#225      39 min 44 sec
Susan Greenfield: Fifty shades of grey matter

Neuroscientist and synaptic pharmacologist Prof Baroness Susan Greenfield discusses how neuroscience sheds light on our understanding of consciousness. Presented by Dr Shane Huntington.

"My group call them neuronal assemblies.  We'll define an assembly of brain cells of neurons as large scale coalitions of brain cells.  Sometimes 10 or even 100 million brain cells.  This is somehow corralled up; that somehow work together in a very fast timeframe, less than a second." -- Prof Baroness Susan Greenfield




Prof Baroness Susan Greenfield
Prof Baroness Susan Greenfield

Susan Greenfield is a neuroscientist at the University of Oxford and has been awarded 30 Honorary Degrees from British and foreign universities. She heads a multi-disciplinary research group exploring novel brain mechanisms linked to neurodegenerative diseases. In addition, she has published a neuroscientific theory of consciousness: The Private Life of the Brain (2003) and developed an interest in the impact of 21st Century technologies on how young people think and feel, as discussed in her book ID: The Quest for Identity in the 21st Century (2008). She further explores the neurobiological approach to identity in her latest book You Me: The Neuroscience of Identity (2011).

In 1998 Susan received the Michael Faraday Medal from the Royal Society. She was awarded a CBE in the Millennium New Year’s Honours List, and a non-political Life Peerage in 2001. Susan recently served as the Chancellor of Heriot Watt University (2005-2012).  In 2000 she was elected to an Honorary Fellowship of the Royal College of Physicians and in 2007 to an Honorary Fellowship of the Royal Society of Edinburgh. Further recognition of her work includes L’Ordre National de la Légion d’Honneur and the American Academy of Achievement Golden Plate Award, both received in 2003, as well as the Australian Society for Medical Research Medal, awarded in 2010. In 2011 she joined the Advisory Board of the Kusuma School of Biological Sciences at the Indian Institute of Technology Delhi and in 2012 she became a Governor of The Florey Institute for Neuroscience and Mental Health.

Credits

Host: Dr Shane Huntington
Producers: Eric van Bemmel, Kelvin Param
Associate Producer: Dr Dyani Lewis
Audio Engineer: Gavin Nebauer
Voiceover: Nerissa Hannink
Series Creators: Kelvin Param & Eric van Bemmel

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VOICEOVER 
Welcome to Up Close, the research talk show from the University of Melbourne, Australia.


SHANE HUNTINGTON 
I'm Shane Huntington.Thanks for joining us. Contemplating our own consciousness is perhaps a uniquely human endeavour, and one that people have grappled with throughout recorded history.  How does our mind control our thoughts and our perceptions of the world around us?  Do other animals experience a sense of self-awareness like we do?  While these questions have long been the domain of philosophers, only since the 1980s have scientists turned their attention to the study of consciousness.  In recent decades, emerging imaging technologies have dramatically expanded our understanding of the brain and our ability to examine its functioning in detail.We are now in a position to locate the brain regions mapped to individual tasks and can even create interfaces between parts of the brain and external robotic electronics.  And it is with the power and promise of technology that we are capable of taking a fresh look at consciousness.  To hear the latest on this episode of Up Close, we speak to a neuroscientist who has been delving into the mysteries of consciousness.  Baroness Susan Greenfield, Professor of Synaptic Pharmacology at Lincoln College, Oxford.  Welcome to Up Close Susan. 

SUSAN GREENFIELD
Shane, it's very good to be here.Thank you.  

SHANE HUNTINGTON
When we talk about consciousness, it's a subject that was once the preserve of philosophy rather than science.  What has changed to allow scientists to start tackling this topic?

SUSAN GREENFIELD
Well I think the brain if you like has come of age.  Now we feel more confident about talking about the mind and consciousness and emotions in physical terms.  This has only really been possible for a few decades, because even when I was starting at university neuroscience wasn't even acknowledged as a subject.  You talked about physiology.  You talked about biochemistry.  You talked about anatomy.  But to talk about an area of study that encompassed all those things, but that was defined by its target, its subject which is the brain, is relatively new.  Although we take it for granted now in universities when we talk about neuroscience, it's actually a very young discipline. And I think it's only once we can look around and look at our colleagues and biochemistry and anatomy and physiology, but say we all have something in common and lets pool our resources, only then can we really tackle what I think is really the biggest question anyone can ask, let alone a scientist, which is what is consciousness?

SHANE HUNTINGTON
Now for the purpose of research, how do we go about defining consciousness?  Is it merely being aware of our surroundings, or is there more to it than that.

