Archive for January, 2007

Pinker on ‘The Mystery of Consciousness’

Saturday, January 27th, 2007

Illustration for TIME by Istvan OroszTime magazine has just published an intriguing article on the neural basis of consciousness. The article was written by Steven Pinker, a cognitive scientist known for his controversial views on language and cognition.

Here are several excerpts from the article…

On the brain being the basis for consciousness:

Scientists have exorcised the ghost from the machine not because they are mechanistic killjoys but because they have amassed evidence that every aspect of consciousness can be tied to the brain. Using functional MRI, cognitive neuroscientists can almost read people's thoughts from the blood flow in their brains. 

On a new basis for morality emerging from neuroscience: 

…the biology of consciousness offers a sounder basis for morality than the unprovable dogma of an immortal soul… once we realize that our own consciousness is a product of our brains and that other people have brains like ours, a denial of other people's sentience becomes ludicrous.

On the evolutionary basis of self deceit:

Evolutionary biologist Robert Trivers has noted that people have a motive to sell themselves as beneficent, rational, competent agents. The best propagandist is the one who believes his own lies, ensuring that he can't leak his deceit through nervous twitches or self-contradictions. So the brain might have been shaped to keep compromising data away from the conscious processes that govern our interaction with other people.

 -MC 

Wandering Minds and the Default Brain Network

Friday, January 19th, 2007

Several news articles have come out today which seem to imply that a recent Science report's main finding is that the mind wanders for a purpose (see this Forbes article), and that "daydreaming improves thinking" (see this Cosmos article). These are typical of fabrications used by popular science journalists to pique the public's interest.

Mason, et al. 2007 (the Science article published today) did not say that the mind wanders for a purpose (though they speculated that there may be one), and specifically mentioned that "the mind may wander simply because it can". Also, I could not find anything about daydreaming improving thinking in the article, except a short sentence about daydreaming possibly improving arousal. (A slap to the face will probably improve arousal; will the next headline be "face slaps improve thinking"?)

The two popular news articles mentioned above present these very speculative statements from the article not only as fact but also as the main results of the research, which I find to be disingenuous.

As a researcher in the area, I would say these are the main points to take from Mason, et al. 2007:
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Brainprints

Tuesday, January 16th, 2007

 Normally, neuroscientists try to discover things about the brain, as if it were one monolithic thing. Might the differences between individual brains be important, or useful?

A recent article in New Scientist describes recent efforts to use each person's unique brain activity patterns as a kind of fingerprint (or 'brainprint') for security purposes. The system uses EEG.

According to the article, "This novel biometric system should be difficult to forge, making it suitable for high-security applications". I'm trying to imagine a CIA operative putting on a little red EEG cap before being allowed into a top secret location…

-MC

Can a Neural Network be Free…

Monday, January 15th, 2007

…from a knee-jerk reaction to its immediate input? Simple Recurrent Network

Although one of the first things that a Neuroscience student learns about is "reflex reactions" such as the patellar reflex (also known as the knee-jerk reflex), the cognitive neuroscientist is interested in the kind of processing that might occur between inputs and outputs in mappings that are not so direct as the knee-jerk reaction. 

An example of a system which is a step up from the knee-jerk reflex is in the reflexes of the sea slug named "Aplysia".  Unlike the patellar reflex, Aplysia's gill and siphon retraction reflexes seem to "habituate" over time — the original input-output mappings are overridden by being repeatedly stimulated.  This is a simple form of memory, but no real "processing" can be said to go on there.

Specifically, cognitive neuroscientists are interested in mappings where "processing" seems to occur before the output decision is made.  As MC pointed out earlier, the opportunity for memory (past experience) to affect those mappings is probably important for "free will". 

But how can past experience affect future mappings in interesting ways? One answer to this question appeared in the year 1990, which began a new era in experimentation with neural network models capable of indirect input-output mappings.  In that year, Elman (inpired by Jordan's 1986 work) demonstrated the Simple Recurrent Network in his paper "Finding Structure in Time".  The concept behind this network is shown in the picture associated with this entry.

The basic idea of the Simple Recurrent Network is that as information comes in (through the input units), an on-line memory of that information is preserved and recirculated (through the "context" units).  Together, the input and context units both influence the hidden layer which can trigger responses in the output layer.  This means that the immediate output of the network is dependent not only on the current input, but also on the inputs that came before it.

The most interesting aspect of the Simple Recurrent Network, however, is that the connections among all the individual units in the network change depending on what the modeler requires the network to output.   The network learns to preserve information in the context layer loops so that it can correctly produce the desired output. For example, if the task of the network is to remember the second word in a sentence, it will amplify or maintain the second word when it comes in, while ignoring the intervening words, so that at the end of the sentence it outputs the target word.

