Wednesday, 6 May 2026
A new brain network involved in Parkinson’s disease challenges our view of the primary motor cortex
In a field like neuroscience, there’s so much knowledge, and it’s changing so constantly, that often, when you read about one discovery, you can best understand its importance in light of another discovery that you hadn’t even heard of before. That’s what happened to me when I read this article explaining a major advance in our understanding of Parkinson’s disease. This article was published in the journal Nature and is entitled “Parkinson’s disease as a somato-cognitive action network disorder.”
Unfortunately, I don’t have the time this week to go into as much detail about this article as I would have liked, but here’s the gist of the discovery that it describes. The somato-cognitive action network (SCAN) is a key network in the brain and is believed to coordinate our planning for movement, our motivations and the physiology of our body’s organs. Apparently, this network is hyperactive in people with Parkinson’s disease. What is very interesting is that part of the SCAN network is located in the primary motor cortex (nicknamed M1) at the surface of the brain, which opens the way to non-invasive treatments such as transcranial magnetic stimulation (TMS).
The joke on me here is that when I read this article, I had never even heard of the SCAN, even though it had been discovered about five years ago and even though one of its discoverers, Nico U.F. Dosenbach, had written an article published in Scientific American in 2023 to explain this discovery. The main point of that article was that the discovery of the SCAN casts doubt on the standard model of M1, Penfield’s motor homunculus, in which the primary motor cortex is depicted as a humanoid-shaped map of the human body, of which every part triggers the voluntary movements of a corresponding part of the body. But it turns out that M1 is more than just a set of mechanical triggers. It also contains groups of neurons that constitute nodes in the SCAN network, many of whose other nodes are located deep beneath the cortex, in other groups of neurons associated with movement. As I was saying, the chain of discoveries never stops!
Finally, a recent article on the subject : This complex brain network may explain many of Parkinson’s stranger symptoms
Body Movement and the Brain | Comments Closed
Monday, 9 March 2026
Two different levels of analysis: the hippocampus at the neuronal level and autism at the molecular level
This week, I’ll address two different topics from the angle that is so central to my website and my book about the human brain: the various levels at which the human brain and the human mind are organized. My first topic today is how the neurons of the hippocampus are affected by chronic stress. The second is how the lower availability of a certain type of neurotransmitter receptor in widespread regions of the brain may contribute significantly to traits of autism. (more…)
Mental Disorders | Comments Closed
Friday, 9 January 2026
Migration of the website from thebrain.mgill.ca to thebrain.lecerveau.ca
In December 2025, I migrated my website The Brain from Top to Bottom from www.thebrain.mcgill.ca to www.thebrain.lecerveau.ca. (If you have visited the site since then, you may not even have noticed, because if you type the old address into your browser, you are now redirected to the new one automatically, and that new address appears in the browser’s address bar.) At the same time, I migrated the French version of this site, Le cerveau à tous les niveaux, from www.lecerveau.mcgill.ca to www.lecerveau.ca. Here too, if you now type the old address, you will be directed to the new one automatically. The main reason that I made these moves is that the McGill University server that used to host this site was constantly being updated with new security and other features that were highly complex and incompatible with this site as I had originally designed it. In this post, I want to share the history behind my decision to migrate these sites. (more…)
From the Simple to the Complex | Comments Closed
