The primary objective is to evaluate and quantify the reproducibility of functional magnetic resonance imaging (fMRI) maps of the eloquent brain areas corresponding to specific neurological functions based on activation maps obtained with different thresholds in patients with benign and biopsy proven low-grade brain neoplasms. Another objective is to access the impairment in neurological function in image guided intracranial radiotherapy using neurocognitive assessment tools and to derive dose response curves relating the impairment in a particular neurological function to the FED received by the area of eloquent brain corresponding to it.

Inclusion Criteria:

• Indication for brain radiotherapy.
• Ability to undergo MRI scans and time to participate in neurocognitive testing.

Study patients will come from the population that is referred to radiotherapy for treatment of their low grade glioma or benign brain lesion and will undergo fractionated radiotherapy. The volunteers will be a spouse or sibling of a patient