Abstract
Schizophrenia has been associated with the dysfunction of prefrontal cortex, which is involved in executive function and working memory. Near-infrared spectroscopy (NIRS) is a novel diffuse optical neuromonitoring method with its own advantages and limitations. In this study, we compared the characteristics of oxygenated hemoglobin concentration changes (Δoxy-Hb) involved in both phonological and categorical verbal production between 40 outpatients with schizophrenia and 40 healthy subjects during a Japanese “shiritori” task using NIRS by Kurume Single Event Related Design (K-SERD). In this task, one session consisted of two contrasting conditions (word production task, control condition), and all subjects alternated between these conditions. Each word was visually presented by a monitor for 0.3 seconds as an activation task and a fixed circle was presented for 12 seconds. In the activation task, subjects had to immediately generate a noun that starts with the last syllable of the presented word and they were required to say only creatures. From the data obtained at each measurement point during the 20 trials, and averaged waveform during activation task (20 trials) was calculated for each channel. During this task, the schizophrenic patients showed significantly smaller activation than the controls in the prefrontal cortex area and inferior parietal area. In addition, there was a significant negative correlation between Δoxy-Hb in the patients with schizophrenia and general psyhopathology score (in left midfrontal area) of PANSS. These findings suggest that NIRS measurement during Japanese shiritori tasks by K-SERD may be useful tool for evaluating psychophysiological indices in patients with schizophrenia, that relationship between activation and general psyhopathology score may be of help in predicting functional outcome in patients.
