BOLD signal changes in response to pseudowords after giving them semantic meaning in the course of special training: an fMRI study

Abstract

Functional magnetic resonance imaging (fMRI) was used to determine the blood oxygenation level-dependent (BOLD) signals in response to pseudoword stimuli. Pseudowords were presented as deviant acoustic stimuli in the oddball paradigm, which activated the involuntary attention. In the course of special training, the meanings of the words of a hypothetical language were assigned to the stimuli. It was found that the local cerebral blood flow in response to the pseudowords presentation changed as a result of their semantization during the short-term learning. After training, significant differences in the BOLD signal parameters were observed on the right in the middle and superior temporal gyrus and on the left in the temporal plane and in the superior temporal gyrus. As a result of short-term training, there was a significant increase in local activity in the right hemisphere in the middle temporal gyrus. The results obtained indicated that the semantization of pseudowords led to the significant enhancing of the involuntary attention system reaction to them. In addition, the hemodynamic response intensity after training became noticeably higher on the left in the temporal plane and in the superior temporal gyrus. Thus, as a result of semantization, there was the BOLD reaction increase in speech-related regions of the neocortex.