Mind and brain identity theories

Also called as 'neuro-reductionism or eliminativism' (Varela et al. 2001), this approach tends to confine human existence in terms of brain functions and sees consciousness as a mere product of the brain. Those who follow this approach assume that there is no physical understanding of the self or mind. A notable example is Francis Crick, who discovered the structure of DNA with James Watson and received a Nobel Prize for this work. Towards the end of his brilliant career, which embraced the study of both human genes and brains, he came to the conclusion that we 'are nothing but a pack of neurons'. In his book The Astonishing Hypothesis (1994), he wrote:

The Astonishing Hypothesis is that 'You', your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behaviour of a vast assembly of nerve cells and their associated molecules.

In other words, according to Crick, the ultimate task of scientific endeavour is to explain consciousness in terms of brain mechanisms. I find this indeed a very 'astonishing hypothesis'. In recent years this approach has been revolutionized by computational processing as well as by the arrival of brain imaging technologies, such as functional Magnetic Resonance Imaging (fMRI), positron emission tomography (PET) and recently magnetic encephalography (MEG). Thanks to these new tools of science, various physiological explanations have been proposed to account for the near-death experience. These include oxygen depletion in the brain (also known as 'cerebral hypoxia'), which is common in a dying brain (Blackmore and Troscianko 1988), but, as we have seen, the NDE can also be experienced in other situations. Whinnery and Whinnery (1990) conducted a study of more than a thousand fighter pilots and examined the relations between NDE and the so-called G-LOC syndrome (i.e. acceleration-induced loss of consciousness). This state could be observed in pilots during extreme acceleration, which can result in low blood levels in the brain. The researchers noticed a large number of features which are common to the NDE:

Tunnel visions and bright lights, floating sensations, automatic movement, autoscopy, OBEs, not wanting to be disturbed, paralysis, vivid dreamlets of beautiful places, pleasurable sensations, euphoria and dissociation, inclusion of friends or family, inclusion of previous memories or thoughts, the experience being very memorable (when it can be remembered), confabulation, and strong urge to explain the experience.

(Whinnery 1997: 245)

An objection to anoxia is that it generates confusional thinking, while NDEs are characterized by extreme clarity of thought (French 2005b). Blackmore (1996a; 1996b), for instance, has argued that this varies a great deal according to the type of anoxia, its speed of onset, and the time until oxygen is restored.

Other theories have recognized the centrality of neurotransmitters. These can include endorphins (Carr 1982; Sotelo et al. 1995), which are naturally released in the brain during particularly stressful moments and can cause pain reduction and pleasant sensations, and other features similar to those manifested during an NDE. Jansen (1989; 2001) has argued that endorphins are not hallucinogenic, but he observed that a sudden increase of the neurotransmitter glutamate both during an NDE and a ketamine experience might be indirectly responsible for aspects of the phenomenon. As we saw in Chapter 5, he proposed a ketamine model of the NDE. Others have addressed serotonin pathways (Morse et al. 1986), activation of the limbic system (Lempert et al. 1994) and temporal lobe anoxic seizures, but none has yet been shown to be responsible for the phenomenon.

The methodological presuppositions of the neuro-reductionist approach have been considered a violation of our human experience by an increasing number of scholars (see, for instance, Varela 1996; Damasio 2003). The main problem with this approach is that the 'objective' measurements of the brain do not allow investigation of the 'subjective' aspects of the human experience. As Leder has put it: 'By not including the "subjective" side of the experience in the reflection, we assume only a partial reflection and our question becomes disembodied' (1990: 7). The argument has been well explored by Thomas Nagel in his article entitled 'What is it like to be a bat?' (1974), where he deals with the 'what it is like' ('subjective') character of human experience. He argues that an organism endowed with a sonar system like a bat does not perceive what an organism equipped with a visual apparatus (like a human being) can perceive. In other words, the fact that an organism has a 'conscious' experience means basically that there is something 'to be' that organism. As Nagel described it, when we say that another organism is conscious, we mean that 'there is something it is like to be that organism . . . something it is like to be for the organism' (Nagel 1974: 436); 'the essence of the belief that bats have experience is that there is something that it is like to be a bat' (ibid.: 438).

The subjective aspect of the human experience was central, for instance, to Western phenomenology, which started from the irreducible nature of conscious experience as distinct from the mental content as represented in the 'philosophy of mind'. In this respect, Merleau-Ponty (1962) discusses the distinction between an 'objective' body, which can be identified with its anatomical description and a lived body, which contrarily lives through and sustains the act of perception. Along the same lines, in Japan, Yasuo Yuasa indicated this as a new research direction that he called 'subjective science', which 'attempts to restore the wholeness of mind while keeping a certain cooperative relationship with objective science' (Yuasa 1989: xv). This is a science that focuses on the inner cosmos of human subjects. In his work, Yuasa compared and opposed his concept of 'subjective science' with that of 'objective science' and argued that we cannot appreciate the meaning of truth in toto, unless we delve into the inner cosmos buried in ourselves (Yuasa 1993).

According to Francisco Varela, the reductionist approach considers the 'subjective' side of human experience as unreliable and unsafe, and regards it as a second order of expression to an objective knowledge, which is considered valid and scientific (Varela et al. 2001). This attitude has its own risks. Probably the most insidious one is derived from the argument that the NDE is a mere product of the brain. None of us can deny that the experience and the brain activities are interconnected. A large number of clinical studies provide evidence of such a relation. Let us take an appealing example such as that of the smell of lavender (Lavandula angustifolia).1 Masatoshi and his colleagues at the Tohoku University in Japan have shown from a PET measurement that the lavender aroma produces 'a metabolic reduction in the right superior temporal gyrus and the right postcentral gyrus and activations in the left posterior part of the cingulate gyrus' (Itoh et al. 2004: 109). These results mean that smelling lavender aroma induces not only a state of relaxation but also increases an arousal level in the subject taking part in their experiment. Other examples are a brain contusion or a lack of oxygen supply, which can result in the loss of consciousness, and a tumor, or a trauma of the temporal lobe, which involve certain distortions of consciousness processes that are distinct and different from those associated with pre-frontal lesions. Infections of the brain or administration of certain drugs with psychoactive properties, such as hypnotics, stimulants, or psychedelics, are conducive to quite characteristic alterations of consciousness. Recent successful results in neurosurgery have shown how there can be a clinical improvement after the intervention. All these situations demonstrate that there is a close connection between consciousness and the brain; however, they do not necessarily prove that the brain actually produces consciousness. In other words, the fact that the mind and the brain are related to each other does not prove they are the same.

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