INTRODUCTION: Working memory (WM) disorders often persist long time after an acquired brain injury (ABI), and involve difficulties in daily life (Azouvi et al. 2017). For several decades, methods of cognitive rehabilitation and training in healthy subjects have been developed. But contrary to the literature on healthy subjects (Papa et al, 2020), to date there are still very few studies evaluating the cerebral correlates of rehabilitation in patients with ABI. The objective of this study is to study the effects of cognitive rehabilitation on brain plasticity. METHODS: PLASTIM-MDTC is a study with a repeated single case experimental design on individuals with moderate to severe TBI. After two baseline cognitive assessments, patients underwent WM rehabilitation during 3 months (3/week). The effectiveness of rehabilitation was evaluated post-rehabilitation and after 3 months. A multimodal MRI was performed before and after rehabilitation. PRELIMINARY RESULTS: We will present the results obtained for 3 patients. The results showed an effectiveness of rehabilitation on the behavioral level and an evolution of the functional activation profile on MRI during an n-back task. Primary outcome measures showed an average improvement in the Brown-Peterson task and a mean decrease in complaints in daily life related to WM. However, the evolution profile differed from one patient to another, with higher improvement in patients with more severe baseline impairments, variability between outcome measure in post and 3 months follow-up assessment, and different fMRI n-back evolution profile (decrease or increase). Interestingly, a far transfer in long-term memory appears in some patients, especially during the 3-months follow-up. DISCUSSION-CONCLUSION: The preliminary results of the PLASTIM study are in agreement with those observed in the repeated case studies of Hubacher et al (2015) on MS patients. The continuation of this research should make it possible to study the different evolution profiles and contribute to the search for early markers of the effectiveness of rehabilitation.