Information content best characterises the hemispheric selectivity of the inferior parietal lobe: a meta-analysis

Our understanding of the inferior parietal lobe (IPL) remains challenged by inconsistencies between neuroimaging and neuropsychological perspectives. To date, others assume that hemispheric specialisation of the IPL is linked with the type of processing; attention processing in the right hemisphere; memory retrieval and semantic judgement in the left hemisphere. Here, we provide compelling evidence associating the type of information being processed with the recruitment of each hemisphere’s IPL. In a meta-analysis, we classify 121 previous fMRI reports of IPL activity arising from episodic memory retrieval, according to the type of information that characterises each fMRI contrast. We demonstrate that the left IPL is more consistently associated with retrieval of the semantic (95% of eligible contrasts) than perceptual aspects of memory (83%). In contrast, the right IPL is more consistently associated with the retrieval of perceptual (97%), than semantic aspects of memory (43%). This work revises assumptions of how the IPL contributes to healthy cognition and has major implications for IPL-related neuropsychological deficits.

Establishing a Developmentally Appropriate fMRI Paradigm Relevant to Presurgical Mapping of Memory in Children

Functional magnetic resonance imaging (fMRI) is an established eloquent cortex mapping technique that is now an integral part of the pre-operative work-up in candidates for epilepsy surgery. Emerging evidence in adults with epilepsy suggests that material-specific fMRI paradigms can predict postoperative memory outcomes, however these paradigms are not suitable for children. In pediatric age, the use of memory fMRI paradigms designed for adults is complicated by the effect of developmental stages in cognitive maturation, the impairment experienced by some people with temporal lobe epilepsy (TLE) and the normal representation of memory function during development, which may differ from adults. We present a memory fMRI paradigm designed to activate mesial temporal lobe structures that is brief, independent of reading ability, and therefore a novel candidate for use in children. Data from 33 adults and 19 children (all healthy controls) show that the paradigm captures the expected leftward asymmetry of mesial temporal activation in adults. A more symmetrical pattern was observed in children, consistent with the progressive emergence of hemispheric specialisation across childhood. These data have important implications for the interpretation of presurgical memory fMRI in the pediatric setting. They also highlight the need to carefully consider the impact of cognitive development on fMRI tools used in clinical practice.

CANDICE A1: Measuring language lateralisation with different language tasks: A systematic review

This is a preprint of a systematic review that aims to summarise research using different language tasks to measure laterality for different components of language processing. Implications of this research for models of hemispheric specialisation for language are discussed, as well as the need to consider how different aspects of language processing can show different patterns of lateralisation both across and within individuals. A protocol for this review can be found at https://osf.io/hyvc4/. This work was published in two peer-reviewed publications:Bradshaw AR, Bishop DVM, Woodhead ZVJ (2017). Methodological considerations in assessment of language lateralisation with fMRI: a systematic review. PeerJ 5:e3557 https://doi.org/10.7717/peerj.3557.Bradshaw AR, Thompson PA, Wilson AC, Bishop DV, Woodhead ZVJ (2017). Measuring language lateralisation with different language tasks: A systematic review. PeerJ 5:e3929 https://doi.org/10.7717/peerj.3929.