Because of a lack of clarity about laws about psilocybin mushrooms, retailers in the late 1990s and early 2000s commercialized and marketed them in smartshops in the Netherlands and the UK, and online. Several websites emerged that have contributed to the accessibility of information on description, use, effects and exchange of experiences among users. Since 2001, six EU countries have tightened their legislation on psilocybin mushrooms in response to concerns about their prevalence and increasing usage. In the 1990s, hallucinogens and their effects on human consciousness were again the subject of scientific study, particularly in Europe. Advances in neuropharmacology and neuropsychology, and the availability of brain imaging techniques have provided impetus for using drugs like psilocybin to probe the "neural underpinnings of psychotic symptom formation including ego disorders and hallucinations". Recent studies in the United States have attracted attention from the popular press and thrust psilocybin back into the limelight.