You are currently browsing the thoughts on thoughts weblog archives for March, 2010.

March 2010
« Feb   Apr »

Archive for March 2010

Altered states - alcohol

When we are looking at consciousness, we are also looking at altered states of consciousness. One of the most common altered state is the result of consuming alcohol. Psyblog has an interesting look at the effects of alcohol (here) especially its effect on attention. Here is part of the posting.

According to a growing body of evidence collected over the last three or more decades, people’s Jekyll and Hyde behaviour while drinking can be understood by a simple idea which has some intriguing ramifications.

The alcohol myopia model says that drink makes our attentional system short-sighted and the more we drink, the more short-sighted it becomes. With more alcohol our brains become less and less able to process peripheral cues and more focused on what is right in front of us. It’s this balance between what is right in front of us and what we don’t notice around the edges that determines how alcohol affects us in different situations.

Here are a few effects which imbibers will recognise immediately:

  • An ego boost: when people drink, they often feel better about themselves. This may be because the attentional short-sightedness induced by alcohol makes all our shortcomings float away and so we feel closer to our ideal selves. This is probably one of the reasons it is so potentially addictive, it is self-actualisation in bottle form.

  • Real worries can get worse: if we’ve had a bad day and we sit quietly with a drink, alcohol can make it worse because all the peripheral cues which are potential distractors are cut out and all we see are our problems.

  • Pleasure in the moment: the flip-side of this attentional focus is that if, while drinking, we are doing something enjoyable, we find it easier to ignore any nagging doubts or stray worries wandering through our minds. We can be totally in the moment listening to music, watching sports or talking with a good friend.

  • In the zone: it’s even possible that for some types of task it may increase performance as we let go of our insecurities. Perhaps that’s why so many writers wrote with a glass of whisky at their side.

Tentatively, I think consciousness is essentially no more than a model of reality, a focus of attention and a working memory operating together. Of course, this may sound simple, but it isn’t – there are many processes that each could be and many ways they could interact.

Several ways of remembering

ScienceDaily reports on the dissertation of Kristina Kompus at Umea University on the entirely different signal paths for spontaneous (just happened to remember) and deliberate (try to remember) activation of memories. (here)

…these two different ways of remembering things are initiated by entirely different signal paths in the brain. Efforts to retrieve a specific memory are dealt with by the upper part of the frontal lobe. This area of the brain is activated not only in connection with memory-related efforts but also in all types of mental efforts and intentions, according to the dissertation. This part of the brain is not involved in the beginning of the process of unintentionally remembering something as a response to external stimuli. Instead, such memories are activated by specific signals from other parts of the brain, namely those that deal with perceived stimuli like smells, pictures, and words….memories do not need to be emotionally charged to be revived spontaneously, unintentionally. Nor do memories that are revived spontaneously activate the brain more than other memories…The studies also reveal that our long-term memory is more flexible that was previously believed. There is not just one single neurological signaling path for reliving old memories but rather several paths that are anatomically separate. …The dissertation uses a combination of two imaging methods for the brain: functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). The methods yield different information about the function of the brain. By combining them, Kristiina Kompus has been able both to determine what part of the brain is activated and how the activation proceeds over extremely brief time intervals, on the order of milliseconds.


This is an extra post and is followed by my regular ‘every 3 days’ posting. It is a copy of part of a post to the LessWrong site. The full post is here. The post is an attempt to allow people to be comfortable with materialism. It is very different to my approach by some may find it more to their taste.

How and why to be a materialist

  1. Accepting materialism is saying “the rest of the world is made of whatever I am”, not just “I am made of whatever the rest of the world is”.  And why not?  In the eyes of science, these are both the same, true statement.  Semantically, the first one tells you something qualitative about matter, and the second one tells you something extremely quantitative about your mind!  It means modern neuroscience and biology can be used to help you understand yourself.  Awesome!
  2. Accepting physics is accepting that your “spirit” might consist of parts which, sufficiently divided and removed from context, might behave in a regular fashion. Then you might as well call the parts “particles” and call your spirit “brain”, and look at all the amazing data we have about them that help describe how you work.
  3. Beware of the works-how-it-feels bias, the fallacious additional assumption that the world works the way you feel about it.  (See How an algorithm feels from the inside.) These pieces of your mind/spirit called particles are extremely tiny; in order of magnitude, they are more than twice as small as your deepest introspection, so you can’t judge them very well based on instinct (a neuron is about a 1011th of your mind, and an atom is about a 1014th of a neuron).  And because they’re so tiny and numerous, they can be put together to form things vastly different from yourself in form and function, like plants and stars.
  4. Your instinct that the laws of physics don’t fully describe you is correct! You are the way you are because of two things:

