Leading Edge
with Geoff Watts 

Geoff Watts : Hello.The first problem confronting anyone aiming to study the brain was for many years,simply to get at it.The organ is,after all,carefully protected inside a rigid box.One of the first scientists to solve that little difficulty was the American neurosurgeon Wilder Penfield.On this recording made in the late 1950s,he's speaking to an ex-patient,about an operation he'd performed to cure her epilepsy. 

Penfield : It was 11 years ago... 

Patient : That's right. 

Penfield : ...that you were here,and you had had as a little girl,an illness that left its mark,and so you began to have attacks which began - I remember you telling me - with a feeling of fear. 

Patient : That's right. 

Penfield : You remember we studied you with the X-ray,with electrograms,saw the pattern of your attack,and there was only one place it could be,and that's right here,in your right temporal region. 

Geoff Watts : By stimulating his patient's brain whilst she was awake,Penfield was able,not only to identify which bit was causing the epilepsy,but also to avoid cutting and so damaging any other vital part of it.To help him study some rather peculiar effects of the surgery on his patient's memory,he recruited a young British psychologist called Brenda Milner.Now in her 80s but still an active researcher,she recalls that pioneering work. 

Brenda Milner : It was unique,in North America certainly,it was unique at that point,the idea was really to find out where the seizures were coming from,and if possible to remove the area of tissue which they called nociferous,that it could interfere not only was it causing seizures,but by this abnormal electrical activity,it could interfere with the functioning of healthy parts of the brain so that people's thinking and reasoning were put off by this electrical activity.What was special here in the surgery for epilepsy,was that you could see a large area of the cortex,and Dr Penfield carried out these operations under local anaesthesia applying ,you know,small electric currents and mapping the responses. Every time he stimulated,after the stimulation,he dropped a little bit of label on the brain,a little paper,so it was literally mapping.
[So it seems that people having visions are seen to be having TLE,and the same electrical storm also interferes with their ability to reason.So it's obvious why religious people (who have had visions) don't make any sense-LB] 

Penfield : So we opened it up there,didn't we? 

Patient : Yes. 

Penfield : Under local anaesthesia,and that showed the underlying brain.This is the brain.Now when we stimulated at three,you had a tingling in your thumb,you've probably forgotten now. 

Brenda Milner : He would stimulate and he would dictate,a secretary would also be in the gallery.It was really quite a performance,it was very....it was something that people coming to Montreal,visitors,you know,like yourself,would want to go into the gallery and see this event. 

Penfield : Then underneath this we stimulated, and to my astonishment,you said "I hear music".Tell us what you heard. 

Patient : Yes.Well I heard what sounded like an orchestra playing,and I asked the nurse where it was coming from,and she asked me the name of it.But I said "I know the song,but I can't think of the name of it". 

Penfield : Then I stimulated again,you remember and asked you about it and you hummed it,would you hum it now,you remember it? 

Patient : Yes. 

Penfield : Go ahead. 

Patient : Da,da da da,dah dah dah,dah dah dah dah dah dah dah dah. 

Penfield : Yes and then when you got to that point,the nurse explained "I know what it is,it's 'Rolling Along Together' ",and you said what? 

Patient : And I said "Yes,that's what it is"! (Penfield laughs) 

Geoff Watts : The voices of Wilder Penfield and patient,and that was Brenda Milner recalling an experiment that became a classic in the history of neuroscience.Penfield died in 1976,but in the organisation he founded,in his adopted home city,the Montreal Neurological Institute, he's a continuing presence. His portrait dominates the main entrance hall,and through the close links he established between research and treatment,his spirit continues to influence the work of his successors. Penfield had little choice but to invade the living brain with electrodes and scalpel.But the advent of new and non-invasive methods of visualising the brain,notably magnetic resonance imaging or MRI,have allowed researchers to study it more often and in far more detail than would have been imaginable in Penfield's day,and it's not only anatomy that these method's reveal,another called PET scanning [Positron Emission Tomography -LB],shows which bits of the brain are most active at a particular moment.By having a subject perform certain tasks or think a specific thought,neuroscientists can find out which region of the brain does what.Virtually all the work going on at the Montreal Institute is informed,directly or indirectly by these methods.Thomasch Paus(??),for example,is using MRI in conjunction with another technique called Transcranial Magnetic Stimulation,TMS for short. His aim is to explore brain function by temporarily disabling small portions of it.Sounds dangerous,but it's not.The magnetic stimulator which does this trick,is fitted inside a hand- held wand,which he can place anywhere on a subject's head.The powerful,but localised magnetic field it generates,disrupts the activity of a small volume of underlying brain tissue.It's almost as if Paus is removing a bit of the brain and then putting it back. 

