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Broca’s area and the search for anatomical asymmetry: commentary and perspectives

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Abstract

We present a brief commentary on the field’s search for an anatomical asymmetry between Broca’s area and its homologue in the non-dominant hemisphere, focusing on a selection of studies, including research from the last decade. We demonstrate that, several years after the influential review of Keller and colleagues from 2009, and despite recent advances in neuroimaging, the existence of a structural asymmetry of Broca’s area is still controversial. This is especially the case for studies of the macroanatomy of this region. We point out the inconsistencies in methodology across studies that could account for the discrepancy in results. Investigations of the microstructure of Broca’s area show a trend of a leftward asymmetry, but it is still unclear how these results relate to language dominance. We suggest that it may be necessary to combine multiple metrics in a systematic manner to find robust asymmetries and to expand the regional scope of structural investigations. Finally, based on the current state of the literature, we should not rule out the possibility that language dominance may simply not be reflected in local anatomical differences in the brain.

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Fig. 1

Notes

  1. We assume that Broca is referring to general speech production processes, and not to the articulation of words, specifically, which likely relies more on the neighboring premotor and motor cortex of the inferior precentral gyrus. The term ‘aphémie’ which Broca used frequently stems from the Greek word for ‘lack of speaking’ (Broca 2006). Refer to Petrides (2016) for a hypothesis of the likely role of each component of the inferior frontal gyrus, and also the neighboring premotor and motor cortex, in speech function.

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Funding

This work was supported by CIHR Foundation Grant FDN-143212 awarded to M.P. N.E. was funded by a Wellcome Trust Ph.D. stipendship in Neuroscience at the University of Oxford (203730/Z/16/Z).

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Authors and Affiliations

  1. Cognitive Neuroscience Unit, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, H3A 2B4, Canada

    Trisanna Sprung-Much, Erika Nolan & Michael Petrides

  2. Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, OX3 9DU, UK

    Nicole Eichert

  3. Department of Psychology, McGill University, Montreal, QC, H3A 1G1, Canada

    Erika Nolan & Michael Petrides

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  1. Trisanna Sprung-Much
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  2. Nicole Eichert
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Correspondence to Trisanna Sprung-Much.

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Sprung-Much, T., Eichert, N., Nolan, E. et al. Broca’s area and the search for anatomical asymmetry: commentary and perspectives. Brain Struct Funct 227, 441–449 (2022). https://doi.org/10.1007/s00429-021-02357-x

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