SUSAN GREENFIELD
That's a brilliant question and I think it's very appropriate we start off with that.  The reason I say that is in your intro you were conflating, if you don't mind me saying, mind and consciousness for example.  So let's just clear all this out of the way before we delve down.  In my view, we should distinguish the brain, mind, consciousness, and dare I say it, the soul.  Sometimes these things are, I say rather blurred.  But everyone knows what the brain is, so we won't have to bother with that.  The mind I think is different from consciousness, although the two can influence each other.  Because we often talk about losing your mind or blowing your mind, but in those conditions you're still conscious.Similarly when you lose consciousness, if you go to sleep, you don't think you're going to lose your mind when go to sleep.  We talk about people having broad minds and narrow minds, and so you don't talk about people having broad consciousnesses really.  So I think we need to distinguish those two things.  The soul, which I assume we're not going to dwell on too much given neither of us, I don't think, have any theological credentials.  I mean this is not a religious interview.  Nonetheless people do raise it and I think we can dismiss that if you like by saying whether you believe in the soul or not its quintessential element is that it's immortal.  It's not perishable therefore.  Everyone knows the brain is perishable, is mortal.  So I would say to people who are concerned about the soul, render unto the neuroscientists the things that are of the neuroscientists, and leave to the theologians issues of the soul.  So if it's okay with you, I think we can put that to one side.  That's not to dismiss it as unimportant, but I don't think it's going to help us in talking about consciousness.  Now we come to consciousness and how we're going to define that.  Again there's some confusion between the subconscious, unconscious, self-conscious, and bog-standard consciousness.  Now I think again, let's just clarify what we mean by those terms.  Self-consciousness, as you were referring to, is something that is very special.  It's that you know you're Shane, and I know I'm me, and when I look in the mirror I know who I am.  A very small child is incapable of that.  Most animals with perhaps the exception of chimpanzees are incapable of that.  We will come on to whether they are conscious or not in a second, but I think one can't assume that self-consciousness and consciousness are synonymous.  I think that it's an added layer if you like this self-consciousness.  A lot of philosophers do agonise and talk about what they call metarepresentation.  That's a valid field of study, but I don' think for us neuroscientists, it's the primary issue.  There's then subconscious which of course preoccupied Freud and the like.  That's a condition where things are at work and at play you are not aware of them.  They are not something that you are thinking about but nonetheless they may impact or influence your behaviours.  So again you're still conscious, but the subconscious is something that will feed in to that.  So that's different, the subconscious from unconscious, and unconscious will be the conditions you're in once the anaesthetist has been at you, or when you go to sleep.  So sorry to sound picky, but I think we need to establish that taxonomy and if you're comfortable with that, we can work within that framework.  So let's think then about defining consciousness.  Okay, which I think is the primary issue - the bog standard consciousness.  Well normally when we are defining something, I think we have two strategies.  One is we refer to a higher set.  You might say love is an emotion.  A chair is a piece of furniture.  Consciousness is a - is a what?  What's the highest set?  There isn't one.  So I think that we flounder a bit if we try to refer to higher sets.The other way is an operational definition.  You might say flight is when you defy gravity.  Love is when I give my mother 10 red roses.  Consciousness is when you do what?  You don't have to do anything.  You can just sit there.  You can go into a floatation tank and close your eyes and your conscious, but you're not doing anything.  So I think the normal strategies we have both fall down, and that's why we agonise  so much because there's no way of defining consciousness.  This is what philosophers agonise about and I think it does bedevil a lot of the progress and that people triumphantly say, you can't define consciousness and therefore you can't study it.I think as a scientist being pragmatic, that's not terribly helpful.  So I would rather lower my sights and accept that we can't give a formal definition, but nonetheless we can have a working definition, and for scientists that's just fine.   My working definition, I know this offends philosophers, is it's what you're going to lose tonight probably.   I also like to say, we all know what consciousness is, so all this dancing around on a pinhead is really wasting time, when if we acknowledge it's what you're going to lose tonight, then we can try and press on as scientists and see what scientists can bring to the party.   

SHANE HUNTINGTON
Susan is it on or off, or is this sort of range of grey here in terms of consciousness?

