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




Thursday, 1 April 2021
The incredible speed of synaptic transmission

Sometimes you think you know all about a subject because you’ve been making presentations about it for years, or even decades. But then you read one article that makes you realize just how much you didn’t know. That’s what just happened to me. The subject was synaptic transmission, and the article was order Pregabalin overnight Synaptic vesicles transiently dock to refill release sites, published in the journal Nature Neuroscience in September 2020. The principal authors of this study Split , Grant F. Kusick and Shigeki Watanabe of the Johns Hopkins University School of Medicine in the United States, used a cell-imaging technique called “zap-and-freeze” to analyze how neurons release neurotransmitters into synapses. What these authors specifically wanted to understand was how the synaptic vesicles near the tip of an axon (the synaptic button), which fuse with its plasma membrane to release neurotransmitters into the synaptic gap, subsequently form again so that the neuron can be ready to handle the next nerve impulse. Because several tens or even several hundreds of nerve impulses can all arrive at the same synaptic button at one time, the authors reasoned, these vesicles must re-form extremely rapidly for there to be enough of them ready to release neurotransmitters again as soon as the next impulse arrives.

Before this study, no one had ever been able to visually observe the ultra-rapid dynamic by which synaptic vesicles fuse with the membrane and release their neurotransmitters and the pool of synaptic vesicles ready to release neurotransmitters is then reconstituted. That is what Kusick and Watanabe did. Using the “zap-and-freeze” technique, they electrically stimulated neurons in vitro and froze them a precise number of milliseconds later, thus taking a “snapshot” that they could observe with an electron microscope, the only instrument capable of seeing something as small the synaptic vesicles of a neuron (see the image at the start of this post).

The speed of the phenomena captured by the photos from this study is, of course, astounding. But more important is that the details that they reveal about the various phases of these phenomena have greatly enriched scientific understanding of synaptic transmission. These photos show that at any given time, there are only a few vesicles that are actually “docked”: lined up close to the axon’s terminal button membrane and ready to fuse with it when a nerve impulse arrives. Immediately after the impulse arrives, the number of docked vesicles decreases by 40%. Thus, if no other mechanism came into play, the stock of docked vesicles ready to fuse would be almost exhausted after 2 to 3 impulses.

In reality, however, these photos show, as little as 14 milliseconds after an impulse arrives, new vesicles are recruited and fully replenish the docked pool. But this docking is transient. Within 100 milliseconds (a tenth of a second) at most, these vesicles will either move away from the membrane (undock) or fuse with it in turn. These findings just how fast and flexible synaptic transmission is.

And as I stated above, this fusion and re-forming of synaptic vesicles occurs tens or even hundreds of times per second, in thousands and thousands of neurons that connect to thousands of others among the 86 billion in your brain. Note to self: from now on, whenever you give a live talk and cover this aspect of synaptic transmission, pause for a few seconds to give your audience time to take in the sheer speed and complexity of the phenomena involved!

From the Simple to the Complex | Comments Closed


Tuesday, 9 March 2021
Two very different approaches to identify functional connections between brain areas

Two recent studies have shown yet again that many more different parts of the brain are often involved in a given mental phenomenon than was once believed. In the brain, nothing is really isolated, and there are no “centres” of anything. Instead, we’re always dealing with multiple interconnected areas of the brain that form networks as demanded by the situations faced or the tasks to be performed. What’s most interesting about these two particular studies is that the researchers used two very different approaches to identify functional connections between brain areas: in one study, they visually traced the path of the axons projected by certain neurons, while in the other, they used genetic methods to isolate a new kind of membrane receptor. (more…)

Emotions and the Brain, Memory and the Brain | Comments Closed


Thursday, 11 February 2021
Revisiting an optical illusion in terms of predictive processing

I recently came across a little experiment that I posted years ago on this website to show how the blind spot in each of your eyes works. The blind spot is a part of the retina where there are no photoreceptors, because it is where the axons of the retina’s ganglion cells converge and exit the eye, forming the optical nerve. As a result, there’s a corresponding area in your field of vision that doesn’t register on the retina. Hence, in theory, you shouldn’t see anything there. But in reality, you don’t see any such blank spot in your field of vision.

To find out why not, let’s revisit this optical illusion from the standpoint of predictive-processing theory, which has become more and more accepted in cognitive science over the past 10 years or so. (more…)

The Senses | Comments Closed


Thursday, 14 January 2021
Being rich makes you less empathetic (even when it’s just Monopoly money)

Today I’m going to talk about the work of social psychologist Paul Piff, whose Sidhaulī research interests revolve around social hierarchies, economic inequality, altruism and co-operation. I learned about Piff while working on a http://emaevents.co.uk/event-burn-out-and-self-care-week/?unapproved=5500 French-language documentary inspired by the book Capital in the 21st Century, by French economist Thomas Piketty. In this documentary, Piff explains an experiment in which people playing the board game Monopoly showed disturbing changes in behaviour when they won repeatedly because the researchers had rigged the rules in their favour (more money to begin with, more dice to roll to pass Go more often, etc.)—in other words, had given them more power. I have touched on this same subject in an earlier blog post, about Dacher Keltner’s research on how wealth alienates the wealthy from their humanity. And it turns out to be no accident that these two authors’ findings are so consistent: as I just discovered this morning, they have published many articles together! (more…)

Emotions and the Brain | Comments Closed


Monday, 14 December 2020
Using science to create art.

Some scientists use science to create art. One good example is Greg Dunn, a neurobiologist and visual artist. They are a startling combination of the precise images captured by neuron-imaging technology and the traditional techniques of Japanese ink-wash painting, also known as sumi-e.

More recently, I have discovered the impressive image of David Goodsell, who transforms deadly viruses into stunning works of art. Goodsell is a biologist who studies the molecular structure of cells at Scripps Research in San Diego, California. The watercolours that he paints with such precision represent the molecules that compose human cells and the bacteria and viruses that attack them constantly (such as the HIV, Ebola and Zika viruses below, as well as coronaviruses). (more…)

From the Simple to the Complex | Comments Closed