Thomasch Paus : You put a coil over the head,of course you don't have to open the skull,as the surgeons have to when they are stimulating the brain electrically,and in this non-invasive way,you deliver electrical current to the brain underneath. 

Geoff Watts : And the area of brain tissue that is temporarily disrupted is presumably fairly close to the surface? 

Thomasch Paus : That's the main limitation of the technique,that in fact we cannot stimulate deep brain structures.We can stimulate only the part of the brain that is right underneath the skull. 

Geoff Watts : Well now,one thing that you want to know,when you you're stimulating,is exactly which bit of the brain is actually being temporarily being disrupted,temporarily knocked out by this technique.First of all you take an image of the patient's brain using which technique? 

Thomasch Paus : Magnetic Resonance Imaging. 

Geoff Watts : Which is a method of seeing structural images of the brain,but without using X-rays,and then how do you move around the wand,by which you're stimulating....? 

Thomasch Paus : Well,the wand has little spheres on top of it,and those sphere's...the position of those spheres,are tracked by a special infra-red camera. 

Geoff Watts : Which is actually up on the wall,here behind us,the patient would be lying here,the subject would be lying here,with their head on this pillow,the wand would be placed on their head,and on the wand there is this little arm with the three spheres.Up on the wall there's a couple of cameras which are locating the position of the wand by the position of these three spheres? 

Thomasch Paus : Correct.Yes. 

Geoff Watts : And then you move this around,and what do you see on the screen. 

Thomasch Paus : What you see is where the centre of the coil is relative to the brain.What we can do is then,mark a position on the brain,where we want to go,and we keep moving the coil until the centre of the coil is aligned with that position in the brain,and that's when we know we are over the part of the brain that we want to study. 

Geoff Watts : So then,we've got a technique here which enables you to disable temporarily, a relatively small part of the brain.What value is this to neuroscience? To be able selectively to disable one particular bit of the brain for a short period? 

Thomasch Paus : Over the past 10 or 15 years,we've been doing a lot of imaging studies with Positron Emission Tomography,with Functional MRI,Functional Magnetic Resonance Imaging,and in all those studies,we've been learning about the different regions lighting up,so to speak,during the performance of different tasks. 

Geoff Watts : Different regions of the brain becoming active during those tasks? 

Thomasch Paus : That's correct,and what we don't know though,is whether all those regions are also critical for the performance.We have seen in our lab,that even though two regions may be active during two different tasks,only one of them is critical.Interruption of the other one does not impair performance. 

Geoff Watts : Well we've got a willing,I hope willing volunteer on the table now, Jennifer.Now you've got the wand,which actually delivers the magnetic stimulation,and you place the wand over her head,and now you've got to move it around until you've chosen,to find the area that you want to stimulate.What area are you going to try to stimulate? 

Thomasch Paus : Well,in this case,we want to simulate the primary motor cortex,the part of the brain that controls movement of the hand or arm,then we are on the right side of the head,so we'll be looking for the right motor cortex and looking for twitches in the left hand,on the other side of the body. 

Geoff Watts : And you can see what part of the brain you're stimulating by looking at the screen,or the monitor behind you,and that red arrow,it looks like with a yellow cross at the end..... 

Thomasch Paus : The yellow cross is.... 

Geoff Watts : ....that's where you're going to be stimulating? 

Thomasch Paus : ....the yellow cross tells us where the coil is,the centre of the coil is,so we want to move that cross to get to the central salcus,which is where we know the motor cortex is. 

Geoff Watts : Okay let's see what happens. 

Thomasch Paus : So,give me a pulse,okay go (click),go (click),go (click),go (click). 

Geoff Watts : Right,now,it was very obvious there,Jennifer's arm which is up off the bed that's she's lying on,there was a sort of a twitch in her fingers,so you're spot on there then? 

