Author:

Keywords:

MONKEY, HUMAN, FMRI

Abstract:

Introduction Recycling of existing neuronal circuits has been proposed as a model for the emergence of human-specific abilities (Dehaene et al., 2007). Alternatively, cortical expansion theories suggested that such features would be mapped on novel associative regions, without any correspondent in non-human primates (Van Essen and Dierker, 2007). To provide support for any of these hypotheses, we compared in a model-free manner the functional architecture of macaques and humans. Methods fMRI data were collected in 4 macaques and 24 healthy humans by 3T MR scanners, installed in the K.U.Leuven and Chieti University, respectively. Participants were scanned during resting state and natural vision, respectively. We first performed independent component analyses on resting state data to delineate monkey and human networks. Next, after warping the monkey maps to human space by cortical expansion, we spatially compared their maps using a hierarchical cluster analysis. Finally, we used inter-species activity correlation (Mantini et al., 2010) on natural vision data to assess similarities and differences in the functional responses across the two species. Results Using resting state data, we revealed striking topological inter-species similarities between sensory-related networks, and we detected monkey equivalents for the human ventral attention and language networks. In addition, we revealed three human-specific, yet not a single monkey-specific cortical network. The networks without any monkey equivalent, likely related to self-awareness, procedural and abstract reasoning, are located in cortical regions that showed a much larger degree of anatomical expansion compared to average (Van Essen and Dierker, 2007). Using natural vision data, we showed that the ventral attention network, as the sensory-related networks, has evolutionary conserved functional properties. This was not true for the human language network. Finally, the human-specific networks showed distinct temporal functional signatures compared to any network in macaques. Conclusion We revealed spatially correspondent brain networks with different functional processing, as predicted by the neuronal recycling theory. Nonetheless, in regions with larger cortical expansion we also identified human-specific networks with distinct temporal signatures compared to networks in macaques. Hence, the combination of cortical expansion and neuronal recycling might explain the emergence of human-specific cognitive abilities. References Dehaene, S. and L. Cohen. Neuron 56.2 (2007): 384-98. Van Essen, D. and D. L. Dierker. Neuron 56.2 (2007): 209-25. Mantini et al. SFN 2010 abstract.