Thank you for your kind introduction.

I am very happy indeed to be back again talking here to this distinguished audience in Lindau. I have chosen a subject today which I think will be of interest to a wide section of thinking people.

It deals with the problem of brain and mind, which is, I would say, the most outstanding problem confronting man today. I first want to tell you that by conscious experience, I don't use the word mind, it's often misused, but by conscious experience I mean something that each of us has privately

for himself. And there are various aspects of it to illustrate. First of all, there is outer sensing, that is everything given to us in perception through all of our receptor organs, such as vision and hearing and touch and so on.

Then there is inner sensing, and this is more subtle. This is the experiences we have in our thinking, in our memories, in our dreams, in our imagining. All of this inner life that we spend so much of our time in communion with, this is inner sensing. And finally, central to it all, is the ego or self.

This is something that gives us our continuity throughout life, our sense of identity and continuity. It is interrupted, of course, by sleep in other less pleasant ways, but it is the stream that has carried us on from our earliest times.

Now, on the basis of this, I want to now go in to consider the brain-mind problem. There is, at the present time, quite remarkable advances in this field, some of them have not been fully understood and followed up. I hope to introduce you to some of these new thinkings that comes out of this work

quite recently. I will base my talk on experimental evidence with regard to the split brain experiments of Sperry and to the speech areas, as have been known for a long time, but which recently have come into prominence again.

Now, we'll have the first slide, please. And here is a human brain, the left hemisphere looked at from the side, and here you see the convolutions and the motor cortex here, and here the sensory somatic cortex, and here

is where vision comes in, and here is where hearing comes, and then the rest of it is labeled interpretive, but there's also speech areas there. In this general diagram, we'll have the next slide. We can simplify it now. Here you have shown the speech areas.

The Broca area here in this inferior frontal convolution, first discovered over a hundred years ago, it's gives right by Broca and defects there, lesions there, gave the patient inability to speak coherently, although he could understand, he couldn't actually make good conversation, good speech.

Behind here is the larger and much more important area, discovered a few years later by Wernicke, and in this area, lesions, this was all done on human lesion work, quite magnificent clinical work, when you come to think of it, back those long time ago, the patient could speak in a kind, still able to speak, but he only spoke nonsense,

he couldn't understand, he lost, as it were, the sense of language. And this is a supplementary one up here. Now, this work, of course, has got immense clinical base now, and all kinds of additional areas, a lexia and a graphia and so on, described. The other point I want to make about this picture is that if you stimulate here with

a gentle current, for example, as Penfield has done, you get interference with speech, particularly here. The patient will be saying, counting, and he'll go on and say, one, two, three, three, three, three, while the stimulus is on, and then goes on afterwards, or he may stop altogether, or he may lose the sense of what he's saying while the stimulus is

applied in this area. And in that way, you can delimit these areas by electrical stimulation with interference results. Much other work has supported this whole idea of the speech areas being localized in this way, and in 98% of human beings, it is in the left hemisphere.

But you can also get, by the way, vocalization by stimulating here. And we'll have now the next slide, which shows you the right hemisphere. So it's the mirror image, and here is the, and along here is the motor area. And if you stimulate here, you get vocalization, all kinds of sounds, but no words clearly

said at all. It's just voice control, motor area. Otherwise, stimulation here gives you nothing in the way of linguistic performance. And lesions here don't interfere with language at all, except in this one to two percent. Now, you might think it's to do with left-handed and right-handedness, but that is not so.

Almost all left-handed patients also, people, have their speech on the other side. Only a few of them have their speech in the right hemisphere, but that is, in this very rare number, a speech in the right side. So that's the first point I want to make, is this remarkable localization of speech

to one side of the brain. And I don't think that this has been fully appreciated when we come to think of how does it come about, how did it grow that way, how did it come that you spoke using your left brain and certain areas there and not your right brain.

This I will come to later. Now, I want to now go into the, oh, by the way, animals, even if you stimulate this area, you hardly get even vocalization, these quarrels, say a chimpanzee and so on. They are practically always mute when you stimulate in all areas, and of course they

have no proper speech. Now, the next evidence I want to jump across to, and we'll go back to the speech after this, is to the work of Sperry. And he split the brain, cutting the corpse, because he was working on split-brain patients.

