Artificial Consciousness/Neural Correlates/Inter-Organ Connection Models/Recticular Activation
The Reticular Activation System (RAS)
[edit | edit source]The Reticular Activation System consists primarily of the Upper Brain Stem, specifically the Reticular Formation which surrounds the actual brain stem itself, and the Thalamus. It has close proximity and connections between it, and the Basal Ganglia, which might mean there is a role for the Basal Ganglia and the Cerebellum to which it is also connected to play in this system. The RAS has two known roles, it is a motor control conduit, and it is thought to be the timing source of brainwaves throughout the cerebral cortex. At first look these roles seem unrelated, however I believe that I can relate them.
Many sensory systems pass through the Thalamus, which is why it was thought to be the seat of consciousness at one time. Today it is thought to be mostly a relay system, although the possibility of being able to switch its relay functions and thus act as a router, has recently been suggested.
Recent work on Attention has connected the thalamus with the Bottom-up Attention System. Maps of the Thalami connections, indicate that each thalamus has several connections to the various different areas of the cerebral cortex hemisphere it services each handled by a different laminae. According to Dr. LaBerge some of these connections are linked to the 5th Layer Pyramidal Neurons, and act to pre-activate the neurons making the mini-columns more sensitive to the input of Layer2/3 Pyramidal Neurons.
According to Dr. Edelman's Dynamic Core Hypothesis, parts of the thalamus resonate with the Gamma Synchronized Oscillations (GSOs) that seem to mark through synchronization, Cross-Modality clusters which he has labelled Functional Clusters. The question is, does the Thalamus resonate in response to the GSOs or does the GSO resonate in response to the Thalamas? Because of the Thalamus tight connection to the rest of the RAS, it makes sense to me that the GSO resonates in response to the Thalamus. However I could be wrong.
If both Dr. LaBerge and I are correct, then, bottom-up activation, will always be associated with GSO frequency information being over-layed over the basic Layer 2/3 memory output without changing the basic information content. The primary difficulty with this hypothesis, is that it needs a channel that is not Mini-Column specific for implicit memory, Recent work on memory during Anesthesia, suggests that implicit long term memory is dependent on the GSO. This suggests a possible link between the thalamus and the S synapse, which might have the ability to trigger similar chemical cascade reactions to those postulated by Kandel and his contemporaries to trigger Fibril growth between neurons, and thus promote long-term memory via the NMDA Synapse. How this secondary route to impose GSO signals onto implicit memory is achieved is not at this time known, however the role of Facilitation of the Neuron should impose a GSO frequency on the neuron similar to that of the 5th layer pyramidal Neurons, despite the fact that 5th layer Pyramids are not involved.