Conceptual Representations and Linguistic Categories in the Brain: The case of Word Classes

The aim of this project is to investigate the neurobiological basis of the linking mechanism of conceptual space with linguistic structures. We continually communicate with each other and talk about any notion by combining linguistic units into a coherent system. However, this process is by no means trivial, as it entails specific mechanisms for encoding a multifactorial and graded reality into formally discrete structures. Therefore, it is crucially related to the way in which we represent and categorize the world and depends on how conceptual categorization interacts with linguistic categorization. The question of how conceptual categories are formed by humans and conveyed through languages dates back many centuries and has long baffled scientists from different disciplines. Several factors co-occur in the categorization of natural, cultural and linguistic elements. However, the neurocognitive basis of encoding multifactorial conceptual categories into formally discrete language systems is almost entirely unknown and the categorization principles that are crucially relevant to language processing in the human brain still have to be defined. In order to provide an answer to critical aspects of these unresolved and crucial questions, in the present paper, we address the neurocognitive representation of the major word classes (specifically, verbs, adjectives and nouns). Word class distinction is a key question at the interface between concepts and grammar: word classes, in fact, 1) specifically testify to the way in which we represent and categorize the world, as they represent the primary building blocks to convey concepts; 2) provide the fundamental units to morphosyntactic operations and semiotic functions: e.g., predication, modification, reference; 3) capture all the primary interface semantic properties that crucially and directly affect the organization (change and acquisition) of language systems. We will discuss data from cognitive neuropsychological and fMRI studies, in order to show 1) how word class distinction represents a privileged viewpoint to investigate knowledge representation and 2) how the neurocognitive representation of word classes can shed new light on the architecture of language in the brain.