If we have the next slide, we'll see what this means. Here is a, this by the way is a chimpanzee brain, but it's just like a human one really in these respects, good enough. Here are the two hemispheres, the left and the right, and here is this great tract of fibers joining the two cerebral hemispheres.

You see, we have one here, and they are apparently independent, except for deep areas here, except for this crossing here of the big commissural tract. It has 200 million fibers, which is an enormous number, and it connects across symmetrical areas on the two sides in almost all parts of the brain.

There are now known to be blind areas to the corpus callosum. We won't bother about those. What you can do in these patients is to sever the corpus callosum. It's a nice clean lesion going through white matter only. If you cut here, you see you destroy all kinds and make a messy damage, but this

is a quite clean and sharp lesion that you can make in this way. Now, why do you do it? It seems a dreadful thing to do on human beings, but there was good therapeutic reason. These subjects have incessant epilepsy. Interfits many times a day, and their life is becoming quite hopeless.

And it was thought that by cutting the corpus callosum, you could stop at least one hemisphere from being incited by the epileptic seizures in the other. And it was also known on animal experiments, as Barry had worked on quite a lot, that cutting the corpus callosum in chimpanzees didn't give too bad an after-effects in the way of performance and behavior.

So they cut the corpus callosum in these subjects to stop the epileptic seizures in one bad hemisphere affecting the other. But it turned out it was better than that. They stopped both hemispheres in almost all cases from having epilepsy, either one. It turned out that it looked like as if this one was inciting this one and this

one backwards and forwards through the corpus callosum. And if you cut it, they behave much better. So the patients have done very well, and there are now over 20 of these patients in the Los Angeles area that have had their cutting of the corpus callosum. And hence, you might say, except for the lower areas,

a complete separation in their two hemispheres. The important thing about these experiments of Sperry's, and I think they're the most important experiments ever done on human brains, was to examine these cases very carefully indeed. And this, I think, is a masterpiece of investigation that he has presented over

the last eight years or so. Next slide. I will show, first of all, a diagram of his. Here is the two brains. Here is the left hemisphere we're looking for on top, the right hemisphere. Here's the corpus callosum connecting the two. And here is the lesion across. One of the things that's very important about this is how you get the information

into these two hemispheres from the receptor organs. And the eyes give you the most sharp separation. Here you will see a visual field, the left visual field and the right visual field. And the left visual field will go into this eye here and this eye here.

And then as you look at the optic nerve and the chiasma here, you'll see that the left visual field comes through to this hemisphere and appears in the right hemisphere. So in the right hemisphere, you get the visual half field of the left. And vice versa, for the right visual field, it comes here and comes here.

So you have a clear separation now. Your brain separation is this hemisphere is a split here. And now all left visual field information comes to this right hemisphere. And the right visual field comes to the left hemisphere. This you will understand is the language hemisphere with the linguistic areas in it.

And also, this diagram shows that for your hands and the sensation from your hands and the movements of your hands, the left hand is run from the right hemisphere here and the right hand from the left hemisphere for movements and sensing. That's because of the decussation of the pathways.

From this basis now, we'll be able to see the way in which the testing is done. Next slide, please. Here is an example. And I've seen these happenings myself. It's a very simple but very elegant technique. The subject sits here. The examiner is here. The subject is looking at a central spot here.

And in fact, the examiner is fixing his gaze there. And the examiner has a way of seeing that he really is doing that all the time. And then you can project onto this screen here, onto the left visual field, which will be this side, or the right visual field, that side, the subject fixing there all the time.

And you have here a screen and the subject's hand, in this case the left hand, can go under the screen so he can't see what's happening at all and perform with sensing, a tactile sense and movement there. That's the setup of the experiment. The important thing that Sperry did was to flash only for a tenth of a second, no longer.

And if you flash for a tenth of a second, the subject's eyes can't move across so that his right eye, so that he could shift his right visual field over to here by moving his eyes or vice versa. So you can be quite sure, in these cases, that what is flashed into the left visual field only goes into the right visual cortex and vice versa.

