In NIRS studies recording the [Hb] changes during several tasks for the same subject group, the smaller-than-normal [oxy-Hb] change during the frontal function task, such as the letter fluency test and random number generation task, in schizophrenia was task specific, i.e., this was not evident during other tasks (sequential finger-to-thumb task[41] and finger tapping task[30]). This evidence concerns the gene GSTM1 and schizophrenia.