Figure 1. A prosed thalamus-cortex (ACC) network for consciousness
The direct projection from the thalamus to ACC serves as a key (if not the only one) core circuits for consciousness. The projection to PFC directly or indirectly may also contribute to this core. In addition, different subnuclei of thalamus project to somatosensory, visual and auditory cortices to convey sensory information from the outside world. Pyramidal cells in these cortical areas form connections with ACC/PFC neurons directly and indirectly. Through callosal projections, each side of ACC may also affect other side of ACC by excitatory connections, these positive feedback circuits provide a dual circuits for maintain consciousness. Furthermore, in case of one side of brain injury, the other side of circuits may take over to maintain minimal level of consciousness. In addition, the pyramidal cells of ACC may also project to subcortical and spinal cord neurons. These long distance positive feedback circuits may also contribute to the consciousness.