Chiara is now working at the Behavioural Insights Team in London, UK.


Position
Chiara is a former Ph.D. student supervised by Sébastien Bouret at the Motivation, Brain and Behavior Team within the Brain & Spine Institute. Chiara obtained her Ph.D. degree on October the 5th, 2015.

 

Contact

chiara.varazzani (at) normalesup.org

 

Academic Education

2012-2015: Ph.D. in Behavioural Neuroscience - Sorbonne Paris Cité University, Paris

2010-2013: ENS Ulm Graduate Diploma - École Normale Supérieure, Paris
2010-2012 : M.Sc. in Cognitive Sciences - CogMaster, École Normale Supérieure and School for Advanced Studies in Social Sciences, Paris
2007-2010: B.A. in Philosophy - UNISR, Milan


Ph.D. project

There is perhaps no more critical factor for the behaviour of an animal than the way it chooses between action and inaction. A simple way to formalise such choices is to evaluate the predicted benefits (e.g. food, money) and costs (e.g. punishments, losses, delays) associated with each action and optimise the rates at which rewards are received and costs avoided. Our motivation to perform a given action depends upon such value ratio. In the current behavioural economics literature, the optimisation of the between /costs ratio stands as the fundamental principle that regulates and explains agents’ behaviour.

In her Ph.D. studies, Chiara has implemented a realistic model of such concepts from behavioural economics by using an empirical type of cost: physical effort. In our everyday life, if we are asked to choose between two options that imply the same reward but different efforts (e.g., working 3 or 7 days per week for the same salary), we usually opt for the alternative that requires the slightest energy expenditure, thus the least effort. However, physical effort has been far less studied compared to other decision costs such as delay or uncertainty.

Chiara’s Ph.D. work aimed at highlighting the neuronal bases of such reward/ effort tradeoff. She has specifically targeted two major actors of the reward and effort system: dopamine and noradrenaline. Her research has shown that dopamine and noradrenaline have distinct but complementary roles in motivation. On the one hand, dopamine tracks the reward value of future outcomes and orient the behaviour towards the least effortful options. On the other hand, noradrenaline enables subjects to face the effort at hand, reducing the sensitivity to anticipated effort. Chiara’s Ph.D. work has allowed to disentangle some of the neuronal circuits implicated in the computation of the reward/effort tradeoff, mainly encoded by dopaminergic neurons and in the local field potential in the ventromedial prefrontal cortex. On the other hand, this work has also highlighted the role of noradrenaline in the energization of behaviour to face the challenge represented by physical effort.

 

Publications

Varazzani C, San-Galli A, Gilardeau S, Bouret S, “Noradrenaline and Dopamine Neurons in the Reward/Effort Trade-off: a direct electrophysiological comparison in behaving monkeys”, Journal of Neuroscience (2015), 35(20):7866-77. [DOI]

 

Spotlight: Floresco, S. B., “Noradrenaline and Dopamine: sharing the workload”, Trends in Neurosciences (2015), [DOI]