Pharmacogenetic and optical dissection for mechanistic understanding of Parkinson's disease: Potential utilities revealed through behavioural assessment

The technology toolbox by which neural elements can be selectively manipulated in vertebrate and invertebrate brains has expanded greatly in recent years, to now include sophisticated optogenetics and novel designer receptors. Application of such tools allow for ascertaining whether a particular behavioural phenotype associates with interrogation of a specific neural circuit. Optogenetics has already found application in the study of Parkinson's disease (PD) circuitry and therapies, whereas novel designer receptors hold promise for enlightening on current understanding of the mechanisms underlying parkinsonian motor and non-motor symptoms. In particular, this new generation of research tools provide a method by which significant insights can be gained on brain networks implicated in brain diseases such as PD. These tools also promise to assist in the development of novel therapies for targeting degenerated dopaminergic and non-dopaminergic neurons in the diseased basal ganglia system of PD patients, for providing symptomatic relief or even reverse neurodegenerative processes. The present review discusses how such technologies, in conjunction with application of sensitive behavioural assays, continue to significantly advance our knowledge of circuit and signalling properties inherent to PD pathology. The discussion also highlights how such experimental approaches provide additional explorative avenues which may result in dramatically improved therapeutic options for PD patients.