Psychophysiological Interactions Underlying Meaning Selection in Ambiguity Resolution

Abstract

In the present study, the interactions among brain areas involved in the processing of non-selected meaning while dealing with ambiguous word pairs were investigated. The study was aimed at clarifying the question of which brain structures and how exactly are involved in supporting the processes of unconscious selection of one of the meanings of a word and what can happen, at the same time, with its unselected meaning. Philips Achieva 3 T MRI scanner was used to obtain fMRI data on 17 healthy right-handed subjects performing the task of completion of adjective-noun pairs comprising words with missed letters: ambiguous pairs, as compared with unambiguous ones, had at least two variants of completion. Psychophysiological interaction analysis was conducted for the volume of interest located within the right and left hippocampus in which the effect of decreased BOLD signal was revealed in previous study. As a result the modulatory effect of the automatic disambiguation process on the functional coupling between the region of interest in the left hippocampus and the left and right inferior frontal gyrus, right caudate nucleus, the right inferior and superior parietal lobules (BA 39/7). The completion of ambiguous word pairs, as compared with unambiguous ones, was associated with a decrease in functional interactions within these integrated brain regions. The revealed data demonstrate the new evidence for involving the processes of suppressing unselected word meanings when choosing the meaning of an ambiguous word.