Thomasch Paus : That's right,so that you can now see it only from the primary motor cortex,because that part of the brain contains fibres that go to the spinal chord,then they relay into the fibre that goes to the muscle. 

Geoff Watts : Jennifer what were you aware of for the moment? You felt,you obviously felt your hand twitching slightly didn't you? 

Jennifer : Mmm-hm,mmm-hm,yeah. 

Geoff Watts : Is it uncomfortable? 

Jennifer : Not at all.No.It's a really subtle sort of sensation.Sort of like a...on the head it's like a tapping,a really.... 

Geoff Watts : Oh you felt something on your head did you? 

Jennifer : Oh just a light tapping,yeah. 

Geoff Watts : And at the moment you felt that tapping on the head,so your fingers twitched? 

Jennifer : That's right,yeah. 

Geoff Watts : It's still a quite literally mind-numbing tasks,I mean it's hugely complicated, when you think of the number of individual cells in the human rain.The amount of activity that's going on,the number of connections between individual cells,and all you can do from the outside,is sort of wave this wand (Thomasch sniggers) and knock out a fairly large chunk of the brain with perhaps hundreds of thousands of nerve cells,do you ever wonder whether it's really feasible to actually get some insight into how the brain is working,using what is necessarily a fairly crude approach? 

Thomasch Paus : It depends on the level.Of course here we are talking about a level of the whole organism,and we can get some ideas about what operations are carried out in different parts of the brain,but we wouldn't know enough about how those operations are implemented at the cellular level.For that we really need to go into the brain and record the activity of those cells,even changes at genomic level,expression of different genes,and study basically the whole system top-down. 

Geoff Watts : Thomasch Paus and his brain manipulator.Another of the MNI staff,Robert Zotoray,is trying to answer a basic question about how the brain processes two of the most familiar of all the sounds we hear,music and speech.Scanning techniques have already demonstrated that music and speech are,generally speaking,processed on opposite sides of the brain.Now,superficially this seems odd,both tasks are after all about dealing with sound. Robert Zotoray has devised a series of tests which demonstrate the logic of their separation. In the case of music he presents his subjects with various combinations of the same or different notes,played on the same or different instruments. 
(Piano plays three notes,followed by two instruments in unison) 

Geoff Watts : Same note or different? 
(Violin type sound plays three,followed by three plucked string notes,three blown notes,and three percussive vibraphone type notes) 

Geoff Watts : In each case his subjects have to say what's going on.Same notes, different instruments,or vice versa,it can be quite tricky.Anyway what emerges from the test scores is that music processing relies principally on frequency - tone, pitch and the like,and by and large,we humans are pretty good at it.On then to the speech part of the test,with me as the guinea pig. 

Robert Zotoray : So for the speech test,what you will hear is two syllables,and they are either spoken by the same individual or not,and the word is either the same exact word or not.So your job will be in the first case,you're going to tell me if the same person has spoken the two sounds.
("hoed","heard") 

Geoff Watts : That's a different person. 

Robert Zotoray : That's correct.
("heard" "heed") 

Geoff Watts : That's the same person. 

Robert Zotoray : I think they were different in fact [I agreed with Geoff -LB]! 

Geoff Watts : Oh! (laughs) 

Robert Zotoray : But I'm not sure I'm right.
("hid","had") 

Geoff Watts : I'm not absolutely certain there,I think that was a different person.Let's have another one. 

Robert Zotoray : Even though I've heard them a million times now,I ...it's not trivial.
("had","hid") 

Geoff Watts : That's a different person,I'm pretty confident about that one. [They sounded the same to me -LB] 

Robert Zotoray : Okay,okay. 

Geoff Watts : You've got differing levels of complexity. 

Robert Zotoray : Yes. 

Geoff Watts : Sometimes the distinction is obvious.... 

Robert Zotoray : That's right. 

Geoff Watts : ...other times it's much trickier. 

Robert Zotoray : That's right.When you hear an adult male versus a small child,the difference acoustically is very large and therefore it's simple to do this.When you hear two children,then it's much more difficult.So even though you've never met me before,you understand what I say perfectly well.But again if you think about it,computationally,this is a complicated problem,that the nervous system must solve.It must be able to figure out what is the message when the message is carried by a quite different package,every single time. So on this same test,you can tell me now,and I'll give you a few more trials,you can tell me if the same word has been spoken,twice,even though it's spoken by different people.For example. ("heed","hard") 

Geoff Watts : That's a different word. 

