, being their DH less represented than in controls. In naïve subjects, the iSP was smaller on the right vs left abductor pollicis brevis (APB) indicating a weaker inhibition from the NDH to the DH. In pianists, interhemispheric inhibition was more symmetric as their DH was better inhibited than in controls. Electromyographic MMs were observed only in naïve subjects (7/14) and only to voluntary movement of the non-dominant hand. Subjects with MM had a lower iSP area on the right APB compared with all the others. Our findings suggest a more symmetrical motor cortex organization in pianists, both in terms of muscle cortical representation and interhemispheric inhibition. Although we cannot disentangle training-related from preexisting conditions, it is possible that long-term bimanual practice may reshape motor cortical representation and rebalance interhemispheric interactions, which in naïve right-handed subjects would both tend to favour the dominant hemisphere