After providing all the funding for The Brain from Top to Bottom for over 10 years, the CIHR Institute of Neurosciences, Mental Health and Addiction informed us that because of budget cuts, they were going to be forced to stop sponsoring us as of March 31st, 2013.

We have approached a number of organizations, all of which have recognized the value of our work. But we have not managed to find the funding we need. We must therefore ask our readers for donations so that we can continue updating and adding new content to The Brain from Top to Bottom web site and blog.

Please, rest assured that we are doing our utmost to continue our mission of providing the general public with the best possible information about the brain and neuroscience in the original spirit of the Internet: the desire to share information free of charge and with no adverstising.

Whether your support is moral, financial, or both, thank you from the bottom of our hearts!

Bruno Dubuc, Patrick Robert, Denis Paquet, and Al Daigen




Tuesday, 30 April 2024
The so-called second brain in your intestines

After I deliver lectures about the human brain, one question that people often ask me is, “Is there really a ‘second brain’ in my belly, and if so, how is that possible?” I have to tell them that for someone like me, who many years ago did his master’s research on an invertebrate—more specifically, on a marine mollusk called the sea slug—there’s nothing surprising about finding neurons in parts of the body besides the brain. Because, like my sea slug, the phylogenetically oldest animals on Earth began by having clusters of neurons (what are often called ganglia) in many different parts of their bodies. For example, the sea slug has ganglia in its mouth, feet, and brain (where the ganglia are no bigger than anywhere else) as well as in its abdomen . It was only later in evolution, and especially in vertebrates, that increasing cephalization occurred: a concentration of neurons in the rostral portion of the neural tube (in other words, in the head). But that doesn’t mean that the other neurons, such as those in the abdomen, disappeared!

We humans still have networks of neurons (known as plexuses) that are located in the walls of our intestines, that control our digestive systems, and that scientists refer to collectively as the enteric nervous system. These neurons can function independently (for example, to control peristalsis—the muscular contractions that move food down our digestive tracts), but are still subject to the influence of the vegetative nervous system.

Personally, I think that it’s a pretty big exaggeration to call the enteric nervous system a “second brain”. This system has only about 500 million neurons in all, which is about 175 times less than the 86 billion neurons in the brain, though still five times more than in the human spinal cord and and about two-thirds the number in a cat’s entire nervous system.

 

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Thursday, 4 April 2024
The Brain Is Not a Space Shuttle

Recently, someone made me aware of an impressive graphic that attempts to use current neuroanatomical data to show how the brain’s circuits are interconnected, somewhat like the graphics that biochemists use to represent cellular metabolism.

I have never before seen any schematic representation of the brain’s circuits that pulls together so much information, both in its detailed version and in its simplified version, which shows the brain’s main circuits in the sagittal plane. The box in the lower left-hand corner of this graphic states that the research required to develop it was done by an aerospace engineer who had worked on the design of the space shuttle’s guidance system and who spent over four years analyzing over 1000 neuroscientific studies to prep this schematic. (more…)

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