Dissociating frontal regions that co-lateralize with different ventral occipitotemporal regions during word processing

Mohamed L Seghier,Cathy J Price

doi:10.1016/j.bandl.2013.04.003

Mohamed L Seghier, Cathy J Price

Open Access

https://doi.org/10.1016/j.bandl.2013.04.003

Copy DOI

Abstract

The ventral occipitotemporal sulcus (vOT) sustains strong interactions with the inferior frontal cortex during word processing. Consequently, activation in both regions co-lateralize towards the same hemisphere in healthy subjects. Because the determinants of lateralisation differ across posterior, middle and anterior vOT subregions, we investigated whether lateralisation in different inferior frontal regions would co-vary with lateralisation in the three different vOT subregions. A whole brain analysis found that, during semantic decisions on written words, laterality covaried in (1) posterior vOT and the precentral gyrus; (2) middle vOT and the pars opercularis, pars triangularis, and supramarginal gyrus; and (3) anterior vOT and the pars orbitalis, middle frontal gyrus and thalamus. These findings increase the spatial resolution of our understanding of how vOT interacts with other brain areas during semantic categorisation on words.

Highlights

The lateralisation of cognitive functions in the human brain illustrates how processing is efficiently distributed across the left and right hemispheres (Hugdahl, 2000)
At p < 0.05 FWE-corrected, lateralization in pars opercularis and pars triangularis was strongly related to lateralization in middle vOT (mvOT), whereas lateralization in pars orbitalis was strongly related to lateralization in anterior vOT (avOT) with this effect being stronger with avOT than mvOT (Z = 3.9) or posterior vOT (pvOT) (Z = 2.8)
Other frontal regions showed significant correlations with laterality in ventral occipitotemporal sulcus (vOT). This included (i) laterality in the precentral gyrus correlating with laterality in pvOT, with this effect being primarily driven by reduced activation in the right precentral gyrus (Z = 4.3) rather than greater activation in left precentral gyrus (Z = 1.9), and (ii) laterality in the middle frontal gyrus correlating with laterality in avOT, with this effect being driven by both increased left (Z = 4.4) and reduced right (Z = 4.0) hemisphere activation

Summary

Introduction

The lateralisation of cognitive functions in the human brain illustrates how processing is efficiently distributed across the left and right hemispheres (Hugdahl, 2000). This is because processing efficiency is thought to be greater when cerebral regions supporting a given function are in the same hemisphere (Ringo, Doty, Demeter, & Simard, 1994). It has been shown that activation is lateralized to the dominant (left) hemisphere during word processing even in the most posterior parts of the reading system, such as the ventral occipito-temporal sulcus (vOT) (Dehaene & Cohen, 2007; Dien, 2009).

Objectives

Methods

Results

Conclusion