The aim of my research is (1) to elucidate the cognitive and neural bases of human memory, through a detailed characterization of the memory deficits seen in patients with medial temporal lobe (MTL) amnesia secondary to neurological disorders such as encephalitis, stroke, or anoxic injury and through neuroimaging studies of individuals with intact memory; and (2) to elucidate the clinical impact of memory disorders in a variety of syndromes in which memory is one of the presenting complaints. With regard to the first aim, prior findings from our laboratory have demonstrated that impairments in autobiographical memory are accompanied by parallel impairments in imagining hypothetical or future events. My current work builds on these findings and aims to elucidate how impairments in future thinking impact other aspects of cognition, including decision making and language processing. We have examined decisions pertaining to future outcomes as well as pertaining to outcomes in the present, and ongoing work aims to further characterize these deficits in domains as diverse as perceptual decisions, preferences about food, and moral decisions. Prior work has also focused on aspects of expressive language, and we now focus on aspects of language comprehension. In addition to characterizing the scope of these cognitive deficits, my work aims to elucidate the mechanisms underlying these impairments, focusing on the role of the hippocampus in relational processing, scene construction, and updating of information. In a variety of studies, we systematically vary demands on these processes and see how they impact the performance of amnesic patients. With regard to the second aim, my work has focused on OEF/OIF/OND Veterans, who often present with co- morbid traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD). Because my earlier work indicated that psychiatric co-morbidities play a major role in the cognitive and behavioral sequelae these individuals experience, my current work focuses specifically on the impact of PTSD-associated memory alterations on various aspects of cognition. Individuals with PTSD tend to retrieve memories that are overgeneral and are biased towards negative information. We postulate that these characteristics have critical ramifications for different aspects of future-oriented behavior and decision making in PTSD. The goals of this work are to document the scope of these alterations, to examine their underlying neural basis through the use of functional neuroimaging, and to establish the feasibility of optimizing future-oriented behavior through information processing manipulations that are known to influence future thinking in healthy individuals.

Memory impairment has a significant impact on a Veteran's ability to lead a productive and fulfilling life, affecting an array of cognitive functions, including the ability to make well-informed healthcare decisions, and directly influencing quality of life. I study the cognitive and neural bases of memory impairment in patients with severe global amnesia as a result of lesions to the medial temporal lobes. Although global amnesia is rare, disruption of the medial temporal lobe memory system occurs in many neurological and psychiatric disorders that affect the Veteran population. Thus, insights gained from the study of amnesia can be applied to the study of other clinical populations. I have examined the impact of memory impairment in Veterans with traumatic brain injury, and currently study how memory impairment may contribute to the development and maintenance of symptoms associated with posttraumatic stress disorder. My work promises to guide clinical assessment of Veterans with memory impairment and may offer new targets for theoretically informed interventions.