Sunday, January 21, 2007

Where is your mind?

Last week, I had a very embarrassing dialogue with my colleague F. I just came out of the seminar room, chewing a pen (there goes the New Year's resolution). F. said, he was sorry to have missed the seminar and how was it? Well, oohm, I made some vague sounds between so-so and ah-well. Unfortunately, he asked what the seminar was about, and I had to realize that I could neither remember the name of the speaker, nor what he was talking about. Just that he used too much red on his slides.

Anyway, after I've been listening to 'Where is my mind' a whole day (very mind-numbing indeed), I stumbled upon an article in the recent Science issue about the question where wandering minds go

    Wandering Minds: The Default Network and Stimulus-Independent Thought
    By: Malia F. Mason, Michael I. Norton, John D. Van Horn, Daniel M. Wegner, Scott T. Grafton, C. Neil Macrae

    Despite evidence pointing to a ubiquitous tendency of human minds to wander, little is known about the neural operations that support this core component of human cognition. Using both thought sampling and brain imaging, the current investigation demonstrated that mind-wandering is associated with activity in a default network of cortical regions that are active when the brain is "at rest." In addition, individuals' reports of the tendency of their minds to wander were correlated with activity in this network.

In case you don't have a subscription, there is a brief free summary by Greg Miller: Peering Inside the Wandering Mind.

The researchers examined the activity of brain regions with the use of functional magnetic resonance imaging (fMRI). Roughly spoken, magnetic resonance imaging is a way to measure the reaction (resonance) of particles to a magnetic field. If the field is tuned appropriately, the particles resonate and extract energy from the field which can be measured. The strength of the signal depends on the concentration of particles that resonate. More information can be obtained by using pulses and measure the reaction of the particles, such as the relaxation time. You find a more precise introduction here.
So far, so good. Theoretically this can be computed with elementary quantum mechanics. The really challenging task is to get useful 3D-pictures out of the data (essentially a Fourier-transform). By now, this can be done with amazing precision. For some more images, see e.g. this site.

For medical purposes, one mostly uses protons (H), of which there are plenty in water, as well as in proteins. The latter have slightly different resonance properties because they are bound differently. Generally, part of the signal depends on the magnetic properties of the surrounding. Now it turns out that the blood oxygen level influences the magnetic properties since haemoglobin is diamagnetic when oxygenated but paramagnetic when deoxygenated. The signal of blood is therefore slightly different depending on the level of oxygenation. These different signals can be detected using an appropriate magnetic resonance pulse sequence, and is called the blood-oxygen-level dependent (BOLD) contrast.

It is generally believed that the BOLD signal is a measure for neural activity, and this has been used in the study of Mason et al. They examined the active regions of the brains of 19 volunteers which were faced with more or less demanding tasks. The researchers found a particular set of brain regions - the 'default network' - which was more active when tasks were less demanding. If the use of this default network during tasks with low processing demands would indeed reflect mind-wandering, changes in the default networks activity during practiced or novel tasks should be related to the participants score on the 'daydream frequency scale'. The results of the study revealed 'a significant positive relation between the frequency of mind-wandering and the change in BOLD signal observed when participants performed practiced relative to novel' working-memory tasks.

However, the researches also note that day-dreaming likely isn't the only thing that goes on in your brain when tasks 'cease to require conscious supervision' - there might as well be the 'general housekeeping functions' being processed. It also leaves open the question why minds wander:

"Although the thoughts the mind produces when wandering are at times useful, such instances do not prove that the mind wanders because these thoughts are adaptive; on the contrary the mind might simply wander because it can."

One way or the other, if you are sitting in a boring seminar chewing a pen, you're not just inattentive, but you're inspiring your brain's default network to increased activity. If nothing else, it sounds at least more scientific than day-dreaming.


TAGS: , , ,

15 comments:

Anonymous said...

Hi Bee,

What do you think triggers random thoughts seen form the physicist's perspective?

I do hope, that we have now established that the mind is NOT algorithmic (in that case we would just follow a pre-defined life)

Maybe Brownian Motion plays a decisive role in our brain. After all we are made up of 70% H2O.

Greetings
Klaus

http://en.wikipedia.org/wiki/Brownian_motion

http://en.wikipedia.org/wiki/Roger_Penrose#Physics_and_consciousness

a quantum diaries survivor said...

Hi Bee,
this is an excellent explanation of the technique of magnetic resonance, and an interesting post! Thanks for pointing out this research.
T.

Bee said...

Hi Klaus,

What do you think triggers random thoughts seen form the physicist's perspective?

