The image of a human head rotates slowly.
With the top portion of the skull removed,
viewers can see the hills and valleys that
cover the surface of the underlying brain.
Bursts of yellow and red indicate activity at
the rear of the brain, where a large
segment has been removed to expose the
inner workings of the optical cortex. These
colors, though, raise a fundamental
question - what does the recorded activity
mean?
The search to answer that
inquiry creates the foundation
of so-called functional
magnetic resonance imaging (fMRI), which
uses the imaging power of MRI in an effort
to understand how the brain performs a
variety of tasks, from vision to long
division. An intriguing overview of this
field awaits visitors at a site hosted by the
Oxford Centre for Functional Magnetic
Resonance Imaging of the Brain (FMRIB).
To get some general background on this
research facility, one can head to the
Introduction to FMRIB. This link explains
that an important goal of the
Centre is to promote research to
understand the brain mechanisms
necessary for complex cognitive
phenomena such as language and memory.
To explore these areas,
investigators at FMRIB rely on a 3 Tesla
magnetic resonance imaging system. (The
site includes photographs of this system
being installed.) Using this system,
investigators will explore how our brain
heals, say, after a stroke, what patterns of
activity in our brain accompany pain, and
many other phenomena.
When asked who uses this
site, Peter Jezzard, head of
the physics group at FMRIB,
said, Mostly other labs in the
business of functional brain imaging,
potential students, and our collaborating
scientific sites. He added that
visitors also include any
volunteers who might go in our magnet,
and, of course, whoever stumbles across it.
Some aspects of this site, however, serve
only members of the Oxford University
system. Steve Smith, head of image
analysis at FMRIB and author of its Web
site, explains: Obviously, we have
a very large amount of information
available only to Oxford computers with all
sorts of stuff about fMRI - how to book
experiments, how to analyze data, etc.
Nevertheless, Smith added
that this site also serves
interested researchers who want
to find out more about [the Centre] and
functional magnetic resonance imaging,
as well as researchers
who want to know what we are working
on, or want to download papers or software
from our site.
For those just getting started in this field,
or simply interested in the mechanics of
fMRI, follow the link labeled Introduction to
FMRI. The text therein explains that
fMRI is a technique for
determining which parts of the brain are
activated by different types of physical
sensation or activity, such as sight, sound
or the movement of a subject's fingers.
This 'brain mapping' is achieved by setting
up an advanced MRI scanner in a special
way, so that the increased blood flow to
the activated areas of the brain show up
on Functional MRI scans.
This introduction continues
with a more detailed
explanation of fMRI. For
example, it describes simple experiments,
and also includes a link to a
high-resolution scan, which shows a brain
from sagittal, coronal, and transverse
views. In the sagittal view, for instance,
visitors can see considerable detail in the
brain, such as the relatively fine features
of the cerebellum. This page also leads to a
rendered three-dimensional image that
shows an up-close view of active areas
inside a brain. Visitors can also view an up
close animation of the rendered brain,
spinning continuously. Loading the rotating
images takes some time, but it's worth the
wait.
When asked where visitors should go if
they had time to see only part of the site,
Jezzard said, I suppose the
examples of MRI images, although we
could do with updating them.
Perhaps updated images might further
fascinate viewers, but the current images -
see Recent MRI Images - seem intriguing
enough and more.
At the moment,
says Smith,
the most popular part of the Web
site is the SUSAN Web page, by a long
way. SUSAN stands for the
Smallest Univalue Segment Assimilating
Nucleus, which the page calls algorithms
that cover image noise filtering,
edge finding and corner finding,
and can improve MRI images. A link to the
SUSAN principle gives visitors a brief
introduction to this process, along with
explanatory diagrams. Smith says,
This [part of our site] includes a
report and software on image-processing
algorithms. Over the next few months
more similar pages will appear.
Some of the most exciting aspects of this
site lie ahead. The main research
attraction, within 12 months,
Smith says, will be online reports
and even software which people can
download. The reports will cover MRI
physics, analysis, and applications.
So add this site to your
bookmarks and keep coming back to see
what Smith and his colleagues add to their
site - and to our general understanding of
how our brain works.
Mike May is the contributing Web
Resources editor of HMS Beagle.