What is "Mind?"

My Brain Hurts

How completely 'subjective' experience can be ported to be experienced by another intelligence 'objectively' remains to be seen.

By most accounts, the mind arises from the integrated activity of large populations of neurons distributed across multiple brain regions. A contrasting model is presented in the present paper that places the mind/brain interface not at the whole brain level but at the level of single neurons. Specifically, it is proposed that each neuron in the nervous system is independently conscious, with conscious content corresponding to the spatial pattern of a portion of that neuron's dendritic electrical activity. For most neurons, such as those in the hypothalamus or posterior sensory cortices, the conscious activity would be assumed to be simple and unable to directly affect the organism's macroscopic conscious behavior. For a subpopulation of layer 5 pyramidal neurons in the lateral prefrontal cortices, however, an arrangement is proposed to be present such that, at any given moment: (i) the spatial pattern of electrical activity in a portion of the dendritic tree of each neuron in the subpopulation individually manifests a complexity and diversity sufficient to account for the complexity and diversity of conscious experience; (ii) the dendritic trees of the neurons in the subpopulation all contain similar spatial electrical patterns; (iii) the spatial electrical pattern in the dendritic tree of each neuron interacts non-linearly with the remaining ambient dendritic electrical activity to determine the neuron's overall axonal response; (iv) the dendritic spatial pattern is reexpressed at the population level by the spatial pattern exhibited by a synchronously firing subgroup of the conscious neurons, thereby providing a mechanism by which conscious activity at the neuronal level can influence overall behavior. The resulting scheme is one in which conscious behavior appears to be the product of a single macroscopic mind, but is actually the integrated output of a chorus of minds, each associated with a different neuron.

The possible involvement of quantum mechanics in consciousness has been summarily dismissed by many authors because the entanglement would, it is usually supposed, have to extend across macroscopic distances and involve spatially dispersed neuronal populations.� The difficulties imposed by such large distances, together with the lack of a plausible mechanism by which entanglement might "jump" across synapses, has been argued to render quantum mechanical theories of consciousness untenable (Grush and Churchland 1995).� With the single-neuron theory, however, the proposed entanglement would need to extend only throughout a portion of the dendritic tree of a single neuron.� While still a formidable proposition, the speculation that quantum mechanical effects might be relevant to consciousness might nevertheless gain in plausibility.

As has been noted by Bieberich, who has articulated an argument similar to the one being offered here (Bieberich 2002), entangled intraneuronal events could conceivably support a complexity of information processing comparable to that attributable to the whole brain in the neural network models.� Such entangled events could, in turn, act as indivisible Whiteheadean subject/object entities with subjective aspects serving as units of conscious experience and with objective aspects contributing to the information content of outgoing electrochemical messages at the axon hillock.� In the final model, then, a single subjective experience would correspond not to the activity of a single neuron but to the occurrence of a single entangled event within a single neuron.� In a logical extension of the single-neuron theory, an individual's brain would be construed as comprising a multiplicity of subjective experiences corresponding not just to the multitude of neurons within that brain, but to the larger number of entangled events within all those neurons.� In sum, the combination problem would be solved by avoiding altogether the need to combine the individual consciousnesses.

although I wouldn't describe a single neuron as being 'conscious'