Functional impairments in the upper extremities following a stroke significantly restrict individuals' activities of daily living and overall quality of life; in this context, Action Observation Training (AOT) has emerged in recent years as an effective rehabilitation method that promotes motor learning processes and cortical activity by activating the mirror neuron system. Although the literature acknowledges the positive effects on neural mechanisms of both unimanuel approaches, which focus on the paretic hand alone, and bimanual approaches, which involve the simultaneous use of both hands, there remains a gap regarding which method yields superior outcomes. This study aims to compare the effectiveness of AOT interventions consisting of exclusively unimanual versus exclusively bimanual activities on upper extremity functions, activities of daily living, and quality of life in chronic stroke patients, while investigating the potential differences between the outcomes of these two distinct approaches.

Stroke is defined as a neurological condition caused by focal damage to the central nervous system due to vascular problems such as cerebral infarction, intracerebral hemorrhage, or subarachnoid hemorrhage. Globally, stroke remains among the leading causes of mortality and disability.

Although stroke-related mortality rates have decreased due to advancements in the medical field, the number of individuals living with motor, sensory, and cognitive impairments following a stroke is increasing. Functional insufficiency of the upper extremity is one of the most common sequelae in stroke patients, significantly restricting grasp-release functions and, consequently, activities of daily living (ADL) such as eating, drinking, dressing, and self-care. Due to these limitations, stroke survivors become dependent at various levels and face inadequacies in fulfilling their physical, emotional, and social roles, which negatively impacts their quality of life. Scientists are conducting various studies to identify effective, low-cost, and easily applicable methods that can reduce the impact of stroke and enhance recovery, thereby alleviating the substantial economic, physical, social, and psychological burden on patients and their caregivers.

Action Observation Therapy (AOT), performed by observing simple actions frequently used in ADL followed by the imitation of those observed actions, has emerged in recent years as a rehabilitation approach used to improve upper extremity functions in the treatment of stroke and various neurological diseases. The neural basis of AOT is the activation of the mirror neuron system, which is active not only during one's own movements but also when observing the movements of others. Studies using Functional Magnetic Resonance Imaging have demonstrated increased mirror neuron activity during actions performed while observing the movements of others. It is stated that observing an action and subsequently attempting to imitate it reduces interhemispheric inhibition, thereby facilitating the activation of the primary motor cortex responsible for the observed movement, easing the execution of the action, resolving motor function impairments, and enabling the relearning of functions.

Research involving ADL and stroke rehabilitation examines the effectiveness, as well as the relative advantages and disadvantages, of treatment approaches involving activities where either a single hand (unimanual) or both hands (bimanual) are used together. Interventions utilizing unimanual movements in stroke patients aim to encourage the use of the patient's paretic upper extremity, achieve improvement in the structure and functions of the affected limb, and thus increase the patient's independence in ADL. In such applications, therapeutic effects are obtained by inducing significant changes in the cortical activities of hemispheres, both contralateral and ipsilateral to the paretic upper extremity. In interventions involving bimanual movements, the patient's paretic and non-paretic upper extremities are used simultaneously during common daily activities, helping the affected extremity reach the level of the less affected limb. This benefit is thought to be related to neural coupling via healthy pathways connecting the two hemispheres of the brain. Additionally, it has been determined via magnetic resonance imaging that motor areas in the brain are more activated during bimanual movements compared to unimanual movements.

Studies conducted using AOT in stroke patients include both unimanual and bimanual activities. However, no research has been found in the literature regarding which approach yields superior benefits. Therefore, the aim of our study is to examine the effects of AOT involving exclusively unimanual and exclusively bimanual activities on upper extremity functions, ADL, and quality of life in chronic stroke patients, and to investigate whether there is a significant difference between the outcomes of these two applications.

Inclusion Criteria:

• Being over 18 years of age,
• Diagnosis of left hemiparetic stroke,
• Having passed between 6 months since the onset of stroke,
• Being in stage 4 or 5 of the hand and stage 4, 5 or 6 of the upper extremity --according to Brunnstrom staging,
• Being able to sit on a chair for 30 minutes without support (patients who scored 20 or more points in total from the Trunk Impairment Scale),
• Scoring 24 or more points from the Mini Mental Test

Exclusion Criteria:

• Unwillingness to participate in the study,
• Having spasticity that prevents grasping and releasing an object (levels 3 and 4 on the Modified Ashworth Scale),
• Having a contracture in any of the affected upper extremity joints,
• Having severe neglect disorder (scoring 21 or higher on the Catherine Bergego Scale),
• Having impaired cooperation, compliance, and behavior during the administration of tests used to obtain data,
• Having a mental impairment that prevents communication and following basic commands (scoring less than 24 on the Mini-Mental Test),
• Having additional neurological and/or orthopedic problems that may affect motor performance and sitting balance,
• Having severe visual and hearing problems (if any, these problems not corrected with assistive devices such as glasses, contact lenses, hearing aids, etc.)

There will be different researchers: the evaluator, the administrator, and the statistical analyst. Neither the evaluator nor the statistical analyst will know which group the participants belong to.