ETD

• Action Observation Therapy
• Bimanual action
• Electroencephalography (EEG)
• Event-Related Desynchronization (ERD)
• Mirror Neuron System
• Mu Rhythm
• Unilateral Cerebral Palsy

Cerebral Palsy (CP) is one of the leading causes of chronic physical disability in childhood, resulting from a non-progressive lesion of the developing brain. In Unilateral Cerebral Palsy (UCP), primarily one side of the body is affected, mainly involving the upper limbs. Consequently, children with UCP experience difficulties in daily manual tasks, such as grasping objects, often accompanied by impaired coordination and motor planning (Klingels et al., 2012). The presence of motor impairments also affects children‘s ability to perform bimanual actions (Hung, Charles & Gordon, 2004). In recent years, research has increasingly focused on the Mirror Neuron System (MNS, Rizzolatti & Craighero, 2004) and its role in motor recovery and rehabilitation. Within this framework, Action Observation Therapy (AOT) has emerged as a promising approach that leverages MNS activation to promote functional recovery. AOT involves systematically observing goal-directed actions and subsequently imitating them, to effectively engage sensorimotor networks involved in motor learning (Buccino et al., 2001; Sgandurra et al., 2011, 2013). A widely studied neurophysiological marker of this engagement is the EEG Mu rhythm, an oscillatory activity in the alpha (8–13 Hz) and beta (15–30 Hz) bands recorded over central scalp regions (primarily C3 and C4), corresponding to sensorimotor areas (Pineda, 2005). The Mu rhythm is typically evident at rest, while it is attenuated (or suppressed) during movement execution or observation. Such suppression, also known as Event-Related Desynchronization (ERD), reflects the activation of sensorimotor areas, whereas the Event-Related Synchronization (ERS) represents the rebound of Mu activity following motor activity or observation of movement, thus indicating cortical inhibition or return to the idle state (Pfurtscheller et al, 1999, Thorpe, Cannon and Fox 2016). Thus far, Mu ERD/ERS has been more extensively studied in unimanual actions, whereas its modulation during bimanual movements remains poorly understood, particularly in children with UCP. In healthy participants, bimanual actions generally produce stronger Mu desynchronization than unimanual ones (Deiber et al., 2001; Formaggio et al., 2013), although the literature remains controversial, with some studies reporting similar Mu-ERD patterns across them (Rueda-Delgado et al., 2014). This study aims to investigate and characterize Mu ERD/ERS patterns, in both the alpha and beta bands components, during bimanual actions in children with UCP compared to Typically Developing (TD) peers. It also aims to explore possible differences between unimanual and bimanual movements in each group, to clarify how motor complexity influences sensorimotor activation and MNS functioning. To achieve this goal, electrical brain activity was recorded through a 128-channel high-density Electroencephalography (HD-EEG) during both observation and execution of bimanual goal-directed actions (e.g., reaching and grasping). Participants (CP and TD peers) first observed short video clips and then replicated the same actions, allowing direct comparison between observation and execution. Video stimuli were presented via a programmed E-Prime task ensuring precise online synchronization with EEG signals. Participants’ active actions were identified offline from a video recorded during the EEG session and aligned with the EEG data. EEG was then preprocessed and Mu ERD/ERS were evaluated through frequency analysis over central and parietal electrodes of both hemispheres to evaluate sensorimotor cortical activation. Preliminary findings indicate atypical Mu modulation in children with CP, with overall weaker desynchronization compared to TD peers. Ongoing analyses will further examine between-group differences in the magnitude and topography of Mu reactivity during bimanual tasks, and in comparison to unimanual actions in both groups. Such comparisons will help clarify how motor complexity, coordination demands, and neural reorganization following early brain injury shape cortical activation, offering insights for individualized rehabilitation strategies.