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2011/2012 During the last ten years several studies have investigated the effects of memory loss in future thinking. These studies have revealed a striking overlap in the brain activity associated with remembering past experiences and foreseeing possible future experiences. This thesis encompasses a series of experiments in Alzheimer’s disease and amnesic patients, through the investigation of memory disorders such as confabulation and forgetfulness, in order to isolate the cognitive mechanisms and the neural correlates underlying the subjective experience of time and their relation with memory. In the first part of this work we show that the close linkage between episodic memory and episodic future thinking lies on cognitive processes related to self-projection and awareness of subjective time, rather than on constructive processes based on previously stored elements. Results in confabulating amnesic patients support these data showing that regardless the underlying pathology and the lesion site, confabulation largely reflects the individual’s tendency to consider habits and over-learned information, perhaps nuanced by personal significance, as unique episodes. This tendency is not limited to the retrieval of past information but involves the planning of the future as well. In the second part of this work, our neuroanatomical results confirm previous findings on the neural correlates of confabulation and amnesia but differ with respect to these studies for the cerebral white matter analysis. Our findings suggest that confabulation might be caused not only by prefrontal lesions, but also by a functional disconnection between the frontal cortex and the medial temporal lobe. Taken together, these observations suggest that the medial temporal lobe, especially the hippocampus, is a good candidate as the neural correlate of temporal consciousness. XXV Ciclo |