SUSAN GREENFIELD
Oh, it's 50 shades of grey matter, yes exactly.  Well this is an idea that I had.  I don't know if others have had it.  When as often happens when you have ideas, you know it's on holiday sitting by the swimming pool, and I was thinking about this and thinking about unconsciousness.  Unconsciousness has long been acknowledged to be graded.  Any medical student will know that you have stages of anaesthesia, that you have stages of sleep, which are quite clear and characterised.  So it struck me if you can have graded unconsciousness, why could you not have also graded consciousness?  That would actually get around a real conundrum that have agonised people and worried people, and that is - is a foetus conscious, is a rat conscious, you know, and so on.  Now my own view is that if you suggest that consciousness isn't all or none.  Isn't like the like going on or the light going off, but more akin to say a dimmer switch, then that does help a lot.  It helps for various reasons, one is the riddle in phylogeny and ontogeny can be helped by saying, yes a rat is conscious - not as conscious as a primate, and a monkey is conscious but not as conscious as a human, and that is quite useful.It also, I would suggest, gets around this problem of trying to draw a Rubicon where you say certain species are conscious and others are not.  I've always been uncomfortable with that, because I could never see where anatomically in the brain, there was suddenly some marvellous new property that allowed you to be conscious compared to some other poor species that wasn't so blessed.Now admittedly a more primitive creature or more modest central nervous system may not have the level of consciousness that we have, but that's the whole point.  By positing that you have graded or variable consciousness, then that does help.  So it then raises the very controversial issue which, again I am happy to discuss, but I don't think is really our central concern this morning, of is a foetus conscious?  Of course this is very important for ethics and abortion debates and so on.  If you assume that a foetus is not conscious, you say well when does it become conscious?  Is it when it when it squishes down the birth canal?  Well if that's the case, it's a bit tough if you're born by caesarean section, you'll never be conscious.  Or is it the timing of birth?  Well that's a bit tough if you're born prematurely, because you can imagine the parents sitting at home saying, well won't bother going and seeing the baby yet in hospital, it's not conscious yet.  Oh look its conscious today.  Time's up.  Again that doesn't quite make sense.So I'm afraid, and this is an ethical minefield, one has to suggest that the foetus is conscious as soon as it has some kind of nervous system and conscious grows as brain grows - like a dimmer switch.  Now why it's also useful thinking of consciousness as continuously variable is it means that we as humans, adult humans, can apply it to our states of mind.  For example, we can talk about levels of consciousness and raising our consciousness, or deepening our consciousness.  We've done this for a long time.  It doesn't matter which way you go, whether it's up or down, one could talk about having more or less of it, and that's quite useful.  Then it's particularly helpful - particularly helpful because if we are adopting a science stance, if we want to look at some correlates of consciousness, then of course, magically we've done something that scientists love.  We've turned something that was erstwhile ineffable, something that you couldn't quite grapple with, we couldn't really easily define.  At least now it's something we can measure, even if we can't define it. So this is very helpful because if we can drop a shopping list in the brain and then go visit the brain, we can look for something that's variable that you can measure.  As soon as you do that, scientists are relaxed and they're relieved because as you will know, being a scientist yourself, that's what we're all about, rather than grappling with some magical mystical quality of the brain.So I think that it's a sensible approach and it fits in with what we know of evolution and what we know about the human states, to think of consciousness as something that's continuously variable.  

SHANE HUNTINGTON
So Susan, when we talk about the scientific examination of consciousness, what sort of things can we measure.  I mean scientists have to measure things.

SUSAN GREENFIELD
They do. They do. 

SHANE HUNTINGTON
What can we do?

SUSAN GREENFIELD
Well I think the first thing is to tackle this issue of causality or correlation.  Now in an ideal world, wouldn't it be great if we knew how consciousness was generated in the brain.  That's really the  holy grail.  But if you think about it, if I said to you, do you know as I was driving in this morning Shane, suddenly I realised how the brain generates consciousness.  It came upon me as an epiphany.  I really now know.  What would you expect me to show you?  Would it be a formula?  Would it be a performing rat?  Would it be a brain scan?  Would you suddenly feel like me?  We don't even know - to the best of my knowledge, no one has come up with, even in the most science fiction type scenario, even given infinite resources and expertise of knowledge, no one has said what kind of answer - what kind of answer.  If I said to you I've built a time travel machine, or I've built a perpetual motion machine, you would know the kind of thing that you would expect to see, or want to see to satisfy that claim.  But if I say, now I know how the brain generated consciousness, I'm going to show you or tell you.  We have no idea.  So I think, although it would be wonderful - a good game to play by the way so anyone who's listening to this they can think about that but - write a science fiction novel on it.  So given we can't do that as yet, we lower our sights as scientists and we look for a correlation.  So if we're going to investigate this issue, what we're going to do, and I always like to say this upfront to people otherwise they'll want their money back, you know, we are not going to be able to describe how the water is turned in to wine, if you like.  You know how the water of objective brain events is transformed in to this astonishing wine of subjective experience.  We're not going to be able to do that, but what we can do as neuroscientists and what we can bring to the party that others cannot, is we can look at things that are happening in the brain, mechanisms and processors that are operative in the brain, that will match up - will we say correlate, with either different types of consciousness or the abolition of consciousness.  If we can do that, if we can come up with a very tight relationship between different levels of consciousness or states of consciousness, or consciousness and its abolition - if we can do that, if we can measure that up with things that are going on the brain, then that's a start, and that's what neuroscience can do.  So I think that should be our agenda. 

