08/02/2010 by admin.

Previously I looked at C. Here is the E in an AtoZ by P. Long in My Brain on My Mind. (here)

Easy Problem. Philosopher’s lingo for the problem in neuroscience of comprehending the neuronal correlates of consciousness. When you see red, what exactly are your neurons doing? When you remember your grandfather’s face, what are your neurons doing? It may be difficult to parse the answer but in principle we can do it. It’s easy. The Hard Problem is the mystery of subjective experience. When long light waves stimulate our neural pathways, why do we experience the color red? And what survival benefit caused our brains to develop, through eons of evolution, an ability to experience a “sense of self,” a self able to see itself as special or heroic or smart or not so smart—as, on occasion, a complete failure?

I am not going to discuss a sense of self here, as it seems self evident that a sense of self is useful.

It is not usually quoted as an example of the hard question. Usually we see colour mentioned. Why does the personal experience of colour seem unexplainable? or at least a different order of mystery from other things?

What is the function of colour? It is definitely not there so that we can know the wavelength of light. We do not need or want to know the wavelength of light and, further more, colour is not a reliable measure of wavelength The colours that we see are ‘corrected’ in so many ways and to such an extent that their mapping to the physical wavelength of light is very approximate. Forget wavelength.

What colour does is to help give us objects. Our experience is of a three-dimensional space that is populated with objects. Objects are created by our perception to have particular locations, sizes and surfaces. We understand the world in terms of its objects and the world at any point in time is just objects in space. We recognize them, remember them, categorize them, name them and so on. Our lives are easier if objects that are not actually shrinking or growing, keep their size no matter how much of our retina they take up. We do not want them to move unless they are mobile even though our eyes are flicking their image around on our retina. We do not want objects to suddenly disappear or appear unless they actually are intermittent. And we do not want the surface of an object to change unless it is actually chemically or physically changing. The light (and sound) that is reflected off (and the feel to touch or smell of) an object is important to recognizing that object – such as noticing the archetypal tiger in the long grass at twilight. What our perception creates is objects and they have surface as important property. Those surfaces have colour as part of their image. So colour is very useful in recognizing and remembering objects.

Why is colour so complex in its nature and so delightful to us? The more complex it is, the more we can differentiate between similar surfaces. As far as delighting us – all the aspects of all our senses delight us or disgust us as appropriate. We build a model of the world; we are aware of parts of that model when we are conscious; we remember that model as we live in it; what is important and memorable in the model at any time is what we attend to and remember.

We do not have an explanation for colour or other aspects of subjective experience, but when put in a biological context, it does not seem any harder than many other questions. When we compare it to other questions in biology, why assume it was somehow different and unsolvable?

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05/02/2010 by admin.

The question of freewill is an endless philosophical argument. Are our actions completely predetermined or completely free? Each side has painted the other into an impossible corner. I want to forget this argument and just try to understand how we actually act. When we understand how we act then both sides will say, ’see I told you so!’, and their disagreement will continue. This is because it is fairly predictable that we will find that decisions between courses of action actually are made and on the other hand those decisions have non-random causes. Thus the decisions are both freely made and causally determined.

The place to start is to get rid of dualism. We each have one brain and the functioning (perception, cognition, motor control, memory etc.) of that one brain gives us one mind. That brain creates a model of the world and a model of ourselves in that world. An edited version of that model is created for memory storage, sharing and perhaps other functions. The sharing of this version of the model is what we call consciousness. So lets suppose we have one brain, one mind, one model, one consciousness.

Next let us think about different kinds of decisions. There are decisions that are made without any part of the cognition entering consciousness. They ‘pop’ into consciousness fully decided. Then there are decisions where portions of the cognition enter consciousness. Why the difference? The decision may take longer; it may require sharing within the brain of the conscious kind; it may require memory and predictive modeling using the mental apparatus of consciousness; it may require a particular use of working memory or attention; or perhaps something else. Whatever the reason, we are not ‘making a conscious decision’, we are simply conscious of parts of the decision process as they are modeled by the mind for conscious awareness.

To the extent that our brain/mind recognizes action options, it is free to make decisions between them. To the extent that our brain/mind is a material biological system, its actions have causes. Before a decision is made it is impossible to calculate what the decision with be (just too big a calculation to accomplish in this universe). After the decision is made it is impossible to imagine it as outside causality less you want to introduce magic or the supernatural. This is simply how it is with extremely complex but material systems – you have both freedom and determinism.