Robert Zotoray : That's a different word.
("had","hod") 

Geoff Watts : Different word. 

Robert Zotoray : Correct. 
("hayed",heard") 

Geoff Watts : Different word. 

Robert Zotoray : It's quite simple isn't it?
("had","heard") 

Geoff Watts : Different word. 

Robert Zotoray : Yeah,this appears to be trivial,because we do it so well,and yet it's one of the main things that people who program speech recognition devices have had difficulty with,but that software is now commercially available,but it's still not really that good.in fact what you have to do is you have to train it on your voice.You have to give it a lot of examples of how you say "had" and "heed" and "hood",and then it will be able to understand you better,any child can do this without any training. [Without any training? Surely they get trained by being immersed in sound and their parents speech? -LB] 

Geoff Watts : My occasionally fumbling performance notwithstanding,Robert Zotoray's experiments show that there is a clear difference about what's important about speech as opposed to music.While both are sounds that need to be processed,the features within them that our brains are looking for are not quite the same. Processing speech is all about interpreting sounds that are changing very rapidly,every few milliseconds.Think how quickly we can speak,and still be understood.Processing music,on the other hand is more about looking for slower changes in pitch and tone.So there is some logic in having one side of the brain - it's actually the left -specialise in speech,the other in music. 

Robert Zotoray : There are no melodies,for example in any musical system anywhere in the world where the notes change every 15-20 milliseconds.Whereas speech sounds do change on that kind of timescale. 

Geoff Watts : So in principle it would be possible to have one bit of the brain which is doing both tasks,but it wouldn't do either as well as having it split between the two sides of the brain. 

Robert Zotoray : Exactly that.The way the brain has evolved [And it DID evolve - LB] is to get the best of both worlds,by having separate sub-systems,one of which is good at one thing,but is not so good at the other,but its twin on the other side,has the reverse characteristics,and that allows us to - for the whole organism - it allows to be good on both ends. 

Geoff Watts : But this seems to leave one question unanswered.In terms of the biology of adaptation,one can well see the advantage of being able to process speech sounds because they are fundamental to human communication.It's less obvious why any bit of the brain should have specialised to process musical sounds,because it's not obvious that music serves any particular purpose in biology. 

Robert Zotoray : Yeah. 

Geoff Watts : So why on Earth does one bit of the brain develop this extraordinary capacity? 

Robert Zotoray : Yeah indeed,there are many people who have posited all sorts of possible you know,advantages to having something like music.It's been linked to everything from mate selection,mother - child bonding to group cohesion for you know coordination of work activities and so on,and these are all very,you know,interesting hypotheses,but of course they can't ever be tested,because we would have to have had some recordings back from pre-Neanderthal (Geoff sniggers) times,and I don't believe there are any! But I think we may be able to think along the following lines,that the evolution of the auditory cortex may have been driven by speech communication,and conceivably,the specialisation of the left auditory cortex for speech processing,may have in a sense,free up other areas of the brain to perform other functions.Being able to use sounds to detect danger or to detect a source of food,or to navigate.Maybe music is a sort of happy accident of this sort of specialisation. 
[This is similar to my supposition that characteristics existent in biology needn't come as requisite to survival,but be a by product of some other development.Similar to Brian Goodwin's views in organism.html at http://members.xoom.com/Templarser/ -LB] 
My understanding of evolution is that there are many kinds of traits that are not selected for initially,but they are the outcome of something else.They are the natural outcome of some specialisation for some other purpose,and then once they are there they get used. 

Geoff Watts : Robert Zotoray,showing how the study of music casts indirect but valuable light on the study of speech and language. (Baby makes proto speech gurgling noises) Psychologist Laura Ann Petito,also researches language and where it's processed within the brain.But her interest in the topic has led her to some extraordinary conclusions about the very nature of language and its interpretation. (Baby gurgles "Ma ma" repeatedly) 

Laura Ann Petito : Well the conventional view has been that language acquisition ,language learning begins by the ability to speak,and the ability to hear,and that when we look at a very young child and we see them going through the classic milestones like babbling and the first attempts at words,that all the timing and the content of that behaviour,all of that is due to the development of the ability to talk and to hear. 

