Functional connectivity in dissociative amnesia: a single-case study

Dissociative amnesia (i.e.inability to consciously recall autobiographical information in the absence of significant brain damage) is one of the most enigmatic and controversial memory disorders. In the past three decades, interest in the understanding of its pathophysiology has emerged. Recent studies used functional imaging methods such as PET, SPECT and functional MRI to provide evidence for metabolic or blood flow changes in areas that are agreed to be involved in memory processing (e.g., hippocampus, parahippocampus, amygdala, prefrontal cortex, temporal cortex). However, most studies used task-based functional neuroimaging, which requires the participant to perform a specific task while brain activity is measured, in order to observe the altered functionality of memory-related brain structures. In the present study we tried to assess the functional reorganization of the brain in a patient affected by dissociative amnesia, looking for altered functional connectivity patterns in resting-state fMRI signal (i.e functional MRI that measures spontaneous fluctuations in absence of a stimulus), via comparison with a control group of 40 healthy subjects. Making use of a theory driven seed-based approach we explore the connectivity of a few brain structures involved in memory processes such as the precuneus, hippocampus and medial temporal cortex. Instead, employing a graph based approach, we seek to explain network and whole brain dynamics that might be impaired by the disorder.