Inclusion Criteria:

- Subject and/or guardian is able to provide written informed consent prior to study
registration

- Age ≥6 years and ≤21 years

- Newly diagnosed, untreated mass in posterior fossa, either benign or malignant

- Is being evaluated for surgical resection of the mass

- Able to tolerate MRI without sedation

- Able to perform fMRI tasks

- Able to perform clinical language testing

Exclusion Criteria:

- Claustrophobia

- Any contraindication to MRI (e.g., pacemaker, aneurysm clip, tissue expander).

- Pregnant or nursing female

- Does not speak English as a primary language (as determined by the P.I. or treating
physician after discussion with a potential subject and his/her family)

- Preexisting language or developmental disorder that would limit ability to cooperate
with testing (as determined by the P.I. or treating physician after interviewing
potential subject and his/her family; for example, a child may be excluded if he/she
has confirmed or suspected autism spectrum disorder, dysarthria, dyslexia, lisp,
hypotonia, or other age inappropriate speech development)