SHANE HUNTINGTON
I'm Shane Huntington, and you're listening to Up Close.  In this episode we're talking about consciousness with neuroscientist Baroness Susan Greenfield.   Susan, we can grow brain cells up in the lab, in a dish, do these sorts of experiments give us an insight into consciousness?  I mean we obviously don't think of these dish experiments as being conscious sets of cells.

SUSAN GREENFIELD
Again it all depends what's the question you're asking.  I think part of the problem with the march that you quite rightly acknowledged of the technology in neuroscience, is sometimes we get seduced by the technology without harnessing it to answer what Karl Popper would have called a falsifiable hypothesis.  So you could have a brilliant computer or a robot.  You could indeed have lots of cells in a dish, but in order to relate that to consciousness you have to ask a question.  If the question is are these cells conscious?  I who work with something slightly more sophisticated, which are slices of brain in chambers that are kept alive - you know mammalian brain slices.  I don't think these are conscious because my own view is that consciousness is something that is an emergent property resulting from the cohesion, not just of the central nervous system, but the immune and the endocrine and autonomic nervous systems as well. I think you have to have that otherwise you'd have biological anarchy and you do need an integrated system.  Now that's my own view, but it's also shared by someone like Antonio Damasio for example, whose talked about this at length and worked on various markers in the bodies that he thinks relate to consciousness as well.  So that's not to say we shouldn't focus on the brain, but I think being reductionist and thinking that a single brain area, or a single network of cells can in themselves be a mini brain and function entirely as a brain as though it were in a body.  I don't think that's very realistic.  

SHANE HUNTINGTON
Determining how consciousness actually happens relies on us being able to measure and identify brain activity and associated conscious experiences.  Could you explain what a neuronal correlate of consciousness is and why this is important for these particular studies?

