Structural Correlates of Functional Language Dominance: A Voxel‐Based Morphometry Study

Abstract

BACKGROUND AND PURPOSE The goal of this study was to explore the structural correlates of functional language dominance by directly comparing the brain morphology of healthy subjects with left- and right-hemisphere language dominance. METHODS Twenty participants were selected based on their language dominance from a cohort of subjects with known language lateralization. Structural differences between both groups were assessed by voxel-based morphometry, a technique that automatically identifies differences in the local gray matter volume between groups using high-resolution T1-weighted magnetic resonance images. RESULTS The main findings can be summarized as follows: (1) Subjects with right-hemisphere language dominance had significantly larger gray matter volume in the right hippocampus than subjects with left-hemisphere language dominance. (2) Leftward structural asymmetries in the posterior superior temporal cortex, including the planum temporale (PT), were observed in both groups. CONCLUSIONS Our study does not support the still prevalent view that asymmetries of the PT are related in a direct way to functional language lateralization. The structural differences found in the hippocampus underline the importance of the medial temporal lobe in the neural language network. They are discussed in the context of recent findings attributing a critical role of the hippocampus in the development of language lateralization.

Structural asymmetry of anterior insula: Behavioral correlates and individual differences

“…In small or select samples, occasional positive structure-function correlations have also been reported (Chiarello et al, 2004; Foundas, Leonard, Gilmore, Fennel, & Heilman, 1994). However, in the current investigation we did not find any correlation of planum temporale asymmetry with our lexical asymmetry measure, and attempts to correlate planar asymmetry with fMRI or Wada test measures of language lateralization have been largely unsuccessful (e.g., Eckert et al, 2006; Dorsaint-Pierre et al, 2006; Jansen et al, 2010; Keller et al, 2011). …”

Intuition, insight, and the right hemisphere: Emergence of higher sociocognitive functions

“…Whereas, intuition is associated with the control of expertise and automatized knowledge within basal ganglia and orbitofrontal networks, insight is associated with cognitive functions in knowledge-lean domains, restructuring within the right temporal lobe, and acting in conjunction with frontoparietal networks. It is interesting in this context that the first quantitative morphometric studies of right-hemisphere language dominant subjects only show greater grey matter volume in the right hippocampus 256. This is consistent with an emerging view that laterality of language localization is a function of maturation of the “what” ventral stream.…”

Relationship Between Brain and Cognitive Processes in Down Syndrome

“…From the correlational analysis we also attested a role for the right middle temporal gyrus in morphosyntactic abilities since higher GM density in this region was positively related to better performance in morphosyntactic production. Consistently, functional and neuroanatomical MRI studies have documented the relationship between the middle temporal gyrus and linguistic processes (Steinmetz et al 1990;Dogil et al 2002;Vandenberghe et al 2002;Jansen et al 2010). How is well known, syntactic processing are particularly impaired in individuals with DS (Price et al, 2008;Martin et al, 2009), as also emerged from our behavioural results on morphosyntactic production.…”