Melitopol’
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




Friday, 26 November 2021
Study on the intrinsic, dynamic activity of the brain confirms a very general principle of its organization

Scientists have known for some time that for our brains to perform any given task, a very short-term sensory memory function must co-operate with some of our longer-term memory functions. Scientists have also known that such encoding on various time scales is correlated with the frequencies at which the neurons oscillate in the associated parts of our brain, ranging from high frequencies in the sensory cortical areas to very low frequencies in the multi modal associative areas. But in an article entitled http://paramountexterminating.com/common-pests/pest-library-bed-bugs-and-other-biting-pests/ Hierarchical dynamics as a macroscopic organizing principle of the human brain, published in the journal PNAS in August 2020, authors Ryan Raut, Abraham Snyder and Marcus Raichle showed that this important principle can be generalized not only to the entire cortex, but also to several sub-structures within it. Throughout all of them, the temporal profile of the spontaneous oscillations in the brain seems to be structured along gradients starting in the high-frequency sensory areas and proceeding to multi modal, higher-function areas where the oscillation frequencies are far lower.

These findings are interesting for reasons that vary from one part of the brain to another. With regard to the cortex, they confirm all sorts of other studies suggesting the existence of such a gradient, which also happens to match the way we subjectively experience the world. To follow the constant, extremely rapid changes that occur in our environment, we do not need to remember their tiniest fluctuations. Imagine yourself walking along a tree-lined lakeshore on a beautiful, windy summer day. Everything around you is moving—the leaves, the trees, the reflections on the water, the trail that passes beneath your feet as you walk along, and so on—but you’re never going to remember all those details. However, if the sky suddenly clouds up and you start hearing thunder, you might well dig into your long-term memory, recall that these are signs of an approaching storm, and come up with a plan A or a plan B in case it starts to rain hard. All of these fairly high-level mental-simulation processes involve much lower brain-wave frequencies.

But this study’s most important new contribution is to show that even though the main sub-cortical structures in the brain—the striatum, thalamus, cerebellum and hippocampus—differ greatly from one another in their neuronal architecture and functional anatomy, they all seem to be organized along such gradients in the frequency of dynamic neural activity, which they generate spontaneously. The illustration at the top of this post shows how these gradients are manifested spatially in each of these four structures. Moreover, these gradients reflect exactly what we already know about the functional organization of each of these structures. This study thus sheds light on some principles of the organization of the human brain that appear to be very general and that involve the dynamic aspect of neural activity, which researchers too often neglect.

From the Simple to the Complex | Comments Closed


Monday, 8 November 2021
An example of the importance of our brain rhythms

A large majority of the neurons in the human brain display rhythmic activity patterns—in other words, they send out one nerve impulse, then go quiet, then send out another nerve impulse, and so on. These patterns, which have different frequencies, are one of the neurons’ preferred means of communicating with one another. But unfortunately, college and university neuroscience textbooks discuss the brain’s neural rhythms only very superficially, even though they are actually starting to shed light on many different scientific mysteries. One good example is the consolidation of learning, which is associated with certain types of neural activity in the hippocampus. That’s just about all that a lot of textbooks have to say on the subject—nothing about what specific mechanism might be involved. Or you might read that your recently acquired memories are consolidated while you’re asleep or reconsolidated when you retrieve them, and that the hippocampus is somehow involved, but that’s it. (more…)

Memory and the Brain | Comments Closed