Activation of the prefrontal cortex during memory learning: Near-infrared spectroscopy study
Article first published online: 12 JAN 2007
Psychiatry and Clinical Neurosciences
Volume 61, Issue 1, pages 31–38, February 2007
How to Cite
MATSUI, M., TANAKA, K., YONEZAWA, M. and KURACHI, M. (2007), Activation of the prefrontal cortex during memory learning: Near-infrared spectroscopy study. Psychiatry and Clinical Neurosciences, 61: 31–38. doi: 10.1111/j.1440-1819.2007.01607.x
- Issue published online: 12 JAN 2007
- Article first published online: 12 JAN 2007
- Received 17 October 2005; revised 26 July 2006; accepted 30 August 2006.
- near infrared spectroscopy;
- memory organization;
- memory strategy;
- prefrontal lobe;
- verbal learning
Abstract Near-infrared spectroscopy (NIRS) is an optical method to determine oxygenated and deoxygenated hemoglobin concentration changes in the human cerebral cortex. The purpose of this study was to examine the hemodynamic response of the prefrontal area during words memory learning using NIRS. A total of 23 healthy subjects participated in the present study. Hemodynamic response in the prefrontal cortex was measured using a NIRS system. The number of words recalled and stimulus category repetition (SCR) were analyzed by the words memory learning task. During the words memory learning task, oxygenated hemoglobin concentrations increased and deoxygenated hemoglobin concentrations decreased. This typical pattern was maintained during each memory stage, but the degree of change of [oxyHb] during encoding from the first condition to the second condition was significantly larger than that during retrieval. This suggests that memory organization is facilitated during encoding of the first condition, and that the retrieval period through two conditions still involves more activation in the prefrontal area than the encoding period. An increase of [oxyHb] was not recognized and activation was inhibited when the strategy was applied. Subjects produced more SCR in the second condition than in the first condition in spite of strategy instruction. This result suggests healthy people can find out implicit category by themselves following learning even without instruction. There were no significant relationships between the behavior indices and the changes in hemoglobin. Further studies are needed to clarify usefulness of NIRS in patients with psychiatric disorder.