Nicole RustPicking up on some of the BIG IDEAS in brain research, which was wonderfully chaotic when we last discussed in December under the hashtag #BrainIdeasCountdown, e.g. https://neuromatch.social/@NicoleCRust/109557289393362842
Here's an attempt to fill in some blanks, and let's flip the hashtag: #BigBrainIdeas. I'll focus on the notion that there are facts, ideas and then there are "Big Ideas" and I'll focus on the last one. Please join in!
I'd argue that one of the most influential Big Ideas about the brain in the latter half of the 20th century is the is the notion that:
The neocortex of the brain is made up of a generic functional element that is repeated again and again and from this repetition, all of cortical function emerges
I'm talking about the cortical column, first described by Vernon Mountcastle in 1957. The unit contains ~10K neurons and humans have ~25 million of them. The rapid evolution of humans is proposed to have followed from a rapid expansion of cortex that happened because of this repetitive crystalline structure. The gist behind the "functional" bit is that each unit always does the same generic computation, and the different functions of different brain areas result from the different inputs that these units receive. @TrackingActions very nicely summarizes the ideas here: https://www.nature.com/articles/s41583-022-00658-6
So what does this generic functional unit do? Proposals vary. One idea, also reflected in deep convolutional neural networks, is that it does two(ish) things: selectivity and invariance, stacked repetitively to support things like recognizing objects. Other proposals suggest that the brain is a prediction machine and each unit contributes a little bit to those predictions in a manner that relies not just on feedforward connectivity, but also feedback. Some proposals suggest that the function of the unit varies along a gradient as a consequence of biophysical properties like receptor expression: https://www.nature.com/articles/s41583-020-0262-x.
Among brain researchers, this Big Idea is polarizing - obvious to some and misguided to others. Where are you in terms of your 'buy in' with this big idea?
#neuroscience #psychology #neuroAI #cognition @cogneurophys #BigBrainIdeas
Nicole Rust (@[email protected])
Here's a slightly more provocative way to pose the question: In The Idea of the Brain, Matthew Cobb argues, "In reality, no major conceptual innovation has been made in our overall understanding of how the brain works for over half a century ... we still think about brains in the way our scientific grandparents did." Setting aside semantic debates about what constitutes a "major conceptual innovation", brain researchers are clearly working on a large number of ideas that their grandparents had not thought of. But what are those, exactly?
Brad Wyble
Yohan John 🤖🧠
Earl K. Miller