Brain Imaging Technology Can Reveal
What a Person is Thinking About
Source: Eurekalert
November 6, 2000
Powerful brain imaging technology is allowing
researchers to actually tell what a person is thinking before they
even say it.
A study, published in the November issue of the
international Journal of Cognitive Neuroscience, has shown that it is
possible for researchers to look at brain imaging data and determine
whether a person is imagining a face or a place.
"With the technology available to us today, we are now
able to identify the content of a person's thought, albeit in a very
limited context," says Dr. Kathleen O'Craven, a cognitive
neuroscientist who led the study at Massachusetts General Hospital.
Dr. O'Craven is now with Toronto's Rotman Research Institute at
Baycrest Centre for Geriatric Care.
In the study, six women and two men, aged 20 to 39, were
put through two cognitive exercises: one involved looking at pictures
of faces, and a second involved looking at pictures of places or
landscapes. Later these same adults were asked to mentally 'imagine'
the faces and the places they had
earlier seen. During both tests, functional magnetic resonance imaging
(fMRI) scans were taken of their brains.
Many previous studies have shown that brain areas can be
selective for processing a particular type of visual information. In
the cortical brain regions associated with mental processing, the
'fusiform' face area responds strongly to faces while the
'parahippocampal' place area responds strongly
to indoor and outdoor scenes depicting the layout of local space.
In this study, Dr. O'Craven and colleague Dr. Nancy
Kanwisher of the Massachusetts Institute of Technology found the
strongest evidence yet that this specialization holds true even when
participants were given no visual stimulus and were simply asked to
'imagine' a face or a place. They also found that the magnitude of
activity in these two brain areas is much livelier or stronger when
one is seeing the picture (physically present in front of them)
compared with just imagining it.
The most fascinating finding, however, is when 'data
coders' (researchers who interpret data) were asked to look at fMRI
scans and guess whether the study participant was thinking of a face
or place. They were able to accurately report what the participant was
thinking about on 85 percent of
the trials!
"What we've shown is that we can actually tell, on a
moment-by-moment basis, what an individual is thinking about, by
measuring brain activity rather than having the person tell us," says
Dr. O'Craven. "Of course, this can be done only in a limited
context -- we've been able to demonstrate it for differentiating
between faces and places -- but the implications are far-reaching."
She says the technique could be used to gain some
insight into what is happening in the minds of people who are unable
to communicate because they are suffering from an injury or disorder
that makes speech impossible.
"We may someday be able to get a glimpse of what a
patient is able to comprehend, even when that person can't answer
questions directly. We could show them pictures of faces and places
and, using fMRI technology, see whether their visual system is
processing them. In addition, if these brain areas respond
differentially to the 'spoken' names of people and places, we may be
able to infer that they understand."
The study was supported by The Bunting Institute at
Radcliffe College and by grants from the National Institute of Mental
Health, the Human Frontiers Science Program, and the Dana
Foundation
by Kelly Connelly - kconnelly@baycrest.org
416-785-2432
Baycrest Center for Geriatric Care
http://www.eurekalert.org/releases/bcfg-bit110600.html