We have all had moments when an object or event reminds us of an experience we would prefer not to think about. When this happens, people often attempt to exclude the unpleasant memory from awareness. These efforts to control memory are an unfortunately ubiquitous occurrence after a traumatic experience. However, there is great variability in people's memory control ability. Whereas some can keep unwanted reminders from awareness, other less fortunate individuals suffer chronic distraction from these memories, undermining their ability to cope in the aftermath of trauma. What causes some people's attention to be captured so persistently by intrusive remindings? Answering this question requires that we understand the nature of attention itself, and, in particular, the nature of the cognitive and neural systems that orient attention to memories.
With support from the National Science Foundation, Michael Anderson at the University of Oregon will examine the mechanisms that focus attention on memories, building on a wealth of cognitive and neurobiological research on visual attention. This prior work shows that there are two forces that determine where attention is in the visual world: internal mechanisms by which we intentionally focus on a particular region in space, and reflexive mechanisms that capture attention and orient it to suddenly appearing stimuli. This project examines whether the neural systems that shift attention to stimuli with abrupt onsets in the visual world are also engaged to orient attention to an unwanted memory. The role of the hippocampus will help distinguish attention guided by memory from that guided by vision. This project will also examine whether intentional control over reflexive shifts of attention in memory is accomplished by inhibitory mechanisms mediated by the prefrontal cortex that suppress memories in the hippocampus, and the reflexive orienting system itself. The research combines traditional cognitive methods, a new approach to measuring intrusive memories, and functional magnetic resonance imaging (fMRI) to understand the neurocognitive basis of mnemonic reflexive orienting and its regulation by inhibition. If correct, this view will forge a highly specific connection between research on attention and long-term memory, and will specify a rich framework in which to understand how human beings control unwanted memories. Such insights are not merely of theoretical significance, but of profound practical importance in ameliorating the conditions of those suffering from intrusive memories. For numerous people experiencing traumas large (e.g. Hurricane Katrina) and small, the need to control unwanted memories is unfortunately all too clear. Basic research specifying the cognitive and neurobiological mechanisms of memory control will inform theories of clinical syndromes characterized by disordered thought control such as post-traumatic stress disorder (intrusive flashbacks), depression (unwanted ruminations), attention deficit / hyperactivity disorder (distractability), obsessive compulsive disorder (obsessive thoughts) and addiction (craving related thoughts).
