Adjudicating competing theories of semantic representation with 7T-fMRI and multivariate decoding

Theories of semantic representation in the brain are numerous and contradictory and are supported by an equally contradictory literature of multivariate neuroimaging studies. Equipped with two pioneering tools – (1) a 7T-fMRI acquisition sequence capable of capturing signal in crucial ventral temporal regions, and (2) four innovative decoding methods that are designed to probe specific hypotheses about the nature of the semantic code – we resolve this confusion. Evidence best supports the hypothesis that the ventral anterior temporal lobe represents complex, multidimensional semantic information via an interdependent, dynamic code similar to that observed in neural networks. Similar representations – highly variable across individuals – were discovered in posterior temporal and occipitotemporal cortex. In summary, this work adjudicates competing theories of semantic cognition, thereby reconciling the discrepancy in results between multivariate imaging and other sources of evidence – neuropsyschology, noninvasive brain stimulation, intracranial electrophysiology, and neural network modelling.