In the three structure model we have previously focused on the conscious and unconscious aspects of the model (see the Appendix). In this post I will look at language and speech in relation to conscious experience and unconscious activity. The diagram below illustrates the relationships to be discussed.
A Three Structure Model of Neural Activity in Relation to Consciousness and Language
One of the central problems in neuroscience is the integration of models of mind and brain. The key challenge in this integration is understanding the role of language. Language and speech are reasonably easy to distinguish in this model. While there are other definitions, in this model I mean language to be the phenomenon of mind which enables communication with others through speech or related methods of communication. In turn by speech I mean the translation of language, the phenomenon of mind into information which is transmitted in the external world. The speech apparatus is the biological apparatus that translates conscious and unconscious language into an external reality.
I will not discuss the speech apparatus in too much detail. To begin with language exists in the conscious and unconscious mind. At one or more locations the language features of mind are translated into the instructions for speech. I imagine that this would be closely related to the language areas. In neuroanatomical terms Wernicke’s area would be involved in language and Broca’s area in speech. However there is some subtle research involving surface electrode recording during neurosurgical operations which reveals that the conventional view of Broca’s area is much too simple. Nevertheless this model does offer us a starting point. Once the language has been translated into speech commands the instructions would be sent down to the cranial nerve nuclei which innervate the muscles of the Larynx, the accessory muscles of respiration, the muscles of the Tongue and the Intercostal musculature amongst others. Here the combination of phonation and articulation shapes the physical characteristics of the air molecules. Waves of compression and rarefaction are generated. Essentially this comprises the information that is being transmitted in the external world.
The speech apparatus is set into motion by neural activity. In this model I consider the neural activity producing speech to be absolute unconscious activity. The activity in the cranial nerves would not I argue be accessible to conscious experience. This was examined in the previous post with reference to activity in the Retina which is transmitted to the visual cortex via the second cranial nerve – the Optic nerve. This is reflected in the above diagram where speech results from absolute unconscious activity.
The remaining part of the diagram is an area of significant interest as it has been covered particularly by Sigmund Freud. We can distinguish between transient unconscious activity which may fluctuate between conscious experience and unconscious activity. When we ask the question ‘can transient unconscious activity give rise to language?’ we find that this has been explored in some detail by Freud and Mesmer before him. Dissociative states and word associations are two of the phenomenon which illustrate the presumptive relationship between transient unconscious activity and language. We determine this relationship by monitoring speech and in the process assume that there is a direct correlation between language and speech (that language is converted directly into speech). This assumption however can be challenged.
Another aspect of the relationship between unconscious activity and speech is that of procedural memory. There is some evidence to suggest that the Cerebellum plays a role in converting well rehearsed actions into an automatic action. The most obvious example might be a student rote learning their material before an exam or an actor preparing for a play. In this case the person may speak for minutes in a quite automatic way retrieving the rehearsed material without needing to attend to the content of that material. There is a curious disconnect between the meaning of that material (language) and the production of that material in the form of speech.
The relationship between conscious experience and language is much more straightforward. This is more closely related to our concept of volition. When we attend to conscious experience there is the assumption that we are able to determine our actions – that language can be generated which reflects our intentions. Inhibition is sometimes uncovered as in the case of the Freudian slip. Otherwise we are able to effortlessly communicate our inner world to others through the extremely effective medium of language/speech.
There is a final consideration which is the relationship of language and speech to each other. If one results from absolute unconscious activity and the other from transient unconscious activity or conscious experience then there is an interesting question about how they coordinate with each other. Another layer of complexity must be built into the model. This is the addition of visual and auditory feedback. We see a person’s lips and tongue moving as they speak but we also hear the words as well as our own. This feedback must contribute to the coordination of speech and language as must other sensory feedback including proprioceptive information.
Appendix – Related Resources on the TAWOP Site
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