The question we should ask about our decisions is not whether they are free or not. We should ask whether they are appropriate and relevant to the situation. Whether they are good decisions.

Here is the abstract from a paper by R. Baumeister, Free Will in Scientific Psychology (here):

Some actions are freer than others, and the difference is palpably important in terms of inner process, subjective perception, and social consequences. Psychology can study the difference between freer and less free actions without making dubious metaphysical commitments. Human evolution seems to have created a relatively new, more complex form of action control that corresponds to popular notions of free will. It is marked by self-control and rational choice, both of which are highly adaptive, especially for functioning within culture. The processes that create these forms of free will may be biologically costly and therefore are only used occasionally, so that people are likely to remain only incompletely self-disciplined, virtuous, and rational.

I would use different words and ideas but he is trying to get past the old and sterile argument of freewill vs determinism.

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02/02/2010 by admin.

There has been an interesting article in PloS One. Mapping Change in Large Netwroks by M. Rosvall and C. Bergstrom. The article is about a method they developed to map network changes and somewhat off the topic of this blog. However, they use the emergence of Neuroscience as a dramatic example of network change.

…In the same diagram, we also highlight the biggest structural change in scientific citation patterns over the past decade: the transformation of neuroscience from interdisciplinary specialty to a mature and stand-alone discipline, comparable to physics or chemistry, economics or law, molecular biology or medicine. In 2001, 102 neuroscience journals, lead by the Journal of Neuroscience, Neuron, and Nature Neuroscience, are assigned with statistical significance to the field of molecular and cell biology. Further, Brain, Behavior, and Immunity, Journal of Geriatric Psychiatry and Neurology, Psychophysiology, and 33 other journals appear with statistical insignificance in psychology and Neurology, Annals of Neurology, Stroke and 77 other journals appear with statistical significance in neurology. In 2003, many of these journals remain in molecular and cell biology, but their assignment to this field is no longer significant. The transformation is underway. In 2005, neuroscience first emerges as an independent discipline. The journals from molecular biology split off completely from their former field and have merged with neurology and a subset of psychology into the significantly stand-alone field of neuroscience.

In their citation behavior, neuroscientists have finally cleaved from their traditional disciplines and united to form what is now the fifth largest field in the sciences (after molecular and cell biology, physics, chemistry, and medicine). Although this interdisciplinary integration has been ongoing since the 1950s, only in the last decade has this change come to dominate the citation structure of the field and overwhelm the intellectual ties along traditional departmental lines.

The diagram that results from their analysis is impressive with its river of neuroscience. ( here ) This research activity has grown over just a decade. Further what is not included is some of the activity in artificial intelligence and robotics that may overlap with neuroscience. It is this revolution in understanding the brain that prompted me to start this blog. I was afraid of how hard it would be for ordinary people to adapt to what the new science was going to show about consciousness.

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30/01/2010 by admin.

A report in Science, Movement Intention after Parietal Cortex Stimulation in Humans, by M. Desnurget and others, has the following summary:

Parietal and premotor cortex regions are serious contenders for bringing motor intentions and motor responses into awareness. We used electrical stimulation in seven patients undergoing awake brain surgery. Stimulating the right inferior parietal regions triggered a strong intention and desire to move the contralateral hand, arm, or foot, whereas stimulating the left inferior parietal region provoked the intention to move the lips and to talk. When stimulation intensity was increased in parietal areas, participants believed they had really performed these movements, although no electromyographic activity was detected. Stimulation of the premotor region triggered overt mouth and contralateral limb movements. Yet, patients firmly denied that they had moved. Conscious intention and motor awareness thus arise from increased parietal activity before movement execution.

So the parietal region is involved in the conscious experience of intention and desire to move (ie the will to move) and the conscious experience of having moved. It is not involved in the movement itself. On the other hand, the premotor region is involved in the movement’s execution but not the the conscious experience of the movement.

The key here may be that the construction of conscious experience is a projection in time of that will be happening later, at the time of the experience. The construction process would therefore need to have access to motor programs that are being created (or even considered) so as to predict and project the sensory effect of the action before it has occurred.

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28/01/2010 by admin.

Human Nature Review has a review by M. Ghin of a book by T. Metzinger, Being No One: The Self-Model Theory of Subjectivity. (here) In it there is a list of constraints ‘which help us to judge whether a given representational state is also a conscious state’ which I find an interesting list.

