Role of left prefrontal lobe in encoding unrelated word pairs - A study using near-infrared spectroscopy

This study was to explore the role of the left prefrontal lobe in semantically encoding unrelated word pairs. 22 subjects were studied unrelated Chinese pairs that were visually presented under both semantic and shadow conditions. Under semantic (or deep) conditions subjects were asked to form a sentence including two words, while under shallow (or deep) conditions they were asked to judge whether two words had the same structure. During the cognitive tasks, optical imager measured the relative changes of 760nm and 850nm absorption when the continuous light diffused through the left prefrontal lobe. In term of the intensity change, the regional blood volume change could be expected. The results showed the activation of left prefrontal lobe, especially the dorsal part, was stronger under deep conditions than that under shallow encoding. It was suggested that near infrared spectroscopy could be used to measure the higher brain function.