What we cannot do

If ever there was an example of a single technology which antivivisectionists quote as a successful alternative to animal studies, it is functional magnetic resonance imaging (fMRI). The Dr Hadwen trust even organised a presentation about this research method from an Oxford University Professor at their recent meeting in Brussels.

As we have pointed out many times, the failure of antivivisectionists to accept the limitations of some of these alternative methods of research is frankly dishonest. Fortunately, there are more credible sources than animal-rights literature.

Nature journal this week carries an extensive review of what we can do and what we cannot do with fMRI. RDS certainly acknowledges the view of the author that MRI is the most important imaging advance since the introduction of x-rays. However, as the review points out, ‘fundamental questions concerning the interpretation of fMRI data abound, as the conclusions drawn often ignore the actual limitations of the methodology’.

The concluding sentences of the review are particularly strong, albeit rather technical:

‘Today, a multimodal approach is more necessary than ever for the study of the brain’s function and dysfunction. Such an approach must include further improvements to MRI technology and its combination with other non-invasive techniques that directly assess the brain’s electrical activity, but it also requires a profound understanding of the neural basis of haemodynamic responses and a tight coupling of human and animal experimentation that will allow us to fathom the homologies between humans and other primates that are amenable to invasive electrophysiological and pharmacological testing. Claims that computational methods and non-invasive neuroimaging (that is, excluding animal experimentation) should be sufficient to understand brain function and disorders are, in my opinion, naive and utterly incorrect’.

Comments

    Page 1 of 1 pages of comments • Follow through:
  1. The review by Prof Logothetis in Nature certainly makes interesting reading. By coincidence this week’s Science carries a news focus piece by Greg Miller on fMRI, prompted by somewhat overblown claims in the New York Times about the ability of fMRI to predict voter intentions.  The Science article includes quotations by Professor Russell Poldrack of UCLA and Prof Steven Petersen of Washington University in St Louis, both of whom are noted experts in the use of fMRI in neuroscience research

    Since its introduction in the early 1990s, fMRI has transformed neuroscience. Now in its teenage years, the fMRI field is still experiencing growing pains. Some cognitive neuroscientists say they’re frustrated that many studies—including some of those that garner the most attention in the popular press—reveal little about the neural mechanisms of human cognition. ‘The problem right now with imaging is that doing experiments right is really, really hard, but getting pictures out is really, really easy,’ says Steven Petersen, a veteran brain-imaging researcher at Washington University in St. Louis, Missouri.

    At the same time, there are signs that the field is maturing, as researchers confront the limitations of fMRI. Such efforts include painstaking experiments that match human fMRI data with analogous fMRI data and electrophysiological recordings of neural activity in monkeys, as well as new analytical methods capable of revealing information processing in the brain that would be impossible to detect with standard methods. ‘I think [these methods] are really going to revolutionize how we think about our data,’ says Poldrack. They also have the potential to introduce more rigor into fMRI research—something that’s badly needed, Poldrack says, otherwise, ‘people will start to see fMRI as neophrenology, just telling stories and not giving explanations’.

    The news item goes on to discuss several of the limitations of fMRI, in particular its relatively poor temporal resolution and the fact that the smallest area that it can measure can contain hundreds of individual nerve cells, and the different techniques that are being used to complement it, including direct measurement of nerve activity in monkeys. A further limitation is that while fMRI studies can show correlation between activity in a particular brain area and a cognative process they do not prove that that brain area causes the process or is even necessary for it. Studies that disrupt activity in those brain areas are required to figure out the mechanism, and while this can sometimes be done using non-invasive transcranial magnetic stimulation if the area being studied is near the surface of the brain in many cases only invasive studies in monkeys can provide the necessary information.

    The articles in Nature and Science are very interesting, in discussing the limitations of a purported ‘alternative’ and the way that animal research in reality complements it and increases its usefulness. This shows how the split between ‘animal’ and ‘non-animal’ scientists, that the antivivisectionists suggest is there, really does not exist.

    Posted by Visigoth / June 13, 2008 | Friday | 10:01 AM |
  2. Page 1 of 1 pages of comments • Follow through:

Only registered users can comment

Please use the login form in the left column.

<< Back to main