The claustrum is a small structure in the temporal lobe that sits just underneath the cerebral cortex – the thick, folded layer of cells that covers the brain’s surface. It forms extensive connections with every area of the cortex. This unusually widespread connectivity has prompted various hypotheses about the claustrum’s function. For example, it might be key to integrating conscious perceptions. Or it could be involved in changing the brain from one mode to another – such as when we switch from concentrating to relaxing, or shift our attention between different problems.
Determining the function of the claustrum requires an understanding of how its connectivity is organised. In the prevailing model, connectivity is based on anatomical location: areas of the claustrum that are close together connect with areas of the cortex that are close together, while distant areas in the claustrum connect to distant areas of the cortex.
The results of a new study from Brain Function CoE researchers argue against this model. Instead, they support a new model in which similar functions dictate which cells in the claustrum connect to which parts of the cortex. The study was carried out by an international group of researchers led by investigator Marcello Rosa.
The researchers conducted experiments on the brain to get a more precise view of how the claustrum connects to the cortex. They focused on the cortex of the parietal lobe, which is responsible for behaviours such as visually guiding movement, feeling sensations, sensing position and movement, and some aspects of visual navigation.
The researchers mapped areas of the parietal lobe cortex with similar functions and traced their connections back to the claustrum. Even if these cortical areas were far apart, they received connections from the same region of the claustrum. The researchers also discovered that the regions of connectivity within the claustrum are much more extensive than previously thought.
Organising connectivity in this way could allow the brain to integrate functions for similar types of tasks, while also allowing it to switch resources from one type of task to another when needed.
The researchers plan to create an even more comprehensive map of the brain, including areas in the frontal, temporal and occipital lobes. They will use this model to further investigate the role of the claustrum.
Gamberini, M., Passarelli, L., Impieri, D., Montanari, G., Diomedi, S., Worthy, K. H., Burman, K. J., Reser, D. H., Fattori, P., Galletti, C., Bakola, S., & Rosa, M. G. P. (2021) Claustral input to the macaque medial posterior parietal cortex (superior parietal lobule and adjacent areas). Cerebral Cortex, doi: 10.1093/cercor/bhab108