SUSAN GREENFIELD
Well as I was saying, I think what we neuroscientists bring to the party isn't any great insights into definition, or indeed into the nature of the water being turned into wine, and what you'd expect and how this inner state is reporting to something that reports to nothing as it were.So what we look for are these correlates, and let's look at the candidates that one could start to study.  The most obvious are specific brain regions, and neuroscientists love talking about - like you did in the introduction.  The centre for this and centre for that.  We like doing that for several reasons.  One is it's easy to understand.  Second, you can study it with brain imaging, and it's very aesthetic to look at, and say it's conceptually very comfortable.  Now I have problems with this.  One is that we know that the brain doesn't work like that.  That although different brain regions have their own signature jobs they have many jobs and indeed any one function conversely is distributed among many brain areas.  So for vision for example, there's at least 30 different brain areas that relate to different aspects of vision.  So you can't say there's a centre for vision, for example.   So even less can you say there would be, I think, a centre for consciousness, and we know that because you can do brain imaging where you anesthetise human subjects and if there was a centre of consciousness, what you'd expect to see is one brain area shutting down, and of course there is uniformed diminution of activity across the whole brain.  So I don't think it's very helpful to posit a centre.  In any event, if you say this is the centre for X, forget about consciousness.  What does that tell you?  It tells you nothing.  Are you any more enlightened as to what's happening?  No you're not.  Just because a brain area is active during a certain task, even if it is causal and might well be a correlation like your monitor light going on, on your iron.  Even if it is causal, you don't know what's going on.  You don't know what's happening.  So just to say an area of activity is linked to the function of something or other, doesn't really tell you what's going on inside the centre.  I think what someone once called an aesthetic explanation, it sounds good but actually if you probe it, it doesn't really help you very much.  So you can't look at single brain areas.Single cells, of which we have what is it 100 billion.  That's not helpful either because many of the die each day.  So if you were to put the whole of consciousness in to a single cell, that's pretty precarious, and that's asking a lot of a single cell to do.  So I don't think anyone realistically would think about that, although there is the old idea of the grandmother cell, where eventually cells become so specialised in the brain that they will respond only to very, very specific stimuli.  This is an idea that has been revived by Christof Koch for example, where he's been recording from human subjects with a Halle Berry neuron he talks about.  But again I have problems with that.  I think one can correlate brain cells firing, being active that is, for specific things but on the whole to give them autonomy and self-control and consciousness, I think doesn't work.  So therefore what we need, if we dismiss the top down approach, which is the macro brain areas and if we dismiss the bottom up, which would be isolated cells or very primitive circuits; we need something in the middle.  We need something that links it and we now know that we need something if you buy into the idea that consciousness is continuously variable, we need something that's going to vary in size.  Something that will measure up to you having deep insightful consciousness and much more superficial consciousness, and my money goes on something that has only recently been discovered, partly because it's been hard to detect by normal techniques.   I call them - my group call them but names can vary - neuronal assemblies.  We'll define an assembly of brain cells of neurons as large scale coalitions of brain cells.  Sometimes 10 or even 100 million brain cells.  This is somehow corralled up that somehow work together in a very fast timeframe, less than a second.  Now we know that such things occur.  There's been pioneering work in the 90s by someone called Amiram Grinvald at the Weizmann Institute in Israel, where he showed that indeed brain cells can work like that.  Now the big problem had been that because they are very quick to form and quick to disband in less than a second, using conventional brain imaging you can't see them at all.  Conventional brain imaging has a time resolution of several seconds.  So another issue and another constraint with brain imaging, aesthetic though it is and powerful though it is, it's a little analogous to the old Victorian photographs where the time resolution was such you could see things that were static like buildings.  What you couldn't see were people and animals moving.  That's not to invalidate the buildings.  That is absolutely what you saw, but there was a lot else going on that you missed.With standard brain imaging, that's the case sadly, that you will be missing out on sub-second events.  Now brain imaging such as pioneered by Grinvald, relies on something you can't do in humans, you can only do it in experimental situations.  That involves giving a dye in the brain that imbeds in the wall of the brain cell, and it's a potentially fluorescent dye which changes its wave length as the activity of the cell changes.  For those people who are technical, as the voltage across the membrane changes, so the dye will fluoresce.  So it's an instant readout - instant of the activity of the cell of the change in the electricity of the cell.  This is therefore called voltage-sensitive dye imaging, or optical imaging.  It's a technique we use in my lab.  But whilst on the one hand it gives you great insights into these new process in the brain, these assemblies, I stress you can't do those on human subjects, so you have to extrapolate and do things indirectly.   But armed with this new technique, we can now appreciate these so called assemblies, these large scale coalitions do indeed vary hugely in size because they're not restricted or defined by anatomical areas.  So one can look at all the different factors that would determine how big or small an assembly is and then see if any same factors would determine what kind of consciousness you have.  So that's a start.  I know it sounds a very cumbersome one but bear in mind we are limited by what you can do to humans and also what the techniques can offer.  

SHANE HUNTINGTON
Now you mentioned Karl Popper earlier.   I think it's interesting when we look at the best scientific theories are the ones that stand up to being falsified.  Is this or the theory at the moment with the brain imaging techniques, is it something that we can test that falsification aspect of, or are the two things too separated at this point?

SUSAN GREENFIELD
I think that's a very good question.  I think in an ideal world it is testable.  It's not an easy thing to do given greater resources, and this isn't a plug for money but I do have to mention it because - and just as an aside.  I'm not ducking the question Shane, but I would like to just mention that the study of consciousness for neuroscientists is very hard because it's still is sort of anathema to the grant giving bodies and to conventional science.  In fact some wag once called it a CLM.  Do you know what the CLM is?

SHANE HUNTINGTON
No.

SUSAN GREENFIELD
A career limiting move.  They said that's only why neuroscience - why Nobel prize winners study it because it's very hard to get a grant.  You have to disguise it as anaesthesia or schizophrenia or something.  You can't apply to the Medical Research Council to study consciousness, you'll laughed out of - I just say that as an aside because it is a problem that does, I think hamper the study of this really exciting issue, because it does have the element of subjectivity and philosophy, I think a lot of traditional neuroscientists run scared at that.  But as John Searle, a philosopher once said, he said to say you're studying the brain and you're not interested in consciousness, is like saying you're studying the stomach but you're not interested in digestion.  Anyway, so that's all to one side.  So the issue is more how falsifiable are these hypothesis?  Well that depends on what hypothesis is.  In my case it's, I think consciousness is correlated with these assemblies and we can study these assemblies and we can vary them, and then we can extrapolate what kind of consciousness you'd have.  I have suggested that in several of my papers and books I've written.  I think it is possible, although what you can't do with humans is the voltage-sensitive dye imaging.  But what you can do is to show scenarios where you would have say a small assembly or a large assembly, you can show with your experiments how these are modified by various drugs and then you can talk about how those drugs modify consciousness in people say.So I think up to a point it is testable.  It's not as testable as it would be if one had more resources and so on.  But I think it's a start and I think that just because things are not perfect or they're not direct doesn't mean to say you should give up on them because if that's what you have, it's better to do something than nothing. 

