Scientific Understanding of Consciousness
Description of Consciousness
Rather than attempting a diagram, which may not accurately portray such a profound concept, I'll give a brief description of my understanding of consciousness and try to touch on some of the salient and most significant features. Just keep in mind that consciousness is an emergent property of neural activity in the brain, most likely in the recursive activity of the Dynamic Core subset of the thalamocortical system. Consciousness is an emergent property of the "convolution" of an instantaneous mental image with a synaptic pattern (memory) comprising the self.
· Neurons fire pulses lasting about 1 to 2 ms.
· Neurons in a quiescent state fire stochastically (likely Poisson) at about 5 Hz.
· Neurons in the active state fire at rates up to about 100 to 200 Hz. I'll use the nominal value 100 Hz.
· Neurons can fire bunches of spikes as spike trains.
· The neural network includes interneurons as well as projection neurons.
· Projection neurons have a dendritic tree of perhaps 10,000 synapses.
· Interneurons, with synaptic connectivity interlacing dendritic trees of projection neurons, dynamically control and shape the firing patterns of projection neurons.
· Visualize a neuronal network laid out by genetics and prior experience where most of the neurons are firing randomly at about 5 Hz and perhaps 5 percent of the neurons are firing at rates up to about 100 Hz..
· On a neuron's dendritic tree of about 10,000 synapses, there may sometimes be a coincidence of input pulses sufficient to cause the neuron to fire.
· With perhaps 20% of the synapses on a dendritic tree active with pulses, there may momentarily be perhaps a dozen synapses with input pulses close enough to coincidence to cause the neuron to fire.
· From moment to moment there may be different groups of synapses sufficiently above threshold to cause the neuron to fire.
· The synaptically connected active neurons at each moment form a neuronal pattern, which changes on the basis of tens-to-hundreds milliseconds.
· The neural network of hundreds of millions of neurons and their many trillions of synapses results in a cacophony of signals circulating in the network.
· When a neuron fires, it sends its signal into the network, but not to any specific neuron. The neuron' s signal joins countless millions of others whose pathways are determined by patterns of well-used synapses constituting memory.
· Whenever specific signals, such as processed signals input from the senses, blend with this cacophony, and synchronize into a recursive pattern determined by the most efficacious synaptic pathway patterns formed by prior experience and memory, a portion of the resulting recursive neuronal activity will contribute to the emergent property of consciousness.
· The neural network consists of a dynamic hierarchy of local and longer-range recursive signaling pathways.
· Consciousness appears to be an emergent property of a specific dynamical state of the cortical network -- a state that is characterized by a critical level of precise temporal coherence among responses of a sufficiently large population of distributed neurons. (Singer; Neuronal Synchronization, 50)
· The recursive signaling network will comprise an approximate Bayesian inference for a model of reality, converging in ~100 to 500 ms. (Bayesian Inference in Brain Functionality)
· The resulting functionality is consistent with Rudolfo Llinás's description of brain functionality as "dreams modulated by the senses." (Llinás & Paré; Brain Modulated by Senses)
The consciousness system at a minimum includes regions of the frontal and parietal association cortex, cingulate gyrus, precuneus, thalamus (especially the medial, midline, and intralamina nuclei), and multiple activating systems located in the basal forebrain, hypothalamus, midbrain, and upper pons. (Blumenfeld; Epilepsy, 249)
For the consciousness system, some researchers would also include the basal ganglia and cerebellum due to the possible roles in controlling attention. (Blumenfeld; Epilepsy, 249)
Much prior work has demonstrated the importance of the midline subcortical structures and association cortex in normal consciousness. (Blumenfeld; Epilepsy, 249)
Link to — Consciousness Subject Outline
Further discussion — Covington Theory of Consciousness