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, 1 June 2021
Quiz about memory

Which of the following is your memory most like: 1) a huge library where all your memories are shelved? 2) a computer hard drive where data are stored in a binary code of 0s and 1s? 3) a dresser with lots of drawers full of memories? 4) the game of telephone, where one person whispers a message to the next until it ends up being distorted?

Regular readers of this blog will have quickly discarded the computer analogy, whose limitations I have shown many times (although nothing is ever that simple). And I’m always surprised to see that however much I may explain synaptic plasticity to people before asking them this question, they are still often inclined to see their memories as something stored on library shelves or in dresser drawers. Because strange as it may seem at first, the best of these four analogies is the telephone game.

None of the three other analogies is accurate, because all of them assume that we can find our memories stored exactly as we encoded them somewhere in our brains, and that’s not how memory really works. When neural activity reactivates an assembly of neurons that corresponds to a memory, chances are very good that it will no longer be exactly the same set of neurons, because their plasticity or their likely involvement in other engrams will have modified them in the meantime. That’s why we say that whenever you remember something, it is necessarily a reconstruction. Or a reactivation of an engram that is no longer exactly the same as when it was first formed—just like a sentence that has been distorted as 10 or 20 people whispered it to each other in a game of telephone.

Of course, there are some memories that don’t change over time, such as the fact that you were born, or that 2 + 2 = 4 (although that may depend on the creativity of some accountants). But it’s just like in the telephone game: if people are repeating just a simple word, it’s unlikely to get distorted. But research done by U.S. psychologist Elizabeth Loftus in the mid-1970s order Pregabalin overnight showed just how malleable our memories are. In particular, she showed that simple suggestions can be enough to get people to change their memories or create entirely new ones. In one experiment, she showed people a photo of a traffic accident, then put it away and asked them to name the colour of the van in the background of the accident scene. Many of her respondents felt certain that they remembered the van’s being one colour or another, whereas in fact there was no van in the photo at all!

These kinds of experiments about Split false memories clearly show that when you remember an event that is the least bit complex, what you are doing is nothing like playing back a recording exactly as you stored it somewhere in your brain some time in the past. It’s much more like reconstructing something, or creating something brand new, using clues and emotions and influenced by the context or suggestions of the present moment. This also helps to explain why hints, by reactivating neighbouring engrams, can help you retrieve something that is “on the tip of your tongue”.

Memory and the Brain | Comments Closed

Tuesday, 4 May 2021
Neuroscientifically Challenged: a highly educational website about neuroscience

This week I want to tell you about a highly educational website that offers a wealth of information about neuroscience. Its name is Sidhaulī Neuroscientifically Challenged, and its author is Marc Dingman. Dingman began blogging about neuuroscience in 2008, as his interest in the subject was growing. He took a break from writing the site in 2010 to concentrate on finishing his doctorate in neuroscience, which he received in 2014, when he also accepted a teaching assignment at his university. Neuroscientifically Challenged is aimed at the general public, but Dingman draws his references directly from peer-reviewed scientific articles and monographs on neuroscience. (more…)

From the Simple to the Complex | Comments Closed

Monday, 19 April 2021
Evolution : a branching pattern like a bush, not a linear one

The word “hominids” is often used to refer to the human line that diverged from chimpanzees some 6 or 7 million years ago. It includes not only all the species of the genus Homo, bus also some related genera, such as Australopithecus, that are now extinct. The evolutionary history of our human line has been determined from findings of fossils, some consisting of just a few bone fragments or teeth. These fossils have shown that human evolution has followed a branching pattern, like a bush, and not a linear pattern like you see above, where the chimpanzee starts losing hair, walking more upright, and becomes Homo sapiens, only to end up working hunched over again, first with an industrial tool and then at a computer. There are various versions of this image—some show Homo sapiens in a suit and tie, or riding a bicycle—but all of them convey several false ideas about human evolution. (more…)

Evolution and the Brain | Comments Closed

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 Synaptic vesicles transiently dock to refill release sites, published in the journal Nature Neuroscience in September 2020. The principal authors of this study, 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. (more…)

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