Basic system level diagram of the brain

HTM seeks to model and understand what is going on in your head.

I tossed this drawing together from memory so it is sure to be missing some connections. I skipped the thalamic connections all together as this was already a very complicated drawing. Also not shown are the connections between the limbic system and the stream passing through the brain stem and the cerebellum. These are important but not necessary to illustrate the basic cortical/limbic data flows. The blue maps are cortex composed of HTM processing modules. The orange modules are some of the key sub-cortical structures.

The blue connections in the various sensory streams are essentially in parallel form.
The broad green hub connections connecting the various highest levels in each lobe are also parallel.
We can quibble about details but it is clear that as data course from area to area it stays in a mostly parallel form. The maps of the various sensory fields, while “crazy quilted,” are preserved in the hierarchical processing.

So where does this all this parallel data come together?

First - I coded the data transformation connections in orange; these may not be what you could consider parallel. When you consider the limbic system the connections look different.

The EC/HC complex has some scaling where representations in multiple scales exist, but each maintains topography. The rest of the limbic system does not look anything like the cortex. The processing models look more like the classic Boltzmann network. Or perhaps a Hopfield Network? What is presented to the lower brain “wraps around” the complexes, transforming the topographic representation into a “spherical input” form. The limbic clusters don’t work the like the cortex so it should not be surprising that the topological format is transformed as the data is conveyed. The connections between the inputs to the limbic system and outputs to the prefrontal cortex all do some data rearrangement to make the data formats compatible.

The cortex prepossesses the senses into a form compatible with the older brain structures and after the lizard brain does it’s processing it projects commands to the prefrontal cortex to be elaborated into actions. These actions could be directed to further internal or external data gathering or into motor drives that move the body.

You can think of the level of processing of these lower brain structures somewhat like what a moth does in flying up to the light in response to all the cues that signal mating time. In the moth genetics have tuned it to fly up to the moon to mate; genetics did not plan for porch lights. With our big brains these old senses and drives are vastly enhanced. These senses should be better at processing sensory cues and turning those drives into suitable action plans. I call this my dumb boss/smart advisor model.

At the lowest levels to the forebrain, the output fibers don’t project to the body, they project to the temporal lobes to be experienced as “thinking” and “recall.” This is really the same thing as the lower brain structures pointing the eyes thought the FEF (frontal Eye Fields) to look at things of interest, but this part is all internal to the brain. These recalled memories are then experienced by the temporal lobe, hippocampus, and related structures in a loop of experience we call consciousness. The blue parts are available to consciousness, the workings of the limbic system are not.

Some of these forebrain activities may result in the selection and production of motor activity - words and actions. These are all stored motor programs that are being called into play, customized by the recalled memories and drives from the limbic system/forebrain. The networks in the various areas settle into states where there is the least “conflict” between the competing activation patterns. Experienced AI researchers will recognize this as a relaxation computing process mediated locally using attractor networks.

This basic layout or something similar should be a path to AI that has what looks like intelligent behavior.


Thanks Bitking for sharing this with us!

I have a few questions:

  • How is the neocortex connected to this older brain strucures? Do these structures connect to the thalamus, or use L4 and L5 as input and output, or do they connect like inter-cortex connections in L2/3? Is it more like driving input, or modulatory input.
  • Can you predict phenomenons, that are produced when disturbing this system. E.g. when applying a specific neurotransmitter, or having a lesion in a specific area, then …

You ask some huge questions not easily answered.

You are asking about the fundamental operations of the most complicated structure known to mankind. The detailed answers could easily fill volumes of textbooks. I will try to hit the highlights here but but I am warning you ahead of time - while this is a very long post I am leaving very much unsaid and unexplained. Let’s start with your first bulleted item.

The thalamus is broadly interconnected with the cortex at all points. Some have described this as the seventh layer of the cortex but that is much too simple. The connections to the body pass through the thalamus to the cortex. There are connections paths between the cortex and the thalamus. Numenta is starting to work in this area. See this thread for more details.

The thalamus also drives a basic heartbeat function that binds activity patterns together. This post addresses part of your question about layers and the thalamus:

Possibly the best description that I have read on the interactions between the thalamus and the cortex is in this paper. It’s a demanding read but well worth the effort. It addresses more of the question about layers and the thalamus:

So on your question regarding information vs modulation - all of the above.

I have been addressing various details of how all these bits work together in the forum for a long time. You can take this collection of posts together as loose documentation of how I see these parts working together. These papers start to address your prediction question; since it describes the basic operations and interactions of the parts it is possible to describe what will happen if you interrupt those functions:

Everything up to this point has been the answer to the thalamus & cortex part of your question

A major sub-cortical structure is the cerebellum
While it is often thought of as connecting movements together to convert the parallel motor commands from the cortex into smooth sequential commands down the spine, it also feeds back into the brain to make our thought coordinated.

How about those other sub-cortical structures?
I refer you to this post. You will have to click-through this to see the nested links.

What are those subcortical structures?

What do they do?

And what are the subcortical connections to the body and its sensors?

More on the “orange part” of the block diagram here:

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