What drives the organization of object knowledge in the brain?

Abstract

Various forms of category-specificity have been described at both the cognitive and neural levels, inviting the inference that different semantic domains are processed by distinct, dedicated mechanisms. In this paper, we argue for an extension of a domain-specific interpretation to these phenomena that is based on network-level analyses of functional coupling among brain regions. On this view, domain-specificity in one region of the brain emerges because of innate connectivity with a network of regions that also process information about that domain. Recent findings are reviewed that converge with this framework, and a new direction is outlined for understanding the neural principles that shape the organization of conceptual knowledge.

Figure 1

Congenitally blind and sighted participants were presented with auditorily spoken words of living things (animals) and nonliving things (tools, nonmanipulable objects) and were asked to make size judgments about the referents of the words. The sighted participants were also shown pictures corresponding to the same stimuli in a separate scan. For sighted participants viewing pictures, the known finding was replicated that nonliving things such as tools and large nonmanipulable objects lead to differential neural responses in medial aspects of ventral temporal-occipital cortex. This pattern of differential BOLD responses for nonliving things in medial aspects of ventral temporal-occipital cortex was also observed in congenitally blind participants and sighted participants performing the size judgment task over auditory stimuli. These data indicate that the medial-to-lateral bias in the distribution of category-specific responses does not depend on visual experience. For details of the study, see ref.