Ph.D. (Cambridge), B.Sc. (Joint Hons.) (Manchester)
My aim is to understand how interacting brain systems give rise to our decision-making abilities and to design more effective interventions to enhance cognition and mental health. I began neuroscience research as an undergraduate, investigating how destruction of ascending sub-cortical 5-HT pathways in rats altered their "time perception" (Graham et al., 1994). My interests further developed during drug discovery at Merck Laboratories where I conducted research on the psychopharmacology of learning and memory. During my Ph.D. at Cambridge, I showed how changes in the conditions under which stimuli were pre-exposed could enhance or impair learning about them in the future – this led to the development of a mathematical theory of associative learning (Graham, 1999). Inspired by neuroscience, this model offered mechanisms for extant findings and predicted new results that led to postdoctoral work funded by Unilever to investigate how pre-exposure could affect consumer choice of brands and products.
More recently I have been using fMRI to investigate brain processes invoked during "executive functioning" tasks (e.g., cognitive set-shifting) - in particular, how interactions between striatal, medial cortical and hippocampal learning systems vie for control over our decision-making behaviour. Neuroimaging these components of cognition as they unfold over time has indicated that early stages of rule identification were associated with maximal caudate (striatal) activation and delayed hippocampal deactivation. In contrast, later stages of rule consolidation were associated with maximal hippocampal activity and reduced caudate activity. This reciprocity between striatal and hippocampal activation and the notion of complementary striato-hippocampal learning systems was confirmed through further functional connectivity analyses. Based on this foundation work, we next explored how an individual's level of intelligence (and hence response strategy) impacts on brain function. This work was then extended to patients with schizophrenia in an attempt to disentangle the effects of intellectual decline from the disorder itself. Currently, we are studying changes in the brain to better understand how physical activity interventions enhance decision-making in healthy volunteers (both young and old), and also ameliorate cognitive deficits in patients with schizophrenia and depression .