    • the laws that describe your soul-pieces or particles, whatever those laws may be, and

    • the way they’re put together,

    and the latter is almost unimaginably more significant!  One way to see this is to look around at all the things that are not you.  Saying how the tiny bits of your soul behave independently does not describe how to put them together, just like describing an octant of a sphere explain say how to turn eight of them into a whole sphere.  Plus, even after your initial construction as a baby, a whole lot of growth and experience has configured what you are today.

    Only to put this into perspective, consider that the all the most fundamental laws of physics know can certainly be written down, without evidence or much explanation, in a text file of less than 1 megabyte.  The information content of the human genome, which so far seems necessary to construct a sustainable brain, is about 640 MB (efficiently encoded, that’s 1.7 bits per nucleotide pair).  Don’t be fooled at how “small” 640 is: it means the number of possible states of that data is at least 8640 times larger than the number of the states of our text file describing all of physics!  Next, the brain itself stores information as you develop, with a capacity of at least 1 terrabyte by the most conservative estimates, which means it has at least around 81500 times the number of possible states of the DNA sequence that first built it.

    So being a desk is different from being a human, not because it’s made of different stuff, but because the stuff is put together extremely differently, more differently than we can fully imagine.  When people say form determines function, they should say FORM in BIG CAPITAL LETTERS.  No wonder you thought particle physics “just doesn’t seem to capture it”!

  5. Your perceived distance between the concepts of “mind” and “particles” is also correct! As JanetK says, “There is no shortcut from electrons to thoughts”. Continuing the connection/theorem analogy, a theorem with superficially unrelated hypotheses and conclusions is not only liable to be very useful, but to have a difficult proof as well.  The analogue of the difficult proof is that, distinct from the discovery of particles themselves, massive amounts of technological progress and research have been required to establish the connection between:

    • how particles work and how you look from the outside (neurochemistry/neurobiology), and

    • how you look from the outside and how you look from the inside (neuropsychology).

    Indeed, the perceptual distance between the second pair is why people use the concepts “brain” and “mind” separately: “brain” is a model for the outside view, and “mind” is a model for the inside view.  The analogue of the theorem’s usefulness is how much neurology can say and do about our minds:

    • treat mental illness,

    • restore lost memories,

    • design brain surgery,

    • explain cognitive biases,

    • physically relate our emotions to each other…

  6. Adjusting emotionally is extremely important as you bring materialism under consideration, not only to accomodate changing your beliefs, but to cope with them when they do change.  You may need to redescribe morality, what makes you happy, and why you want to be alive, but none of these things needs to be revoked, and LessWrong is by far the best community I’ve ever seen to help with this transition.  For example, Eliezer has written a chronological account of his Coming of Age as a rationalist, and he has certainly maintained a sense of morality and life-worth.  I recommend building an appropriate emotional safety net while you consider materialism, not just to combat the bias of fear, but so you’re ready when one day you realize oh my gosh I’m a materialist!

A possible reason for consciousness

The MindHacks blog had a link to a interview of Nicholas Humphrey by Alan Saunders in Philosophers Zone (here). Here is another interesting observation from the recording. He is giving a possible reason for consciousness.

…What these experiments establish is a lot of other evidence which corroborates it, is that perception, the representation of things in the world, their characteristics, their physical characteristics, is going on independent of sensation. So that raises the huge question of, OK, well then what is sensation for? In the old days people didn’t need to ask that question because they said, ‘Well sensation is what gives the information for perception. You first have an image, your eye,you sensed that as a set of coloured sensations. You then build up your infer the existence of the objects out there in the world. We now know you don’t need that first step, you can go directly to perception. So, what is sensation for?

