The interactive functional biases of manual, language and attention systems

Abstract

Hemispheric lateralisation is a fundamental principle of functional brain organisation. We studied two core cognitive functions—language and visuospatial attention—that typically lateralise in opposite cerebral hemispheres. In this work, we tested both left- and right-handed participants on lexical decision-making as well as on symmetry detection by means of a visual half-field paradigm with various target–distractor combinations simultaneously presented to opposite visual fields. Laterality indexes were analysed using a behavioural metrics in single individuals as well as between individuals. We observed that lateralisation of language and visuospatial attention as well as their relationship generally followed a left–right profile, albeit with differences as a function of handedness and target–distractor combination. In particular, right-handed individuals tended towards a typical pattern whereas left-handed individuals demonstrated increased individual variation and atypical organisation. That the atypical variants varied as a function of target–distractor combination and thus interhemispheric communication underlines its dynamic role in characterising lateralisation properties. The data further revealed distinctive relationships between right-handedness and left-hemispheric dominance for language together with right-hemispheric dominance for visuospatial processing. Overall, these findings illustrate the role of broader mechanisms in supporting hemispheric lateralisation of cognition and behaviour, relying on common principles but controlled by internal and external factors.

When Age Tips the Balance: a Dual Mechanism Affecting Hemispheric Specialization for Language

“…The lateralization of individual functions, such as language, may be closely associated with the lateralization of many seemingly independent processes 43 . Several studies suggest that the LH specialization for language may be linked to the concept of “complementary lateralization.” This stands in contrast to the preferential specialization of the contralateral hemisphere (the RH) for other high-level cognitive functions like visuospatial processing 67–71 . It has also been reported that the absence of functional lateralization for language production reduces performance in language tasks and other non-verbal, high-level functions 72 .…”

Attention and Interhemispheric Communication: Implications for Language Dominance

“…This is further supported by data from individuals with agenesis of the corpus callosum who show an increased distribution of language processing across hemispheres in addition to right-hemispheric dominance (Hinkley et al, 2016). The left-sided superiority such as for the ability to recognise written words or to extract meaning has been demonstrated in neuroimaging work (Price, 2000;Josse and Tzourio-Mazoyer, 2004), and behavioural research that has revealed performance advantages when words are presented to the right as compared to left visual field (Hunter and Brysbaert, 2008;Serrien and O'Regan, 2022). Two influential models are proposed in the literature to explain these lateralised effects.…”

“…Two additional language-related variants have been confirmed through neuroimaging work: no hemispheric dominance with bilateral representations, a pattern that is rather equally present in both handedness groups, in addition to right-hemispheric dominance that is usually only observed in a small subgroup of lefthanders (Tzourio-Mazoyer et al, 2016;Vingerhoets, 2019). Taking these differences into account, it is therefore relevant to consider the profiles that characterise their behaviour (Serrien and O'Regan, 2022). Our data revealed that the participants from both handedness groups had distinct sensitivity during intra-and interhemispheric conditions.…”

“…Target word performance was measured using reaction time (i.e., averaged bimanual responses) and response accuracy (i.e., percentage of correct responses). We further computed a laterality index for reaction time ( (Serrien and O'Regan, 2022). LI RT and LI ACC were calculated separately for intra-and interhemispheric trials.…”

“…The concept of complementary organisation has especially been addressed in the literature for assessing whether lateralisation of one cognitive function can predict the asymmetric processing of another one (Cai et al, 2013;Brederoo et al, 2020;Serrien and O'Regan, 2022). We used the premise of complementarity to examine more closely the activation-inhibition synergy.…”