I’ve written numerous times here that I tend to think that AGI (artificial general intelligence) and mind uploading are both ultimately possible. (Possibly centuries in the future, but possible.) I’ve also noted that we’ll have to have a working understanding of the mind, how it works, how it is structured, before we can do either, but that gaining that understanding is possible.
I often get push-back on this idea. One of the arguments I commonly hear is, perhaps the mind doesn’t have a structure. Maybe it’s just an unstructured mess from which our consciousness arises, or the structure may be so complicated that it’s forever outside of our ability to understand it.
I think this is unlikely, for two reasons, one broad and one narrow.
The first broad one is that everything else in biology follows recognizable systems and subsystems and has a systematic structure that we’ve been able to discover. (Think organs in a body or cell machinery.) Many of these systems are profoundly complex, but they haven’t shown themselves to be undiscoverable. Arguing that the mind is unstructured is arguing that everything is systematic until we get to the mind, then the rules change. It’s possible, but doesn’t seem likely to me.
To discuss the second more narrow reason, it’s necessary to mention a couple of facts about brains. Before I started reading neuroscience, I thought of the brain as a computer, and the mind as the software of that computer. This is a common conception held by many programmers and other people knowledgeable about computing. While it could be broadly true, there are some crucial caveats to keep in mind.
The division between hardware and software is an innovation of modern computing. Interestingly, the earliest electronic computers didn’t fully have that division, often requiring physical rewiring to be reprogrammed. The ability to load and reload new software dramatically increased the flexibility and usefulness of computing systems.
This ability is why, when we speak of the architecture of an operating system or application software, such as Microsoft Windows, we generally do so without reference to the hardware that it’s running on. To be sure, the architecture of an operating system does address the hardware, in the case of Windows with an architectural layer called the HAL (hardware abstraction layer). The HAL and device drivers deal directly with the hardware so most of the software system doesn’t have to.
In addition, modern hardware includes a system bus, a mechanism that allows any component of the system to talk to any other component without regard to how near or far it is on the system board. And memory chips are random access, generally allowing any desired memory location to be accessed by a memory address.
For these reasons, pointing to a specific part of a CPU or memory chip for a piece of Windows functionality is a meaningless exercise. Yes, the code that implements that feature does physically exist transitorily in those chips, but the exact location of that code right then is not particularly meaningful. It’s exact location varies for a wide variety of reasons, from the timing of when it was loaded, to various transitory needs of the operating system.
It’s often noted that if we didn’t understand software, examining computer hardware in the same way we typically examine the brain would tell us very little about the software architecture. And that is right, if brains worked like modern computers.
However brains don’t work like that. There’s no mechanism to reload software and no system bus. The hardware-software divide doesn’t exist. To be clear, there’s extensive evidence that brains are information processing systems, but their architectures are very different from general purpose digital computers.
What this means is that specific functionality in the brain exists in specific locations. The functionality in most locations depends on what’s connected to that location. For example, vision processing happens in the occipital lobe. It doesn’t happen there because there’s anything necessarily special about the neurons in the occipital lobe, but because that’s where the vision processing nucleus of the thalamus connects to, and that nucleus does vision processing because that’s where the connections from the eye retinas go.
The same applies to the other processing centers in the brain. The parietal lobe processes touch sensations from throughout the body, with specific parts of the parietal lobe dealing with specific body parts. The temporal lobe processes auditory information, the frontal lobe plans and initiates movement, the cerebellum provides fine motor coordination, and so on. The parts of the brain that process sensations from feet are always in the same location. The parts that recognize certain visual shapes or colors are also generally in the same location.
There is some variance between individual brains. For instance, the language centers are usually in the left hemisphere of the brain but a few people have them on the right side. (The functionality of the two hemispheres, each controlling half of the body, is similar but not identical.) But these variations are rarely major. The location of functionality is dependent on where the connections from the senses come in, where the motor control connections come out, and where connections from other brain regions connect, and all of that is similar in individual brains of the same species.
Of course, the brain has plasticity, so if someone is blind during development, many of the neurons that typically service vision, in the absence of any signals from the eyes, can get recruited to help in the processing going on in adjacent areas. But in a healthy person, the majority of the functions can be physically identified to a specific part of the brain.
Now, there are areas of the brain which do appear to have specialized hardware. The neurons in the hippocampus are reportedly able to strengthen and weaken synapses faster than in other regions, which no doubt aids its role in long term memory storage. The amygdala, given its role in generating primal emotions, probably has more hard coded functionality than elsewhere in the brain. Most of this specialized hardware appears to be in the midbrain or lower. The neocortex regions, again, get their specialization by what connects to them.
Memories themselves are stored in the patterns of synapses (connections between neurons) throughout the brain, with visual portions of a memory stored in the visual processing centers, auditory portions in the auditory processing centers, etc. A full memory has to be retrieved (via connections) from all these regions.
The coordination of consciousness, sleep, and attention happen in the thalamus, which also appears to be heavily involved in integration of sensory information and motor control. The thalamus outsources most of its work through its extensive connections to the neocortex, which essentially serves as a gigantic expansion substrate for it. (The thalamus is often described as an information hub for the neocortex, but given its many other crucial functions, I think it’s better to see the thalamus as the main system calling subroutines in the neocortex.)
All of which is to say that studying brain modules and how they are interconnected, in other words studying the structure of the brain, is also studying the software, the architecture of the mind. This is the second reason I mentioned above. Without the software-hardware divide, the physical structure of the brain is also its logical structure, and science already has some understanding of it.
None of this is to say that the understandings of all these areas is anywhere near complete. Indeed, there are still areas of the brain whose purposes are not well understood at all. And given the enormous complexity, 86 billion neurons (most of which are in the cerebellum) and up to a quadrillion synapses, no one has yet managed to trace the neural circuits throughout to see precisely how a particular thought or decision happens.
But new imaging techniques are constantly being developed, and detailed knowledge increases each year. A final understanding is a long way off, but there’s no fundamental barrier to it being achievable.