Using Imagination to Understand the Neural Basis of Episodic Memory

“…2005), episodic future thinking (Atance and O’Neill, 2001; Addis et al., 2007; Schacter and Addis, 2007; Szpunar et al., 2007), the default mode (Raichle et al., 2001) and daydreaming (Mason et al., 2007), leading to suggestions that it performs a general function (Buckner and Carroll, 2007;…”

“…theory of mind (Kumaran and Maguire, 2005; Amodio and Frith, 2006) and episodic future thinking (Addis et al., 2007) suggesting that the amPFC and PCC might be supporting pro- cesses related to the self (Conway and Pleydell-Pearce, 2000) and mental time travel (Wheeler et al., 1997; Tulving, 2002).”

“…a purely created imagined experience does not have the same reliance or effect on the imaginer’s self-schema compared with a real episodic memory (Conway and Pleydell-Pearce, 2000; Gallagher, 2000) although both likely involve the adoption of an egocentric viewpoint (Burgess, 2006) on the part…”

“…bears a striking resemblance to networks found to support self-reflection (Johnson et al., 2002), theory of mind (Kumaran and Maguire, 2005; Amodio and Frith, 2006) and episodic future thinking (Addis et al., 2007) suggesting that the amPFC and PCC might be supporting pro- cesses related…”

“Moreover, by using rich imaginary memories as a well matched comparison task we were able to isolate processes specific to episodic memory, such as the use of self-schema (Conway and Pleydell-Pearce, 2000; Gallagher, 2000), a sense of familiarity and mental time travel (Tulving, 2002).”

“, 2001), and perhaps even daydreaming (Mason et al., 2007).”

“…network (also replicated in this study with the RM RO contrast) has also been activated in a variety of other circumstances including navigation (Burgess et al., 2002; Hartley et al., 2003; Spiers and Maguire, 2006), spatial tasks (Maguire et al., 2003; Kumaran and Maguire, 2005), episodic…”

“…a key component of episodic memory recall lends additional support to constructive theories of episodic memory (Bartlett, 1932; Schacter et al., 1998) and the recently proposed constructive episodic simulation function of the episodic memory system (Schacter and Addis, 2007; Schacter et al., 2007).”

“They refer to this process as “scene construction,” a term emphasizing that mental simulation often un-folds in one’s mind as an imagined scene with rich visual and spatial content (see also Hassabis et al. 2007).”

“Consistent with this finding, patients with hippocampal amnesia lack the ability to imagine a coherent scene presumably void of a temporal context (Hassabis et al., 2007b; see also Hassabis et al., 2007a; Addis et al., 2009).”

“The default network is active during a variety of internally-oriented task conditions, including thinking about the future (Szpunar et al., 2007), self-referential processing (Kelley et al., 2002), and visual imagery ( Hassabis et al., 2007 ).”

“For example, in a 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…”

“A functional-imaging study of this task in healthy adults showed that the hippocampus was activated during the period of imaginatio”

“Notably, there was also substantial involvement of the hippocampal formation for autobiographical memory and prospection: This may be due to the temporal extension of the self and greater recombination of contextualized event details involved in remembering and prospection (Hassabis, Kumaran, & Maguire, 2007 ; Schacte…”

“The network to which it belongs has been linked to scene construction (AndrewsHanna, Reidler, Huang, et al., 2010; Hassabis et al., 2007) and the spontaneous generation of thoughts (Christoff et al.”

“Consistent with this, imagining novel, fictitious scenes activates the sameMTL regions as future event simulation (Hassabis et al., 2007).”

“Studies in human subjects show that overlapping hippocampal networks are activated during episodic recall and imagination of fictitious experiences (Hassabis et al. 2007).”

“It is still debated what these more general abilities may be: they could include selfreferential processing [50], cognitive–affective simulation of possible outcomes [233], mind-wandering [237] or the (re)construction of spatial contexts [154].”

“…functional networks for the processing of environmental stimuli, the apparent functional homogeneity of the DMN during environmentally directed tasks (Shulman et al., 1997; Mazoyer et al., 2001) breaks down in tasks that isolate specific internally directed processes (Hassabis et al., 2007).”

“The contribution of the hippocampus to spatial information and navigation has an extensive basis in the literature stemming from early evidence of location-modulated cells in the rodent hippocampus (for review, see Burgess et al., 2002).”