1. Global availability – an item that is in consciousness is integrated into an overall world-model.

1. Presentationality- consciousness is experienced as in the now.

2. Convolved holism- objects in consciousness are made up of other objects in a heirarchy.

3. Dyamicity – experience is constantly changing or flow of events.

4. Perspectivalness – we are the point of view for conscious experience

5. Transparency – we do not see the construction of the conscious experience but have the illusion of direct contact with the world.

6. Offline activation – there can be consciousness without sensory input (daydreams, hallucinations etc.)

7. Representation of intensities – we can experience levels of intensity of qualia.

8. Homogeneity – qualia are not mixtures of two other qualia.

9. Adaptivity – consciousness has features that can be evolved

It sounds interesting. I will have to follow up on this, especially those constraints that we have not touched on much: convolved holism, representation of intensities and homogeneity.

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24/01/2010 by admin.

ScienceDaily had an article on the research of B. Strowbridge and P. Larimer. (here) Their ‘first’ is to create stimulus-specific sustained activity patterns in brain circuits maintained in vitro using pieces of rodent hippocampus – memory in a petri dish.

Mossy cells are unusual because they maintain much of their normal activity even when kept alive in thin brain slices. The spontaneous electrical activity found in mossy cells was critical to their discovery of memory traces in this brain region.

When stimulating electrodes were inserted in the hippocampal brain slice the spontaneous activity in the mossy cells remembered which electrode had been activated. The memory in vitro lasted about 10 seconds, about as long as many types of working memories studied in people.

“This is the first time anyone has stored information in spontaneously active pieces of mammalian brain tissue. It is probably not a coincidence that we were able to show this memory effect in the hippocampus, the brain region most associated with human memory,” said Strowbridge.

The scientists measured the frequency of synaptic inputs onto the mossy cells to determine whether or not the hippocampus had retained memory…They also found the brain circuit that enabled the hippocampus to remember which input pathway had been activated. The memory effect occurred because of a rare type of brain cell called semilunar granule cells, described in 1893 by the father of neuroscience, Ramón y Cajal. The semilunar granule cells have an unusual form of persistent activity, allowing them to maintain memory and connect to the mossy cells.

Working memory is intimately involved with consciousness.

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21/01/2010 by admin.

ScienceDaily has a report (here) on research by R. Malach, L. Fisch and I. Fried published in Neuron. They found an ‘ignition’ of intense neural activity associated with consciously seeing an image. They use a very powerful method (not available to everyone). Epileptic patients who have electrodes implanted in their brains in preparation for surgery are asked to volunteer of tests on perceptual awareness.

The subjects looked at a computer screen, which briefly presented a ‘target’ image… followed by a ‘mask’ … at different time intervals after the target image had been presented. This allowed the experimenter to control the visibility of the images — the patients sometimes recognized the targets and sometimes failed to do so. By comparing the electrode recordings to the patients’ reports of whether they had correctly recognized the image or not, the scientists were able to pinpoint when, where and what was happening in the brain as transitions in perceptual awareness took place.

Malach: ‘We found that there was a rapid burst of neural activity occurring in the high-order visual centers of the brain (centers that are sensitive to entire images of objects, such as faces) whenever patients had correctly recognized the target image.’ The scientists also found that the transition from not seeing to seeing happens abruptly. Fisch: ‘When the mask was presented too soon after the target image, it ‘killed’ the visual input signals, resulting in the patients being unable to recognize the object. The patients suddenly became consciously aware of the target image at a clear threshold, suggesting that the brain needs a specific amount of time to process the input signals in order for conscious perceptual awareness to be ‘ignited.”

This study is the first of its kind to uncover strong evidence linking ‘ignition’ of bursts of neural activity to perceptual awareness in humans. More questions remain: Is this the sole mechanism involved in the transition to perceptual awareness? To what extent is it a local phenomenon?

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18/01/2010 by admin.

Here is an interesting take on consciousness. It is the C in an AtoZ by P. Long in My Brain on My Mind. (here)

Consciousness, according to neuroscientists Francis Crick and Christof Koch, is “attention times working memory.” “Working memory” being the type of memory that holds online whatever you are attending to right now. Add to “attention times working memory” a third element of consciousness—the sense of self, the sense of “I” as distinct from the object of perception. If I am conscious of something, I “know” it. I am “aware” of it. As neurobiologist António Damásio puts it in The Feeling of What Happens, “Consciousness goes beyond being awake and attentive: it requires an inner sense of the self in the act of knowing.” (It also requires the neurotransmitter acetylcholine.)

