10/03/2010 by admin.

Here is the abstract of a paper (here) in PNAS, Phase-dependent neuronal coding of objects in short-term memory, by M. Siegel and others:

The ability to hold multiple objects in memory is fundamental to intelligent behavior, but its neural basis remains poorly understood. It has been suggested that multiple items may be held in memory by oscillatory activity across neuronal populations, but yet there is little direct evidence. Here, we show that neuronal information about two objects held in short-term memory is enhanced at specific phases of underlying oscillatory population activity. We recorded neuronal activity from the prefrontal cortices of monkeys remembering two visual objects over a brief interval. We found that during this memory interval prefrontal population activity was rhythmically synchronized at frequencies around 32 and 3 Hz and that spikes carried the most information about the memorized objects at specific phases. Further, according to their order of presentation, optimal encoding of the first presented object was significantly earlier in the 32 Hz cycle than that for the second object. Our results suggest that oscillatory neuronal synchronization mediates a phase-dependent coding of memorized objects in the prefrontal cortex. Encoding at distinct phases may play a role for disambiguating information about multiple objects in short-term memory.

Does this bring us any closer to understanding short-term memory? I think so, but it is not clear exactly how.

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07/03/2010 by admin.

Mind Hacks (here) has reported on a recent study of how the brain goes to sleep. M. Magnin and his group asked permission of patients with inserted electrodes (in preparation for epilepsy surgery) to record from the electrodes during normal activities. In this case the activity was falling asleep.

They found that as people drifted off to sleep, the deep brain area the thalamus wound down several minutes before the cortex. This is surprising because the thalamus has traditionally been considered a structure that regulates alertness and ‘relays’ information to the rest of the brain from the body and the spinal cord. It was often assumed that it would ’shut down’ the cortex first, because this is often considered to be where our ‘higher’ conscious functions like abstract thought and complex perception lie, while continuing with its minimal vigilance functions. A bit like a neural ’standby’ setting. Instead, what seems to happen is that the thalamus ‘disconnects’ itself and leaves the cortex freewheeling before it finally settles down into inactivity. Indeed, freewheeling is, perhaps, a good description here. The researchers found lots of uneven activity in the upper brain areas as they were left to drift off. Interestingly, sleep onset is one of the times when we are most likely to experience hallucinations. In fact, they are so common as to have been given their own name - hypnagogic hallucinations - while this drifting off period is known as hypnagogia.

How interesting.

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03/03/2010 by admin.

There is an interesting post by J. Lehrer in Frontal Cortex (here). He examines the metaphor of consciousness being the result of a ‘vote’.

Like Crick and Koch, I believe our head holds a raucous parliament of cells that endlessly debate what sensations and feelings should become conscious. These neurons are distributed all across the brain, and their firing unfolds over time. This means that we are not a place: we are a process. As the influential philosopher Daniel Dennett wrote, our mind is made up “of multiple channels in which specialist circuits try, in parallel pandemoniums, to do their various things, creating Multiple Drafts as they go.” What we call reality is merely the final draft. (Of course, the very next moment requires a whole new manuscript.)

And yet, and yet…There is the problem of the election. If this blink of conscious perception is a vote, then where is the voter? We can disguise the mystery with euphemisms (top-down attention, executive control, etc.) but the mystery still exists, as mysterious as ever. We deny the ghost, but still rely on models, metaphors and analogies in which the ghost controls the machine.

The problem as I see it is that the mechanism of the election is not the right metaphor. If things are visualized in a sequential way, it is difficult to lose the ghost. First we imagine two areas of neurons and that they are organized in similar maps, like the map of the retina in the thalamus and the one or more maps of the retina in the cortex and enlarge the number of maps to cover all the things that might be in the content of consciousness. This we suspect exists. Then we imagine that the neurons in one area communicate with those with similar map positions in the other area, and vice versa, to give feedback loops. This also we suspect to exist between the thalamus and the cortex and between separate areas of the cortex. And further we imagine that these parallel loops between two versions of the same map type are a bit sloppy so that there is a good deal of overlap. Now we have a massive set of parallel overlapping feedback loops. This resembles, not a digital computer, but an enormous analogue computer. When the input to such a network changes, there would be a short period of instability and then it would settle down to a stable state. This would be the ‘best fit scenario’, ‘the lowest energy configuration’, the ‘consistent perception’, etc. As a general idea, this could be thought of as an ‘election’ without the need for ‘voters’.

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01/03/2010 by admin.

This bit of baggage is the idea of the ‘tabula rasa’ or the blank slate which originated with John Locke in the late 1600s.

