Michael Shermer, editor of Skeptic magazine, has a great article in Scientific American about the limits of interpreting fMRI scanning studies -- particularly how they are presented in the media. The biggest point is that the brain is not a collection of modules isolated from one another; rather, it is a collection of interconnected systems with diverse roles in diverse tasks:
A number of interconnected neural networks may in some cases be localized and bundled into modulelike units, but in most ways they are better described as being splayed out over, under or through the brain's crevasses. The metaphor of "distributed intelligence" -- sometimes used to describe the World Wide Web's power -- more closely matches the network distribution of tasks in the brain than the module metaphor does.
Of course, there are areas that specialize in certain types of processing, such as the visual cortex at the back of the brain and Broca's area for language in the left frontal lobe. And roughly speaking, reason and rationality happen in the cortical areas, whereas emotion and irrationality are experienced in the limbic system.
Nevertheless, as many neuroscientists now believe, the metaphor of "neural networks" is superior to that of mental modules. The latter forces us to think of the brain as a kludge of encapsulated organs specialized for one function and no other, whereas the former more accurately reflects what modern neuroscience tells us is actually happening during cognition. Brain-scanning technologies such as fMRI will continue to generate copious data for our metaphorical theories -- and as long as our skeptical networks are active, we should be able to better map neural networks and their accompanying functions onto the landscape of our behaviors.
Read the whole thing. I have talked about this subject here.
Hat-tip: Marginal Revolution
- Log in to post comments
More like this
Sorry, this is quickly becoming a pet peeve of mine, so it might be a bit ranty...
This is actually an area where fMRI is much stronger than just about every other form of neuroscience.
Think of EEG where attempting to locate a particular effect usually relies on reducing the source to a single point in cortex.
Think single unit electrophysiology, which looks at a few square mm of cortex and often talk as if they are observing neural processing that is unique and wholly generated by that single cortical area (parietal reach regions, mirror neurons, or short term memory).
Think of cellular physiologists who study CA1 hippocampal neurons and extrapolate their results explain all long term memory.
All methods have certainly have their limitations, and each field adds a different important piece of the puzzle. I don't mean to say that fMRI is the pinnacle of neuroscientific study. However, one of it's major strengths is that scientists need to make absolutely no assumptions about where a particular activity takes place, nor if that activity is restricted to a single stripe of cortex or distributed throughout the brain. Techniques for network analysis of fMRI data (BOLD correlation, partial coherence) have actually generated some of the strongest evidence for the distributed processing hypothesis.
I agree that the media often oversimplifies neuroimaging findings, but the same can be said of pretty much any media coverage of nearly any scientific finding. And, certainly, some groups who use fMRI are believers in the modular hypothesis. However, the sudden vogue for picking on fMRI and it's media coverage does more harm than good by adding to misconceptions about the nuances of the neuroscience fields.
Well, after reading the whole thing I'll retract the 'does more harm' bit. The whole article is certainly better than other things I had seen on the subject, even if it's not perfect.
It's an issue of fMRI having too much sensitivity & too little specificity.
There's good reason to believe in distributed processing. But you have to chuckle a bit when you consider it *solely* from the the perspective of fMRI: eg, Whenever you do any task, everything lights up, so that must mean it's all distributed.