The goal of this study is to learn about the cognitive and behavioral functioning of children being treated for cancer.

Inclusion Criteria:

Children Treated for Posterior Fossa Tumors:

• As per medical record or clinical report, successfully completed all medical treatment for either an M0 posterior fossa medulloblastoma without dissemination or posterior fossa low-grade astrocytoma without relapse or evidence of residual disease.
• For medulloblastoma survivors only: Previously treated with gross total resection (GTR), craniospinal irradiation with conformal posterior fossa boost radiotherapy (CSI + Boost) and chemotherapy
• For low grade astrocytoma survivors only: Previously treated with gross total resection ONLY (no chemotherapy or radiotherapy).
• As per medical record or clinician report, between 1-10 years post completion of their medical treatment for their posterior fossa brain tumor.
• Subject is between the ages of 6 through 16 years at time of consent.
• As per medical record or parent report, subject is able to tolerate an MRI without sedation.

Healthy Control Participants:

• No major medical illness, as determined by medical interview by study physician.
• As per parent report, subject is between the ages of 6 through 16 years at time of consent.
• As per parent report, subject is able to tolerate an MRI without sedation.

Exclusion Criteria:

All Participants:

• Full Scale IQ as documented to be below a standard score of <70 based upon the study IQ assessment completed after consent.
• As per self or parent report, completed any portion of the neuropsychological battery used in this study within the last year.
• MRI contraindications (e.g., implanted ferromagnetic devices, claustrophobia) as per radiology clinical operating procedures.
• As per self or parent report or medical record, currently taking medications that have CNS effects (i.e., antidepressants, neuroleptics, anti-seizure medications, drugs that affect blood pressure or heart rate, alpha-agonists, adrenergic blockers, lithium, sedating antihistamines, and some medications for the treatment of asthma).
• As per self or parent report, non-fluency in English language as demonstrated by current educational placement in a non-English-speaking classroom setting.

Participants will be recruited at MSK and three participating sites (Columbia University, University of Washington and University of Texas Southwestern).