SHANE HUNTINGTON
It sounds like you're in a similar boat to the dark matter cosmologist really.   You see the effect but it's very hard to measure what's causing it and they seem to be doing very well.

SUSAN GREENFIELD
Yeah exactly.

SHANE HUNTINGTON
Financially.

SUSAN GREENFIELD
Well the other thing that you're working on with consciousness is of course inevitably if you're linking as we are, physiology with phenomenology, at the end of the day you cannot escape.  You need direct human reports on what they're feeling or thinking.  Now of course that involves subjectivity but that's what consciousness is.  So you do have to rely eventually on people saying, I feel sad or I feel sleepy.  You have to rely on subjective reports if you're interested in a subjective phenomenon.  But that's the nature of the beast.  

SHANE HUNTINGTON
I'm Shane Huntington, and you're listening to Up Close.  In this episode, we're talking about consciousness with neuroscientist, Baroness Susan Greenfield.   Susan, are there illnesses in brain conditions where these neuronal assemblies are disrupted?

SUSAN GREENFIELD
Well modified.  I wouldn't say disrupted. That implies that they're automatically disbanded in some way.  Yes let's talk about two, which I have suggested one can relate to these assemblies.  Let's take for example schizophrenia, where we know among other things there's excessive amounts of the chemical messenger dopamine, among other things it's not just that.  If you look at the phenomenology of schizophrenia, it's very similar in many ways to a small child.  They're easily distracted, they have short attention spans, they can't interpret proverbs, they take the world very literally.  The sensory world implodes on them in a way that it doesn't in healthy adults.In childhood, we know that there are fewer connections between brain cells and therefore this would determine the size of the assembly just couldn't be big because there wouldn't be enough connectivity there.  In schizophrenia one could have again a smaller assembly because the chemical messenger dopamine could, without getting in to the technical details, restrict the activity of the cells so that it stayed smaller.So you can see that one could start to think of it like that.  Now what's very interesting is one can then think of the opposite scenario from one where the sensory world implodes on you, you're reactive to every moment, and that is clinical depression.  In clinical depression, people say they feel emotionally numb, they feel remote, the outside world seems very grey and distant, they are divorced if you like from the press of the outside world.  So in some senses it's the kind of opposite of schizophrenia, which is too much involved with the outside world or implodes in on you here, you're distant remote and emotionally numb.  Schizophrenia in childhood are highly emotionally charged scenarios, whereas in depression, as I say, there is what's called a flattening of affect.  That's to say the person is sort of numb. Now I've suggested that depression is a large scale assembly because it's not instantly or constantly updated or modified by inputs from outside, which is why you have this persistent and sometimes obstinate obsessive thinking.  So you can think of these two relating - I'm simplifying things a bit into smaller and larger assemblies.  Now what's really interesting in comparing them is if one talks about pain, it's well known and this has been experimentally shown, although horrible experiments.  I don't know how people could bring themselves to do it.  To give pain to schizophrenics and they have a higher threshold for pain than normal people.It's well known in depression, again this has been properly done, it's not just anecdote, that depressed people feel pain more.   My own suggestion is that this gives us an insight in to pain and assemblies.  That the degree of pain you feel could be related to the size of the assembly.  So you see you can start to look at different brain states and you can start to compare them and you can start to then extrapolate to other things like neuropathic pain - how you feel pain.  I think in that sense there is some use in doing that.  You know again, it's not confronting the head on miracle, but nonetheless what we can do is we can start to nibble around the edges.  

SHANE HUNTINGTON
What about enhancements to the assembly.  I mean drugs and so forth.  I mean what is possible there?

SUSAN GREENFIELD
Well again, I've never done this first hand but I would have thought meditation is something where one could imagine a very large scale assembly where you've shut out the outside world entirely, where as far as I can gather in certain states of meditation you say the same word over and over again - ohm, ohm, ohm.  Almost to stop you being distracted so the assembly can grow, so one can think of that, I think, as an enhancement.  But we mustn't confuse enhancing thought, such as happens with mediation, with just modifying your senses as might happen with LSD, and that's a very different thing.  Just because you're modifying your senses isn't saying you're enhancing your consciousness.  

