Project Title: Cue-induced impulsivity: understanding environmental influences on risky decision making.
Supervisor 1: Professor Martin Yeomans
Supervisor 2: Dr Hans S. Crombag
Research at Sussex found a relationship between impulsive decision making and lack of ability to control eating, supporting broader research that implicates impulsivity as a risk factor for development of obesity and an impediment to weight loss. Most recently, studies at Sussex suggest that pre-exposure to food cues increases impulsive responding in those prone to uncontrolled eating. This novel finding implies that impulsive decision making may be cued by environmental stimuli that predict reward. Moreover, our observation of increased impulsivity following exposure to food cues fits with broader understanding of the role of environmental cues in relapse to drug addiction. The proposed studentship redresses this shortfall in understanding using a unique combination of studies in humans and other animals. In the initial stage, a set of experimental studies will train rodents to acquire associations between novel cues and availability or termination (stop-signal) of food or drug rewards using Pavlovian and instrumental learning paradigms. The effects of these cues on impulsive responding will then be tested using animal models of impulsivity, such as delay– or probability discounting and 5-CSRT. In parallel, the student will conduct studies with human volunteers to extend our initial findings using exposure to real food cues (e.g. labelling or advertisement) to examine how these impact impulsive responding measured using tests of reward sensitivity (delay discounting) and inhibitory control (the Stop task). A critical study will then move from real cues to studies where neutral cues will be explicitly trained to be food-associated and their effect on impulsivity are assessed. If time then permits, the studentship could move in one of two directions: a) examining how prior eating habits (restrained versus non-restrained) modulate cued impulsive decision making or b) testing the neural basis of cued impulsivity. For the latter, we propose to examine the role of circuitries involving the amygdala, prefrontal cortex, and LH in cue-induced impulsivity, using an optogenetic approach. Through viral introduction of fast-acting, light-sensitive ion channel/pump (channelrodhopsins or halorodopsins) wewould be able to rapidly activate/inactivate selected brain areas using light to assess their status in cue-induced impulsivity. In total, we envisage a studentship with a combination of 3-4 experimental studies in human volunteers and 4-6 related studies using animal models that together will greatly enhance our understanding of how environmental cues may exacerbate impulsive decision making.
Applicants for this 4-year PhD, starting in October 2012, should possess or expect to be awarded an Upper Second or 1st Class Honours degree (or equivalent) ina relevant subject. Studentships are available to UK nationals and EU students who meet the UK residency requirements. The studentship will support the student’s stipend and tuition fees. Please send your initial enquires by email: For the attention of 'Postgraduate Coordinator' to: firstname.lastname@example.org. If you wish to discuss the details of the project further, please contact Prof Martin Yeomans email@example.com
Details of application procedures can be found at: http://www.sussex.ac.uk/study/pg/applying/