Dr Carolina Rezaval

Supervisor Details

Contact Details

School of Biosciences, University of Birmingham

Scientific Background

Research Interests

Our lab uses the fruit fly Drosophila to unravel the mechanisms underlying behavioural choices. By studying how the brain makes decisions at a genetic, cellular and circuit level, in an accessible experimental system, we aim to reveal fundamental principles that might be present across species.

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) guide behavioural choices. However, how the brain selects specific actions remains unknown.

Our lab addresses this fascinating question using the fruit fly model, Drosophila. Fruit flies exhibit complex behaviours that are controlled by a relatively small brain. Thanks to sophisticated tools available in the fruit fly, we can interrupt specific genes, as well as visualise and manipulate individual neurons with great resolution. With these tools, we can study how the fly brain responds when there are conflicting options available, and how it chooses amongst them.

By studying how the brain makes decisions at a genetic, cellular and circuit level in an accessible experimental system, we aim to reveal fundamental principles underlying behavioural choices that might be present across species.

Scientific Inspiration

Leonardo Da Vinci

Passion and commitment. Being an architect, anatomist, artist and scientist, Leonardo Da Vinci was clearly a genius. But I particularly admire his relentless search for creativity, innovation, and fulfilment. I have learnt from him that great science comes from passionate curiosity, pursuing your interests, and continuous learning.

Marie Curie

Don’t give up. There will be times in your life when people tell you that you can’t accomplish something or you feel you can’t make it. Despite a career of physically demanding work, and being constantly discriminated for being a woman, Marie Curie never gave up. She made amazing discoveries, for which she was awarded the Nobel Prize twice.

Anonymous collaborative scientists in the world

Generosity, kindness and collaboration. I admire scientists who support and encourage each other, and are willing to work together. Also, in our lab, we believe in racial justice, diversity, and inclusion.

Research Groups

Rezaval Lab

Birmingham Fly Facility

Centre for Neurogenetics

Structural and Molecular Cell Biology

Supervision Style

In three words or phrases: student-centred, supportive, collaborative.

Provision of Training

I foster a collaborative and supportive learning environment where students receive structured guidance in the early stages of their PhD. Experienced postdocs and PhD students will work closely with you, offering hands-on technical training, while I focus on nurturing your critical thinking, soft skills, advice in methods, data analysis through individual meetings and lab discussions. As your confidence and expertise grow, I encourage greater independence, empowering you to take full ownership of your research as you develop and refine your own methods and approaches

Progression Monitoring and Management

I am dedicated to helping you reach your full potential, providing guidance and encouragement throughout your PhD. Together, we will set clear goals and regularly review your progress to ensure you stay on track. In the early stages, we will meet weekly, and we’ll adjust the frequency as needed. If any challenges arise, we will work together to find solutions, ensuring your steady growth and progress towards your aspirations. My goal is to empower you to confidently achieve the objectives you set for yourself.

Communication

I regularly communicate with lab members through Teams chats but maintain an open-door policy, always available to discuss any concerns—whether scientific or personal. I do not usually email team members during the weekend, but they are welcome to reach out if needed. I encourage open communication and am always here for guidance, to address any issues affecting progress, or simply to discuss science

PhD Students can expect scheduled meetings with me:

In a group meeting

Typically, once per week. But you can approach me spontaneously with a question, a problem, or anything you want to share.

In year 1 of PhD study

At least once per week. I’m always available for my students.

In year 2 of PhD study

At least once per week.

In year 3 of PhD study

At least once per fortnight.

These meetings will be face to face, and I am usually contactable for an instant response every working day.

Working Pattern

The timing of work in my lab is completely flexible, and (other than attending pre-arranged meetings), I expect students to manage their own time.

Notice Period for Feedback

I need at least 1 week’s notice to provide feedback on written work of up to 5000 words.

MIBTP Project Details

Current Projects (2025-26)

Primary supervisor for:

How Does the Brain Make Decisions During Conflicting Situations?

See the PhD Opportunities section to see if this project is currently open for applications via MIBTP.

Please Note: The main page lists projects via BBSRC Research Theme(s) quoted and then relevant Topic(s).

How Does the Brain Make Decisions During Conflicting Situations?

Secondary Supervisor(s): Professor Alicia Hidalgo

University of Registration: University of Birmingham

BBSRC Research Themes: Understanding the Rules of Life (Neuroscience and Behaviour, Systems Biology)

Project Outline

Every day, we make choices that involve balancing opportunities with risks—but what’s actually happening in our brains as we make these decisions remains largely unknown. A central mystery in neuroscience is how the brain evaluates conflicting options and prioritizes specific actions. Evidence suggests there are sex differences in decision-making and unique vulnerabilities to neurological disorders across genders. Therefore, understanding how the brain makes decisions across contexts and genders holds important medical, economical, and societal benefits.

Studying decision-making in mammals is challenging due to the brain's complexity, but it is feasible in the fruit fly Drosophila, where single cells and circuits can be easily observed and manipulated.

Capitalising on these advantages, we discovered a fascinating brain mechanism that allows flies prioritise behaviours during conflicting situations (Cazale-Debat et.al Nature, 2024 doi: 10.1038/s41586-024-07890-3).