SHANE HUNTINGTON
In terms of take one species for example of humans, it would be nice for us to be able to say that different people have different levels of consciousness.  Do you see that in these experiments on some of the model animals where there is a range of grey as you refer to it, of the level of consciousness within that particular species?

SUSAN GREENFIELD
One has to be very careful here, because one can immediately see a minefield opening up of political correctness where you say someone's only got shallow consciousness and someone else has got deep consciousness.   Nonetheless, that's what some people think.  I am sure philosophers will think they have a deeper level of consciousness.  Certainly in ancient Greek tragedy, or Aristophanes the philosophers always thought they had loftier thoughts than everyone else.  I think that to avoid that rather invidious comparison of one person to another, it's better to think of any human individuals having the potential for a vast range of levels of consciousness.  You can for example, go to a party at a rave, you can blow your mind, let yourself go.  You could have the level of consciousness that's more infantile where you are not self-conscious.  One hopes one's not on the dance floor- too self-conscious, where you're just reactive to a world that's perhaps stripped of all cognitive content, you know where the flash of the lights and the beat of the music dominates.  One could talk about that being a shallow consciousness and indeed would pay money to be like that.  Wine, women, and songs, drugs and sex and rock'n'roll, all have this abrogation of the sense of self at their heart you know and we have a sensational time.  You don't say let's go out now and have a cognitive time Shane do you.  So in one sense, yes you can have a range.  You can do that or you can go meditate by a lake and the human species is capable of doing both those things.  

SHANE HUNTINGTON
You mentioned earlier the differentiation between the mind and consciousness, so I ask you to talk a bit about the mind.

SUSAN GREENFIELD
Yes, because the two are related but they are distinct entities, and thank you for that because I think it does tie in with this idea of losing the mind and blowing the mind and when we talk about schizophrenia and so on.  So just to back track a second for anyone listening whose not grounded in neuroscience, one of the most exciting things that really has, I think, characterised much research over the last decade is the real awareness of the so called plasticity of the brain.  That's to say how well the brain - the human brain, does it superlatively.  Other species do it but we do it better than any of them.  How we adapt to the environment, and incidentally that's why we occupy more ecological niches than any other species on the planet, is we don't run fast or see well, we're not strong, but we learn, we adapt.Now the way this happens is that when you're born, your brain undergoes an astonishing growth compared to say a chimp.  This is caused by the growth of connections between your brain cells and you can see over the first two years of life an amazing change in what happens in terms of the connectivity.  Now why that is very advantageous for us as a species is that it means that our unique experiences, our individual experiences, even if we're clones - that's to say identical twins, will actually be shaped and updated and strengthened and so on by that experience with the outside world.   There's some enchanting examples of human plasticity such as London taxi drivers who have a bigger area of their brain because they have to memorise the streets of London.  A fascinating one of piano playing where even over five days people that have played the piano, or even thought of about playing the piano, have changes in their scans that you don't see in the controls - you just stared at the piano and so on.  So we know, and this is very well acknowledged and there's some wonderful books out about plasticity, and it seems to me that this personalisation of the brain through the environment is what we could call the mind.  Because when you're born as a small child you don't have one - yeah.  But as you grow you develop a mind, and this mind is the personalisation of your brain that enables you to see the world and to react with it in a unique way that no one has ever done before, nor they ever since.  In other species they will also have to greater or lesser extensibility, but it's particularly marked in us, which is why we talk about the mind of humans.  We don't really talk about the mind of a rat on the whole because they are much more reactive.  They're living in the sensory world, whereas what a mind does - what connections do, is enable you to see the world in terms of other things, in terms of your previous experiences, in terms of different words, in terms of associations, so we can shift from what we would call sensory to cognitive.  Now there can be moments in our lives when we decide we don't want to do that, when we don't want to access those connections.  In which case we'll take a drug that may impair the neurons talking to each other, the brain cells talking to each other, or we can put ourselves in environment that is dominated by the senses where you're in a world of I say bright lights flashing, flashing lights and throbbing music that doesn't have any content but nonetheless is appealing by virtue of its sensory premium.  People have always done this since the ancient Greeks.  They play Euripides' Bacchae was all about this king who tried to suppress women worshiping the wine gods Dionysus, in fact got torn apart for his pains.  But there the prophet says there's two forces in there, the wine force and the bread force, and one of them - the wine force is where you let yourself go, and we talk about letting yourself go, losing your mind.  The very word ecstasy in Greek is to stand outside of yourself.  So think this has always happened and this is why I am at pains to differentiate consciousness from mind because I think these scenarios where you are of course still conscious, you've lost your mind or blown your mind. I think that we can think of the mind, as I say as these growth of connections, as this personalisation of the brain that may or may not be accessed according to what you're doing or where you are.

