What do tiny bees and dead salmon have to do with the history of MRI? This post by Dr David Higgins and Dr Matthew Clemence explores how the flexibility of MRI lends itself to important applications outside of medicine and examines how the use of functional MRI has more recently brought us much closer to real scientific observation of the brain.
MRI is a rapidly evolving imaging modality, and the history of MRI has always been intertwined with research. Its flexibility lends itself to fascinating applications outside of medicine; even bees, and fish.
In neurobiology, honeybees are a common model for analysing underlying neural mechanisms because of their simply structured nervous system. By investigating the bee brain’s anatomy, correlations between anatomy and function can be studied. See Haddad et al 2004 for MR images of tiny bee brains. One early project looked to see if there were any magnetic structures inside the bee – which MRI was uniquely sensitive to – that might help bees navigate. Bees have been studied by MRI surprising often, perhaps because their behaviour is extraordinary, emerging as it does from such apparently simple creatures. MRI has helped our understanding of this important crop animal (Tomanek et al, 1996).
Looking at the function of intact, living neuroanatomy has been a dream for students of the human mind for centuries. Phrenology (from Ancient Greek φρήν (phrēn) “mind”, and λόγος (logos) “knowledge”), which supposed that the lumps and bumps on the skull reflected personality traits, was developed in 1796 and remained influential up until the 1840s. While, in a marked understatement from Wikipedia, “the methodological rigor of phrenology was doubtful even for the standards of its time”, the underlying concept that that the brain is the organ of the mind – and that certain brain areas have localised, specific functions – is based in fact. Technology developments in electroencephalography, near-infrared spectroscopy and most recently functional MRI have brought us much closer to real scientific observation of the brain.
Which brings us to a dead salmon…
Functional MRI (fMRI) was a revolutionary technique used to identify highly localised changes in blood flow resulting from differential load on regions of the brain. John (Jack) Belliveau at Massachusetts General Hospital showed in a key Science paper that these changes could be measured with MRI (Belliveau et al, 1991) in conjunction with a Gadolinium contrast agent, but it was Seiji Ogawa who demonstrated a practical, non-invasive method with the University of Minnesota (Ogawa et al, 1990). For the first time, scientists had access to detailed 3D anatomical images of the brain in action, through a safe technique that could be repeatedly used on volunteers. Its ease of use, combined with wide availability, allowed the technique to be adopted rapidly in psychology and neuroscience, often in the hands of the non-MRI specialist. Some of the early studies exploring this new ability to “read minds” often drew overly broad conclusions from badly designed experiments. This almost relegated fMRI into a category of “modern phrenology”.
The dead salmon experiment showed how, with naive experimental design and data analysis, fMRI could give convincing results on a dead Atlantic salmon (Bennett et al, 2010) and was a salutary lesson to would be fMRI researchers to improve their methodology (Lyon, 2017).
Now, once again fMRI is being used to tease out our inner thoughts, whether to attempt to detect lying for legal purposes or read letters directly from the visual cortex. This could have a dramatic impact in patients with “locked in syndrome” through the development of brain computer interfaces (Sorger, 2010).
fMRI has also found an unusual application in neuromarketing: the application of neuroimaging methods to product marketing, to more effectively “match products with people”. Companies can incorporate use of fMRI in the design process of a product, as well as in assessing the effectiveness of an advertising campaign, even if the “product” is a political candidate. “Political marketing is aimed at selling an existing candidate but, with more foresight, can also be used to “design” a better candidate” (Ariely & Berns, 2010). Imaging our brains may reveal what we really think (or how we’re likely to vote), even if we can’t fully articulate our preferences yet.
If all this sounds hard to believe, perhaps a look at our brain scans could help you decide whether to believe us. “The relative reduction in prefrontal grey matter relative to white may also predispose to a general antisocial disinhibited tendency which, coupled with increased white matter, results in excessive lying.” (Yang et al, 2005).
Just check the study passes the dead salmon test!
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Ariely D & Berns G. Neuromarketing: the hope and hype of neuroimaging in business. Nat Rev Neurosci 2010;11:284–292. doi:10.1038/nrn2795
Belliveau JW et al. Functional mapping of the human visual cortex by magnetic resonance imaging. Science 1991;254:716-719. doi:10.1126/science.1948051
Bennett et al 2009. Neural correlates of interspecies perspective taking in the post-mortem Atlantic salmon: An argument for proper multiple comparisons correction. J Serendipitous Unexpected Results 2010;1:1–5. See https://www.nature.com/articles/nj7420-437a
Haddad D et al. NMR imaging of the honeybee brain. J Insect Sci 2004;4:7. doi:10.1093/jis/4.1.7
Lyon L. Dead salmon and voodoo correlations: should we be sceptical about functional MRI? Brain 2017;140;e53. doi:10.1093/brain/awx180
Ogawa S et al. Brain magnetic resonance imaging with contrast dependent on blood oxygenation. Proc Natl Acad Sci U S A. 1990;87:9868-9872. doi:10.1073/pnas.87.24.9868
Sorger et al. A real-time fMRI-based spelling device immediately enabling robust motor-independent communication. Curr Biol 2012;22:1333-8. doi:10.1016/j.cub.2012.05.022
Tomanek B et al. Magnetic resonance microscopy of internal structure of drone and queen honey bees, Journal of Apicultural Research, 1996;35:3-9. doi:10.1080/00218839.1996.11100907
Dr David Higgins and Dr Matthew Clemence are Senior Scientists at Philips, part of the UK&I MR Clinical Science team and the wider global Philips Clinical Science group. They provide: MR physics support; advanced teaching on the functions of the MR system; prototype pulse sequence deployment and monitoring; novel pulse sequence development advice; guidance for novel image reconstruction and analysis projects; advice for novel interfacing novel hardware.