Combining concepts across categorical domains: a linking role of the precuneus.

Giuseppe Rabini,Silvia Ubaldi,Scott L Fairhall

doi:10.1162/nol_a_00039

Giuseppe Rabini, Silvia Ubaldi + Show 1 more

Open Access

https://doi.org/10.1162/nol_a_00039

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Abstract

The human capacity for semantic knowledge entails not only the representation of single concepts but the capacity to combine these concepts into the increasingly complex ideas that underlie human thought. This process involves not only the combination of concepts from within the same semantic category but frequently the conceptual combination across semantic domains. In this fMRI study (N=24) we investigate the cortical mechanisms underlying our ability to combine concepts across different semantic domains. Using five different semantic domains (People, Places, Food, Objects and Animals), we present sentences depicting concepts drawn from a single semantic domain as well as sentences that combine concepts from two of these domains. Contrasting single-category and combined-category sentences reveals that the precuneus is more active when concepts from different domains have to be combined. At the same time, we observe that distributed category selectivity representations persist when higher-order meaning involves the combination of categories and that this category-selective response is captured by the combination of the single categories composing the sentence. Collectively, these results suggest that the combination of concepts across different semantic domains is mediated by the precuneus, which functions to link together category-selective representations distributed across the cortex.

Highlights

The human capacity for semantic knowledge involves the representation of single concepts and the capacity to combine these concepts into the increasingly complex ideas that underlie human thought
There remain two open questions: 1) Do specific brain regions coordinate information contained in category-selective cortical regions? And 2) do complex ideas that combine category information from multiple domains continue to utilise those domain-selective representations of single concepts, or do derived multi-categorical concepts rely more on domain-general semantic mechanisms?
We asked two related questions: (1) Do specific brain regions play a particular role in combining concepts from different domains? (2) Do units of meaning that combine object categories continue to show a decentralised cortical representation, or are they represented in more centralised domain-general semantic regions?

Summary

Introduction

The human capacity for semantic knowledge involves the representation of single concepts and the capacity to combine these concepts into the increasingly complex ideas that underlie human thought. Reading about a boy playing with his dog in the garden requires the system to link concepts from distinct conceptual domains (i.e., people, animals and places) to build a distinct and coherent representation. To date, it is still unclear how category-selective brain regions interact when concepts from different domains has to be combined into a higher-order semantic units. 2) do complex ideas that combine category information from multiple domains continue to utilise those domain-selective representations of single concepts, or do derived multi-categorical concepts rely more on domain-general semantic mechanisms? There remain two open questions: 1) Do specific brain regions coordinate information contained in category-selective cortical regions? And 2) do complex ideas that combine category information from multiple domains continue to utilise those domain-selective representations of single concepts, or do derived multi-categorical concepts rely more on domain-general semantic mechanisms?

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