Scene Construction in Amnesia: An fMRI Study

In recent years, there has been substantial interest in how the human hippocampus not only supports recollection of past experiences, but also the construction of fictitious and future events, and the leverage this might offer for understanding the operating mechanisms of the hippocampus. Evidence that patients with bilateral hippocampal damage and amnesia cannot construct novel or future scenes/events has been influential in driving this line of research forward. There are, however, some patients with hippocampal damage and amnesia who retain the ability to construct novel scenes. This dissociation may indicate that the hippocampus is not required for scene construction, or alternatively, there could be residual function in remnant hippocampal tissue sufficient to support the basic construction of scenes. Resolving this controversy is central to current theoretical debates about the hippocampus. To investigate, we used fMRI and a scene construction task to test patient P01, who has dense amnesia, similar to 50% bilateral hippocampal volume loss, and intact scene construction. We found that scene construction in P01 was associated with increased activity in a set of brain areas, including medial temporal, retrosplenial, and posterior parietal cortices, that overlapped considerably with the regions engaged in control participants performing the same task. Most notably, the remnant of P01's right hippocampus exhibited increased activity during scene construction. This suggests that the intact scene construction observed in some hippocampal-damaged amnesic patients may be supported by residual function in their lesioned hippocampus, in accordance with theoretical frameworks that ascribe a vital role to the hippocampus in scene construction.