Abstract
In addition to positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) that can measure brain function in vivo, near-infrared spectroscopy (NIRS) is being used in various fields of neuroscience. In the near-infrared region, light with wavelength of 760nm and 850nm have different characteristics of absorbing two different states of hemoglobin (Hb), the oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb). The relative metabolic changes of O2Hb, HHb and the total of them, the blood volume within the measured regions, can be detected. This study explored the feasibility of NIRS in detecting higher brain function, by investigating the role of the left prefrontal lobe in semantically encoding unrelated word pairs. The subjects studied unrelated word pairs that were visually presented under both semantic and shallow conditions. In semantic (or deep) task, subjects were asked to form a sentence including the two words, while in perceptual (or shallow) task, they were asked to judge whether the two words had the same orthographic structures. Optical imager measured the relative changes of 760nm and 850nm absorption when the continuous light diffused through the left prefrontal lobe during the encoding tasks. In terms of intensity change, the regional blood volume change could be measured. Finally, subjects performed the recognition task. The results showed that recognition performance was better in semantic task than that in the perceptual task. Correspondingly, the blood volume of the left prefrontal lobe, especially the dorsal part, increased in the semantic task as compared with the perceptual task. The proportion of the activated subjects out of the total subjects was higher in regions C and D than in regions A and B. it demonstrated that the left prefrontal lobe contributed to semantic encoding of unrelated word pairs. The present research also suggested that NIRS can be used to measure higher brain function non-invasively, for example, memory process.
| Keywords: | prefrontal lobe; semantic encoding; episodic memory; near infrared spectroscopy; functional brain imaging |
|---|
[Chinese Version | Index | Acta Psychologica Sinica | Other Journals | Subscription form | Enquiry ]
Mail any comments and suggestions to
hkier-journal@cuhk.edu.hk .