Functional Mapping of the Human Brain

The Fifth International Conference on Functional Map ping of the Human Brain (HBM99) was held in Düsseldorf, Germany, from June 22 to 26, 1999. During this conference, which was CME accredited, more than 1300 scientists from 28 countries around the world came together to discuss their most recent findings in cognitive neurophysiology obtained with modern brain-mapping techniques such as electroencephalogra phy, magnetoencephalography, functional magnetic res onance imaging, positron emission tomography, single photon emission computed tomography, optical imag ing, and neuroanatomical tools. A further part of the meeting focused on research of systems physiology us ing brain-mapping techniques in neurological and psychiatric disorders including neurorehabilitation and surgical neuronavigation. The third large topic covered methodological issues related to the theme of the conference. The principal medium for scientific presentation were posters that were displayed throughout the entire meeting. In addition, there were plenary lectures and dedicated symposia on spatio-temporal information processing in the human brain and dynamic neuroreceptor mapping. The scientific sessions were flanked by an educational program devoted to the methodological foundations of the modern neuroimaging techniques. A great part of the scientific contributions centered around control of executive functions. Evidence was presented showing that premotor cortex and parietal cortex are topographically highly organized brain areas subserving control of spatially and temporally struc tured motor acts including generation of language. Fur thermore, it was demonstrated that control of behavior is critically influenced by the level of awareness. Whereas automated, predicted behavior was reported to be anticipatory, allowing it to monitor subliminal stimu lus deviations, conscious behavior is reactive and requires intact short-term memory. Imaging data were presented showing that the transition from automated to conscious behavior involves the dorsolateral prefrontal and premotor cortex and the cerebellum bilaterally. Also, a large number of contributions were devoted to the physiological mechanisms of visual, somesthetic, and pain perception. In vision research, it is well estab lished that visual attention modulates brain activity in a number of extrastriate visual areas and in thalamus. Now, evidence has been provided showing that visual attention to cued targets leads to enhanced activations with a retinotopic organization in the medial occipitotemporal cortex. Moreover, many contributions addressed processes underlying memory and learning as well as language perception. These functions were shown to be cognitive processes with strong modulation by the emotional content of the task, involving not only cortical brain areas and the hippocampal formation but also subcortical structures such as the thalamus and the amygdala. A number of presentations showed that the advent of functional imaging and deep electrode record ings in nonhuman primates opens up a new avenue for understanding the electrophysiological processes under lying cerebral activations. The application of modern brain-mapping techniques to neurological and psychiatric brain diseases is opening new perspectives in clinical research. For example, the cerebral perfusion deficit was reported to be detectable before brain tissue becomes infarcted in stroke and its temporal evolution can be followed during a migraine attack. These findings bear considerable impact on pathophysiology and modern patient management. Recovery from aphasia was shown to require the left temporal cortex in the first weeks after brain infarction and to involve the right hemispheric homologue of Broca’s area in the chronic stage after infarction. In psy chiatric patients with obsessive-compulsive disorder, it was shown that emotional stimuli engage specific brain areas including the insular cortex, regardless of the con text in which the emotion was perceived. In schizo phrenic patients, widely distributed systems of cortical and subcortical activations involving amygdala and prefrontal cortex were reported to differ from those acti vated in healthy controls during the perception of emo tional stimuli. Because the relation of these findings to behavioral abnormalities such as catatonia and impaired processing of affect and possibly because genetic and drug effects are becoming increasingly better defined, there is the prospect of an improved understanding of the pathophysiology of these psychiatric disorders. Finally, a plethora of methodologically oriented con tributions illustrated the continuing development shortly occurring in data acquisition and analysis. Of particular interest were the advancements in the field of functional magnetic resonance imaging (fMRI). Recently, for example, it has become possible to visualize the tempo ral evolution of brain activity changes in the different parts of the brain even in single-event recordings. This will open new avenues for the understanding of attention as