This is a continuation of an investigation into the problem of integration in neuroscience (see Appendix for earlier posts in the series).
A Three Structure Model of Neural Activity in Relation to Consciousness and Language
Here I will consider the first two structures within the model – neural activity and consciousness. The model states that neural activity leads to conscious experience. However we do not need to reinvent the wheel. Freud had developed an eloquent model which incorporates conscious and unconscious activity and from an experiential perspective this has construct validity. As I write this I am breathing and my heart is beating. I am not aware of this until I attend to these phenomenon. I know that the Medulla Cardiovascular Centre regulates heart rate through sympathetic and parasympathetic outflow. As soon as the need arises the cardiovascular centre will modify the heart rate but I will not need to be aware of it. Indeed if I start to run quickly this will happen automatically. I do not have time to think about it.
For the Medullary Respiratory Centre the situation is the same. Activity in the neurons here will causes me to breathe more quickly. I do not focus my activity on the respiratory rate when I run quickly. I just breathe more quickly due to a number of factors including activity in the neurons in the Medullary Respiratory Centre. Again neuronal activity is happening which I am not consciously aware of. In this model, unconscious activity means one of two things.
1. Unconscious activity results from neuronal activity. This unconscious activity can become conscious experience if it is attended to.
2. Unconscious activity is neuronal activity. This activity can never become conscious experience as there is no mechanism for it to do so.
Thus two types of unconscious activity are described here and in practice both types are likely. I will refer to unconscious activity which can never become conscious experience as Absolute Unconscious
Experience Activity. I would refer to activity in the Optic Nerve as being Absolute Unconscious Experience Activity. Although activity here is essential for visual perception, the activity here occurs at an early stage of visual processing and would be referred to as sensation rather than perception. Activity in the Optic Nerve can impact on our conscious experience.
The second type of unconscious activity I will refer to as Transient Unconscious Activity
Experience. In this case neuronal activity does not reach conscious experience when it is unconscious activity. However it is capable of reaching conscious awareness. An example of breathing will again help to illustrate the point. As I think about this sentence I am concentrating on the concepts but am unaware of my breathing. If instead I focus on my breathing I become aware of the air moving through my nose and the sensation of my lungs expanding as well as the rhythm of inspiration and expiration. Unconscious Activity experience has become conscious experience. The neuronal correlates are much more complex however and would likely include range from components of the Peripheral Nervous System through to the Medulla, the Thalamus, Insular Cortex, Primary and Secondary Somatosensory Cortex, Somatosensory Association Cortices, Primary Motor Cortex and Premotor Cortex. The neuronal activity needs to occur in these areas. In one state of mind however I am unaware of this. In the other state I am aware of some of this background neuronal activity.
The three structure model must expand to incorporate these two types of unconscious activity.
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