Global Excellence Seminar with Alizee Lopez-Persem

  • 31 October 2019 |
  • Alizee Lopez-Persem |
  • MR Conference Room |
  • Time 11:00-12:00 |

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On Thursday 31 October 2019, Postdoctoral Research Associate Alizee Lopez-Persem is giving a lecture entitled: "The Brain Valuation System and its role in decision making".

Abstract: 

‘Do you prefer a French fry or a cookie?’ While this question is simple for us to answer,  the processes engaged in the brain that allow us providing an answer remains a central question in neuroscience of decision-making and many aspects of it are unclear. A decomposition of this process might help us to understand the involved mechanisms. Indeed, first, we need to assign what we will call a 'subjective value’ to each option – i.e. the quantification of how much we like each of these options. Then, we need to compare those values to finally being able to select one of them. Assigning a value seems to be the function of an interesting brain network mainly composed of the ventromedial prefrontal cortex (vmPFC) and the ventral striatum – a network that overlaps the reward circuitry identified in animal studies – and which is called the Brain Valuation System (BVS). In the first study that I will present, we investigated the specific properties of the Brain Valuation System established through fMRI in humans in a large dataset of intra-EEG recordings in epileptic patients. We were able to replicate those properties and to provide insights on the underlying dynamics of this network. In the second study, conducted in fMRI, we investigated how this brain network was involved during binary choices. We specifically investigated whether prior preferences defined at the category level (savory versus sweet food for example) would define a default policy towards one or the other item (French fry versus cookie). At the behavioral level, we found that prior preferences induce a bias that leads participants to choose the default option more often (and faster) than its value would predict. At the neural level, we found that prior preference influenced the BVS baseline activity and that decision value was expressed by the vmPFC in a default versus alternative framing. Altogether, these findings shed light on the distinct cognitive mechanisms underlying value-based decision-making i) by exploring the neural properties of value assignment and ii) by proposing a general solution to the neural implementation of the comparison between option values. We believe this demonstration points to hidden default policies as sources of bias in choices.

Biography: 

I'm a neuroscientist interested in the neural basis of decision-making. During my PhD with mathias Pessiglione in Paris, I investigated the Brain Valuation System, a network involved in subjective valuation and decision-making processes through fMRI and iEEG in humans. My post-doctoral project now in Oxford, in the department of Experimental Psychology, with Jerome Sallet and Matthew Rushworth, is to closely investigate two subparts of the Brain Valuation System, the vmPFC and the OFC, in terms in anatomy and functional connectivity, in both humans and monkeys. 

The talk will be held on Thursday 21 October 2019 at 11 o'clock in the MR Conference Room.