Showing posts with label Neuroscience. Show all posts
Showing posts with label Neuroscience. Show all posts

25 May 2012

Facts and Feelings

WESTERN PHILOSOPHERS have pondered the questions of 'what is knowledge?', and 'what is truth?' for centuries. Without, it must be said, coming to any kind of consensus. And without, it seems to me, acknowledging that the inability to come to a consensus after many centuries says there is something terribly wrong with the whole enterprise of philosophy! The question of why two philosophers can never agree is part of a larger question that interests me. On the surface there seem to be very different modes of knowing and processing knowledge. We distinguish intellect from feelings for instance, and reasoning from intuition. We have always insisted that the differences are important and have often valued one over the others. The classic contest is between reason and emotion. But some research (now decades old in fact) raises the question of whether these are even valid categories when it comes to knowledge.

I've already mentioned, several times, a case study cited by Antonio Damasio in which he meets a patient with damage to his ventro-medial pre-frontal cortex (red in the image). This part of the brain is involved in the regulation of emotions. Emotional impulses typically come from deeper brain structures in the so-called Limbic System; a series of related structures in the lower and mid-brain. However emotions are also processed and regulated by our neo-cortex. In the patient mentioned by Damasio his awareness of emotions is extremely attenuated. Asked to describe his journey to the appointment his emotional tone was flat, even when describing the traffic accident he witnessed along the way. The emotions do not register. But his narrative shows that his powers of observation and understanding are not impeded; for example his recall of the trip is detailed and the facts are accurately related. He understands cause and effect. What is missing is the emotional response. And this shows when the patient is asked whether an appointment on Tuesday or Thursday next week would suit him better. He has a complete grasp of the facts relating to the choice - his and other's schedules, traffic conditions at different times etc, and he understands the task: but after 30 minutes of reviewing the facts he cannot come to a decision. The facts appear to be evenly weighted in his mind. Each fact is as important as every other fact. So that he has no basis on which to make a decision. (Descartes' Error. p.192ff.) (see also Grabenhorst & Rolls, van den Bos & Güroğlu).

This points to a very important conclusion: that facts alone are not the basis of how we make decisions. We need to know the relative value of each fact, and this information comes from the emotional response we have in relation to the fact. When we consider the facts we don't just decide what we believe to be true. In any given situation there are likely to be hundreds of true facts. We need to decide, given the context, which facts are relevant and important, i.e. salient. Facts make for sense, and emotions make for salience. We simply cannot make decisions without both.

Salience is terribly important. I recently learned for instance that schizophrenia is going to be renamed salience syndrome in the DSM-V (The DSM Diagnostic and Statistical Manual of Mental Disorders, 5th ed. due out next year) The current thinking is that a person with the disorder assigns the wrong level of salience to their experience which leads to delusions. Cause and effect can become confused or disconnected, and coincidences start to take on far too much salience. Inner experience can seem as though it is connected to external events in ways that only the sufferer can detect. An urge to act may not be felt as coming from 'me' so must be coming from outside. And so on. Schizophrenia means 'split mind' (though the etymology of Greek phren 'mind' is unknown), which is not at all descriptive of the disorder and has often lead to confusion amongst lay people. Correctly assessing the salience of our experience is virtually a definition of sanity, though the definition has a broad and ill-defined boundary.

So part of the reason that philosophers (or people generally) cannot agree on things is that we have different notions of value and salience, and since these are primarily emotional they are difficult to articulate. In fact we tend to unconsciously absorb the values and notions of salience from the people around us. Values are strongly conditioned by relatives, friends, race, region, and religion (i.e. by all the various groups we are members of). Attempts to articulate universal values have so far failed to convince everyone. The problem of inarticulate values is exacerbated by those aiming at what they call 'rationality' or 'objectivity' since this usually involves consciously suppressing emotional responses.

Incidentally, this shows that unless the Vulcans of Star Trek were wired very differently from humans, that Mr Spock & co. would have been unable to make decisions. Without a way to assign value to facts they would all be just like Damasio's brain damaged patient.

