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, 27 May 2014
The Variety and Structural Complexity of Neurons

The purpose of most of the posts in this blog is to summarize recent studies in the cognitive sciences and attempt to make them more accessible—in particular by providing links to selected pages on this website. But the purpose of some of the other posts is simply to draw attention to existing resources on various aspects of neuroscience. Today’s post falls in the latter category. It deals with the neuron and the work by Kristen Harris and her colleagues to reveal it in all its complexity (see the first two links below).

Neurons are like any other cells in the human body, except that they have two special characteristic structures that let them carry out their communication function: long extensions called axons, of which there is typically only one per neuron, and multiple branches called dendrites, which are generally shorter. The combinations of various shapes and sizes of axons and dendrites results in hundreds of types and sub-types of neurons, some of them quite remarkable esthetically. The catalogue of these structures is growing every day, thanks to increasingly sophisticated staining methods.

The shape of any particular neuron is determined largely by its pattern of connections with other neurons, which in turn depends on the function of the neural pathway in question. All of these structures are first laid down while the embryo is developing in utero, and then, after birth, they are shaped continuously by the individual’s interactions with the environment. Those neural pathways that do not get used very much are gradually eliminated, while those that get used a lot strengthen their connections, sometimes even modifying the complex microstructure of the dendritic spines (see the video at the first link below) so that the synaptic contact between two neurons becomes more intimate.

But what is really staggering is not so much the unique, highly complex, three-dimensional sculpture that every neuron represents, but rather that every individual has about 85 billion more of them, hundreds or thousands of which interact with it.

d_lien Waltz through hippocampal neuropil
a_lien SynapseWeb – Anatomy
i_lien Neurons: A Curious Collection of Shapes and Sizes

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