Similarities and differences between parietal and frontal patients in autobiographical and constructed experience tasks.

Recent findings suggest that constructed experience, the ability to envision future events, activates the same cortical network as recollection of past events. For example, damage to one key area, the hippocampus, impairs patients' ability to remember the past and to imagine novel experiences (Hassabis, Kumaran, Vann, & Maguire, 2007). Here, we investigated whether damage to two other areas, posterior parietal cortex and prefrontal cortex, also impairs this ability. Patients with bilateral posterior parietal lesions or unilateral prefrontal lesions were tested in their ability to describe imaginary future events. Only parietal patients were impaired at freely describing autobiographical memories, but both patient groups were impaired when elaborating constructed experiences. This dissociation suggests that parietal and prefrontal structures are differentially involved in constructed experience. Current tasks may impose overly broad cognitive demands making it impossible to specify the deficient cognitive component in any patient group. These findings provide additional constraints regarding the mechanistic role of the parietal cortex in memory.