Let us then suppose the mind to be, as we say, white paper void of all characters, without any ideas. How comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? Whence has it all the materials of reason and knowledge? To this I answer, in one word, from EXPERIENCE.

This lack of human nature or of inherited mental abilities was a good argument against tyranny, bigotry, racism, sexism, slavery etc. because we were all born with equally empty brains. Only force, exploitation and bad luck can make us unequal. For a long time, behind ideas of politics, education, morality and so on, has been the assumption that the newborn brain is without structure. Of course we can still have these good things without the theory of tabula rasa. If it is actually not a correct theory we can abandon it, and still get on with democracy, universal education and other aspects of equality in our societies.

The continual return to the ‘nature verses nurture’ argument is the attempt to advance or eliminate the tabula rasa philosophy. However, the argument has already been settled.

1. Nature is important. The brain is born with an enormous amount of structure and with learning programs in place. We have some instincts is well. There is a ‘human nature’ and a long list of activities and beliefs that are found in all societies.

2. Nurture is important. Almost everything we do or think is affected by our memories. We learn through experience. The environment makes lasting changes to our brains. All those remembered facts and skills that make us unique come from experience.

3. Nature and nurture cannot be separated. It is silly to say that some mental ability is x% inherited and 1-x% acquired. Everything is an inseparable mixture of the two working together. Nothing happens due to genetics; nothing happens due to environment; everything happens due to the interaction of genetics and environment.

Alison Gopnik says:

The brain is highly structured, but it is also extremely flexible. It’s not a blank slate, but it isn’t written in stone either.

What effect does the denial of in-born structure in the brain have on the subject of consciousness? The biggest problem is about the relationship between language and consciousness. Of course, we are unsure of the detailed relationship. But trying to understand the relationship may be treated as more than a straight forward scientific question and instead treated as a political or sociological one.

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26/02/2010 by admin.

As Descartes almost invented the idea of consciousness about 400 years ago, it is no wonder that his notion of what consciousness is has become deeply embedded in our culture. He famously said ‘cognito ergo sum’ which is usually translated as ‘I think, therefore I am’ but a better translation, in the context of his philosophy, would be ‘I introspect, therefore I am’. He thought that introspection gave us the only direct knowledge of anything (in this case our own thoughts) because the knowledge did not pass through the error prone sensory processes. This was the bedrock on which he built his philosophy. To Descartes there were two sorts of things: material things that took up space and consciousness that took up no space (was immaterial). This dualism has the problem of interaction between mind and body. Is everything actually mind (idealism) or is everything actually body (materialism) or do both exist and interact or do both exist and not interact? Dualism say both exist and has tried (in vain, I would say) to figure out how they interact or how they correspond if they do not interact. A lot of weird and wonderful philosophy has come out of this problem. G. Ryle called Cartesian Dualism ‘the dogma of the Ghost in the Machine’.

The long standing habit of imagining the mind as a THING as opposed to a process forces the idea that it is an immaterial thing. We, after all, cannot find this thing or the space it occupies etc. But if the mind is not a THING, it can be a process that is carried out by material things and there is no problem.

We have experimental evidence that our knowledge of our own thoughts via introspection is not direct and without error. But the idea of an immaterial mind is so deep in our culture that sometimes the experimental evidence appears paradoxical even to the researchers familiar with it. We are in the middle of a real paradigm shift here – it is not mind verses matter, it is matter doing mind as a physiological function. We do not say ‘where is the digestion?’; can’t find the thing; so digestion must be immaterial. We say digestion is a physiological function of the alimentary canal. Mind is a function like digestion, circulation, immunity etc.

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23/02/2010 by admin.

There has long been a view of human thought called Economic Man that was developed by economists since the 1800s. People are seen as making rational decisions for their own financial self-interest. The model was distilled into mathematical equations used by economists. The idea of Economic Man as an approximation of the financial behaviour of groups of people is reasonable. However, an ultra-rational, ultra-selfish ideal of human behaviour has, in the later half of the last century, been put forward as something to try to achieve.

A few economists have been critics of the Economic Man model but this is not my concern here. Economists can model people and markets and enterprises as they need and they are not meant to be descriptions of the biological world. It is the use of the ideal Economic Man in other contexts that is the problem, especially assuming it say something about what goes on in the human head. There are a some of problems with Economic Man as an explanation of general human behaviour:

1. There is no intrinsic motivation and therefore no explanation of why people can be selfless heroes or take pleasure in craftsmanship, humour, goodness etc. The only motivations allowed are greed and other forms of short-term self-interest.