Intuition and Reason


People I know have been using the term 'intuition' a lot lately and have consistently failed to respond to my request to know what they mean by it. I think I'm in a position to offer a definition which demystifies the word. Let's start with reasoning. In reasoning, as I have indicated, we don't just manipulate facts to make sense. In reasoning we tap into emotions to give value to facts, and then compare the relative values to decide which is salient, or which is most salient. Saliency is a much more fuzzy concept than truth. We know that two intelligent people can reasonably come to opposing conclusions given a set of facts. This is the basis of of arguments in politics and well as philosophy for example. It's so much a part of our daily lives that it hardly needs an example, but the classic illustration is between conservative and liberal politics. Given identical facts, right and left leaning people will come to completely different conclusions about appropriate courses of action, because each assesses the salience of competing facts differently. (The different values of left and right are summarised very well in a diagram produced by David McCandless and Stefanie Posavec for the Information is Beautiful website. See also McCandless on TED) The irreconcilability of left and right rests not on the facts per se, but on what each side considers to be the most salient facts. This is true of the irreconcilability of philosophies, ideologies, and religions also.

The champions of reason initially saw it as a way of freeing us from superstition. The great discovery of the Enlightenment was facts that were apparently independent of belief systems (though geometry was known to have this property since antiquity). Gravity affects the Atheist and the Christian in precisely the same way. If we measure the acceleration due to gravity anywhere on the earth then it is about 10 ms-2 with a variation proportional to our distance from the centre of the earth, and the density of the material directly under us, and a margin of error. In a world where most conflicts are based on mutually antagonistic belief systems this revelation from science seemed to be incredibly valuable. The hope was that we had discovered a reliable way to make decisions, and there were things we could all agree on! Some people still see science in this light, but most of us now acknowledge that values play a role in science as well. Though of course some religieux still fail to acknowledge facts that conflict with their (highly valued) belief systems.

Reason came to be associated with the conscious manipulation of these facts divorced from emotional involvement. And the Romantics (over) reacted to this by revalorising emotions at the expense of reason (leading Romantics tended to break with the values of the society around them). Unfortunately there is a great deal of difference between a value independent fact (like gravity), and value independent thinking (which amounts to suppressing one's awareness of emotions and therefore empathy). We still have to decide what facts are relevant to any situation, and all too often empathy is left out of rational equations. Cold reason has caused atrocities every bit as wicked as unchecked emotions have.

So reason, it seemed, could free us from superstition. Obviously it has failed to do so. Why? It could only have succeeded if the supernatural had low salience for us. In fact supernatural thinking tends to have a high value, and therefore high salience for many people I know (C.f. On Credulity), and though they are a bit credulous they are by no means cretinous. The survival of the supernatural is partly due to the pernicious influence of the Romantics who celebrated the irrational, but of course they only tapped into something that already existed in the hearts and minds of people. There is a very great reluctance to abandon the supernatural, many of us value it, and continue to find it salient in understanding our experience. People who rail against religion (often to a highly irrational extreme, marked by very strong emotions) on the whole seem to be ignorant of this dynamic, making their criticisms unhelpful (and I'm specifically thinking of Richard Dawkins here).

Which brings us to intuition. Unlike reasoning where we try to consciously compare the values we have assigned to facts, intuition is the same process undertaken unconsciously. Experientially it seems as if we leap to a conclusion, or the answer to a problem appears as if from nowhere. We tend to be quite naive about this and since we don't see a process, we assume that one doesn't exist or that it is a bit magical. Intuition then becomes mystified. All that is happening is that we are weighing the value of facts subconsciously and coming to an unconscious decision. It may also be that our phenomenal ability to detect patterns operates better at an unconscious level, since it it something we developed early in evolutionary terms (other animals also use pattern recognition to help them survive).

It may even feel as though trying to think consciously about a problem is counter-productive. Perhaps this is because we cast the net too widely and overload our judgement of salience with too many facts; or perhaps our intellectual (or ideological) values actually conflict with our unconscious values; or perhaps we are just alienated from our body and emotions which makes are values difficult to access. In any case often we solve a problem by allowing ourselves to work on it unconsciously. Many of the great advances in science have come through allowing the problem to mull over unconsciously. Breakthroughs often come after a night's sleep and have even come in dreams (like the structure of the benzene molecule). There's nothing very mysterious about this process, and in many ways it is simply the same as "reasoning" - connecting facts and/or experience, to emotions and values, to decide what makes the most sense of the given facts under the circumstances.

