Future Directions for Chemosensory Connectomes: Best Practices and Specific Challenges

Abstract

Ecological chemosensory stimuli almost always evoke responses in more than one sensory system. Moreover, any sensory processing takes place along a hierarchy of brain regions. So far, the field of chemosensory neuroimaging is dominated by studies that examine the role of brain regions in isolation. However, to completely understand neural processing of chemosensation, we must also examine interactions between regions. In general, the use of connectivity methods has increased in the neuroimaging field, providing important insights to physical sensory processing, such as vision, audition, and touch. A similar trend has been observed in chemosensory neuroimaging, however, these established techniques have largely not been rigorously applied to imaging studies on the chemical senses, leaving network insights overlooked. In this article, we first highlight some recent work in chemosensory connectomics and we summarize different connectomics techniques. Then, we outline specific challenges for chemosensory connectome neuroimaging studies. Finally, we review best practices from the general connectomics and neuroimaging fields. We recommend future studies to develop or use the following methods we perceive as key to improve chemosensory connectomics: (1) optimized study designs, (2) reporting guidelines, (3) consensus on brain parcellations, (4) consortium research, and (5) data sharing.

Interconnected sub-networks of the macaque monkey gustatory connectome

“…Within the growing field of connectomics, there is an evident gap in available studies on chemosensory networks ( Veldhuizen et al, 2022 ). A contemporary review of published chemosensory connectivity research in humans identified only 15 studies to have examined gustatory networks by fMRI ( Farruggia et al, 2022 ).…”

Graph theory applications in congenital heart disease

“…One of the most important applications of graph theory is the connectome in neuroscience. Since the coining of the term connectome in 2005, the number of related studies has markedly increased, with more than 1000 publications per year over the past few years 21 . Graph theoretical analysis of complex brain networks reveals that the human connectome can be a diagnostic marker of several neurodegenerative and psychiatric diseases 22 .…”

Functional Connectivity of the Chemosenses: A Review

“…We recommend considering one or more of these approaches in subsequent data-driven studies of chemosensory-brain relationships. In consonance, we also advise readers to consider best practices in chemosensory neuroimaging before designing study methods (see Veldhuizen, 2022).…”