| Summary: | When confronted with an unwelcome reminder, people often inhibit the unwanted memory from awareness, a process that causes forgetting. This suppression-induced forgetting (SIF), also sometimes known as motivated forgetting, can be empirically measured by the Think/No-Think (TNT) task. Chapter 1 reviews the literature on memory inhibition. Imaging work indicates suppressing retrieval engages the right dorsolateral prefrontal cortex (rDLPFC), which in turn may inhibit the retrieval processes within the hippocampus. This thesis, using a range of methods, aims to better understand the neuropsychology of motivated forgetting. Chapter 2 investigates whether the ability to inhibit unwanted memories can be modulated through electrical stimulation. Stimulation methods do not appear to improve inhibition, at least in this cohort, one possible reason for this being the increased perceived thought control ability. Chapter 3 reports the first ever adaptation of the TNT task in patients with unilateral frontal lesions. Pilot testing in Chapter 4 reports the study in patients with unilateral frontal lesions. The results suggested that patients with left frontal lesions showed a robust SIF, compared to those with right-frontal lesions who showed none. Finally, Chapter 5 attempted to identify the structural connectivity underlying inhibitory control of motivated forgetting. The results indicate that the DLPFC is connected to the hippocampus by a subset of the two tracts, namely the anterior thalamic projection connecting the DLPFC to the caudate nucleus, and the fornix. Future directions to expand on the finding of this thesis are discussed in Chapter 6.
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