Brain activation for reading and listening comprehension: An fMRI study of modality effects and individual differences in language comprehension

Abstract

The study compared the brain activation patterns associated with the comprehension of written and spoken Portuguese sentences. An fMRI study measured brain activity while participants read and listened to sentences about general world knowledge. Participants had to decide if the sentences were true or false. To mirror the transient nature of spoken sentences, visual input was presented in rapid serial visual presentation format. The results showed a common core of amodal left inferior frontal and middle temporal gyri activation, as well as modality specific brain activation associated with listening and reading comprehension. Reading comprehension was associated with more left-lateralized activation and with left inferior occipital cortex (including fusiform gyrus) activation. Listening comprehension was associated with extensive bilateral temporal cortex activation and more overall activation of the whole cortex. Results also showed individual differences in brain activation for reading comprehension. Readers with lower working memory capacity showed more activation of right-hemisphere areas (spillover of activation) and more activation in the prefrontal cortex, potentially associated with more demand placed on executive control processes. Readers with higher working memory capacity showed more activation in a frontal-posterior network of areas (left angular and precentral gyri, and right inferior frontal gyrus). The activation of this network may be associated with phonological rehearsal of linguistic information when reading text presented in rapid serial visual format. The study demonstrates the modality fingerprints for language comprehension and indicates how low- and high working memory capacity readers deal with reading text presented in serial format.

Figure 1

Cortical areas activated for listening and reading comprehension (p < 0.001, uncorrected; T = 4.02; extent threshold = 20 voxels; (a) illustrates the overlap of common subsets of cortical areas of activation for listening comprehension and/or reading comprehension contrasted with fixation (red = listening only; green = reading only; white = listening and reading), and shows the areas of activation (b) only in listening comprehension and (c) only in reading comprehension)

Figure 2

Brain activation for the contrast between reading and listening comprehension (p < 0.001 uncorrected; T = 4.02; extent threshold = 20 voxels; blue ellipses highlight the bilateral middle and superior temporal gyri activation for listening comprehension > reading comprehension; red ellipsis highlights the left inferior occipital lobe activation for reading comprehension > listening comprehension)

Figure 3

Correlation between brain activation for reading comprehension and reading span scores. (p < 0.001, extent threshold = 20 voxels; top: negative correlation with activation for reading comprehension: LMFG MNI: x = -34; y = 52; z = 10, cluster size = 45 voxels (t = 7.01); bottom: positive correlation with activation for reading comprehension: L angular gyrus MNI: x = -34, y = -58, z = -18, cluster size = 21 voxels (t = 4.82); L precentral + postcentral gyri MNI: x = -28, y = -32, z = 56, cluster size = 31 voxels (t = 5.80); L postcentral gyrus + paracentral lobule MNI: x = -16, y = -34, z = 60, cluster size = 41 voxels (t = 7.46); R middle + inferior frontal gyri MNI: x = 42, y = 22, z = 32, cluster size = 23 voxels (t = 4.88))