Self Comes to Mind

consciousnessSelf Comes to Mind: Constructing the Conscious Brain

Antonio Damasio

Damasio envisages consciousness as a loop between the self and the body. His view that the self comprises the whole of consciousness, conflicts with descriptions of altered states of consciousness, where the self disappears, and with the normal experience that we are conscious of aspects of the external world that are not part of the self. The argument that the body via the brain stem comprises the whole input into consciousness and drives value judgments conflicts with much of modern neuroscientific study where inputs from the external world are processed via regions such as the orbitofrontal, the amygdala, the dorsolateral frontal and the basal ganglia. The body as a generator of consciousness has become fashionable in this century, perhaps because there is a tacit recognition that the 20th century brain as a computer story is not an unqualified winner, and the bodily consciousness story looks like a way of preserving a classical or macroscopic explanation for consciousness.

Consciousness and the self:  Damasio’s definition of consciousness looks flawed, in identifying consciousness entirely with the self. Such a view has to contend with the descriptions of altered states of consciousness, whether arising spontaneously, or artificially induced by mental training or drugs, which repeatedly specify the disappearance of the self. Even in our normal conscious life, the self appears to be only a part of the contents of consciousness. In looking at external objects, we may for a time not be consciously thinking about the self or its concerns. Even if we are simultaneously conscious of the self contemplating the tree outside the window, there is no reason to see the tree as something particularly appertaining to the self. Damasio himself quotes William James as noting that the external contents of consciousness often dominate our conscious experience. The tree is represented or mapped as our brain state, but may be mapped onto the brain states of other entities that have no connection to our self, and in most philosophies the quanta that comprise the tree, and to which our brain mapping correlates, continue to exist even when there are no sentient beings around.

Brain stem and brain regions: In terms of consciousness and the brain, Damasio starts by discussing the brain stem. I think the danger with Damasio’s approach here is that he may overstate the importance of this part of the brain. Neuroscience has certainly demonstrated that the brain stem is necessary for consciousness, and that from the brain stem the ascending reticular activating system goes to the thalamus and thence to the cortex. However, neuroscience demonstrates that conscious activity involves the joint activity of numbers of brain regions other than the brain stem. Thus the brain stem looks to be necessary but not sufficient to support the human contents of consciousness.

The Self:  Damasio goes on to try and define the self. In a somewhat puzzling passage he tries to chop the self into two. There is ‘self-as-object’ which is an observer.  However for Damasio there is another self, the ‘self-as-knower’ that is conceived as being stacked on top of the ‘self-as-object’. This other self seems to refer to our emotional or in Damasio’s terms ‘feeling’ response to certain aspects of life that are close to us such as family or important possessions. However, there seem to be difficulties with this distinction. The self can certainly be seen as a subject of experience, but whether particular parts can be chopped away as a different type of self seems dubious, and the idea that the experience of certain external objects or relationships can cross some arbitrary line to become a part of the self seems contrary to experience. In fact, this notion of the self sometimes seems more akin to knowledge or even culture, especially when he suggests that the self is changing or will change as a result of changes in modern and future media. Many older people have experienced huge changes in culture and media in the course of their lifetime, but it is questionable whether this has registered as a different type of self. A more conventional view might be that the self is a core of experience which would be the same for a hunter gatherer as for a near-future media addict.

Central to Damasio’s thesis is the idea that the body is the foundation of the mind and more importantly the self. Uncontroversially, he points out that the bodily functions are mapped or represented in the brain. His next step is to bring forward the concept of a ‘protoself’, which is suggested to foreshadow the self. The protoself comprises signalling from the body that is mapped onto the upper brain stem of more primitive creatures that have not evolved a cortex. The initial aspect of the protoself in Damasio’s theory is the level of primordial feelings with feelings of emotion seen as variations on this primordial level.

Conflict with neuroscience:  Damasio relates the awareness of self and the primordial feelings almost exclusively to input from the body to the brain stem. Certainly, the inclusion of brain-body interaction in neuroscience and consciousness studies is an advance on the 20th century concept of the brain as a computer unrelated to the rest of the body. However, this does not get us over the problem that much of the input to the brain is not from the body to the brain stem, but from the eyes, ears and nose to the sensory cortex from which it is projected to the parietal and temporal cortices and finally the frontal cortex.  Damasio does talk a bit about the bodily sense of the sense organs themselves and the regions immediately around them, but it is difficult to deny that the main flow of information from the environment to the cortex is not to do with the immediate surrounds of the sensory organs, but with the electrical and chemical flow of information through axons and synapses to the sensory cortices.

Furthermore at least some of the bodily sensation is initially set off by signalling from the brain to the body. The orbitofrontal, primarily involved with evaluating the potential for rewards or punishers and also the amygdala project to the hypothalamus, which is the brain’s route for communicating to the autonomic nervous and endocrine systems. It is also known the visceral responses are mapped onto the orbitofrontal, suggesting that it’s evaluation of the visceral responses might be at least as relevant as the brain stem.

It is true that the nuclei that produce dopamine and other neuromodulators are located in the brain stem, but research suggests that these act in response to the basal ganglia, which are in turn influenced by the orbitofrontal, the amygdala and the dorsolateral prefrontal. It is important not to be too restrictive about this. The brain is everywhere interactive with signalling and feedback to signalling between a whole variety of brain regions. The basal ganglia in particular receive inputs from and gives feedback to most regions of the cortex. The patterns described by Damasio probably occur, but do not appear to be the main pathways revealed by research.  It is thus apparent that the body-only theory is strangely out of step with other parts of mainstream neuroscience.

