Study aim: Comparing the effects of progressive motor imagery and mirror therapy techniques on phantom limb pain and prosthesis embodiment in individuals with unilateral below-the-knee amputees using fMRI Design: A two-group, parallel-group, double-blind, randomized based on the random number table, phase II clinical trial on 20 participants with unilateral below-the-knee lower limb amputations. Settings and conduct: The samples will select based on a simple non-probability method from the available statistical population, the Red Crescent Rehabilitation Center or private clinics in Tehran, that meets the inclusion criteria. Blinding: Participants in this study do not know whether they are in the GMI intervention group or the mirror therapy control group. This blinding helps reduce psychological effects and patient expectations and prevents bias in reporting results. Also, the researcher who evaluates the results will be unaware of the groups to which the participants were assigned. The person who analyzes the data will also be unaware of the information about the group allocation. Participants/Inclusion and exclusion criteria: Before startiing the study, a screening test will be conducted on the subjects using The Kinesthetic and Visual Imagery Questionnaire (KVIQ). Subjects will be asked to answer questions 4 and 5 of this questionnaire, which are related to lower limb function, and if they score 4 or 5 on each question, they will be included in the study. Intervention groups: These participants will be randomly assigned to two intervention groups: GMI (intervention group) and mirror therapy (control group). GMI group will undergo GMI intervention at least once a day for 6 weeks. Control group will undergo mirror therapy daily for 15 minutes for 6 weeks (5 days a week). Main outcome variables: Phantom pain؛ Prosthesis Embodiment؛ Graded Motor Imagery Technique؛ Activity of cortical areas of the brain