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




Monday, 2 January 2023
Theories of consciousness

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Today I’d like to tell you about an article that you really shouldn’t miss if you’re interested in the various theories of consciousness in the cognitive sciences: “Theories of consciousness”, by Anil K. Seth and Tim Bayne, published in Nature Reviews Neuroscience in May 2022.

The authors start by identifying some of the classic problems in the study of consciousness. The first is the question of subjective experience itself, or, as philosopher Thomas Nagel famously put it, “what is it like to be” you, or me, or maybe even a bat? Next is the distinction between these subjective, phenomenological properties of consciousness and its functional properties, if indeed it has any. For example, has consciousness been encouraged and shaped by evolution? Does it play a particular functional role in the complex architecture of our cognitive systems? And lastly, why do we become conscious of one mental image or other piece of content and not another? And why do any given neuronal states cause us to have particular types of auditory, visual or tactile experiences—or, as philosophers call them, “qualia”—rather than others?

After presenting a table of no fewer than 22 different theories of consciousness, Seth and Bayne go into a bit more detail on four major families of such theories (see diagram above).

Higher-order theories posit that a mental state is conscious if it is the subject of a meta-representation—in other words, when this state is a representation of other, lower-order representations, such as sensory ones.

Global workspace theories suggest that conscious mental states are those that are globally accessible to a wide range of cognitive processes, such as attention, evaluation, memory and language.

Integrated information theories associate consciousness with the degree of integration of information and its causal power in physical systems, thus positing consciousness as a fundamental property of systems. (I discussed this theory briefly in an earlier post, available only on the French version of this blog.)

Theories of re-entry and predictive processing emphasize “top-down” influences in brain networks—in other words, the facilitating and modulating effects that central processes have on sensory inputs.

The authors then go on to evaluate these various approaches.

The Emergence of Consciousness | Comments Closed


Tuesday, 13 December 2022
The Dog Vision

The Dog VISION website pulls off the neat trick of giving you some idea of how dogs see the world. As you probably know, every species of animal has its own particular set of sensory systems through which it perceives not THE world but rather ITS world. Thinkers such as James Gibson (pp. 26-34) and Francisco Varela (pp.191) developed their ideas about this relationship between an animal’s body and its environment in the 1970s and 1980s, drawing on the pioneering work of Jakob von Uexküll and his landmark book A Foray Into the Worlds of Animals and Humans, published in 1934. All of these biologists, psychologists and philosophers (I’m also thinking of Thomas Nagel and his famous paper, “What Is It Like to be a Bat?” ) have warned us against the ready temptation to assume that other species of animals have the same relationship with the world that we do. For example, Varela, who studied colour perception extensively, liked to say that every species “lives in its own chromatic space” and that for any given species, this space is not necessarily optimal, but has simply proven adequate to ensure the survival of that species to the present time. (more…)

The Senses | Comments Closed


Monday, 21 November 2022
Zebrafish brain images may reveal neuronal bases of emotional memory

As is well known, memories with heavy emotional connotations—especially negative ones—are very strong. In extreme cases of post-traumatic stress, such memories can be so recurrent and intrusive that they make life a living hell. In mammals, the brain structure most highly involved in such negative memories is the amygdala. But while much research has been done on the hippocampus, which is the brain structure involved in spatial, lexical and other forms of memory, the amygdala has received much less attention, in part because it is so hard to access. To get around this problem, a research team at the University of Southern California, in Los Angeles, used larval zebrafish and a fluorescence-based imaging method to visualize the changes that occurred in the synapses of the pallium (the fish brain structure equivalent to the amygdala) after aversive conditioning. The surprising results were published in the journal PNAS in January 2022, in an article entitled “Regional synapse gain and loss accompany memory formation in larval zebrafish”. (more…)

Memory and the Brain | Comments Closed


Monday, 31 October 2022
A set of stunning animations

Today I want to let you know about a set of stunning animations produced by the DNA Learning Center, which was founded by the Cold Spring Harbor Laboratory in 1988 to educate the general public about issues related to genetics. The DNA Learning Center’s Biology Animations web page contains some 50 animations about DNA, RNA, proteins and their complex interactions. Most of these animations are just a few minutes long, and all of them are are so realistic that they take your breath away—a far cry from the 2D and 3D animations that you may have seen where everything is smooth and steady and all the colours are uniform. Instead, in these animations, everything moves and pulsates, as if you were moving through the living molecular jungles inside the tiniest human cells. (more…)

From the Simple to the Complex | Comments Closed


Monday, 10 October 2022
A free neuroscience textbook

Today I want to tell you about an excellent neuroscience textbook that you can read online absolutely for free! Neuroscience: Canadian 2nd Edition Open Textbook” is a very complete, typical undergraduate-level treatment of its subject, divided into four units: 1. Neuroscience: The Basics; 2. Neurodegeneration; 3. Fundamental Neuroscience Techniques (and when to use them); and 4. Emergent Topics in Neuroscience. Unit 1 covers not only the anatomy and physiology of the entire nervous system, but also those of the system, which is so closely linked to it. Unit 3, on neuroscience techniques, is fairly extensive, explaining highly complex techniques such as optogenetics. Unit 4 delves into subjects that are getting a lot of attention from cognitive scientists today and that you’d never have seen in a neuroscience textbook 10 or 20 years ago, such as the beneficial effects of art, exercise and meditation on the brain. The book also includes quiz questions and links to videos on other websites. (more…)

From the Simple to the Complex | Comments Closed