Geoff Watts : That does indeed seem logical.Speech is after all how most humans communicate.Most, but not all.Some deaf children with deaf parents grow up using sign language.For many years now,Laura Ann Petito has been convinced that the language processing abilities of the human brain are based on something more fundamental than the specific ability to process sound.What the brain is really interested in,so she thinks,is patterns of nerve impulses,irrespective of whether they represent patterns of sound entering the ear or the visual patterns of hand movements picked up by the eye. But a hunch is one thing,proof is another.The way forward,she decided,was to investigate very young babies,to compare the development of sign language with that of speech. 

Laura Ann Petito : All human children,achieve the early milestones of language on the same timetable.... 

Geoff Watts : Is it.....? 

Laura Ann Petito : ....so around 6 months all children begin to babble,and around 12 months they begin to produce their first word,and so these are very regular milestones.Again the hypothesis has always been that the reason those milestones are so universal,despite such vastly different home environments,is because that's reflecting the rate at which the brain is connecting to the oral facial region,and beginning to get control of the ability to produce sound.But then we compare that to profoundly deaf children.Imagine this,this is a brain stripped of speech.It's a soundless brain.The brain is not getting that stimulation.What's going to happen with the source of language? 

Geoff Watts : So what you wanted to discover was whether the sort of milestones that you get in normal hearing children as they're developing language,you would get counterparts of those in children learning sign language? 

Laura Ann Petito : That's right.The question was really about the human brain,and what was the driving force behind the capacity for language? Was it just the capacity for speech,or was there something more than simply our ability to simply talk? 

Geoff Watts : Okay,well let's consider some of those milestones.The...one you've mentioned briefly already,babbling.By babbling you mean what,in children who can hear and are learning speech? 

Laura Ann Petito : Okay,one of the interesting things that all children do is at a particular developmental moment,beginning around 6 months,they extract out a very select set of the sounds that they've heard,and then they combine them in little bite size chunks,with a consonant and a vowel,consonant,vowel,and they do this rhythmically. "Ba,ba,ba,ba,ba","ma,ma,ma,ma,ma". A little bit later,they start combining,so they'll go "Ah,ga,ba,da",so they start combining sounds,and a little bit later,around 12 months,you'll see long strings of these sing-song units,almost as if they were uttering a full sentence in their native language,but meaningless. Ah,ba,dab-ar,ba-dah?",so it takes on a question formation, 
[Notably,Laura alters the pitch of her voice,in order to insinuate a question.Work has been done,showing that pitch can convey emotion,and that sort of work led to changes in aircraft warning signals,from sirens,to discrete sets of notes with varying intervals.This work was covered by Ch4's "Equinox" strand -LB] 
and all of this is what then human words get slotted into. 

Geoff Watts : So that's hearing children learning spoken language.... 

Laura Ann Petito : Right. 

Geoff Watts : ...you were then looking for the counterparts of that among children learning sign language? 

Laura Ann Petito : Actually....yes,deaf children exposed to sign language,also produce a highly select set of hand movements,and these hand movements were combined in rhythmically moving and holding,move,hold,move,hold,just like a consonant, vowel, consonant, vowel, 
[Perhaps the brain is more like a computer than supposed! It works in binary!!! Actually,in Roger Penrose's "Shadow's of the Mind" (following ENM) is shown the partially discrete on- off nature of neural impulses.We know synapses are varied with chemical signals,but perhaps there is a PCM like coding (a mark-space type signal) that creates these basic gestures? -LB] 
alternating patterns,and they were entirely meaningless.So they didn't want anything,it was just kind of the sound play that you see in a baby called "crib speech".It was the hand play that was ultimately going to be used to construct all the signs and their language. 

Geoff Watts : So just as in a child you get these sort of "ba,ba,ba,ba" sounds,and then sort of "wareuggh" meaningless sounds as well....

Laura Ann Petito : That's right,that's right. 

Geoff Watts : ...then in the sign language learning children,you would get these repetitive little what? Clutching, rolling movements with the fingers.....? 

Laura Ann Petito : That's right. 

Geoff Watts : .....and also much wider,more abstract movements? 

