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How does the brain make decisions when faced with conflicting options?

Primary Supervisor: Dr Carolina Rezaval, School of Biosciences

Secondary supervisor: Dr Alicia Hidalgo

PhD project title: How does the brain make decisions when faced with conflicting options?

University of Registration: University of Birmingham

Project outline:

Animals engage in daily activities that are essential for survival and reproduction, such as feeding, mating or fighting for resources. How does an animal prioritise one behaviour over others? We know that cues conveying external information (e.g., threats from other animals, access to food) and internal state (e.g., fear, hunger, tiredness) guide behavioural choices. However, exactly how action-selection occurs in the brain remains unknown.

This research proposal aims to understand how the brain makes decisions when faced with conflicting options using the fruit fly model, Drosophila melanogaster.

Fruit flies exhibit complex behaviours that are controlled by a relatively small brain. Furthermore, sophisticated genetic tools are available which facilitate the control of individual neurons with temporal resolution, enabling us to probe the circuitry underlying behaviour.

Using Drosophila as a model system provides a unique opportunity to address fundamental aspects of action-selection: how does the brain integrate information from the outside world and internal state to select the most appropriate action for each situation? What neurons and mechanisms underlie these behavioural decisions?

To address these questions, the PhD student will use a range of cutting-edge techniques: genetics, confocal microscopy, optogenetics, thermogenetics, molecular biology, and behavioural assays. To record neural activity in behaving flies, we will collaborate with groups at Oxford University and Tel Aviv University.


How the brain selects appropriate actions is a fascinating question that remains unknown. Choosing appropriate actions is not only crucial for our life but can, collectively, influence the course of our society. Furthermore, action-selection processes are impaired in addiction and neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease. Understanding how different neurons contribute to optimal action-selection in a genetically tractable experimental system will help us advance our knowledge of how the brain works, and what goes wrong in disease.

More information

Check out our lab webpage:

Watch a 3-minute video about Dr Rezaval's past work.

Dr. Rezaval's previous work at Oxford University can be found here:


  1. ‘Cracking neural circuits in a tiny brain: new approaches for understanding the neural circuitry of Drosophila’. Olsen and Wilson. Trends Neurosci. 2008 Oct;31(10):512-20. doi: 10.1016/j.tins.2008.07.006. Epub 2008 Sep 3.
  2. ‘100 years of Drosophila research and its impact on vertebrate neuroscience: a history lesson for the future’. Bellen HJ1, Tong C, Tsuda H. Nat Rev Neurosci. 2010 Jul;11(7):514-22. doi: 10.1038/nrn2839.
  3. ‘Neuromodulation of Innate Behaviors in Drosophila’. Kim SM1, Su CY1, Wang JW1. Annu Rev Neurosci. 2017 Jul 25;40:327-348. doi: 10.1146/annurev-neuro-072116-031558. Epub 2017 Apr 24.
  4. ‘Neuronal Decision-Making Circuits’. Current Biology 18, R928–R932, October 14, 2008 ª2008 Elsevier Ltd All rights reserved DOI 10.1016/j.cub.2008.07.081

BBSRC Strategic Research Priority: Understanding the rules of life: Neuroscience and Behaviour

Techniques that will be undertaken during the project:

This project will foster cross-disciplinary collaborations with researchers in the School of Engineering to develop video tracking systems for automation of behaviour, researchers working on cognitive neuroscience and decision making in the School of Psychology, and researchers in the private sector interested in targeting insect reproductive behaviours for pest control (e.g., Oxitec, Oxford insect technologies).

Contact: Dr Carolina Rezaval, University of Birmingham