- Hypothesis-Testing Substudy is defined as a study with a specific hypothesis to be tested that can be completed with a few healthy volunteers or patients. Hypothesis-testing substudies will undergo statistical and PIRC reviews after 6 subjects (if there is one group) or after 12 (6 per arm) if two groups are studied before additional subjects are recruited. In the event of subject dropout or unsuccessful recording, replacement will be recruited. Together, the P.I. and PIRC will decide whether to continue the hypothesis substudy with more subjects without an amendment or whether an amendment or new protocol would be necessary. A memo requesting a review of hypothesis-testing substudies for possible additional enrollment will be sent to PIRC and the statistical reviewer. The memo will be forwarded to the CNS IRB.