I am interested in higher level perceptual and learning processes, and how these shape decision-making and behaviour. In particular, I try to understand how individual variability in such processes may contribute to seemingly irrational choices that may have health-harming consequences. This is relevant not just to an array of mental disorders but also to over-consumption and obesity. I think that it is very important that we do not consider the brain in isolation from either the body or from its external environment and that the study of high level cognitive processes must be shaped by close consideration of underlying metabolic and endocrine signals. This work benefits from collaboration with Professors Steve O’Rahilly and Sadaf Farooqi.
In addition, the study of fundamental reward-related processes in the human brain benefits from close links with basic neuroscientists at the Behavioural and Clinical Neuroscience Institute, notably Professor Wolfram Schultz. And in attempting to extend the work beyond the laboratory to larger samples in naturalistic settings, I work closely with Professor Theresa Marteau at the Behaviour and Health Research Unit (http://www.bhru.iph.cam.ac.uk/).
My work has focused on how combined functional neuroimaging, behavioural and pharmacological studies can elucidate brain processes involved in responding to environmental stimuli and determining food choice. Pharmacological perturbations , for example with dopamine agonists and antagonists, can be used to explore the neurotransmitter basis for these processes and ensuing measures of food-related behaviours are set up to determine the relevance of these lab and imaging-based measures to real-world choice and consumption. These studies have formed the basis for targeted assessment of brain structural changes associated with obesity.
The overall aim, through systematic exploration of these processes, is to understand choice and behaviour in detail and to determine the basis for marked variability in susceptibility to internally- and environmentally-driven consumption. Through this understanding, a fuller comprehension of the multiple factors contributing to obesity will be possible
Ronan L, Alexander-Bloch AF, Wagstyl K, Farooqi S, Brayne C, Tyler LK; Cam-CAN, Fletcher PC. Obesity associated with increased brain age from midlife. Neurobiol Aging. 2016 Jul 27;47:63-70. PMID: 27562529
Medic N, Ziauddeen H, Forwood SE, Davies KM, Ahern AL, Jebb SA, Marteau TM, Fletcher PC. The Presence of Real Food Usurps Hypothetical Health Value Judgment in Overweight People. eNeuro. 2016 Apr 29;3(2). PMID: 27280152. PMCID: PMC4894914
Diederen KM, Spencer T, Vestergaard MD, Fletcher PC, Schultz W. Adaptive Prediction Error Coding in the Human Midbrain and Striatum Facilitates Behavioral Adaptation and Learning Efficiency. Neuron. 2016 Jun 1;90(5):1127-38. PMID: 27181060. PMCID: PMC4893165
Medic N, Ziauddeen H, Ersche KD, Farooqi IS, Bullmore ET, Nathan PJ, Ronan L, Fletcher PC. Increased body mass index is associated with specific regional alterations in brain structure. Int J Obes (Lond). 2016 Jul;40(7):1177-82. PMID: 27089992. PMCID: PMC4936515
Teufel C, Subramaniam N, Dobler V, Perez J, Finnemann J, Mehta PR, Goodyer IM, Fletcher PC. Shift toward prior knowledge confers a perceptual advantage in early psychosis and psychosis-prone healthy individuals. Proc Natl Acad Sci U S A. 2015 Oct 27;112(43):13401-6. PMID: 26460044. PMCID: PMC4629373
Medic N, Ziauddeen H, Vestergaard MD, Henning E, Schultz W, Farooqi IS, Fletcher PC. Dopamine modulates the neural representation of subjective value of food in hungry subjects. J Neurosci. 2014 Dec 10;34(50):16856-64. PMID: 25505337. PMCID: PMC4261106