Autobiographical memory after temporal lobe lesions

To investigate how the brain organizes and stores autobiographical memory, eight subjects with focal lesions of the temporal lobe and one comparison subject with frontal lobe lesion were studied with the Autobiographical Memory Interview (AMI). The AMI surveys both personal semantic memory and autobiographical incidents from childhood, early adulthood and recent life. Left mesial temporal lobe lesion caused anterograde and time-limited retrograde autobiographical memory changes. More extensive left temporal lobe lesion disrupted personal semantic memory dating back to childhood, but did not impair recollection of autobiographical incidents. However, bilateral temporal lobe lesions caused extensive autobiographical memory deficits which varied in temporal extent according to the particular location of damage. Bilateral prefrontal cortex damage also resulted in severe impairment, which appeared to be related to disorganized retrieval. The findings suggest that many verbal-semantic aspects of autobiographical memory are mediated by left temporal structures, whereas autobiographical episodes are more widely distributed and dependent upon interactions of prefrontal cortex with diverse temporal lobe regions.