It seems to me that a number of fallacies about how we think persist in spite of new evidence which is constantly emerging. Folk ideas about the mind are still in the process of assimilating the ideas of the 19th century psycho-analytic movement and it's more popular spawn, let alone the insights of neuroscience. As I understand it there is no fundamental difference between reason and intuition, they are the same process operating at different levels of awareness. There is nothing magical about intuition (I frequently rely on it), though the unconscious nature of it does lend itself to magical explanations.

In a sense the magical explanations of intuition are rather egocentric: 'I' am the owner of all that I'm aware of in my mind and body, and since intuition is unconscious it must be 'not I'. And being both 'I', in that the inputs and outputs happen in my mind, and not 'I', in that I am unaware of the process of producing the output from the input: then something super-natural must be happening.

Embodied Cognition

Another fallacy about reasoning is that it is wholly abstract and divorced from experience. George Lakoff and Mark Johnson have showed that this is not so. Lakoff and Johnson have showed for instance that when we think abstractly we employ metaphors which draw on our physical experience of being embodied. We employ metaphors like UP IS GOOD/DOWN IS BAD. So if the stock market 'rises', then that is a good thing. But the stock market is only a notional entity and is not able to move about in space. Our reasoning here depends on the experience we have of moving about in space with our bodies. UP IS GOOD is likely related to an upright position being consistent with life, and lying down with death. And note that UP is not always GOOD. When we have a "high" fever this is a negative. Temperature being "high" or "low" is also a spatial metaphor (perhaps related to the position of the sun in the sky).

If I say "a thought just came into my head" I am performing quite a complex metaphorical translation. I am employing a range of metaphors: thoughts are objects, thoughts are agents, my head is my awareness, my head is a container--therefore awareness is a container). I'm relying on my experience of placing objects into containers, without which the sentence would not make sense. I'm also placing my first-person perspective inside that same container. The thought has to enter the same container, because containers can also hide objects. The unconscious is a container I cannot see into for instance. And note that the thought is an autonomous agent - it comes into my head, without me willing it (c.f. my previous statements on intuition). Although we all have an experience like this, the expression is metaphorical. Even apparently simple statements of fact are often couched in terms which rely on a complex interlocking system of metaphors that ultimately depend on how we physically interact with the world.

This argument from linguistics is confirmed from a neuroscience angle by the existence of mirror and canonical neurons, which form part of the motor cortex. When we do an action, say clenching a fist, parts of the motor cortex are active. Mirror neurons are active when we see someone else perform an action. Canonical neurons are active when we are presented with an object, or an image of an object, and we imagine how we might manipulate it. It is an unsurprising conclusion that we relate to the world in terms of how we might interact with it or manipulate it. However these same interactions form the basis of the metaphors that we use in abstract thought, which is not generally recognised.

Reason, then, is very much embodied and abstract thought depends on metaphors arising from our physical interactions with the world. Reason relies on assessing the salience of a fact by connecting it to our emotions, which we experience as bodily sensations. Reason also relies on metaphors and abstractions which are based in how we physically interact with the world. When we consider the nature of belief we need to keep all this in mind. A belief is a proposition that we have decided is not only true, but which has great salience. To shift a belief by offering alternative truths is ineffective. One can only shift a belief by changing the relative importance of the facts - that is by addressing salience. Indeed if we hold something to be highly salient, then the "fact" that it is untrue might not be salient - and we can comfortably and tenaciously believe untrue propositions. I would say that it is frequently the case with fundamentalist religious beliefs. In a future essay I want to look at how scientists have failed to communicate the salience of evolution, and allowed some religious people to continue to deny it despite the "facts". This is paralleled by Buddhist responses to the demonstrable fact that rebirth is factually implausible.

~~oOo~~

Bibliography

  • Damasio, Antonio. Descarte's Error. London: Vintage Books, 2006.
  • Grabenhorst, Fabian & Rolls, Edmund T. 'Value, pleasure and choice in the ventral prefrontal cortex.' Trends in Cognitive Sciences. 1 February 2011 (Vol. 15, Issue 2, pp. 56-67) doi:10.1016/j.tics.2010.12.004
  • Lakoff, George & Johnson, Mark. Metaphors We Live By. University of Chicago Press.
  • van den Bos, Wouter & Güroğlu, Berna. 'The Role of the Ventral Medial Prefrontal Cortex in Social Decision Making.' The Journal of Neuroscience, June 17, 2009 • 29(24):7631–7632. DOI:10.1523/JNEUROSCI.1821-09.2009
  • van Os J. 'Salience syndrome' replaces 'schizophrenia' in DSM-V and ICD-11: psychiatry's evidence-based entry into the 21st century? Acta Psychiatr Scand. 2009 Nov;120(5):363-72.
~o~

2012 article on Phineas Gage in the Guardian.


