Thanks to a dramatic improvement in imaging techniques it is now possible to generate high-resolution pictures of the monkey brain in a quality never seen before. A research group led by neurophysiologist Prof. Nikos Logothetis of the Max Planck Institute for Biological Cybernetics and physician Prof. Dr. Heinz Guggenberger of the Eberhard Karl University (both in Tübingen, Germany) was the first ever to successfully use the so-called fMRI technique (from functional magnetic resonance imaging) to produce detailed pictures of active brain regions in monkeys which have been anesthetized but are still capable of perception (nature neuroscience, Vol. 2, No. 6, June 1999). Until now, many scientists were convinced that it would be impossible to gather such images from anesthetized monkeys.
The fMRI technique uses a strong magnetic field to detect brain regions which are active and thus more strongly perfused. It promises new impetus for the area of brain research. fMRI makes it possible to pinpoint the precise regions of the monkey's visual cortex (that region of the cerebral cortex responsible for sight) where optical stimuli are processed. The non-invasive measurements are carried out under anesthesia conditions that meet the most up-to-date standards in human clinical medicine. The eyelids are held open artificially so the animals can see the presented test pattern. At the same time, constant irrigation prevents any damage to the eyes. The monkey wakes up and is fully conscious an average of 15 minutes after the experiment. The new technique places much less strain on the animal than conventional methods and makes it unnecessary to put them to sleep after the experiment.
The improved method made it possible to visualize brain volumes as small as 0.5
microliters in anesthetized monkeys and 2 microliters in a control group of
alert monkeys. (One microliter is one millionth of a liter.) This is the highest
resolution ever achieved in pictures of the pri
Contact: Nikos K. Logothetis