Novel insights into weight gain

Researchers monitored brain activity as patients anticipated and then received a sweet treat (a chocolate milkshake). They found that both the dlHPC and the LH activated simultaneously when participants anticipated receiving the rewarding meal. These researchers confirmed using stimulation techniques that this specific zone of the hippocampus, the dlHPC, and LH exhibited extremely strong connectivity, as well.

In individuals with obesity, researchers found that the impairment of this hypothalamus-hippocampus circuit was directly proportional to their BMI. That is, in participants with a high BMI, the connection was even more disturbed.

To further validate the connection, Halpern's team used a technique called "brain clearing," to analyze brain tissue. The technique revealed melanin-concentrating hormone, a hormone known to regulate feeding behavior that is produced in the LH. They found the presence of MCH in the dlHPC, and nowhere else, confirming a link between the two regions.

Reference: Daniel A. N. Barbosa, Sandra Gattas, Juliana S. Salgado, Fiene Marie Kuijper, Allan R. Wang, Yuhao Huang, Bina Kakusa, Christoph Leuze, Artur Luczak, Paul Rapp, Robert C. Malenka, Dora Hermes, Kai J. Miller, Boris D. Heifets, Cara Bohon, Jennifer A. McNab, Casey H. Halpern. An orexigenic subnetwork within the human hippocampus. Nature, 2023; DOI: 10.1038/s41586-023-06459-w