Neuropsychiatric disease states, including anxiety, depression, and substance use disorder, present a major socioeconomic burden on almost all cultures across the world. Substance use and mood disorders also show high comorbidity. Despite decades of research, treatment strategies are largely ineffective, and relapse is common. The circuitry underlying these disorders has been reasonably well elucidated. Nevertheless, we still have much to learn about how external factors such as addictive drugs affect the brain to produce maladaptive and compulsive patterns of behaviour that are difficult to change, even despite strong external motivation. Furthermore, although it is evident that there are individual differences in susceptibility toward psychiatric disease states, the mechanism behind this susceptibility, and the reason for high comorbidity between them remains unclear. This symposium brings together emerging and established researchers from Australia, China and the United States to present their work on the neurobiological mechanisms on substance use and mood disorders. Importantly, invited presenters will include researchers from early- to late-career research status who are using sophisticated behavioural paradigms and cutting edge preclinical techniques, including antidromic optical phototagging, to functionally implicate brain regions and receptors in several neuropsychiatric disease states.

Dr Erin Campbell is an early career fellow at the Florey Institute of Neuroscience and Mental Health in Melbourne, Australia. Her research looks at context-induced relapse to alcohol seeking following voluntary abstinence. This model of abstinence is particularly powerful because it is self-imposed, rather than enforced by the experimenter, making it much more like the human condition. Dr Campbell has been using this model to explore the neural circuitry underlying abstinence and relapse. Here she will report on the involvement of the somatostatin 2 receptor subtype in this form of relapse. Dr Helen Nasser recently completed a fellowship at the National Institute of Drug Abuse in Baltimore, United States, where she was investigating individual differences in reward-seeking behaviour. Dr Nasser will report on experiments that combine functional disconnection, electrophysiology and antidromic optical phototagging to understand the circuitry that underlies sign- and goal-tracking. Animals with a tendency towards developing sign-tracking behaviour in response to rewards are more likely to show reduced behavioural flexibility; a pattern characteristic of addiction. Therefore, understanding the neural mechanisms that subserve these differences is an important step towards understanding individual differences in propensity towards substance use disorder. Dr Christina Perry is an NHMRC-ARC dementia research development fellow at the Florey Institute of Neuroscience and Mental Health in Melbourne, Australia. She uses complex a touchscreen testing platform to explore the degenerative effects of chronic alcohol exposure. Here she will describe evidence that alcohol caused cell loss in the prefrontal cortex but not the striatum of outbred rats, and that this loss was accompanied with deficits in executive function. This helps explain why it may be difficult for people with long-term alcohol use disorder to overcome ingrained patterns of behaviour. Finally, Professor Jian-Hui Liang is a practicing psychiatrist and expert in neuropsychopharmacology at the School of Pharmaceutical Sciences, Peking University, China. His research examines the neural mechanisms in preclinical models of opioid and alcohol addiction. Here, Professor Liang will present new rodent and behavioural models that will facilitate more sensitive testing of the mechanisms that underlie comorbidity between anxiety and depression, as well as providing a tool for screening novel antidepressant and anxiolytic drugs.