Deficits in prospective memory following damage to the prefrontal cortex

Neuropsychological investigations of prospective memory (PM), representing memory of future intentions or plans, have evolved over the past two decades. The broadly accepted divisions involved in PM consist of a prospective memory component (PMC), a process for remembering to remember, and a retrospective memory component, a process for remembering the content of the intended action. Previous functional neuroimaing studies have provided some evidence that the rostral prefrontal cortex (BA10) is one of areas that is critical for prospective remembering. However, the question of whether damage to part of the prefrontal cortex affects attenuated performance for PMC remains unresolved. In this study, 74 participants with traumatic brain injury (TBI) including focal damage to frontal or temporal lobe areas were administered thirteen standard neuropsychological tests and the PM task. To identify influential areas contributing to PM performance, discriminant function analysis was conducted. The results indicated that the following three areas are highly contributory to PM performance: the right dorsolateral prefrontal cortex; the right ventromedial prefrontal cortex; and the left dorsomedial prefrontal cortex. Comparing differences in neuropsychological test scores showed that orientation scores were significantly higher in the greater PM performance group, suggesting that PMC represents an integrated memory function associated with awareness of current status. These data contribute to our understanding of the neural substrates and functional characteristics of the PMC.