Laura Ann Petito : That's right.A movement and a hold,a movement and a hold,just like the opening and closing of the mouth.But the mystery was where could that come from,it's not coming from the jaw itself,because these children aren't speaking.So again,it suggested that something else was contributing to the universal appearance of the milestone babbling at around 6 months,that was more than just coming from a child's developing speech. 

Geoff Watts : To study speech babbling in infants is quite straightforward,to pick out and follow hand babbling is much harder.The few researchers who'd even noticed deaf infants making these hand movements attached no importance to it.Laura Ann Petito set about recording their actions. 

Laura Ann Petito : Borrowing from robotics,we used the...what's called the Optitrack system,and this is a very sophisticated system, where you put light emitting diodes,these are little... they're called LEDs -Light Emitting Diodes, on the baby,little baby hands,on the infant hands and on their feet,and they're seated in a play seat,and there's lots of toys and adults around them,and we engage in the normal play and discourse with them,but while they're engaged in this happy normal play,the computer is picking up where the lights are, and then sending it into a computer that generates for us in 3D and in real time,the path movements and trajectories of the child's movements,the velocity of the hands,and by using this technology,we were able to look at hearing children who had never been exposed to sign language,and deaf children to had been exposed to sign language,and see that not only to the naked eye is there a fundamental difference between this little rhythmic activity that only deaf children make,but also to harness its physical properties. 

Geoff Watts : Let's move into the brain now..... 

Laura Ann Petito : Yes. 

Geoff Watts : ...because the whole essence of you theory is that it doesn't really matter whether we're communicating by sign language,or communicating as we are now by speech,but it should be the same bits of the brain which are active.Now have you attempted to explore that? 

Laura Ann Petito : Yes,okay that's exactly what the implication of the acquisition studies were. Our question was ,moving beyond the fact that the left hemisphere is responsible for language,what is the neural basis of that tissue? Is that tissue dedicated exclusively to processing sound,or is that tissue....has it evolved to abstract away from sound,and is it sensitive to particular types of patterns that are encoded in natural language? So to test this,we went to brain scanning,we able to give hearing people and deaf people these visual stimuli.They were in a scanner,they looked at a TV screen,and we were showing them these very specific parts of sign language grammar.Now if you were a hearing person looking at this.... 

Geoff Watts : It wouldn't mean anything. 

Laura Ann Petito : .....it wouldn't mean anything to you,it just would be visual.Sure enough when we looked at the hearing people's brains that's what they showed us.They have no activation of the tissue,in the classic parts of the language centres,because for them these particular parts of hand movements had no meaning. 

Geoff Watts : They weren't language? 

Laura Ann Petito : No.But for the deaf people,when they saw the rhythmic manual hand movements,the same tissue activated when a hearing person hears "ba,ta,pa".Now this is remarkable,because this tissue around the ear - it's called the superior temple gyrus - this tissue is not getting any auditory input,yet that tissue when it's seeing something visual,just a....it's becoming activated with something like the human hand. It led to the conclusion that the human brain is not dedicated for processing sound per se,or producing sound per se,but somehow the brain is this very powerful machine that abstracted away from talking itself,to the types of elegant patterns that our natural language presses in sound. 

Geoff Watts : So what the brain is interested in,is not patterns that are produced by sounds per se.It's interested in patterns. 

Laura Ann Petito : Exactly. [Which presumably is why music and maths are linked -LB] 

Geoff Watts : And the patterns themselves that its interested in,could be produced not necessarily by sound,but as a consequence of visual imagery as well? 

Laura Ann Petito : Exactly.It teaches us something quite extraordinary.It means that we have to fundamentally reconceptualise the nature of language.We have to decouple,just pull apart speech from language,and look again at the essence of this thing we're using right now,and see it in a new light,and see the brain's capacity to participate in this activity in an entirely new light. 

Geoff Watts : If Laura Ann Petito is right,deaf-blind people who's only language is touch,that is patterns of sensation transmitted through the skin,should also use the same part of the brain when communicating.This is all a world away from Wilder Penfield and his locally anaesthetised patients,lying on the operating table and telling him what they sensed or thought as he applied electrodes to their brains. Today's neuroscientists can gather their information without the need to inflict a scratch on their subjects,never mind sawing off a piece of the cranium.But despite all we've learned,they and Penfield have one thing in common,what's understood about the brain is still only the tiniest fraction of what remains to be discovered. 
23 July 2000