SHANE HUNTINGTON
Susan, I recall a case from 1848, Phineas Gage, a railway worker had a one metre iron pole put through his skull.   Was his degree of consciousness changed as a result of this sort of accident?

SUSAN GREENFIELD
Well first thing, it wasn't put through as sort of a deliberate intervention.  It was because he was pushing down explosive to try and remove debris for laying tracks from the east to the west coast in the States - he was in Vermont.  Sadly the explosion went off prematurely and drove the so called tamping iron through an area of the brain called the prefrontal cortex.  Now why this is interesting, and I'm pleased you've flagged it, is that he earned his place in history because he didn't die.  He wasn't seemingly mentally impaired, and in fact in those merciless days before Social Security, he actually went back to work.  It was only as the days turned to weeks, turned to months, that people noticed a difference.  Astonishing it was because he had this great hole through is head.  What the difference was that he became more childlike, more irascible, quick to anger, and indeed more reckless.  He was the first case of what was then to be a sadly repeated syndrome seen with shrapnel wounds in the first and second world war, when people had similar damage and this presented with the same so called frontal syndrome.  Now what this was, was if you like a return to childhood, if one summarises it crudely.  That fits because we know this frontal part of the brain which occupies 33 per cent of the human brain, only 17 per cent in chimps, is very much a sort of Johnny come lately on the evolutionary scene.  As always evolution reflects in development and we know that the prefrontal cortex is very important area, is only fully operational in the human brain in late teenage years, early twenties.  Now this raises some interesting questions because I have suggested that an underactive prefrontal cortex is very similar to what I would call a small assembly mode.  That is to say a world where you are living in the here and now.  You're not aware of consequences, hence you can be reckless.  You're very much governed from moment to moment.  You live in a sensory world more than you would a cognitive world.  So I would have said that what had happened to Phineas, and indeed to others perhaps you have malfunction of the prefrontal cortex, is that they are much more in the small assembly mode, much more living the kind of consciousness, having the sort of view of world that a child might have where you're very impressed and distracted by, and reactive to the outside world as opposed to some inner world that is more specific or idiosyncratic to you.  

SHANE HUNTINGTON
Susan, we have this incredible array of technologies, some just coming about now, some that we've had for several decades.  How far away do you think we are from a scenario where you would find in a typical medical textbook, an explanation of consciousness that is widely accepted?

SUSAN GREENFIELD
Okay, well I think no day soon.  I think we should differentiate what we mean by explanation and description or definition, and they're different things. You know we maybe able to at some stage work with philosophers on some kind of definition that doesn't use the usual strategies, but that doesn't mean to say that we'll be able to explain it.  I think an explanation awaits and this is probably going to be an input from philosophers or mathematicians.  We need something that we then deliver in brain terms.  We need to know what kind of answer we would expect and at the moment I can't see neuroscience delivering that.  What I can see neuroscience delivering are increasingly tight correlations as I've said, that may inspire a theory such as my own, concerning neuronal assemblies.  But I'd be the first person to put my hand up and say, just because I say neuronal assemblies are very appropriate and faithful correlates of phenomenological states, does not mean to say that is an explanation.  It doesn't it.  It's an index of consciousness.  It's not an explanation of consciousness. 

SHANE HUNTINGTON
Baroness Susan Greenfield, Professor of Synaptic Pharmacology at Lincoln College, Oxford, thank you for being our guest on Up Close today and talking about neuroscience and consciousness.

SUSAN GREENFIELD
It was my pleasure Shane.  Thank you very much.  

SHANE HUNTINGTON
Relevant links, a full transcript, and more info on this episode can be found at our website at upclose.unimelb.edu.au.   Up Close is a production of the University of Melbourne Australia.  This episode was recorded on 23 November 2012.  Our producers for this episode were Kelvin Param and Eric van Bemmel.  Associate producer Dyani Lewis.  Audio engineer Gavin Nebauer.  Up Close is created by Eric van Bemmel and Kelvin Param.  I'm Shane Huntington.  Until next time, goodbye.  

VOICEOVER
You've been listening to Up Close.  We're also on Twitter and Facebook.  For more info visit upclose.unimelb.edu.au.  Copyright 2012, the University of Melbourne.


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