Automaticity, unconsciousness and speech production

Is the human brain able to preserve functions, or fragments of functions, in isolated specialised units while the brain at a global level is severely damaged? Furthermore, could one imagine preserved functions in a brain that did not support any mental events?

These are questions that are addressed in a paper entitled “Words without mind” in a recent issue of Journal of Cognitive Neuroscience by Nicholas Schiff and his colleagues at New York Hospital and the New York Medical Centre. Here, they describe a 49-year old woman (LR) who spontaneously utters words that are unrelated to any environmental context, despite the fact that she has been deeply unconscious for 20 years. LR has suffered from three successive hemorrhages – brain damage due to blood flow from ruptured blood vessels – and brain scans with MRI (Magnetic Ressonance Imagery) showed severe damage to a number of brain regions, first of all most of her cerebral cortex of the right hemisphere, and some deeper structures, a.o. her right basal ganglia and thalamus. Only few, isolated islands of LR’s brain were left relatively unharmed after the hemorrhages, some of which were Broca’s and Wernicke’s area in the left hemisphere. They have long been known as the neural basis of the articulation of words and the understanding of words, respectively. But even those areas, though less affected than the rest of the brain, had a metabolism of 66% of the normal value in the case of Wernicke’s area, and only 50% for Broca’s area.

Being in a vegetative state means having no awareness of oneself or the environment This severe brain damage led her initially to become comatose, though later she regained sleep-wake cycles. At the time of the observations, leading to the study of Schiff and his colleagues, she is diagnosed as being vegetative, that is, as having no awareness of herself or of the environment. Yet, during one observation, she uttered the word “down” twice, and at other occasions, she has spoken words in both English and Spanish. All of these words, however, have occurred without any external prompting, and any attempt to provoke or stimulate her talking has been unsuccessful.

Now, Schiff and his colleagues have taken the case of LR to support the view that the brain consists of modules that each subserves specific functions, such as speech production, capable of functioning more or less in isolation. So, even though it may seem surprising that a vegetative brain can generate proper articulation, timed activation of musculature, vocal cords, and many other aspects of word utterances, Schiff and his colleagues suggest that words are generated by motor fixed action patterns. Thus, they suggest that there are important similarities between the word production of LR and Tourette’s syndrome – a kind of “verbal tics” when words suddenly and unwillingly are uttered by people, suffering from this neurological condition.

Furthermore, Schiff and colleagues describe the word utterances of LR as results of the isolated fragments of her brain alone, since she shows no evidence of having any conscious mentality. This is also indicated by the title of the article: “Words without mind”.

The word utterances of LR are the results of the isolated fragments of her brain alone It has been a long lasting discussion whether the psychological functions of the brain are dependent on specific and specialised modular areas only, or whether an understanding of the entire brain is necessary to understand its specific functions. So, clearly, the study of LR seems very important in its support of a modular view, although, of course, it does not mark an ending of the discussion. That is, even though the case of LR strongly indicates that the brain has modules that can function independently of the global state of the brain, it does not say whether the every day functioning of the brains of normal people should be understood as a large collection of such small modules. In theory, we might still need an understanding of the brain at a global level to understand “every day brains”.

Furthermore, one might find the title, and the theoretical view that follows from it, debatable. Saying that LR produces “words without mind” is to go even further than to say that LR does so based on automatic processes alone. Schiff et al. suggest that LR produces words based on certain neural events alone. However, an alternative explanation would be that LR, though unconscious, still has mental events. One could then argue that unconscious mentality is the true causal background for her abilities.

In the philosophical literature, unconscious mentality is sometimes defined as being potentially conscious. That is, if the brain supports a certain cognitive event that would appear before a subject as a conscious event, were he to turn his attention towards it, this cognitive event would then qualify as unconsciously mental. One might point out that LR, given her vegetative state, is unable to be conscious of anything, and thus also incapable of having any unconscious mentality according to this definition. However, since there are different interpretations of the exact nature of unconscious mentality, it remains an open question whether LR’s brain would be able to support unconscious events or not. Furthermore, since the neural substrate of unconscious mentality, let alone consciousness, is unknown, we cannot deduce from the case history if it is a case of no mentality or just a case of no conscious mentality.

Copyright © M. Overgaard

Morten Overgaard, Ph.d.

Hammel Neurocenter

Denmark

References and links

Web Workshop on SCR from 6/6 to 13/6

Words without Mind

The Neurology of Impaired Consciousness

The challenge of detecting consciousness in severly brain-injured persons