Human Brainstem: Cytoarchitecture, Chemoarchitecture, Myeloarchitecture Reveals Breakthrough Finding by Renowned Brain Mapper Dr. George Paxinos
New technologies continue to be invaluable enablers in scientific research, vividly demonstrated by the recent discovery of a region in the brain by esteemed brain cartographer Dr. George Paxinos and his colleagues. In an upcoming Elsevier book, Human Brainstem: Cytoarchitecture, Chemoarchitecture, Myeloarchitecture, Dr. Paxinos, Dr. Teri Furlong and Dr. Charles Watson provide evidence for the existence of what they called the Endorestiform Nucleus, a previously undetected area near the junction of the brain and the spinal cord. Using new and improved staining techniques, they found the Endorestiform Nucleus within the inferior cerebellar peduncle (also known as the restiform body).
“The nucleus is like an island in the river of information that flows from the spinal cord and the brainstem to the cerebellum and relates to touch, pressure, vibration, temperature, proprioception and pain, inputs relevant to the involvement of the cerebellum in fine motor control,” said Dr. Paxinos, who initially suspected the existence of this nucleus 30 years ago.
The Long Journey to a Remarkable Realization
In studying and mapping the human brain, Dr. Paxinos first noticed what seemed to be a previously unidentified region in 1990. However, he wasn’t ready to proclaim a new discovery, unsure whether it was indeed a separate entity not yet known to exist or part of another nucleus. Dr. Paxinos drew a line around the area in his 1995 atlas of the human brainstem, without naming it, sensing that it was indeed a distinct, undetected nucleus. Although he updated the diagrams in two subsequent decades, he still was not ready to call the area a nucleus.
Furthering Dr. Paxinos’s suspicion, one of his colleagues, Bill Mehler, found that the area in question receives input from the spinal cord, as evidenced in cases where a therapeutic anterolateral cordotomy is performed on cancer patients to relieve their pain.
Finally, in the last 18 months, Dr. Paxinos and his colleagues updated their previous brainstem atlas. As he was making one last check of the many diagrams and photographs in the new book before sending it off to Elsevier for publication, the area in question once again stood out. Dr. Paxinos could definitely see that it was not a part of a previously named region, but rather existed on its own. He jokes that he did not find the Endorestiform Nucleus that day – it found him.
Putting This Discovery Into Perspective
Dr. Paxinos believes the new region receives information from the spinal cord and likely relays that information to the cerebellum. Given its location, he suspects a role in sensory-motor coordination. The name was chosen because the Endorestiform Nucleus sits within what Dr. Paxinos calls the “big freeway” connecting the brain and spinal cord. His hope is that this discovery will assist researchers who wish to map the distribution of neuroactive substances in the human brain .
This is the first nucleus identified by Dr. Paxinos and his team initially in the human brain, before searching for it in other primates. They previously identified all other nuclei first in the rat or monkey, and then were able to demonstrate their existence in the human. This research is sometimes difficult because the human tissue is obtained long after death, so not high quality.
The team finds it intriguing that the newly identified brain region does not seem to exist in rats; so far, they also have not found it in the marmoset, but believe it might exist in the rhesus monkey. Dr. Paxinos will soon begin evaluating that area more thoroughly in the rhesus and in a deceased chimpanzee provided to him by the Taronga Park Zoo in Sydney, in the latter case to determine if the extreme homology between the ape’s brain and the human brain also includes the Endorestiform Nucleus.
Part of a Highly Anticipated Brainstem Atlas
The identification of the Endorestiform Nucleus discovery is one of the highlights of Human Brainstem: Cytoarchitecture, Chemoarchitecture, Myeloarchitecture, scheduled for publication in March 2019 .
The first detailed diagrammatic and photographic atlas on the human brainstem in more than twenty years, the book will serve as an accurate, comprehensive and convenient reference for advanced students, researchers and pathologists. The up-to-date brain map represents all areas of the medulla, pons and midbrain in the plane transverse to the longitudinal axis of the brainstem. The book includes 64 plates and 64 accompanying diagrams with an interplate distance of one millimeter, as well as photographs of Nissl and acetylcholinesterase (AChE) stained sections at half-millimeter interval between the diagramed plates. With more than three times the number of photographs than the previous edition, the new book will extend Dr. Paxinos’s lifelong efforts to increase the understanding of the structure, function and development of the brain.
The discovery of the Endorestiform Nucleus – now one of nearly 700 nuclei in the human brain – further demonstrates the dedication and determination of the research community to provide clinicians with new information that could break ground in treatment, prevention and cure. Something you first see today may lead to an “aha!” moment in a month, a year…or even thirty years.
Find more information on Human Brainstem: Cytoarchitecture, Chemoarchitecture, Myeloarchitecture, or pre-order the book here.
Neuroscience – SciTech Connect