Then the hands, for example, now to give you a look at the picture, he could have, for example, the word pencil flashed here in the left visual field and his hand goes out here and searches all these various object spoons and so on

and pyramids and spheres and will search them or feel them and always comes up with the right object. It's extremely accurately done by the left visual field to the left hand and yet the subject knows nothing about this.

He doesn't seem the message. He hasn't, in fact, known what the hand was doing at all and he doesn't know it's a success. He knows nothing. The next slide will give you an example of that. Here, the word nut is flashed on the left visual field. There's the fixation point and it goes into, as I've described,

into the right hemisphere here and which runs, of course, the left hand and by the decussation and the left hand goes up and finds from these objects here screened from view the nut amongst all the other objects and this you can do with any variety of common nouns that you'd like for objects.

You can flash here and the subject will go out and a hundred percent will get it right and not only knows that this left, this right hemisphere working the left hand can not only get the right object but can demonstrate its use. It can put the nut onto a bolt if there's one there and all that sort of thing. Yet, the subject, the speaking subject doesn't know anything

as shown by the query. The remarkable thing about this is... Oh, you could do it also if you put a picture of an object here like a key or something, they can find it there and so on. You could do it for... But you can't do it for verbs. It's only for common nouns. If you flash onto the left field here, nod or wink or point or something like that,

some verb, no result. Only for names of common objects can there be an understanding by the right hemisphere of the signal and appropriate action. So this is remarkable. I don't need to tell you that if you put it on the right hemisphere

the subject performs as normal and knows what he's doing. They put it into the right visual field to the left hemisphere and the subject knows what is happening all the time. The remarkable thing about these experiments then is that the uniqueness and exclusiveness of the dominant hemisphere, this is the speech hemisphere, in giving the subject information

in being able to talk to you and know what's going on and in fact it is all the goings on in this hemisphere which gives you the whole expression and personality of the subject recognized by his relatives and friends as before and it's only what goes on in this hemisphere

that is in fact now behaving as the self of the subject in relationship to the self. What's going on in this hemisphere, the split from the left, the right hemisphere, the minor hemisphere, is all unknown to the subject and he will describe his left hand. I don't know this left hand.

It's no good to me. I can't do anything with it. It does things on its own like doing successfully retrievals and so on. The subject doesn't know how it happens and is embarrassed by the success often of the left hand which he knows nothing about and nor does he know anything about anything flashed onto the left visual field except in a vague way.

So here we have split the subject in a quite remarkable way and speech and consciousness go entirely with the left hemisphere. I should mention that in all cases so far split they have been left speakers speech in the left hemisphere. There's been no right speaking person so far treated

but one can assume that it would be symmetrical in that case. The unity of the conscious experience that we all have the mental singleness as Bermer calls it is preserved at the expense of losing all that goes on in the right hemisphere. This is another world completely unknown to the subject

what actions there but I hope to show you that this right hemisphere is a very clever hemisphere in all kinds of ways. It can read and retrieve as you see here and it can do in fact many other things even more significant. For example if you can put here not just a name of an object

but you can put for lighting fires printed out the left hand can go out and find a match or if you can put here measuring instrument it will find a ruler. In all kinds of ways it's clever and I'll give you other examples

if you put a dollar sign here and this is an American civilization you have to understand with a dollar sign is put here there are no dollar notes out there but the left hand goes out and searches around and comes up with a quarter instead a coin and this is a successful retrieval. Likewise if you put here

as a picture of a big wall clock there then the left hand there's no big wall clock here but the left hand will go out and eventually after searching everything and looking comes up with a child's toy wristlet watch. It's the nearest the left hand can do and you can see that the right hemisphere therefore

programming the left hand in the light of that information it's got is a quite intelligent and clever hemisphere but nothing of this is known to the subject. Now we'll go back next slide to the Sperry diagram. Here we have his diagram again that you've seen already

and here you can see Rick printed out here some of the programming that's done on the two sides that we've done the visual fields already and the right and left hands the left hemisphere here right visual field right hand also mostly right ear but for smell it's entirely the other way