There is another theory of consciousness, the quantum physics theory of consciousness, in which quarks, a fundamental particle, have proto­consciousness. This theory is said to have an aggregation problem—how would zillions of protoconscious particles make a conscious being? It puts consciousness outside life forms and into moonrocks and spoons. I will leave that theory right here.

In dreamless sleep, we are not conscious. Under anesthesia, we are not conscious. Walking down the street in a daze, we are barely conscious. Consciousness may involve what neuroscientist Jean-Pierre Changeux postulates is a “global workspace”—a metaphorical space of thought, feeling, and attention. He thinks it’s created by the firing of batches of neurons originating in the brain stem whose extra-long axons fan up and down the brain and back and forth through both hemispheres, connecting reciprocally with neurons in the thalamus (sensory relay station) and in the cerebral cortex. These neurons are focusing attention, receiving sensory news and assessing it, repressing the irrelevant, reactivating long-term memory circuits, and, by comparing the new and the known, registering a felt sense of “satisfaction” or “truth,” which is brought home by a surge of the reward system (mainly dopamine).

Crick and Koch propose, rather, that the part of our gray matter necessary for consciousness is the claustrum, a structure flat as a sheet located deep in the brain on both sides. Looked at face-on, it is shaped a bit like the United States. This claustrum maintains busy connections to most other parts of the brain (necessary for any conductor role). It also has a type of neuron internal to itself, able to rise up with others of its kind and fire synchronously. This may be the claustrum’s way of creating coherence out of the informational cacophony passing through. For consciousness feels coherent. Never mind that your brain at this moment is processing a zillion different data bits.

Gerald Edelman’s (global) theory of consciousness sees it resulting from neuronal activity all over the brain. Edelman (along with Changeux and others) applies the theory of evolution to populations of neurons. Beginning early in an individual’s development, neurons firing and connecting with other neurons form shifting populations as they interact with input from the environment. The brain’s reward system mediates which populations survive as the fittest. Edelman’s theory speaks to the fact that no two brains are exactly alike; even identical twins do not have identical brains.

How, in Edelman’s scheme, does consciousness achieve its coherence? By the recirculation of parallel signals. If you are a neuron, you receive a signal, say from a light wave, then relay it to the next neuron via an electrical pulse. Imagine a Fourth of July fireworks, a starburst in the night sky. Different groups of neurons register the light, the shape, the boom. After receiving their respective signals, populations of neurons pass them back and forth to other populations of neurons. What emerges is one glorious starburst.

I myself do not have a theory of consciousness. Still, I am a conscious (occasionally) being. My sense of myself, my sense of an “I,” has some sort of neuronal correlate. I am conscious (aware) of the fact that I am teaching a writing seminar (observed object with neuronal correlate) on the literary form known as the abecedarium (observed object with neuronal correlate). I am conscious (aware) that I will be submitting my own abecedarium—this one—to the brainy writers in the class. Because I can imagine the future, because I can plan ahead (thanks in part to my frontal lobes), I feel apprehensive. How crazy! To imagine I could comprehend the Homo sapiens brain, the most complex object in the known universe, within the 26 compartments of an abecedarium.

I will try. I will color the cones and rods and convoluted lobes printed in black outline in my anatomy coloring book. I will teach my neurons to know themselves. As I write this, I picture our class seated around our big table. I can picture the face of each writer at the table. To each face I can attach a name. This is proof that, as of today, I have dodged dementia.

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15/01/2010 by admin.

There is a site called Less Wrong that I visit (here) because occasionally there is an outstanding post there. I do not comment on the posts as a rule because it is something of a boys club of AI guys and I don’t feel that I belong. But last week there was a post that got me a little worked up and I commented. My efforts lost me some karma but never mind, I didn’t know I had been playing the Less Wrong game. Here is the comment:

“The local worldview reduces everything to some combination of physics, mathematics, and computer science, with the exact combination depending on the person. I think it is manifestly the case that this does not work for consciousness.”

No it doesn’t work because you have left out BIOLOGY. You cannot just jump from physics and algorithms to how brains function.

Here is the outline of a possible path:

1. We know that consciousness has an important function because it consumes a great deal of energy – that’s how evolution works.

