MRI studies reveal new connections in the human brain

MRI studies of healthy, adult human brains appear to have revealed new connectivity patterns, according to a recent study published in Brain Connectivity.

Brian L. Edlow, MD, Massachusetts General Hospital and Harvard Medical School, and colleagues analyzed a total of six human subjects with no history of neurological, psychiatric, or medical disease. The median age of the six subjects was 27.5 years old.

The authors found proof of previously unidentified connections between regions of the brain known to play a role in homeostasis.

“Probabilistic tractography analyses in six healthy adults revealed connections between six brainstem nuclei and seven forebrain regions, several over long distances between the caudal medulla and cerebral cortex,” the authors wrote. “The strongest evidence for brainstem-homeostatic forebrain connectivity in this study was between the brainstem’s midline raphe and the medial temporal lobe. The subiculum and amygdala were the sampled forebrain nodes with the most extensive brainstem connections. Within the human brainstem-homeostatic forebrain connectome, we observed that a lateral forebrain bundle, whose connectivity is distinct from that of rodents and non-human primates, is the primary conduit for connections between the brainstem and medial temporal lobe.”

Edlow et al. suggested that there is a “central homeostatic network” (CHN) within the human brain which that integrates forebrain and brainstem structures used in homeostasis. This network, the authors explained, regulates both autonomic functions (cardiac muscle, smooth muscle, and sweat glands) and respiratory functions.

The authors added that a better understanding of this network could help future research teams study certain disorders.

“The CHN connectome identified in this study represents an initial step towards elucidating the neuroanatomy of human homeostasis and defining altered connectivity in future studies of patients with disorders of homeostasis,” the authors wrote.

Christopher Pawela, PhD, co-editor-in-chief of Brain Connectivity and assistant professor at the Medical College of Wisconsin, had high praise for the MGH-USC Human Connectome MRI scanner used by Edlow’s team.

"This study demonstrates the power of this unique instrument to unravel structural connections in brain regions that were previously difficult to image with conventional MRI scanners,” Pawela said.

The entire study is available to read on the publisher’s website for a limited time.