The Relationship Between Semantic Memory Network and Tip-of-the-Tongue Phenomenon: Evidence From a Large-Scale Diffusion MRI Dataset.

The tip-of-the-tongue (TOT) phenomenon is traditionally considered a retrieval failure; however, it may also reflect cognitive advantages in semantic memory. Semantic memory refers to the repository of general world knowledge, including word meanings, objects, people, and their relationships, and is underpinned by a network of multiple brain regions. Prior studies on the relationship between semantic memory and TOT occurrences have yielded inconsistent results, warranting further investigation. Here, we examined this relationship by applying graph theory to analyze the topological properties of the semantic memory network, using diffusion magnetic resonance imaging (dMRI) data from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) repository (N = 576; age: 18-87). Our results demonstrated that global metrics of the semantic memory structural network-global efficiency, local efficiency, mean degree centrality, and mean clustering coefficient-positively predicted TOT rates. At the nodal level, increased metrics in the right posterior lateral temporal cortex (pLTC) and left dorsomedial prefrontal cortex (dmPFC) were associated with higher TOT rates. These findings suggest that a more extensive semantic memory, characterized by a richer network of general knowledge, may hinder word retrieval.