The Annual Society for Neuroscience (SfN) meeting features the latest discoveries in brain research, from the basic mechanisms to translational and clinical studies. Here are some highlights from the conference.
This year, the conference celebrated its 50th anniversary in the "Windy City," Chicago, IL, USA. Unsurprisingly, this convention attracted close to 30,000 delegates around the workings of the brain, "the universe between your ears" unassuming but possibly, the most complex structure of the universe.
A zoo of brains
We must humbly acknowledge that much of what we know about the structure and function of the human brain today has been extrapolated from decades of studies on rodent models, lower vertebrates, and indeed, even invertebrate nervous systems. The 50th SfN reported on a "zoo" of Daphnias, inebriated fruit flies, severed zebrafish spinal cords, and RNAi-knocked roundworms, having had specific populations of their limited subset of neurons knocked out by RNAi.
"I think; therefore I am?"
The purpose and function of the brain have kept philosophers busy for hundreds of years. We live in fascinating times where we can finally design and make the tools and skills to embark on the global mapping of the detailed molecular identity and projections of every single neuron and glial cell in the human brain.
Overwhelmed by complex data sets, we are now in a state of ordered confusion and, at best, a fragmented knowledge about how the brain wires and connects the "connectome." Still, we cannot define consciousness without referring to metaphysical metaphors, like Christof Koch at Allen Brain Atlas. He supports a reductionist view, simply stating that consciousness can be confined to a limited circuit of neurons in the brain. It is a fascinating prospect that the neuroanatomists Golgi and Cajal at the turn of the 20th century, thought they had it all figured out by showing their ingenious silver impregnation methods able for the first time to discern sub-cellular details about the normal and pathological micro-anatomy of the brain.
The main conundrum of that day was whether the neurons were continuous or interconnected by what we today define as synaptic contacts. However, it is self-evident that it is not enough to know how single neurons work and fire together in isolation to understand the matter that builds up our minds.
The neuronal mosaic
As it has turned out, neurons exhibit striking and stochastic cellular diversity. How is this diversity generated? This is exceedingly difficult to study since neurons are diverse, subtypes intermingled, and fail to divide, plus the fact that single-cell approaches have limited resolution.
The frequent occurrence in the human brain of "brain only" somatic mutations absent from blood DNA may surprise most and may occur from the first cell division till the last. Single-cell genomes can differ by hundreds of mutations from one neuron to the next neighboring nerve cell, causing somatic "mosaicism."
Autistic Spectrum Disorder, ASD shows excess mutation frequency in critical exons of genes expressed in the early brain compared to normal siblings. De novo somatic mosaicism occurs in neuropsychiatric disorders, as can be exemplified by the somatic activation of the AKT3-mTOR pathway causing hemispheric developmental brain malformations.