Damasio’s emphasises the insular cortex as important for awareness of emotions and the self is supported by recent studies, but it is nonetheless curious that he seems to connect this only to the brain stem and not to the other brain regions known to be evolved with emotion and evaluation of stimuli. Studies to date suggest that the insular is indeed more connected to emotion or feelings related to body states, with other emotion related regions more involved with external inputs, but there is no discussion of this in Damasio’s book. He does mention the role of the cingulate cortex, but this also seems to be more related to bodily pain than internal signals. The brain’s regions are heavily interconnected and it is quite reasonable to think that the insular interacts with other areas and particularly with the basal ganglia, but it is quite another thing to give it the exclusive position it appears to have here.

Value system:  Here Damasio does ask an insightful question. “Where is the engine for the value systems?” Kevin O’ Regan has asked essentially the same question, as to what metric could determine a neural value system, although here he was positing this as an argument against the existence of such a system, which, however, brain research has now shown to actually exist.

Neuromodulator molecules including dopamine are involved in this process, and these are produced by nuclei in the brain stem. Damasio thinks that the dopamine and other molecules are not the answer to this question, but this may be partly because he is looking for these molecules to initiate the value choice, whereas research suggests that they act in response to computations elsewhere and above all in the orbitofrontal and the basal ganglia. What is in many mainstream accounts the main processing of the value system going for the temporal or other cortices to the orbitofrontal and amygdala and thence to the basal ganglia which act on the neuromodulators is here almost entirely left out of the discussion. Damasio presumably has arguments against such a scheme but it is very surprising that he ignores something which has strong experimental support. Damasio does ask important questions, such as what prompts the nuclei to release the neuromodulators, where are they released to and what is the result of this release, but he does not pursue the answer to these questions.

Few would disagree with his assessment of the overall objective of the value assessment system which is to allow complex organisms to survive for long enough to reproduce. His emphasis on homeostasis, the balance of conditions necessary for the survival of the organisms is perhaps a bit narrow, because the requirement to reproduce involves complex choices that are not directly related to homeostasis. Life would be simpler and less challenging for organisms if they did not have to reproduce. The requirement for reproduction increases the difficulty of ascribing value judgements just to homeostasis, because in order to reproduce the organism will need a value system that can override these initial homeostatic promptings.

Damasio approaches the question of the reward system from the point of view of the single cell responding to its environment. But here there is a difference of type between the response of the single cell and of humans. The single cell response can be explained in terms of an algorithm that measured temperature, light or some indicator of the presence of prey or predator. Some aspects of the life of the higher organism can also be explained in this way, but not all of them. How do we choose between the attractions of two different types of food or drink, two different habitats or the physical and mental attractions of two different possible mates, let alone the more complex choices of two or more different possible career or life paths. This is where there is a lack of an obvious metric in existing neuroscience. There are also clearly much more complex inputs than what is required just for homeostasis. We might for career or whatever reasons decide to live in the Arctic although it is easier to maintain homeostasis in a temperate climate, and what we lack is a precise algorithm or metric for such a decision.

Damasio’s approach is almost wholly dependent on organisms sensing their own internal conditions, but this looks far from adequate for dealing with the full range of human conditions. He somewhat sidesteps the issue by pointing to those responses to rewards and punishers which are best dealt with by a fast automatic response like withdrawing a hand from a hot surface. But this is adequate for only this sub-set of experiences.

Maybe Damasio thinks that more complex decisions are a function of rational problem solving, but the choice between say drinking wine or beer does not yield to this, and even for say a career decision, where rational deliberation might be involved, we would also form future scenarios which would contain an emotional or ‘feeling’ colouring for which there is no particular metric or algorithm. Damasio does mention the need for “some kind of internal scale” with neuromodulators speeding up the response to this scale, but he does not attempt to explain how inputs from bodily organs to the brain stem would calibrate such as scale beyond simple responses to heat, humidity, lack of specific nutrients etc. Admittedly, he does point out that a difference between primitive and more advanced organism is that the more advanced organisms have mechanisms to predict the likely delivery of rewards or punishers. But what is lacking is the metric for the actual rewards or punishers. It may be true that what is eventually being predicted is the future bodily welfare as a result of a particular reward or punisher, but the evidence of modern studies puts most of the mechanism for achieving this in areas such as the orbitofrontal, amygdala, dorsolateral prefrontal, and basal ganglia. The neuromodulators to which Damasio does give some prominence appear to act in response to the processing of the other brain regions, and in many cases it is these modulators rather than the viscera that look as if they deliver the anticipated rewards.

Qualia and the hard problem:  Towards the end of this book Damasio does ask the crucial question, as to why qualia or subjective perception feels like anything at all. The answer however is less than satisfactory. Neurons which are not conscious in themselves are supposed to interact with bodily inputs that are also non-conscious in themselves and these two are somehow blended together into a conscious whole. This is a 0+0=1 equation, in which two non-conscious elements combine into a conscious one. This scheme needs some physical basis or process to justify it, and this is missing.

 

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