2. Animals move – therefore they must have a model of where they are, where they are going etc. - like the old Swedish joke, ‘I cant yump when I got no place to stood’.

3. To make a model, animals need to sense the environment and translate the info into elements of the model (perception).

4. In order to use the model to plan and monitor motor action, they have to also model themselves – so the model is of the animal-in-the-world - the tree is not the real tree in reality but the modeled tree and the me in the model is not the real me in reality but the modeled me.

5. In order to make a good model that was useful it would have to be a unified global model of the animal in the world – all the parts of the model have to be brought together in order to create the best fit scenario and in order for various functions to use the information.

6. In order to make a good model that could be used to plan and valuate actions it would have to model the needs of the animal such as goals, motivations, emotions etc – the model has to have a theory of mind for the animal - so my thoughts in the model are not my real thoughts in reality but the modeled mind. When we introspect we are aware of our model of ourselves but not of ourselves in reality. Definitions can be a problem here – do we use the word ‘mind’ for cognition or for awareness? For we have trouble if we confuse these two things.

7. To make the model more useful it should be predictive to overcome the time it takes to construct the model – so if ‘now’ is t, then the model would be created from the information the brain has at t-x used to predict what reality will be after x duration where x is the time it takes to construct the model – this allows errors in motor actions to be monitored and corrected because the sensory data coming it does not match the model prediction – even the ‘now’ is a modeled now and not the now in reality.

8. So the biological criteria for a good model are unity, speed, accuracy and predictive power. The elements used to create the model must be easily manipulated in order to achieve these goals and must also be capable of being stored as memories, imagined, communicated etc. The qualia of the model will be anything and everything that is biologically possible and makes a good model. We have the data that the sense organs can measure and some effective ways of representing that information in the model.

So the question “Why red?” can be answered with “Why not – it works.” And the question “Where is the red?” can be answered by “In the structural elements of the model”. If someone has a better way to model the frequency of light, I have never heard of it.

If you cannot envisage this modeling as a sequential computer program that is because it isn’t one. It is a massively parallel assembly of overlapping feedback loops that involve most of the cortex, the thalamus, the basal ganglia and even points in the brain stem. It has more in common with analogue computers then digital ones.

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12/01/2010 by admin.

An item in the Scientific American (here), Reviving Consciousness in Injured Brains by C. Koch, describes the effects of deep-brain stimulation. It is a reminder not to confuse the content of consciousness with its functional container.

Most scholars concerned with the material basis of consciousness are cortical chauvinists. They focus on the two cortical hemispheres that crown the brain. It is here that perception, action, memory, thought and consciousness are said to have their seat.

There is no question that the great specificity of any one conscious perceptual experience… is mediated by coalitions of synchronized cortical nerve cells and their associated targets in the satellites of the cortex, thalamus, amygdala, claustrum and basal ganglia. Groups of cortical neurons are the elements that construct the content of each particular rich and vivid experience. Yet content can be provided only if the basic infrastructure to represent and process this content is intact. And it is here that the less glamorous regions of the brain, down in the catacombs, come in… injury to large chunks of cortical tissue, particularly of the so-called silent frontal lobes, can lead to a loss of specific conscious content but without any massive impairment in the victim’s behavior. … But destruction of tissue the size of a sugar cube in the brain stem and in parts of the thalamus, especially if they occur simultaneously on the left and right sides, may leave the patient comatose, stuporous or otherwise unable to function… can cause consciousness to flee permanently…

pioneers are finding innovative ways to help. Their technology of choice is deep-brain stimulation (DBS). The method has been much in the public eye as a way to ameliorate the symptoms of Parkinson’s disease. Electrodes are implanted into a region just below the thalamus, the quail-egg-shaped structure in the center of the brain. When the electric current is turned on, the rigor and tremors of this movement disorder disappear instantly…Over the past 15 years neurosurgeon Takamitsu Yamamoto and his colleagues at the Nihon University School of Medicine in Tokyo stimulated parts of the intralaminar nuclei (ILN) of the thalamus in vegetative state and minimum conscious state patients. These regions were targeted because they are involved in producing arousal and in controlling widespread activity throughout the cortex. Indeed, according to the late neurosurgeon Joseph Bogen of the University of Southern California, the ILN is the one structure absolutely essential to consciousness.

The deep-brain stimulation is helpful to some patients, but it is early days. The research does show (again) that the cortex does not work without control from older parts of the brain.

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