That's an interesting question! Though its not so directly related to the study by Mason et al. They didn't say anything about the possible triggers, but rather stated that there just are random thoughts, which might be more or less dominant depending on the situation. Btw, I didn't mention it, but they call that 'Stimulus Independent Thought' (SIT).

From my perspective I'd say SITs don't need no extra trigger, because our natural surrounding provides us already with a complete overflow of input. The question that's far more important in this regard is which information is NOT processed, i.e. what is filtered out. It seems to me the typical candidate with a high score on the 'day-dream scale' would be able to block out a significant amount of external stimuli which makes more room for the 'stimulus independent thoughts'.

But I admit that I don't know very much about neuroscience, and I'm not sure if that is supported by research studies.

Yes, you are right, maybe Brownian motion plays a role in our brain, but I doubt it's a very important role. If you're sitting in that seminar, even if not listening, there's just too much other stuff to be processed. Say, the speaker's voice, papers that you've read but left open questions, the argument with your husband yesterday, etc. Below all that, Brownian motion and quantum mechanics might come into play.

What do you think?

Hi Tommaso,

thanks for the kind words :-) I've always found MRI totally amazing, it was quite a challenge to keep it brief. Best,

B.

Anonymous said...

Hi,

God does play dice!

This is why I answer the posting now, not tomorrow, or not at all.

Our brain is an electrical apparatus,not hard-wired with copper cabeling. Signal take their parths by exchange of ions (Na, K)
in a "liquid-like" environment.

I think that the "wobbeliness" should account for much of the unpredictability influencing the positions of charge-carrires and magnitude of charges inside the brain tissue.

On a level below quantummechanics would rule.

If I understand you right, all memories and percieved impulses should carry a certain "weight" which results in a "ranking" which playes a role in triggering your next random thought.

Best Klaus

http://en.wikipedia.org/wiki/Bohr-Einstein_debates

http://www.hawking.org.uk/pdf/dice.pdf

Arun said...

From a non-physics angle:

"A clever verse from ancient India describes the mind as a restless monkey that is stung by a scorpion, drunk, and possessed by a demon, all at the same time. We are all proud owners of this monkey....."

QUASAR9 said...

That revolving image of the brain
brings to Mind the saying
"You got me in a spin..."

Bee said: "From my perspective I'd say SITs don't need no extra trigger, because our natural surrounding provides us already with a complete overflow of input. The question that's far more important in this regard is which information is NOT processed, i.e. what is filtered out."

Makes you wonder doesn't it
That maybe all the information of the universe is available to the mind, The Universal Mind - but somehow individuals SIT on the information - or do not process it.

In other words when we re-search
we focus our attention to see further or deeper (telescopically or microscopically) at what we are looking at ...
the thing is even when we are daydreaming we are focusing on something other than what the group of minds around us or seminar are focussing on.

All we really do is spend our time focusing on microcosms of the cosmos - even when we search Space

No finite mind can hope to encompass or embrace all that is, was (has been) or will be - we can only enkoy the tidbits on which we are focussed.

I mean even if we know the answer is 42, we still want to fill our time and Minds with experiences, feelings, emotions, knowledge, and 'memories' - the curious thing is that humans can lose their memory or memories - and even lose their Minds.

Bee, On a different Matter
two stories from Science Daily
Physicists Closing In On Mysterious Missing Particle That Gives Matter Mass
and
Ultra-Dense Optical Storage - On One Photon

stefan said...

Dear Bee,


that's a very interesting post, which raises lots of lots of puzzling questions. Maybe one of the next posts in the mind series shold now be about "What are our minds?" ;-), but that's a difficult issue... Are there any neuroscientists around?

Anyway, from what little I am aware of about neuroscience, the filtering and throwing away of large parts of the enormous amount of stimuli flooding our mind from the senses is, indeed, very essential. Some mental disorders are connected to malfunctions of these filtering mechanism, whatever they may be. So, you are probably right, and the default network will show a larger activity when there are fewer stimuli.

About the role of quantum mechanics or Brownian motion, I am not sure if they play a role at all in the workings of the mind. If I understand it correctly, current opinion in neuroscience is that "thoughts" are realized in the brain as coordinated patterns of electrical activity in space and time within networks of neurons. This somehow periodic, resonant activity of groups of neurons is superimposed on the constant Brownian noise of electric activity. That would mean that the brain does not make use of Brownian noise, but that it works in spite of Brownian noise. It may be, on the other hand, that occasional large coherent fluctuations trigger at random couplings among different thought patterns, or even create new ones.

But of course, I am not sure whether what I just wrote has anything to do with reality or is complete nonsense.

But really, many things to let my thougths wonder about when they are wandering...