Reference: Van Horn, J. D., et al. (2012). Mapping Connectivity Damage in the Case of Phineas Gage. PLoS ONE, 7(5): e37454. DOI: 10.1371/journal.pone.0037454

16 March 2012

Here Be Dragons: On The Limits of Science.

THOSE WHO RAIL against science usually make the same point: viz that science has limitations which stem from the nature of the human psyche and senses, and that there are places where "science cannot go". Some things are simply "not measurable" and consciousness is always at the top of the list of things not amenable to measurable.

In theology this is known as the "God of the gaps" argument. Retreating in the face of the successes of science, some Christian theologians resorted to arguing that God was to be found where science ended: i.e. in the gaps between measurements. Some Buddhists (and others) argue that the "true nature" of consciousness (or reality, or whatever) is found only where scientific investigation ends. Consciousness is off the edge of the map:
here be dragons (or nāgas in our case). However other theologians realised that the God of the gaps argument meant that as knowledge expanded, God shrank. Some of those who realised this preferred the even more irrational all-or-nothing argument: i.e. the whole universe was God's work. Buddhists who adopt a God of the gaps argument will find themselves increasingly marginalised as the scientific investigation of consciousness proceeds.

Perhaps the first person to complain about the obsession of scientists with measurement, and certainly one of the most vociferous, was the poet and engraver William Blake (1757-1827). Blake saw visions of God, Jesus, and/or angels most days of his life. He conversed with his visions and to him they were as much a part of life as his wife, his few friends, his house, or the city of London where he lived. Blake hated Isaac Newton with a blazing passion, and the depiction of him (above) with his dividers doing geometry while ignoring the texture of the world around him, was ironic and polemical, though not the everyone seems to get this. For Blake the empirical approach could not measure the higher truth he felt he met in his visions. In his own time Blake was considered a (mostly) harmless crank, but later he was championed by arch Romantic and co-founder of the Pre-Raphaelite Brotherhood, Dante Gabriel Rossetti. Today (for good or ill) Blake would no doubt be treated as "mentally ill".

In the wake of Blake we sometimes find Buddhists at the forefront of the attack on science and materialism, along with Christian fundamentalists, social studies scholars and French philosophers. Sadly the understanding of science in these attacks seems not to have progressed much beyond Blake's time, and we see scientists accused of seeking or claiming
Absolute Knowledge, or thinking they can solve all the worlds problems. In fact it is religions which claim absolute knowledge (which they don't have) and the ability to solve all the world's problems (which they have demonstrably not done). Most people are distinctly better off for having science in the world, and recently Harvard Professor Steven Pinker has suggested, in his book The Better Angels of Our Nature, that the values of the Enlightenment have contributed to a long term reduction in violence across the globe. His claim is hotly contested, but one feels that with the retreat of Christianity a vengeful spirit is being exorcised from Europe. That there is a substrate of violent behaviour remaining should not detract from the achievements of Enlightenment values. Secularism and trade have created a more stable, peaceful and unified Europe than Christianity ever did (current problems not withstanding).

But what of this claim that consciousness is inaccessible to science? I think this claim is now demonstrably false. The map is now a globe, we may not have every island and cove mapped, but we know the rough shape of the continents. Turns out there are no dragons.

However before looking more closely at this issue I want to briefly mention another anti-materialist claim: that the brain is simply not complex enough to sustain consciousness. I had wondered about this, but I now think this is one of many failures of imagination on the part of the anti-science lobby. Part of the problem is that it's difficult to get a handle on big numbers. So if I say that the human brain has about 100 billions neurons each with 1000 connections to other neurons, i.e. 100 trillion connections in total, this doesn't really mean anything to most people. To get a sense of it there is a very interesting TED talk by
Henry Markram which shows a visualisation from a realistic computer model of a tiny part of the brain of a rat. Here we are visualising a model equivalent to perhaps 1 ten-millionth of the human brain, and yet the complexity is both staggering and beautiful. Does a brain possess the complexity required to produce and sustain consciousness? I would say undoubtedly, yes, it does.