the left nostril here and the right there that's uncrossed and then here is the main language center and also the calculation all kinds of arithmetical calculations can be done here here it's only very simple calculation such as for example two and seven the hand can find all these numbers

if you put two and seven up on the screen it can go and find a nine and get it successful in the left hand but nothing complicated no multiplication it doesn't understand or subtraction or division whereas of course the right hand and the flashes on the right visual field it is behaving rather normally

but not as well it's a bit deteriorated. So the point I now have is that what else can we show here there's everything that's in the left visual field there's nothing gets through to here and the answer is no that's too much of a claim if you for example put some

on the left visual field here you put a picture giving a very frightening look of a gun pointing at you or something the subject doesn't see that he knows nothing about it nothing has got through to his conscious left hemisphere but he gets all the symptoms of fear

and shaking and trembling and looking anxious but doesn't know he feels fearful but doesn't know why he feels fearful because the picture was never registered only it was only registered there another example is one of Sperry's more amusing pictures he put a picture of a nude here

a nude lady and this picture was not seen by the subject but the subject suddenly started to giggle and look, blush a bit it happened to be a lady who was looking at the picture she didn't know why she had no idea why she felt embarrassed and this went on for several minutes so something gets across that has got into here

and this we can take this the deeper centers say through the hypothalamus which is still able to communicate across the midline but this was quite crude information another thing is that if you put a painful stimulus on the finger on the left hand the subject will feel again discomfort consciously

but not know why or where or what is happening it just has a feeling of discomfort only this vague and crude information crosses and that can be explained by communication at the lower level you see the problem now is here is the left speaking hemisphere with all the consciousness of the subject

all of the self of the subject everything from the past that can be remembered and so on is performed by this hemisphere this hemisphere is now completely separated from the conscious subject except in this crude manner I just described now I have put up the hypothesis next slide

shown in this next diagram that here is a diagram now it's an information flow diagram I have you know this is not an anatomical diagram and it shows quite a number of things I think and all in fact of the results of Sperry is diagrammed here

we look at the central part here only for a start this we'll come to later here is in this diagram the left hemisphere here is the right hemisphere the dominant hemisphere so-called the minor hemisphere this is the speaking hemisphere and the one that gives consciousness to the subject and because of the decussation shown here

the right side of receptors comes up here for the most part and informs the dominant hemisphere of the right world and the right visual field and likewise for the left side to the minor hemisphere it is all shown here and the motor actions of the cortex decussate and come out here and work the right hand

from the dominant left hemisphere and vice versa here and normally here is the corpus callosum these two hemispheres are tremendously connected across 200 million fibers and the basic rate of firing at rest even might be 20 a second and that's 4 000 million impulses a second

are passing from one hemisphere to the other one way or the other way across here and so you can see that normally our two hemispheres are very adequately connected for every purpose you could imagine and likewise of course all parts of one hemisphere connected to other parts but this is just as efficient the separation of the brain into the anatomical separation to two hemispheres

is fully looked after by this immense commissure here now if you cut the commissure you find out as in these tests show that this speaking dominant hemisphere is the only one which gives the subject conscious experiences of any kind and it's the only one from which the subject

the conscious subject can program a hand murky's right hand do this or that as normal then it's done from this hemisphere this hemisphere has so far as the subject is concerned is completely inactive it cannot be operated at all or programmed at all by any willing of the subject

this is an experimental fact so my theory is that the conscious self was only in liaison with the dominant hemisphere normally there was nothing here the linking between the mind-brain problem is only for the left dominant hemisphere the speaking hemisphere

the ideational hemisphere and the arrows show you that this by the way is not meant to indicate that the conscious self is hovering above the brain somewhere or other this is information flow only and so here you have then the situation that everything coming into the right hemisphere comes through here the right side comes in here to the left hemisphere

is experienced worked up thought and actions can be programmed from here and speech can be operated from here in the linguistic areas and so on and this is the way that happens in these split-brain patients and what goes on here is unknown to them although it has a great deal of high level performance

more and more as we should come to talk about in a way it's got the status of an animal brain you can work on animals and you can get all kinds of reactions from them but you cannot know what kind of conscious self the animal had because it's got no way of communicating adequately with you