I am a cognitive neuroscientist in the Cognitive Neural Sciences Laboratory (School of Psychology) and the Cognition, Ageing and Neurodegenerative Disease Laboratory (School of Pharmacy and Biomedical Sciences).
 
A single response in a reaction time task takes roughly half a second. In that time, the brain encodes a stimulus, accumulates evidence towards a decision, prepares and executes a movement, and, if the response was wrong, registers the error and adjusts what it does next. My research asks whether these components can be measured separately, how their temporal dynamics unfold within a single response and fluctuate across many, how they differ between people, and which of them change first in ageing and neurodegenerative disease.
 
I focus on response inhibition, cognitive control, error monitoring, and motor control. These depend on frontal cortico-basal ganglia circuits, whose function is shaped by dopaminergic neuromodulation and by genetic variation in the systems that regulate it. I am particularly interested in how the dynamics and neurochemistry of these circuits give rise to the moment-to-moment variability seen in behaviour. The same circuits are disrupted early in Parkinson’s disease and are sensitive to ageing, brain injury, and psychiatric illness, so the behaviour they support is a candidate source of early markers of decline. Whether such markers are reliable and specific enough to be clinically useful remains open, and testing this is a large part of my work.
 
My approach is model-based systems neuroscience: theoretical accounts of these processes are formalised and tested against several kinds of evidence together. These include experiments designed to isolate a single process, evidence-accumulation and other computational models that estimate the parameters of decision and action, psychometric analysis of individual differences, EEG, transcranial direct current stimulation, and genotyping. I place considerable weight on experimental design and statistical inference, because a model parameter or group difference is only as interpretable as the design that produced it and the analysis used to estimate it.
 
Much of this work concerns the measures and constructs themselves: whether tasks measure what they are thought to, how reliable model-derived parameters are, whether constructs such as inhibition and control correspond to distinct underlying processes, and what behavioural and neural data can legitimately tell us about the mechanisms that produce them.
 
I contribute to three large cohort studies: PredictPD, on the onset and progression of Parkinson’s disease; FIND-TBI, on long-term outcomes and neurodegenerative risk after traumatic brain injury; and NeuroCogGen, on the latent structure of cognitive and motor abilities across the lifespan and the genetic contributions to their development and decline. The longer-term aim across this work is a precision cognitive medicine, in which decline is detected in the individual, characterised by the processes affected, and matched to an appropriate intervention.
 
My other interests include the psychometrics of intelligence, the metatheory and philosophy of experimental science and statistical inference, and identifying targets for interventions that preserve cognitive and motor function in later life. I am committed to open, reproducible research and to widening access to and representation in science and higher education.