To develop criteria for the classification of fibromyalgia, we studied 558 consecutive patients: 293 patients with fibromyalgia and 265 control patients. Interviews and examinations were performed by trained, blinded assessors. Control patients for the group with primary fibromyalgia were matched for age and sex, and limited to patients with disorders that could be confused with primary fibromyalgia. Control patients for the group with secondary-concomitant fibromyalgia were matched for age, sex, and concomitant rheumatic disorders. Widespread pain (axial plus upper and lower segment plus left-and right-sided pain) was found in 97.6% of all patients with fibromyalgia and in 69.1% of all control patients. The combination of widespread pain and mild or greater tenderness in 2 11 of 18 tender point sites yielded a sensitivity of 88.4% and a specificity of 81

It is possible that brain cortical function is mediated by dynamic modulation of coherent firing in groups of neurons. Indeed, a correlation of firing between cortical neurons, seen following sensory stimuli or during motor behaviour, has been described. However, the time course of modifications of correlation in relation to behaviour was not evaluated systematically. Here we show that correlated firing between single neurons, recorded simultaneously in the frontal cortex of monkeys performing a behavioural task, evolves within a fraction of a second, and in systematic relation to behavioural events. Moreover, the dynamic patterns of correlation depend on the distance between neurons, and can emerge even without modulation of the firing rates. These findings support the notion that neurons can associate rapidly into a functional group in order to perform a computational task, at the same time becoming dissociated from concurrently activated competing groups. Thus, they call for a revision of prevailing models of neural coding that rely solely on single neuron firing rates.

Understanding how the brain works is probably the greatest scientific and intellectual challenge of our generation. The cerebral cortex is the instrument by which we carry the most complex mental functions. Fortunately, there exists an immense body of knowledge concerning both cortical structure and the properties of single neurons in the cortex. With the advent of the supercomputer, there has been increased interest in neural network modeling. What is needed is a new approach to an understanding of the mammalian cerebral cortex that will provide a link between the physiological description and the computer model. This book meets that need by combining anatomy, physiology, and modeling to achieve a quantitative description of cortical function. The material is presented didactically, starting with descriptive anatomy and comprehensively examining all aspects of modeling. The book gradually leads the reader from the macroscopic cortical anatomy and standard electrophysiological properties of single neurons to neural network models and synfire chains. The most modern trends in neural network modeling are explored.

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1. Activity of up to 10 single units was recorded in parallel from frontal areas of behaving monkeys. 2. Spatiotemporal firing patterns were revealed by a method that detects all excessively repeating patterns regardless of their complexity or single-unit composition. 3. Excess of repeating patterns was found in 30-60% of the cases examined when timing jitter of 1-3 ms was allowed. 4. An independent test refuted the hypothesis that these patterns represented chance events. 5. In a given behavioral condition there were usually many different patterns, each repeating several times, and not one (or a few) pattern repeating many times. 6. In 13 out of 20 cases, when a single unit elevated its firing rate in association with an external event beyond 40/s, most of the spikes within that period were associated with excessively repeating spatiotemporal patterns. 7. Of 157 types of patterns whose excess was most marked, 107 were composed of spikes from one single unit, 45 of the patterns contained spikes from two single units, and only one was composed of spikes from three different single units. 8. These properties suggest that the patterns were generated by reverberations in a synfire mode within self-exciting cell assemblies.