Although this network cannot be said to have "free" will — especially because of the way its connections are forcefully trained — its operation can hint at the type of phenomena researchers should seek in trying to understand cognition in neural systems.

-PL 

The Will to be Free, Part I

Sunday, January 7th, 2007

Freedom to choose is the first axiom of our being. We assume freedom with each action that we take, and we are annoyed when we are forced to act "against our will". A recent article on free will at the New York Times explains that determinism is a direct implication of the brain being the seat of the mind in conjunction with Newtonian physics (also see the recent Mind Hacks post). Why, then, do we assume at each moment that we have free will? How is it that someone could use force and coercion to take away a freedom that we never had to begin with?

An increasingly common argument against determinism is based in quantum physics. Certainly Newtonian physics (where every cause must have a pre-determined effect) implies determinism, the argument goes, but quantum physics allows for some 'wiggle room'. Such wiggling takes place at the subatomic level in the form of random movements, such that events in the world supposedly have a base of random chance behind them.

I actually find quantum physics to be a negative for free will: I would rather have a predictable and determined will than one that was based on a series of coin flips. At least a determined will allows for the maintenance of a self that can choose (even if the same decision is made every time).

But why don't we make the same decision every time? Because we have memory.
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Neuroscience Blogs of Note, Part 2

Monday, January 1st, 2007

brainsurprise3.pngI will follow up MC's recent post with a brief review of three other neuroscience-related blogs that are worth mentioning as we begin Neurevolution.
Brain Waves (http://brainwaves.corante.com/) is a self-labeled "neurotechnology" blog. Written by Zack Lynch, it is a real-world look at the effects and benefits derived from neuroscience research with regards to society, culture and economics. The author has a background in evolutionary biology but brings to light articles spanning a wide range of topics including neuroeconomics, nanotechnology, pharmaceutical research, perceptual illusions, and music appreciation. The focus of the blog however is on neurotechnology — on technological advancements that permit the improvement or study of the brain.

SCLin's Neuroscience Blog (http://forebrain.blogspot.com/) contains pointers to and summaries of recent neuroscience articles which focus on computational and cognitive neuroscience issues. While too technical to be of much value to the layperson, it reports on articles dealing with cutting-edge questions in neuroscience, such as the nature of the information code in the brain (e.g. meaningful representations in the prefrontal cortex) and information flow through neural pathways (e.g. the short-latency activation of dopaminergic neurons by visual stimuli).

Although It may be hard to classify as a neuroscience blog, Neurophilosophy (http://neurophilosophy.wordpress.com/) does contain a fair number of interesting posts for the neuroscientist, such as a recent one on mind-computer interfaces for robots. Recent articles however have focused more on topics as varied as biological mimicry, hibernation, bionic hands, animals that blow bubbles to smell underwater, and other non-neuroscience topics. As such, it focuses on fascinating science questions in general, of which neuroscience is certainly a part.

This ends our first review.  Stay tuned for further reviews, as well as new content and pointers to other interesting articles!

-PL 

Neuroscience Blogs of Note

Monday, January 1st, 2007

A wired brainAs the first post on Neurevolution, I would like to review several other neuroscience blogs that have been around for a while.

First is Mind Hacks, a blog by the two authors of the book by the same name. According to the authors, the blog and book include "neuroscience and psychology tricks to find out what's going on inside your brain". Many of the topics covered are very similar to those that will be covered here: issues at the edge of cognition and neuroscience.

A post of particular interest simply quoted Marvin Minsky (a prominent figure in the field of artificial intelligence) from his book Society of Mind.

People ask if machines have souls. And I ask back whether souls can learn. It does not seem a fair exchange – if souls can live for endless time and yet not use that time to learn – to trade all change for changelessness.

What are those old and fierce beliefs in spirits, souls, and essences? They're all insinuation that we're helpless to improve ourselves. To look for our virtues in such thoughts seems just as wrongly aimed a search as seeking art in canvas cloths by scraping off the painter's works.

I found this quote very moving, as it expresses (by comparison) the wonderful joy of learning and change. It's also profound because it questions certain long-held assumptions about what immortality would be like, and what we would want it to be like.

Another post of interest explained how the retina ("the only part of the central nervous system visible from outside the body") and associated structures can reveal a great deal about cognitive functions. It turns out that as items are stored in working memory the pupil dilates (more with each successive item), and as the items are recalled and repeated back to the experimenter the pupil contracts down to its normal size. What does this say about system integration in the brain? It likely means that even low-level regions controlling pupil dilation or eye-movement initiation are tied intimately with regions involved in higher level cognition such as working memory. 
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