As a pharmacy student at the University of Wisconsin–Madison, Natasha Mason was struck by the high volume of patients who complained about opiates and antidepressants not working, but at the same time became more and more dependent on them.This observation triggered an interest in the behavioural effects of psychedelic drugs, which took her career in a psychopharmacological direction. She now researches the neural effects of cannabis, both when people are under the influence of the drug, and over the longer term, at Maastricht University in the Netherlands.Mason is also interested in the positive and negative effects of developing a tolerance to cannabis.“Recreational users tend to use cannabis for the relaxing or the euphoric effects. So here, tolerance can be seen as kind of a maladaptive thing. You have to use more of the drug to get the high that you want … This is where addiction dependence can come in,” she says.“But tolerance can be a good thing in regards to the clinical use of this drug. Individuals who are using cannabis for pain do not want the high, because this also comes with the impairment as well.”This 12-part Working Scientist podcast series, Tales of the Synapse, is produced in partnership with Nature Neuroscience and introduced by Jean Mary Zarate, a senior editor at the journal. The series features brain scientists from all over the world who talk about their career journeys, collaborations and the societal impact of their research. Hosted on Acast. See acast.com/privacy for more information.