The goal of this clinical trial is to investigate whether electroencephalographic features are associated with the multidimensional clinical characteristics of adults with chronic non-specific neck pain and whether clinical and brain function measures change following physiotherapy. Participants with chronic non-specific neck pain will receive six weekly treatment sessions consisting of a manual physiotherapy and neck-specific exercise programme, including a home exercise programme. Clinical, psychophysical, and 64-channel electroencephalographic assessments will be performed at baseline and approximately one week after completion of the intervention. Clinical outcomes will also be reassessed 12 weeks after the last treatment session. Electroencephalographic recordings will be obtained while participants are seated comfortably and instructed to remain relaxed. EEG-derived measures will be examined in relation to pain intensity, neck-related disability, psychological and cognitive-affective factors, sleep quality, and psychophysical pain responses. Healthy participants without chronic neck pain will undergo a comparable baseline assessment to provide reference data for the interpretation of brain function in the clinical group.