Francis Crick, one of the famous discoverers of the DNA structure and one of the formulators of the Central Dogma of Molecular Biology, used his prestige, which was great, to encourage research into consciousness. He did this because he liked to go after the big, important questions. And he felt that consciousness had been neglected and was ripe to be investigated. Crick made brain research acceptable and even popular.

At the time of his death, he was interested in the claustrum. His ideas on this were less developed then was usual of Crick in his papers. But he was in a hurry to leave this idea behind before he died. Here is the abstract from the review paper, What is the function of the claustrum?, by F. Crick and C. Koch in Phil. Trans. R. soc. B 2005 (here):

The claustrum is a thin, irregular, sheet-like neuronal structure hidden beneath the inner surface of the neocortex in the general region of the insula. Its function is enigmatic. Its anatomy is quite remarkable in that it receives input from almost all regions of cortex and projects back to almost all regions of cortex. We here briefly summarize what is known about the claustrum, speculate on its possible relationship to the processes that give rise to integrated conscious percepts, propose mechanisms that enable information to travel widely within the claustrum and discuss experiments to address these questions.

We will see what comes of it in future.

]]> http://charbonniers.org/2010/03/19/the-claustrum/feed/ http://charbonniers.org/2010/03/16/what-happens-in-meditation/ http://charbonniers.org/2010/03/16/what-happens-in-meditation/#comments Tue, 16 Mar 2010 05:54:27 +0000 admin http://charbonniers.org/2010/03/16/what-happens-in-meditation/

An article in the November issue of Mind by B. Reiner about the progress in creating meditation by stimulating parts of the brain, Secrets of How Meditation Works, has an interesting pointer to fast-spiking interneurons:

From the perspective of neuroscience, meditation can be characterized as a series of mental exercises by which a person strengthens control over the workings of his or her own brain. The simplest of these practices is focused attention, during which one concentrates on a single object or experience—say, one’s breathing. … But focused-attention meditation is fairly basic compared with the kind of contemplation conducted by experienced Buddhists. Called open-monitoring meditation, this advanced method is, in many ways, a form of metacognition—the objective is not to focus one’s attention but rather to use one’s brain to monitor the universe of mental experience without directing attention to any one task. … the long-term meditators’ brain waves were in sync at unusually high speed. Brain waves, … occur at different speeds … Gamma waves are the fastest of the bunch, and in normal people they happen only in very short bursts during REM sleep and, rarely, waking cognition. The Davidson study was remarkable in that it showed that long-term meditators are able to produce sustained gamma activity in a manner that had never been previously observed in a human being. As such, sustained gamma activity emerged as a proxy for at least some aspects of the meditative state. … (In studies in Nature C. Moore, L. Tsai and K. Deisseroth) confirmed the hypothesis that gamma rhythm results from the activation of fast-spiking interneurons, so named because they fire at a higher than normal rate and have short, local connections within the cerebral cortex. … In addition, abnormal gamma synchronization is a hallmark of disorders such as autism and schizophrenia, and it may contribute to altered cognition in these and other mental illnesses.

The abstract below is of a paper (here) in the Proceedings of the Royal Society, Synchronization of spontaneous eyeblinks while viewing video stories, by N. Tamami and others.

Blinks are generally suppressed during a task that requires visual attention and tend to occur immediately before or after the task when the timing of its onset and offset are explicitly given. During the viewing of video stories, blinks are expected to occur at explicit breaks such as scene changes. However, given that the scene length is unpredictable, there should also be appropriate timing for blinking within a scene to prevent temporal loss of critical visual information. Here, we show that spontaneous blinks were highly synchronized between and within subjects when they viewed the same short video stories, but were not explicitly tied to the scene breaks. Synchronized blinks occurred during scenes that required less attention such as at the conclusion of an action, during the absence of the main character, during a long shot and during repeated presentations of a similar scene. In contrast, blink synchronization was not observed when subjects viewed a background video or when they listened to a story read aloud. The results suggest that humans share a mechanism for controlling the timing of blinks that searches for an implicit timing that is appropriate to minimize the chance of losing critical information while viewing a stream of visual events.

By and large we are not conscious of our blinks, although we can attend to them for short periods. Nor do we usually have conscious intentions to blink. It appears that a good deal of comprehension is needed to control the timing of blinks and the knowledge would usually be used in the blinking system before that comprehension entered consciousness.

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.

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.

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’.

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.

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.

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.

]]> http://charbonniers.org/2010/02/23/baggage-3-economic-man/feed/ http://charbonniers.org/2010/02/20/baggage-2-skinner/ http://charbonniers.org/2010/02/20/baggage-2-skinner/#comments Sat, 20 Feb 2010 09:00:36 +0000 admin http://charbonniers.org/2010/02/20/baggage-2-skinner/

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.