When animals, including humans, are deeply focused on something they desire—they may become less aware of potential dangers around them. This phenomenon, often referred to as “love blindness,” is a widespread behavioural tendency where the pursuit of a valued reward, like a mate, can overshadow possible risks. In the animal world, this kind of focus can help increase the chances of finding a mate and reproducing, but it also makes individuals more vulnerable to threats, such as predators.

In our study, we explored how the brain balances risk and reward during courtship, focusing on male fruit flies. We discovered a neural mechanism controlled by dopamine, a chemical linked to reward and pleasure, which allows the flies to reduce their sensitivity to danger as they get closer to mating. In the early stages of courtship, visual signals alert the flies to nearby threats, activating certain neurons that cause the flies to stop courting. This response is mediated by serotonin, another brain chemical that temporarily inhibits the courtship drive to ensure survival.

However, as the male flies advance in the courtship process, the brain gradually shifts gears. Dopamine levels rise, which reduces the response to threats, allowing the flies to stay focused on courtship instead of fleeing from danger. By tracking brain activity, we observed that the closer the flies get to mating, the higher the dopamine levels rise, eventually blocking the pathway that would normally alert them to visual threats. This allows the flies to “tune out” distractions and prioritise mating.

In essence, dopamine acts as a sensory filter, adjusting the flies’ perception of threats based on their proximity to achieving their goal. This filtering system enables the brain to prioritise between competing actions, choosing reproduction over survival when it matters most.

This PhD project will take this discovery further, aiming to answer key questions: (i) Does this dopamine-driven filtering mechanism also exist in females, and are there sex-specific differences? (ii) Is this neural mechanism applicable to other high-stakes decisions beyond mating versus predator avoidance? (iii) Is this neural mechanism an evolutionarily conserved strategy present across species, including mice and humans?

As a PhD student on this project, you’ll work at the cutting edge of neuroscience, using state-of-the-art techniques including advanced genetics, neural circuit tracing/connectomics, multiphoton imaging to capture neural activity in live, behaving flies, optogenetics, CRISPR for gene editing, and custom coding for data analysis. You will collaborate with researchers working with flies, rodents and humans in Germany and Switzerland.

This project offers an unprecedented opportunity to uncover decision-making processes during conflicts at remarkable molecular, cellular, and neural circuit level, revealing fundamental principles of brain function across species and genders.

For more information about Carolina Rezaval’s lab and research please visit: https://www.rezavallab.org/

Please, kindly get in touch with Carolina Rezaval directly to discuss your application prior to submission.

Aims

1. How is dopamine ramping generated?

Dopamine ramping has been studied in mammals, but the molecular mechanisms remain unknown. This objective will explore how dopamine ramping is generated in the fly brain using live imaging (e.g., multiphoton microscopy) to monitor neural activity during behaviour. Advanced genetic tools, along with molecular biology (CRISPR), will be used to manipulate genes in dopamine-producing neurons to assess their effects on ramping.

2. Do dopamine-driven filters mediate decision-making across conflicts?

We will test whether dopamine's filtering function extends to other decision-making contexts, such as feeding versus threat avoidance. We will conduct behavioural assays and use neural circuit tracing/connectomics, live imaging, optogenetics, and custom coding for data analysis to map how dopamine connects to circuits regulating competing behaviours.

3. Sex differences in decision-making:

Males and females face different evolutionary pressures, which may lead to distinct decision-making strategies. This aim will investigate sex-specific neural circuits in decision-making, using the methods outlined above, to determine whether dopamine influences males and females differently when resolving conflict scenarios.

Collaborative Opportunities

We will collaborate with Prof. Tobias Hauser, a leader in computational-psychiatry at Tübingen University. His expertise in decision-making and its dysfunction in psychiatric disorders will enable cross-species comparisons, examining whether dopamine-driven filtering mechanisms observed in Drosophila are conserved in humans.

References

Mating proximity blinds threat perception. NatureLink opens in a new window (2024). https://doi.org/10.1038/s41586-024-07890-3.
Laurie Cazalé-Debat*, Lisa Scheunemann*, Megan Day, Tania Fernandez-d.V. Alquicira, Anna Dimtsi, Youchong Zhang, Lauren A Blackburn, Charles Ballardini, Katie Greenin-Whitehead, Eric Reynolds, Andrew C Lin$, David Owald, and Carolina Rezaval.

A neuronal mechanism controlling the choice between feeding and sexual behaviors in Drosophila.

Cheriyamkunnel SJ*, Rose S*, Jacob PF, Blackburn LA, Glasgow S, Moorse J, Winstanley M, Moynihan PJ, Waddell S, Rezaval C. Curr Biol. 2021

Neuroscience: How the brain prioritizes behaviors.

Barajas-Azpeleta, R, Tastekin I and Ribeiro C. Curr Biol. 2021.

Bellen, H., Tong, C. & Tsuda, H. 100 years of Drosophila research and its impact on vertebrate neuroscience: a history lesson for the future. Nat Rev Neurosci 11, 514–522 (2010). https://doi.org/10.1038/nrn2839

Co-supervisor on a project with Professor Stephane De Brito.

Previous Projects (2024-25)

Primary supervisor for:

Neural basis of reproductive behaviour for exploitation in pest control

Previous Projects (2023-24)

Primary supervisor for:

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