2. The model does not realistically treat choices made between long and short-term goals or between individual and group goals. These ‘no-right-answer’ choices are the more interesting to many people.

3. The model only can only deal with people in modern, free-market, money economies and not with primitive economies, such as those based on reciprocal gift giving. Nor does it deal with family dynamics involving the care of children. Sociologists have needed to develop a variation called Homo sociologicus to introduce some of the effects of social environment.

4. It ignores the deeply cooperative nature of human societies.

5. Some people confuse morality with the emulating of Economic Man.

6. The model has a very simplistic notion of cognition – that thinking does not (or should not) be affected by emotions, instincts, feelings etc. Rationality takes on a very restrictive meaning.

How does Economic Man interfere with the understanding of consciousness? For some of the general public, the Economic Man model is the only one they have encountered. They use it far outside the restricted area where it is a valid approximation of human behaviour. This give these people an anti-biological, anti-sociological, anti-psychological, anti-philosophical view of their mental life. The black and white, one dimensional viewpoint that results is a hangup to following the subtleties of neuroscience.

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20/02/2010 by admin.

In the middle of the last century, Skinner’s theory of radical behaviourism ruled psychology. The theory held that mental life was unimportant and only environmental events caused behaviour. The important mechanism was conditioning especially operant conditioning. The theory has now almost gone from the scene but while it was accepted (40s,50s,60s) there were practically no attempts to understand consciousness. The idea still surfaces from time to time. It still lingers in the minds of people who were students in the middle of the century and took a psychology course or two.

Chomsky was a critic who was instrumental in the fall from grace of behaviourism. Here is some of his comments:

Skinner maintains, that “behavior is shaped and maintained by its consequences” and that as the consequences contingent on behavior are investigated, more and more “they are taking over the explanatory functions previously assigned to personalities, states of mind, feelings, traits of character, purposes, and intentions”… As a science of behavior adopts the strategy of physics and biology, the autonomous agent to which behavior has traditionally been attributed is replaced by the environment — the environment in which the species evolved and in which the behavior of the individual is shaped and maintained….In support of his belief that science will demonstrate that behavior is entirely a function of antecedent events, Skinner notes that physics advanced only when it “stopped personifying things” and attributing to them “wills, impulses, feelings, purposes,” and so on. Therefore, he concludes, the science of behavior will progress only when it stops personifying people and avoids reference to “internal states.” No doubt physics advanced by rejecting the view that a rock’s wish to fall is a factor in its “behavior,” because in fact a rock has no such wish. For Skinner’s argument to have any force, he must show that people have wills, impulses, feelings, purposes, and the like no more than rocks do. If people do differ from rocks in this respect, then a science of human behavior will have to take account of this fact.

We can hear in this quote that Chomsky’s views have their own problems because of his discomfort with some basic biological concepts like evolution. However, he did end the dominance of behaviourism.

There was little wrong with Skinner’s scientific results. We can think of his work as treating the brain as a ‘black box’ and only concerning himself with the inputs and outputs. The error was to insist that there was no mechanisms within the black box and we should just not even talk about peeking in the box.

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18/02/2010 by admin.

In the early 1900s Freud published his influential books; through most of the century his ideas gained influence; but at the end of the century they had been abandoned by psychology. The problem is that Freud’s view of the mind still influences many people in other fields and the general public. His words and concepts are now part of the culture.

He divided each of us into a warring set of actors: ego, id, superego, conscious mind, unconscious mind. As a result, ordinary people have a feeling that they are the result of a struggle within their heads. His theory diminished our trust of rationality and responsibility by claiming that our thoughts and actions were the result of hidden infantile sexual hangups.

J. Kihlstrom says (here):

No empirical evidence indicates that psychoanalysis is more effective, or more efficient, than other forms of psychotherapy, such as systematic desensitization or assertiveness training. No empirical evidence indicates the mechanisms by which psychoanalysis achieves its effects, such as they are, are those specifically predicated on the theory, such as transference and catharsis.

Of course, Freud lived at a particular period of time, and it might be argued that his theories were valid when applied to European culture at the turn of the last century, even if they are no longer apropos today. However, recent historical analyses show that Freud’s construal of his case material was systematically distorted and biased by his theories of unconscious conflict and infantile sexuality, and that he misinterpreted and misrepresented the scientific evidence available to him. Freud’s theories were not just a product of his time: they were misleading and incorrect even when he published them.

