Figure 1.

Schematic illustration of stimuli, experimental paradigm, and functional magnetic resonance imaging (fMRI) acquisition. A) Still images from three example video clips showing Finnish vowel /a/ and /y/ articulations and an expanding circle with a final position of left 45° oblique oval are shown at constant intervals. The video clips of the visual conditions were edited to be comparable in timing and spatial frequency; also a circle transformation into oval resembled the mouth opening in the vowel articulation. B) The subjects were shown, in different conditions, an expanding circle into an oval of four alternative directions, still face, and articulation of Finnish vowels /o/, /y/, /a/, and /i/. The subjects were performing a one-back task where consecutive repetition of a stimulus constituted a target (i.e., when a given circle expansion direction was repeated consecutively, or when a given vowel was presented in a row). During presentation of the expanding circle, still face, and vowel articulations, there was background stimulation either with low frequency (LF; center frequency at 250 Hz) sounds, mid-frequency (MF; center frequency at 2000 Hz) sounds, or silence. The functional echo planar imaging (EPI) acquisitions of 0.8 s were performed at intervals of 9.2 s using sparse sampling technique. Each stimulus block lasted for 30 s at a time.