Minimizing the interference of tumor recurrence or progression: Two actions will be taken to minimize the interference of tumor recurrence or progression with the evaluation of performance alterations caused by radiation. First, patient inclusion will be restricted to patients with slow growing tumors, e.g., meningioma, low grade glioma and anaplastic astrocytoma so that the chance for tumor recurrence or progression is small. Secondly, patients who develop disease progression at any of the post-radiotherapy follow-ups will be excluded from the study, as it would not be possible to distinguish the effects of disease progression from radiotherapy side effects on the fMRI or the 3MS examination, and the findings would not be interpretable.