3 ms·

Let's call the phenomenon you seem to dismiss as obvious and uninteresting, that neurons "right on top of each other" have similar receptive fields, 'minicolumn

Let's call the phenomenon you seem to dismiss as obvious and uninteresting, that neurons "right on top of each other" have similar receptive fields, 'minicolumns.' These exist consistently across the cortex. We've mapped out their shape and connections. This is what one looks like https://www.youtube.com/watch?v=jmdPOaTpZWA https://www.youtube.com/watch?v=jmdPOaTpZWA (this even links to the paper you cited but calls them 'cortical columns'). Let's call the larger column structures with significant horizontal coverage posited by Mountcastle 'hypercolumns.' As you and others have noted these seem to be limited or non-existent. As I've said thanks to updates to our technology we've refined the idea of 'cortical columns' into a class which doesn't have useful explanatory power ('hypercolumns') and one which does ('minicolumns'.) The vertical integration of processing across layers of cortex by a collection of neurons is IMO of significant interest and import. You may disagree, but please don't pretend that these structures don't exist.

georgewfraser 5y ago
The fact that neurons on top of each other have similar firing properties is very interesting, and is indeed a uniform organizing principle of the cortex. Calling this “minicolumns” is very misleading because it implies some level of horizontal organizational structure. That is not a universal organizational principle of the brain—it exists in certain areas, in certain species. It’s an accident of history that a lot of the early neuroscience in mammals was done in primary visual cortex in macaques and primary sensory cortex of rats and mice, which do work like this (though at very different spatial scales). This led to the hypothesis of the “cortical column” as a universal, intermediate level of structure in the cortex, but when you look at other areas they just don’t work like that. However this idea is so attractive that it just won’t die. Meanwhile, cortical column fans (including neuroscientists!) engage in a motte-and-bailey argument, where the bailey is “the cortex is divided into columns that represent an intermediate level of modularity” and the motte is “neurons on top of each other usually have similar firing properties”.

georgewfraser 5y ago

The fact that neurons on top of each other have similar firing properties is very interesting, and is indeed a uniform organizing principle of the cortex. Calling this “minicolumns” is very misleading because it implies some level of horizontal organizational structure. That is not a universal organizational principle of the brain—it exists in certain areas, in certain species. It’s an accident of history that a lot of the early neuroscience in mammals was done in primary visual cortex in macaques and primary sensory cortex of rats and mice, which do work like this (though at very different spatial scales). This led to the hypothesis of the “cortical column” as a universal, intermediate level of structure in the cortex, but when you look at other areas they just don’t work like that. However this idea is so attractive that it just won’t die. Meanwhile, cortical column fans (including neuroscientists!) engage in a motte-and-bailey argument, where the bailey is “the cortex is divided into columns that represent an intermediate level of modularity” and the motte is “neurons on top of each other usually have similar firing properties”.