Drew Westen, a psychologist at Harvard Medical School, agrees that Freud’s theories are archaic and obsolete, but argues that Freud’s legacy lives on in a number of theoretical propositions that are widely accepted by scientists: the existence of unconscious mental processes; the importance of conflict and ambivalence in behavior; the childhood origins of adult personality; mental representations as a mediator of social behavior; and stages of psychological development. However, some of these propositions are debatable. For example, there is no evidence that childrearing practices have any lasting impact on personality. More important, Westen’s argument skirts the question of whether Freud’s view of these matters was correct. It is one thing to say that unconscious motives play a role in behavior. It is something quite different to say that our every thought and deed is driven by repressed sexual and aggressive urges; that children harbor erotic feelings toward the parent of the opposite sex; and that young boys are hostile toward their fathers, who they regard as rivals for their mothers’ affections. This is what Freud believed, and so far as we can tell Freud was wrong in every respect. For example, the unconscious mind revealed in laboratory studies of automaticity and implicit memory bears no resemblance to the unconscious mind of psychoanalytic theory.

This theory, because it permeates common culture, especially literature, hinders the development and acceptance of a satisfactory understanding of consciousness.

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14/02/2010 by admin.

There is a article in Brain, Default network connectivity reflects the level of consciousness in non-communicative brain-damaged patients, by A. Vanhaudenhuyse and a large group. (here) The abstract is below:

The ‘default network’ is defined as a set of areas, encompassing posterior-cingulate/precuneus, anterior cingulate/mesiofrontal cortex and temporo-parietal junctions, that show more activity at rest than during attention-demanding tasks. Recent studies have shown that it is possible to reliably identify this network in the absence of any task, by resting state functional magnetic resonance imaging connectivity analyses in healthy volunteers. However, the functional significance of these spontaneous brain activity fluctuations remains unclear. The aim of this study was to test if the integrity of this resting-state connectivity pattern in the default network would differ in different pathological alterations of consciousness. Fourteen non-communicative brain-damaged patients and 14 healthy controls participated in the study. Connectivity was investigated using probabilistic independent component analysis, and an automated template-matching component selection approach. Connectivity in all default network areas was found to be negatively correlated with the degree of clinical consciousness impairment, ranging from healthy controls and locked-in syndrome to minimally conscious, vegetative then coma patients. Furthermore, precuneus connectivity was found to be significantly stronger in minimally conscious patients as compared with unconscious patients. Locked-in syndrome patient’s default network connectivity was not significantly different from controls. Our results show that default network connectivity is decreased in severely brain-damaged patients, in proportion to their degree of consciousness impairment. Future prospective studies in a larger patient population are needed in order to evaluate the prognostic value of the presented methodology.

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11/02/2010 by admin.

I try to be consistent in expressing my ideas about mental activity, but sometimes the wrong word comes through because I do not notice it. I avoid the phrase ‘conscious mind’ because it carries baggage of two distinct minds in one brain, a hangover from the popularity of Freud’s theories. I use the word ‘consciousness’ instead, in the hope that it does not imply two minds. Just to ensure that I am on firm ground, I took the trouble to look up how others use the word. And here is what I found:

Dictionary definition of ‘consciousness’: 1. the state of being conscious (lost consciousness during the fight); 2a. awareness, perception (had no consciousness of being ridiculed); 2b. in combination - awareness of (class consciousness); 3. the totality of a person’s thoughts and feelings, or a class of these (moral consciousness).

Everyday definition of ‘consciousness’: aware of yourself and surroundings; alert cognitive state; awake, responsive, not asleep or comatose.

Everyday definition of ‘being conscious of’: awareness of intent or effort; knowing and perceiving; being aware of.

Political definition of ‘x-consciousness’: a sense of identity with a group based on attitudes, beliefs, sensitivities, and self interest. (examples: class consciousness, Black consciousness).

Religious definitions of ‘consciousness’: used as a word to translate from eastern religions their beliefs and ideas associated with mind, life force, stages along a path of self-development or enlightenment.

Definition of ’stream of consciousness’: a literary device to illustrate a character’s mental life using an internal narrative; the continuous flow of ideas and feelings that constitute an individual’s experience.

Definition of ’self-consciousness’: awareness of awareness; embarrassment from being aware of self and other’s awareness of you; introspection.

Scientific definition of ‘consciousness’: a process arising out of one or more types of mind activities that are associated with the brain and that involve awareness; the subjective aspect of neurological activity.

And my definition: A brain function that produces a shared awareness, across various parts of the brain, of some aspects of a model of the self-in-the-world.

This does not seem inconsistent with the scientific use and the everyday use, but is much more restrictive than many of the other definitions.

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