And so to the idea that consciousness is not accessible to measurement. For many decades now neuroscientists have been studying the way that brain injuries affect consciousness, cognition, and personality. This has given us a rough overview of the way that mind depends on brain. More recently various types of brain scan have allowed us to begin to show in more detail the correlations between brain activity and mental activity, increasingly this is done in real time. We can be reasonably certain that mental activity is always associated with brain activity. Some studies in animals have gone to a much greater level of detail with brain mapping. One group have precisely mapped out each of the 300 or so neurons of a nematode worm and all of the synapses. They have produced the
Worm Atlas to help visualise it. The effort to map out the 100 trillion connections in a human brain has been formalised in the Human Connectome Project. It seems likely that with persistence a complete map of a human brain and all its connections will eventually be realised. This will give us undreamed of insights into how the brain, and therefore the mind, functions.

I glossed over some of the aspects of consciousness that can and have been studied when I reviewed Thomas Metzinger talking about the
first-person perspective. This is one of the ways of studying of how consciousness, particularly self consciousness, is affected by injury. But some neuroscientists have gone further and created non-invasive, and non-destructive ways to test and challenge our sense of self. I've already described Thomas Metzinger's article which links the idea of a soul with out-of-body experiences (OBE), but the OBE provides other insights into the flexibility and contingency of our sense of ownership over our body. A recent feature article in Nature News surveys the life and work of Henrik Ehrsson in this area. Ehrsson uses virtual reality equipment to alter how the body is incorporated into the Self-Model. The self --that is the thinking, ego centre--can be experienced as transferred to an inanimate object for instance. That is to say that the sense of "I" being behind the eyes can be disrupted so that it seems to be located outside the body, and even inside an inanimate artificial body. Similarly inanimate objects can be incorporated into the body image to the extent that seeing them touched can produce a 'felt' sensation. This tells us that the sense of self is not hard wired, but virtual. Metzinger talks about it as a "simulation".

As author and
blogger Ed Yong says "Ehrsson's work also intrigues neuroscientists and philosophers because it turns a slippery, metaphysical construct — the self — into something that scientists can dissect." He also cites neuroscientist David Eagleman: "We can say if we wobble the signals this way, our conscious experience wobbles in this way. That's a lever we didn't have before". And Thomas Metzinger: "There are things like selfhood that people think cannot be touched by the hard sciences. They are now demonstrably tractable."

The field of neuroscience has made huge progress in the last 20 years. News of this progress leaks out in popular press coverage only to a limited extent, and often with distortions. More can be gleaned from popular books by authors such as Vilayanur Ramachandran, Oliver Sacks and Antonio Damasio (to name some of my favourites). But look at the bibliographies of such books, or do a
Google scholar search and you'll get a better idea of the scope and scale of the enterprise. Lay people can scarcely imagine it, and even with my degree in chemistry I cannot follow the great bulk of it, and must rely on interpreters and popularisers to get a sense of what the scientists are discovering.

Of course for Buddhists some of the most interesting research in this area is the study of how meditation affects the brain in the short and long term. We are now getting information about which parts of the brain are activated by different styles of meditation, and how regular meditation practice creates long term changes in the brain. It is these kinds of studies, with objective evidence of benefit that relies on data and not metaphysical claims or mere subjectivity, which are helping to popularise mindfulness techniques (including meditation) beyond our usual audience.

It seems to me that the perceived limitations of science are often in fact the limitations of the perceptions of the critics of science. In the Romantic critique of science there, ironically, seems to be a massive failure of imagination, and inability to take in and think about what is actually happening in the world. Very few critics seem to have understood the impact of the two great figures of the philosophy of science in the 20th century: Karl Popper and Thomas Kuhn; let along the progress of knowledge itself. Too many seem to ignore the various revolutions in thinking that have occurred in the years since Blake vented his spleen at the great figures of the Enlightenment. In my view Blake is
not a good role model. He may have been a Romantic figure--a lonely visionary, enunciating a higher truth that lesser mortals could not comprehend --but he was unable to sustain relationships with his friends for instance, and was patently a very frustrated and angry man, who blamed his inability to communicate on others. Blake was no saint, and, in the end, not much of a prophet either.

