ETD

• action observation therapy
• children
• electroencephalography
• event related desynchronizatio
• mirror neuron system
• mu rhythm
• tipical development
• unilateral
• unilateral cerebral palsy

Cerebral Palsy (CP) is one of the leading causes of motor disability in children resulting from a non-progressive lesion occurring in the developing fetal or infant brain. One of the most represented CP subtypes is Unilateral CP (UCP), which is characterized by motor impairments predominantly affecting one side of the body. The upper limbs are usually more affected than the lower limbs, resulting in difficulties with everyday manual activities such as grasping, reaching, releasing, and manipulating objects (Klingels et al., 2012). A promising rehabilitative approach in the context of UCP is the Action Observation Treatment (AOT; Sgandurra et., al 2011, Buccino et., al 2001), which consists in the systematic observation of goal-directed actions, followed by their execution. This approach is based on the principle that observing others’ actions activates the same neural circuits involved in motor execution, allowing sensorimotor networks to be engaged through observation. The therapeutic rationale is grounded in the activation of the Mirror Neuron System (MNS, Rizzolatti & Craighero, 2004), which plays a key role in action understanding, imitation, and motor learning (Buccino et al., 2001). Therefore, by supporting the internal motor simulation, AOT would provide an alternative route to access an impaired motor system and reinforce voluntary motor function (Buchignani et al., 2019). Although the AOT underlying neurophysiological mechanism (i.e. MNS activation) is well known, the functioning of such mechanisms in children with UCP remains underexplored, particularly using techniques that directly measure brain electrical activity, such as Electroencephalography (EEG). Indeed, a sensitive marker of sensorimotor cortical activation and a proxy for MNS engagement (Pineda 2005, Thorpe, Cannon & Fox 2016) is represented by the EEG Mu Rhythm and its modulation. The mu rhythm consists of two main frequency bands: mu alpha (8–13 Hz) and mu beta (15–30 Hz); and it is recorded from central scalp electrodes (primarily C3, C4) overlying the sensorimotor cortex. Mu Rhythm is predominantly observed at rest, while during action execution and observation, it is typically suppressed or desynchronized, reflecting a decrease in power. This suppression, also known as Event-Related Desynchronization (ERD), reveals the engagement of underlying sensorimotor cortical areas; the Event-Related Synchronization (ERS) describes the rebound in power, indicating a return to an idling state following the execution or observation of a movement (Pfurtscheller et al., 1999; Thorpe, Cannon, & Fox, 2016). In Typically Developing (TD) populations, mu desynchronization is topographically more lateralised to the hemisphere contralateral to the hand performing the movement during action execution, while during action observation, it is predominantly bilaterally expressed (Thorpe, Cannon, & Fox, 2016). In contrast, much less is known in children with UCP (Demas et al., 2019), and given the little evidence available in this field, further research is needed to elucidate how mu reactivity may differ in this clinical population. This study aims to investigate the neurophysiological signature of action observation and execution in children with UCP compared to TD peers (aged 5–15 years). In particular, it will assess the modulation of sensorimotor cortical activity during observation and execution of actions performed with the dominant and non-dominant hand through the evaluation of mu rhythm ERD and ERS. The experimental paradigm consisted in a block-designed visuo-motor task implemented through a custom script in E-Prime software. Children first observed videos of unimanual goal-directed actions (e.g., grasping, holding, placing) and were then asked to reproduce the observed actions with either their dominant or non-dominant hand. Cortical activity was recorded using a 128-channel high-density EEG (HD-EEG) system, and the EEG signal was marked with specific task-related events to allow precise temporal alignment between neural activity and behavioral events. The EEG signal was then preprocessed to remove noise and artifacts and segmented into epochs of interest. Finally, ERD/ERS, in the alpha and beta bands components, were evaluated through frequency analysis to assess sensorimotor cortical activation during actions observed and performed with the dominant and non-dominant hand. Preliminary findings suggest that children with UCP show weaker mu rhythm modulation during both action observation and execution compared to TD peers, especially when using their non-dominant hand. Further analysis will elucidate specific differences in terms of both ERD/ERS magnitude and topographical distribution within (dominant vs non-dominant hand) and between (UCP vs TD) groups. These variations might indicate altered cortical engagement and compensatory sensorimotor processing following the brain injury. Characterizing mu rhythm modulation in children with UCP may provide key insights into sensorimotor processing and inform targeted rehabilitation strategies, such as AOT, to enhance upper limb function and daily activity participation.