Céline Amiez

Stem Cell and Brain Research Institute, INSERM U1208, 18 avenue du Doyen Lépine, 69500 Bron
Website : https://sbri.fr/public-profile/23/single-member

Title

Sulcal variability identifies differential evolution of frontal cortical regions in primates

Abstract

Although the relative expansion of the frontal cortex in primate evolution is generally accepted, the nature of its scaling and inter-species anatomo-functional comparisons of the frontal areas remain controversial. Indeed, a large literature has emphasized the link between the extent of gyrification, the rapid expansion of the cerebral cortex, and the complexity of the computational processing performed in a given brain. Although important, these discussions of cortical gyrification have not considered another major dimension of sulcal pattern organization, i.e. its variability. I present here results showing how the medial and the lateral frontal cortical sulcal organization has evolved through the primate order. By performing within- and across-species comparison of sulcal morphological variability based on neuroimaging anatomical scans, I provide evidences that both regions are comparable anatomically and functionally from Old World monkeys to Hominoidea, at the sole exception of the ventrolateral prefrontal cortex. In this latter region, although chimpanzees display the precursor of the human ascending sulcus rostrally limiting Broca’s area (Area 44), this precursor does not join the insula as in human. This lack of opercularization prevents the formation of the frontal operculum, and consequently prevents the formation of the sulci featuring the pars triangularis and therefore the formation of a full Broca’s complex. These discoveries, together with recent paleontological studies suggesting that the frontal operculum appears only in Neanderthals concomitantly with modern language abilities suggests that the frontal operculum might be key to support language functions.

Biosketch

After a PhD in Bron (France) during which I performed electrophysiological recordings and pharmacological perturbations in prefrontal areas in behaving macaques, I spent 7.5 years in Michael Petrides’ lab at McGill University (Canada) where I performed many functional magnetic resonance imaging studies in humans. In 2010, I joined the team “Neurobiology of executive functions” within the laboratory Stem Cell and Brain Research institute/INSERM U1208 (Bron, France). I was recruited by the CNRS in 2013 as a Research Associate (CR1) and then as a Research Director (DR2) in 2021. My research aims at identifying the organization of networks involved in high cognitive functions, and more particularly in cognitive adaptation and cognitive control of speech, and whether and how these networks evolved in the primate order. My research is organized into 2 major axes : 1) the study of the organization and the mode of functioning of these networks in humans and macaques, i.e. the model closest to the human brain allowing invasive studies, and 2) the study of the evolution of these networks in primates, from old-world monkeys (macaque, baboon), to apes (chimpanzee), and humans.