I have a hypothesis about consciousness. I came to these ideas while studying the Basal Ganglia (BG) and Reinforcement Learning (RL), so I will first describe how I think the BG & RL works. I’m going to assume you all know how RL works.
Basal Ganglia
The BG is thought to perform RL. The BG is composed of two primary structures: the Striatum and the Globus Pallidus (GP). Every area of the cortex sends axons to a corresponding area of the Striatum. The Striatum sends axons to the GP, which in turn sends axons to the Thalamus.
- The purpose of the Striatum is to find valuable things.
- The purpose of the GP is to weight the valuable things which the Striatum found and determine the net Expected Value.
- The purpose of the Thalamus is to modulate the brain in such a way as to maximize this expected value.
Example:
- You see a tasty apple with a small bruise on it. The Cortex outputs an SDR representation of this visual scene.
- Your striatum transforms the visual SDR into an SDR which encodes just the apple and the bruise on it.
- Your GP has associated a (positive) weight with the apple and a (negative) weight with the bruise on it. Your GP outputs the net result.
- Your thalamus directs you to either eat the apple or not.
Hypothesis
The Striatum gives feed forward input to the Pre Frontal Cortex (PFC).
Implications
Assuming this is true, then the PFC is an HTM which is analysing all of the good and bad things in your world.
While the sensory cortexes see the world as it physically exists, the PFC sees the world as it matters to the animal. The PFC uses as feed-forward input the things which RL has deemed important (this RL process happens in the Striatum).
This seems like a useful capability for any animal to have.
Continuing the Example: When you see an apple, your visual cortex sees a round red object while your PFC sees tasty food.
Other Thoughts
I’m not sure how this hypothesis leads to “consciousness” but I can see how this would allow you to be more aware of your emotions. Without this you can only see what phyically exists. With this you can see things which don’t physically exist, but which are still important. Things like abstract ideas.
I’m not aware of any single task which can’t be done without a PFC connected like this. The reason is that given enough trys RL should figure out most problems, even if the RL is using only the sensory information in the rear half of the brain.
It stands to reason that there exists an area of the PFC which receives feed forward input from the Striatum and is also valued by that same area of the Striatum. I wonder what’s happening in this area of the brain… In order for this area to reach a stead state of activations, it would need to form a stable feedback loop between the PFC’s analysis of the world and the estimated value of this analysis.
Dmac