Abstract

Semantic processing is key to our understanding of the external environment and linguistic inputs. It subserves high-level processes such as inferential reasoning, concept formation, and language understanding. We reviewed data from electrophysiological, functional imaging, and lesion studies to highlight that the main brain areas involved in semantics, namely the left inferior frontal gyrus (LIFG), the posterior temporal cortex (PTC), the inferior parietal cortex (IPC), the anterior temporal lobe (ATL), and the insular cortex are multimodal hubs, but they also bear unique functional specializations and computational properties, such as functional and computational gradients. Based on the reviewed evidence, we propose a model of semantics, whereby the semantic network is linked to the language network and semantic processing is underlain by three functionally specialized, but crucially not encapsulated, components that are linked through complex direct and indirect connectivity: The inferential/logical (centered in the LIFG), the conceptual (centered in the ATL), and the lexical (centered in the PTC) networks. We discuss the advantage of such a tripartite model over alternative localizationist and connectionist models in addressing the issues of functional specialization and integration