Humans have limitations, but one of the stand-out characteristics of humans is not accepting those limitations and pushing beyond them. So, yes, science has limits, but they are not set by outdated views, and ideological criticism. We are usually limited only by the scope of our imagination.

~~oOo~~


Further listening, reading and viewing

21 March 2008

An Experience of Awakening?

A friend sent me this today, and I was so struck by it that I thought I'd make it the basis of my rave today. It's billed as "what it feels like to have a stroke", which it does describe. Because of her ability to observe and articulate her observations (the benefits of a scientific training!) we get an incredibly detailed account of the progress of Jill's stroke. She notices a lot more than the average person might, and her neuroscience training gives her a vocabulary and a conceptual framework to understand and communicate her experience. However it goes well beyond the what happens when parts of her brain start shutting down. Perhaps it is best to watch the video clip and then read my comments.





I'll just summarise what Jill says about the hemispheres.

Left: linear/methodical, interested in past and future, interested in details. The left hemisphere categorises, associates, and makes projections and predictions about the future. It thinks in language and is responsible for our internal chatter. Source of the though "I am" - separate individual.

Right: interested in here and now. Thinks in pictures and kinesthetics. Information as a flow of energy, experiences as a collage. Interested in how here and now looks, sounds, smells etc. Knows that we are all one, perfect, whole and beautiful.

Once Jill's stroke is underway it suppresses the activity in her left hemisphere. She describes the experience in terms of losing a sense of the distinction between the atoms of her arm and the atoms of the wall, and not being able to define the boundaries of her body. There is just energy and she is captivated by this. At the same time her "internal brain chatter" falls silent. She has an expansive feeling, and feels "at one with all the energy" and "it's beautiful there". When her recollection of her past falls away it is a profound relief - imagine losing 37 years of emotional baggage! It was euphoric. All job stress was gone, all stress of any kind was gone, and there was an experience of profound peacefulness.

What Jill is using a language that anyone familiar with Buddhism should be acquainted with. She talks about losing a sense of being a limited and isolated self, of losing the "I am" (ahaṇkāra). The immersion in right-brain consciousness gave her a sense of unboundedness (aparimāna) associated with euphoria (sukha, pamojja, piti), and sense of unbounded love for and solidarity with everyone (mettañca sabbalokasmiṃ mānasam bhāvaye aparimānaṃ - Metta Sutta). She repeats the word "peace" (śanti). She gestures and describes a sense of liberation (vimutti). The falling silent of internal chatter sounds very much like entering the second dhyana. However she does not describe things in terms of dependent arising, and I can't help wondering what she would make of the teaching on this.

Jill is describing a classic mystical experience which is familiar to those described in many religious traditions. What is interesting is how closely her explanation follows the conceptual landscape of Buddhism. She doesn't say whether she follows any particular tradition.There ar of course resonances with other traditions. At times she appears to be describing the insight that is summarised as "I am brahman" in the Upaniṣads, for instance. Interestingly Jill does not meet God, or interpret her experience in theistic terms. What makes Jills story profound is that she retains the ability to experience that kind of consciousness, more or less at will (is what she implies anyway). This resonates very powerfully with my own spiritual aspirations.

It seems very likely that Jill's stroke affected that part of her brain that has been dubbed the "God Spot". More recent research has shown that it is more of a network of a dozen or so regions than a spot, but the name is evocative. Stimulation of the brain, whether by epileptic seizure or electrodes applied to the scalp, has been able to reproduce the kinds of feelings that mystics and Jill are talking about. Atheists have taken this as proof of the non-existence of God, but that is to suggest that they understand the effect which is claiming too much. How could, for instance mediation - intense samādhi - produce a vision or an experience of unboundedness? No one knows. No one really understands the relationship between the brain and consciousness except to say that we do know there is one.

Of course what is missing from Jill's presentation is any kind of method. Jill says that anyone can choose what kind of consciousness they dwell in from moment to moment. But we can't follow Jill because she achieved this Awakening via a life threatening (random?) blood clot. And actually although it sounds it, in practice changing our level of consciousness is not that easy. Fortunately the Buddha has described a method which is reported to produce just these kinds of experiences, especially the experience of blissful unbounded consciousness which sees things in terms of energy (ie process) and which makes no distinction between self and other.

Dr Jill Bolte Taylor also has a book out called My Stroke of Insight, and an interesting website.