…Sensations have some very strange and wonderful properties, chief of which perhaps is their extraordinary thickness in time. Sensations are not instants, they’re not physical instants. Every sensation seems to last for more time than it actually occupies. And so instead of moving through life like a kind of point on a single trajectory, we move through it as a substantial entity. I’ve used the analogy we move through life as in a kind of time-ship which has both a prow and an after-end to it, and space inside to move around.

…So I’ve been trying to come up with a new story about why consciousness should matter and why it should have evolved. … the new line I’m taking is not to be looking for things which consciousness helps us to achieve. It doesn’t give us any particular new skills, it’s not like for example the wings of a bird enables the bird to fly. Your understanding English enables you to understand what I’m saying now. I don’t think consciousness enables us to do anything, what I think it does is it encourages us to do things which we wouldn’t do otherwise; to think about ourselves and relate to the world in ways which we wouldn’t do otherwise.

In other words, consciousness changes our psychology, not in the sense of giving us new cognitive skills, but changing our sense of what it is to be ourselves and what it is to live in the extraordinary world which consciousness delivers to us. Basically, it makes ourselves think of ourselves as being of hugely greater metaphysical significance (we don’t of course use that word ) but simply thinking of ourselves as mattering, of our lives as mattering, and indirectly of course, of other people’s lives as mattering because we have been privileged to have been given this miraculous phenomenon at the centre of our lives.

I have to say that this sounds like an interesting side effect of consciousness rather than a reason for its existence. However, it is worth thinking about.

Perception does not depend on sensation

The MindHacks blog had a link to a interview of Nicholas Humphrey by Alan Saunders in Philosophers Zone (here). There are a number of interesting observations in the recording. Here is one about the separation of perception and sensation.

…The essential point to make is that seeing, hearing or touch or smelling for that matter, is not a single dimension, it hasn’t got just one dimension to it. It’s terribly important to distinguish perception from sensation. The perception of red means understanding, representing the effect about the world, that there is a traffic light out there and that it has a particular coloured light coming from it, or to take another example, that there’s a tree standing in the forest and that it’s quite a particular shape and position and so on. Those are facts about the world, and we use our eyes, use other senses, to get that kind of other information.

Sensation, by contrast, isn’t about what’s out there in the world, it’s about our own response to the stimulation falling on our sense organs… These two things, sensation and perception, are often confused and it’s been traditional in philosophy and certainly I think it’s most people’s view that actually perception depends on sensation. We only get to know that the traffic light is red because first of all we have a sensation. …

What I try to do in the beginning of the book is to show that actually and amazingly this isn’t the case. Perception proceeds independently of sensation; we don’t have to have the sensation in order to get to know what’s out there in the world. And I go through a lot of examples to make that case. Perhaps the most remarkable is the phenomenon of blind sight. It’s something I guess I was responsible for discovering many years ago when I was working, not with human beings but with monkeys.

As a student in Cambridge I had the opportunity to study a monkey who had the visual cortex at the back of her brain removed. My supervisor had done the experiment. He had established that this monkey was apparently quite blind … I had the chance to spend some time with this monkey, she was called Helen, and over literally a few days, sitting with her, playing with her, it became clear to me that she wasn’t actually as blind as she was meant to be. … But I realised there was something very strange about her vision. There must have been something wrong with her you could have guessed, because she didn’t have any visual cortex to see with, but what I became convinced of was that she didn’t believe that she could see. She didn’t seem to have the evidence in front of her eyes if I can put it like that, that she could see. Although every day she would demonstrate objectively that she could. She would run, climb a tree, she would pick up a bit of chocolate from the floor or whatever it may be, she’d come up and take my hand. Out of that work I began to speculate about the possibility of unconscious vision, visual perception occurring without the possibility, without I should say, the fact of sensation. So the subject wouldn’t understand why they could see or have any reasons to believe that they could see.

The claustrum

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.

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.

Blinking together

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.

Phases to separate memories

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.

Turning off consciousness

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.