Abstract
This study investigated the regions of brain damage affecting prospective memory (PM) in patients with traumatic brain injury (TBI). The subjects were 55 TBI patients who had sustained brain contusions and intracerebral hematomas involving the prefrontal cortex and the temporal lobe. The self-initiated PM task described by Umeda et al (2000) was used to evaluate PM. Based on the results of the PM task, patients were classified into 2 groups : (1) the group able or unable to remember the intention to remember, and (2) the group able or unable to remember the contents of the intention. Furthermore, all instances of damage to areas of the frontal lobe (dorsolateral, ventrolateral, medial, and orbital) and the temporal lobe (lateral and medial) were totaled. The influence of each brain lesion on the results of the PM task was analyzed using discriminant analysis.
The results of the analysis were as follows. (1) The brain lesions with the greatest effect on remembering the intention to remember were those of the medial temporal lobe (MTL), followed by those of the medial frontal lobe (MFL). (2) The brain lesions with the greatest effect on remembering the contents of the intention to remember were those of the MTL, followed by those of the dorsolateral frontal and lateral temporal lobes ; the influence of the MFL was low.
These results suggest that the MTL contributes most to both remembering the intention to remember and remembering the contents of the intention to remember, and that each region of the frontal lobe differs in degree of involvement in remembering.
