The neocortex [1] is on average 3 millimeters thick, has an area of around 1500 square centimeters, has more or less 15 billion neurons, and is organized in approximately 150,000 vertical circuits called cortical columns [2].
Each cortical column occupies an area of about 1 square millimeter, must have, on average, 100,000 neurons, and is organized in 6 horizontal layers [3].
These layers receive inputs, process information internally, interact with each other, and then send their outputs to other areas of the brain.
Apparently, cortical columns are the functional units or minimal circuits in the neocortex, and neurons [4] are the minimal units of computing in the brain. All cortical lobes and sub regions are made of roughly the same circuits, and all work in a similar way [5].
They interact with adjacent columns, or other areas of the neocortex, with the thalamus, and the basal ganglia in loops [6]. They have a variety of neurons that have different functions such as the definition of location, shape, orientation, displacement, and other features of objects [7].
These objects may be physical in the environment (e.g. a cup, rock, car, ball, etc.) and captured by the senses, or abstract (e.g. imaginary shapes in euclidean space, objects, or constructs such as time, love, democracy, etc.) as recreated in the circuits.
There has been a huge amount of research about these topics since the 1950s [8]. It seems, according to my limited exposure to this branch of knowledge, the consensus, albeit with some objections [9], is that the above is roughly how the neocortex works.
However, there seem to be no real breakthroughs in how thoughts are created, how logic, emotions, and reason work, or how the cortical columns are structured and function in detail.
Some types of neurons are identified, others are not well known, and others are hypothetical or speculated. For example, that grid, motor, and displacement cells all reside directly in the cortical columns [10], and other theories.
However, I speculate two things:
1. As the neocortex has the capacity to store data, process, and make fully formed computations in great quantities; but the resources of the body are limited (e.g. the limbs, organs, senses, etc.); and the intermediary relay and association parts of the brain (e.g. basal ganglia, thalamus, association areas, etc.) are adapted to manage those limited resources; we tend to have a limited capacity to think and process things in parallel.
In other words, just as action selection in the brain chooses the next action out of competing candidates [12], the same must happen with ideas and thoughts as they can’t all be processed simultaneously.
I think this is seen, for example, in basic tasks as higher order thinking limitations, orders of intentionality limitations [12], subitizing [13], how many close friends we have, the limited number of terms in a large number of math, physical, chemical, financial, and other equations [14], etc.
It seems the human brain’s ability to think in parallel is limited, on average, to a range of four to six objects, abstract or physical, at the same time.
2. By genetics and by experience (culture) we have thousands, or millions of schemas (rules) [15] in our brain, coded in the neocortex and many other areas such as the cerebellum, amygdala, etc. These schemas, associated with the current state of the environment as informed by our senses, together with the regular operation of neurotransmitters and hormones, as programmed for those circumstances, push our computations, thus our behavior, in certain directions.
In other words free will does not exist.
We have a sort of feeling or emotion that every conscious action is the product of our will, but in reality it is the other way around: Our brain spontaneously generates an impulse, for example “I am hungry”; then a series of computations and associations occur; then a series of actions and perhaps mental operations are ordered and executed; and then we end up eating a sandwich.
We experience the emotion of “decision” as if we effectively made decisions, but those emotions are post facto. In other words, the brain ordered us to eat a sandwich and then “convinced” us that we “decided” to do such action.
The above may be originated in the environment as well (which must have been the original format in evolution and most common in most animals, including humans). For example, where the organism smells food; the sense of smell is passed through the thalamus and is relayed to the neocortex; the neocortex processes the information; the information is sent back to the thalamus and basal ganglia for affirmation; and, finally, a series of actions are ordered that end up in the organism eating a sandwich.
Totally convinced that it was his or her free will.
References
[1] Neocortex – by Wikipedia: https://en.wikipedia.org/wiki/Neocortex
[2] The columnar organization of the neocortex – 1997 – by Vernon B. Mountcastle: http://etherplan.com/the-columnar-organization-of-the-neocortex.pdf
[3] Review of Clinical and Functional Neuroscience – Chapter 11 – The Cerebral Cortex – Dartmouth.edu: https://www.dartmouth.edu/~rswenson/NeuroSci/chapter_11.html
[4] Neuronal cell types – by Richard H. Masland – Cell.com: https://www.cell.com/current-biology/pdf/S0960-9822(04)00440-3.pdf
[5] Jeff Hawkins at the Johns Hopkins APL Colloquium Series – A Framework for Intelligence and Cortical Computation: https://youtu.be/pmIs9Eh08gA
[6] The Basal Ganglia – Direct and Indirect Pathways – by Brains Explained: https://youtu.be/NcIWYCkKwVA
[7] A Theory of How Columns in the Neocortex Enable Learning the Structure of the World – by Jeff Hawkins, Subutai Ahmad and Yuwei Cui: https://www.frontiersin.org/articles/10.3389/fncir.2017.00081/full
[8] Nature Magazine, February 18th, 2015:
“He [Vernon Mountcastle] published a landmark paper describing these discoveries in the Journal of Neurophysiology in 1957. This was quickly followed in 1959 by four papers co-authored with Tom Powell, an anatomist at the University of Oxford, UK, showing that the macaque monkey cortex had a similar organization. Mountcastle’s discoveries alerted his neighbours at Hopkins, David Hubel and Torsten Wiesel, to look for columns in the primary visual cortices of cats and monkeys, which they found a few years later.”
Vernon B. Mountcastle (1918–2015): https://www.nature.com/articles/518304a
[9] The cortical column: a structure without a function – by Jonathan C Horton and Daniel L Adams: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569491/
[10] Does the Neocortex Use Grid Cell-Like Mechanisms to Learn the Structure of Objects? – by Jeff Hawkins of Numenta, at the Simons Institute: https://youtu.be/zVGQeFFjhEk
[11] Basal ganglia action selection – by Scholarpedia, curated by Tony J. Prescott: http://www.scholarpedia.org/article/Action_selection#The_basal_ganglia
[12] The Social Brain Hypothesis – by Robin I.M. Dunbar: http://etherplan.com/the-social-brain-hypothesis.pdf
[13] Subitizing – by Wikipedia: https://en.wikipedia.org/wiki/Subitizing
[14] Using Genetics and Brain Capacity to Model Reality – by Donald McIntyre: https://etherplan.com/2020/10/08/using-genetics-and-brain-capacity-to-model-reality/12920/
[15] Schema (psychology) – by Wikipedia: https://en.wikipedia.org/wiki/Schema_(psychology)
