## 1 Introduction  
Parkinson's disease (PD) is a progressive neurodegenerative disorder that is primarily treated with pharmacological approaches targeting the dopaminergic system [1]. These treatments, such as levodopa [2, 3] or dopamine receptor agonists [4, 5], aim to alleviate motor symptoms and slow the progression of the disease. Although effective in the short term, their benefits often diminish over time, accompanied by side effects and limited efficacy in treating non-motor symptoms [2]. Advanced treatments such as intrajejunal levodopa infusion, deep brain stimulation or gene therapy are often reserved for later stages when oral medications lose their effectiveness [6]. In this context, non-pharmacological interventions are gaining increasing attention due to their potential to complement existing therapies. Neurofeedback (NFB), a non-invasive method developed over 60 years ago [7], is one such intervention. NFB provides real-time feedback on subconscious neural activity, enabling self-regulation through sensory cues such as visual or auditory stimuli [8; 9; 10; 11; 12]. This method operates on the principles of instrumental conditioning, reinforcing desired neural activity patterns [13; 14]. Over time, participants learn to regulate neural activity and apply these skills in everyday settings, resulting in cortical changes [9; 10; 15]. Various NFB methods have been developed, including the following:  
Electroencephalographic Neurofeedback (EEG-NFB): Measures electrical brain activity via scalp electrodes [11]. Functional Magnetic Resonance Imaging Neurofeedback (fMRI-NFB): Detects changes in blood oxygenation and flow during brain activity, with high spatial resolution [16]. Deep Brain Stimulation Neurofeedback (DBS-NFB): Involves implanted electrodes that regulate excessive neural activity, often used with pharmacological treatments [17]. Functional Near-Infrared Spectroscopy Neurofeedback (fNIRS-NFB): Utilizes near-infrared light to assess brain hemodynamics, showing promise in conditions like ADHD and stroke recovery [18; 19]. Magnetoencephalographic Neurofeedback (MEG-NFB): Measures magnetic fields from neural activity with high temporal and spatial resolution, beneficial in ADHD treatment [20; 21]. While promising, the underlying mechanisms of NFB remain partially understood. [PERSON] [22] proposed a multilevel computational model to describe its effects, comprising three phases. In the initial \"exploration\" phase\", individuals test strategies--such as focused breathing or recalling positive memories--to alter, for example, EEG signals and receive positive feedback. In this phase, frontal-striatal connectivity is strengthened as participants identify effective strategies. In the subsequent \"reinforcement\" phase, these strategies are consolidated through instrumental learning, strengthening connections between the striatum and thalamus and stabilizing EEG patterns. Finally, in the \"awareness\" phase, participants develop an internal representation of the targeted brain state that enables them to maintain improvements without external feedback. Given its potential to influence neural plasticity, NFB represents a promising avenue for treating motor deficits in PD. This review examines the role of EEG-based NFB in improving motor symptoms and addresses critical gaps in its application and efficacy in PD patients. EEG Neurofeedback  
EEG-NFB uses electroencephalography to detect neural activity through electrical signals generated by neurons [23]. These signals, captured by scalp electrodes, record synchronized activity from pyramidal neurons and classify brain waves based on frequency and amplitude [10]. Treatment protocols commonly target specific brain waves, such as alpha, beta, or theta, to achieve desired physiological effects (Table 1). During training, participants receive real-time feedback about their brain activity, enabling them to practice and modify their neural responses over time. In recent years, the use of EEG NFB and the number of studies in this area have increased.