Our brains are amazingly complex information processing machines, constantly transforming sensory information into useful decisions and actions. I’m interested in finding out how large networks of neurons encode and transmit information, and make us one of the most intelligent species on the planet.
Perceptual decision-making and learning
The human brain is highly flexible, enabling us to learn new skills throughout life. In particular, training on basic visual tasks has been shown to induce lasting improvements in performance, a phenomenon called perceptual learning. For example, radiologists are able to identify fine patterns of tumours in images that show no pattern to the layman. Why is that? Is the radiologist really seeing better? Or is she using the visual information in a more effective way than the layman? And what are the neurophysiological and molecular underpinnings of these changes in performance?
During my PhD, I am investigating how improvements in performance during visual learning are related to changes in coupling between visual and decision-related areas of the brain. I use behavioural training in combination with magnetoencephalography to measure neural information processing and connectivity.
Neuromodulation: pharmacology and pupillometry
Systems of modulatory neurotransmitters orchestrate the efficiency of neural information processing throughout the brain, and play an important role in neuroplasticity that underlies learning and adaptive behaviour. I use pharmacology in healthy human volunteers to investigate how the neuromodulators acetylcholine and norepinephrine shape patterns of brain connectivity and influence the way in which we learn new visual skills.
While pharmacological interventions allow us to assess the causal effect of specific neuromodulators, they work on slow timescales of hours to days. An exciting line of research suggests that dilation of the pupil can be used as a proxy for fast, phasic release of neuromodulators from the brainstem. I am investigating to what extend such fast changes in pupil diameter reflect internal processes in decision-making and learning.
Decision-making biases and gain modulation
Humans are prone to a confirmation bias in decision-making, neglecting evidence that is dissonant with the beliefs they hold. Such a confirmation bias, while ensuring minimal cognitive dissonance, prevents decision-making from being optimal in an objective sense. When making low-level perceptual decisions, however, humans are traditionally assumed to behave at or near optimality. Using a novel two-stage perceptual decision making task, I investigate to what extend observers are influenced by commitment to a previously made choice. In collaboration with Bharath Chandra Talluri, Marius Usher, Zohar Bronfman and Noam Brezis.
The functional role of intrinsic neural activity
When we are not engaged in a specific task, our brains are never ‘at rest’ but show structured patterns of large-scale oscillatory activity, also termed ‘intrinsic coupling modes’. Research suggests that this intrinsic neural activity plays important functional roles, and may determine whether we perceive upcoming visual stimuli. Using EEG, I investigated how our of near-threshold stimuli is determined by the power and phase of ongoing neural oscillations. I worked on this project during my MSc at UCL, with Maren Urner, Joseph Brooks, Markus Bauer and Geraint Rees.
Temporal dynamics of conscious perception
From the moment we lay our eyes on a visual scene, we are able to extract its content within several hundreds of milliseconds. How does a visual percept unfold, and how much time does the brain need to extract specific visual features? I investigated these questions using magnetoencephalography at the ENS in Paris, where I did my internship with Catherine Tallon-Baudry.