PS: The explanations about MRI are really very much to the point :-)

Bee said...

Dear Klaus,

God does play dice!

Without quantum mechanics, He doesn't.


I think that the "wobbeliness" should account for much of the unpredictability influencing the positions of charge-carrires and magnitude of charges inside the brain tissue.

If I understand you right, all memories and percieved impulses should carry a certain "weight" which results in a "ranking" which playes a role in triggering your next random thought.


Yeah, roughly. See, I do think random motion has some influence on our thoughts, but it can't be very much. Why would that influence only be important in the 'default network' and not elsewhere? Even if you're daydreaming, you're still able to sit on a chair, so the rest of the brain can't be so much randomized.

Despite all the wobbliness, it's apparently very easily possible to perform coherent neural actions. On the other hand, it's without doubts that primary sensory information is a very dominant signal - otherwise the human race wouldn't have survived that long. Also, it's apparent that memories can carry a significant weight, whether we like that or not.

I'd say, if you manage to keep all that strong signals out of the 'default network', randomness might become more important. Maybe that's what meditation does?

Dear Quasar,

I doubt that we really 'loose' our memories. They might become inaccessible, but I don't think they are ever really lost...

No finite mind can hope to encompass or embrace all that is, was (has been) or will be...

Sadly enough, I agree on that.

from Science Daily
Physicists Closing In On Mysterious Missing Particle That Gives Matter Mass


Thanks for the links... The upshot is... 'Trischuk predicts that if the Higgs-boson exists, researchers will find it in the next couple of years...'

I don't quite see, what's new about that.

Best,

B.

QUASAR9 said...

Hi Bee, I wasn't suggesting there was anything new in the article, just that two year time gap is getting closer - and
"While the observation of a Higgs, at just the mass indicated by current precision measurements of the W mass might close the standard model, an inconsistency between the two would lead to the much more interesting prospect of starting us down the path to particle physics beyond the current paradigm."

QUASAR9 said...

Bee, just been watching Jodie Foster in Contact - if you haven't seen the film they find an Alien message which turns out to be the plans to build a magical machine or one person pod (spacecraft) to whisk you thru to another Galaxy.
President Clinton finances the $1 Trillion launch pad -
Jodie Foster thinks she's travelled thru a wormhole to the centre of the galaxy (or wherever)

Whereas in Physical reality the machine never went anywhere. Then she's left with the dilemma of whether her esperience was real or delusional - and whether you can travel at the speed of light in the mind - even if not in the physical pod.

The amazing thing really is that they thought they might have been able to keep communications with something travelling at the speed of light - oh yeah - and then the fact that she (and the pod) might have actually been gone for 18 hours - which means she would have gone as far as ... ... and back

QUASAR9 said...

It is hard to hang on to some memories - do we remember the class, the lesson or seminar, do we remember the people in the room

do we remember the people on the plane journey - do we rember where we went to and where from

do we remember where we were on New Years Day 2001 - and what do we remember of that day

can we remember being in the womb or could we remember anything before being in the womb.

Curious you say we do not lose memories, they are just no longer accessible to us - though we are still the same being - you now you 20 or 30 years ago.

And what about you 40 or 50 years ago? We are clearly more than just memory - some we try to hold onto, some we try to let go, some we try to remember, some we try to forget

Some we try to learn or accumulate as knowledge, some we try to conjure up as deductive logic or inspiration or imagination - but our memories ultimately do not define us any more than our genes, just as we the car we drive or computer we operate does not define us (or who we are) - it simply tells us & others what car we drive (or not) and what computer, laptop and/or operating system we are using.

I have trouble remembering all my cars, never mind girlfriends, memory can be so selective and at times even deceptive (or coloured)as in romanticized memories

Bee said...

Hi Quasar,

It's my personal believe that information, memory, everything that was and will be, is contained inside everyone of us. Just that we can't access it. Don't worry if you can't recall all your girlfriends... forgetting is a great gift. Best,

B.

PS: Yes, I've seen 'Contact'. I remember being very disappointed by the end. It was just too vague and fuzzy. And it took them an eternity to figure out how to read the message, even though it was obvious, no? But overall seen, I liked the atmosphere of the movie. Very calm and thoughtful. Kind of stylish. And good actors.

Rae Ann said...

My mind wanders way too much, but that's when I'm happiest. ;-)

Plato said...

I just wanted to place this link here called,"Window into the MInd" for examination.

Zuberr Nowrung said...

Hi,
I also read a lot about the Mind, it's really fascinating to know those stuffs. What stuffs? I dunno, it's all in my mind LOL
I've started blogging about the mind as well on The Mind and It's Education. I love my new blog lol