Semantic dementia patients, who have severe deficits in semantic memory with relative preservation of episodic memory consequent to atrophy of the anterior temporal lobes, showed a reduction relative to controls in internal (episodic) details on the Autobiographical Interview when imagining the future, together
with a preserved ability to generate internal details when remembering the past (Irish, et al., 2012; see Figure 2). Based on these findings, Irish http://www.selleckchem.com/products/INCB18424.html et al. (2012) argued that simulating novel future events, in contrast to remembering past events, relies on general conceptual knowledge that provides a “scaffolding into which specific episodic details can be integrated” (p. 2187). Consistent with these observations, Duval et al. (2012) also reported that semantic dementia patients exhibited impaired episodic future thinking despite intact episodic recall. Weiler et al. (2011) reported a similar pattern in two patients with thalamic lesions, who exhibited intact episodic memory together with an impaired ability to imagine fictitious and impersonal events and a somewhat milder deficit in imagining personal future events. Finally, although we noted earlier that a number of studies of amnesic patients have revealed parallel deficits in remembering the past
selleck chemical and imagining the future or imagining novel scenes or events (Andelman et al., 2010; Hassabis et al., 2007b; Klein et al., 2002; Race et al., 2011; Romero and Moscovitch, 2012; Tulving, 1985), not all such studies show this effect. For example, in a Urease study that used the Autobiographical Interview as well as measures of scene construction based on prior work by Hassabis et al. (2007b), Squire et al. (2010) reported that amnesic patients with damage to the hippocampus showed an intact ability to create detailed imaginary future events and suggested that findings of imagination impairments in previous cases
reflect the presence of extra-hippocampal damage (for further discussion of this point, see Maguire and Hassabis, 2011; Squire et al., 2011). However, the hippocampal patients in the Squire et al. (2010) study exhibited only mild levels of retrograde amnesia; they were able to retrieve events from the remote past normally and showed only a mild, nonsignificant deficit for retrieving memories from the recent past. Thus, as noted by Addis and Schacter (2012), the results of this study could also be interpreted as support for the idea that a relatively intact ability to retrieve much of the past can provide a basis for imagining the future, even when the hippocampus is damaged. Squire et al. (2010) also reported that the severely amnesic patient E.P., who is characterized by extensive medial temporal lobe damage, showed an intact ability to imagine future events. However, although E.P.