“Instead, they represent imaginary scenes or scenarios that might or might not occur to the individual within a particular future time frame (e.g., Addis et al., 2007; Addis, Pan, et al., 2009; Hassabis et al., 2007; Okuda et al., 2003; Spreng & Grady, 2010; Szpunar et al., 2007).”

“Such self-generated information may also result from activity in retrosplenial cortex, known to be involved in episodic memory (Hassabis, Kumaran, & Maguire, 2007 ), as well as the anterior temporal pole, previously associated with socioemotional knowledge (Zahn et al, 2007 ), also observed for the main effect of JA.”

“…to remember the past is compromised, such as mild cognitive impairment (Gamboz et al., 2010), mild Alzheimer's disease (Addis et al., 2009b), amnesic patients with medial temporal lobe damage (Tulving, 1985; Hassabis et al., 2007b; Race et al., 2011) and developmental amnesia (Kwan et al., 2010).”

“MODELS IN THIS SPECIAL ISSUE Because BIC is a framework that attempts to explain MTL function across different levels of analysis and research domains, the model shares many features with other models that have been proposed.”

“…also been associated with counterfactual thinking (Gomez Beldarrain et al., 2005; Van Hoeck et al., 2013), prospective memory and future thinking (Hassabis et al., 2007; Schacter et al., 2007; Abraham et al., 2008; Addis et al., 2009; Szpunar et al., 2009; Burgess et al., 2011; Volle et al.,…”

“…the finding that the pattern of brain activation associated with the retrieval of autobiographical memories closely resembles the pattern associated with the simulation of future or fictitious episodes (e.g., Addis et al., 2007; Botzung et al., 2008; Hassabis et al., 2007b; Szpunar et al., 2007).”

“…a dramatic surge of research activity within the last few years, with growing evidence in favor of a link between remembering the past, imagining the future, and engaging in mental simulation processes (Addis et al., 2007; Hassabis and Maguire, 2007; Hassabis et al., 2007; Schacter et al., 2012).”

“…or imagining one’s personal future (Andreasen et al., 1995; Schacter et al., 2007; Spreng et al., 2009), scene construction (Hassabis and Maguire, 2007; Hassabis et al., 2007), social cognition (Iacoboni et al., 2004; Spreng et al., 2009; Spreng and Grady, 2010; Mar, 2011; Andrews-Hanna, in…”

“Such investigations would also address the possibility that future-thinking deficits in amnesia reflect impairments in self-projection (Buckner and Carroll, 2007; but see Hassabis et al., 2007b).”

“…example, as mentioned by M&C, the two capacities are supported by the same core network of brain regions (Addis et al. 2007; Benoit & Schacter 2015; Hassabis et al. 2007a; Szpunar et al. 2007), are similarly deficient in amnesic patients (Hassabis et al. 2007b; Klein et al. 2002b; Race et al.…”

“…including general semantic processing (Binder et al. 2009), mental scene construction and visuo-spatial imagery (Cavanna and Trimble 2006; Hassabis et al. 2007; Schacter and Addis 2009; Spreng et al. 2009), self-referential processing (Gusnard et al. 2001), and autobiographical memory…”

“, 2009; Seghier and Price, 2012), as well as when individuals simulate novel scenes (Hassabis et al., 2007) and imagine their autobiographical future (Addis et al.”

“Though many researchers have suggested there is a close relationship between remembering and the defaultmode network (Vincent et al., 2006; Hassabis et al., 2007; Schacter and Addis, 2007), our findings indicate that the association is largely restricted to remembering that significantly involves self-referential”

“Neuroscientists have also accumulated evidence that the hippocampus is involved in replaying sequences (from memory or imagination) for consolidation into cortex [212,213] so that they can be presumably committed to cortical long-term memory and fast inference.”

“…(Barense et al., 2005; Lee et al., 2005a,b; Barense et al., 2007; Bussey and Saksida, 2007; Lee et al., 2012), and even short-term planning and imagining of future events (Addis et al., 2007; Hassabis et al., 2007a,b; Addis and Schacter, 2008, 2011; Voss et al., 2011; Johnson et al., 2012).”

“Participants were then asked to vividly imagine 12 common everyday locations such as a bar, restaurant, or bank, and to describe them in as much detail as possible (Hassabis, Kumaran, Maguire 2007; Hassabis, Kumaran, Vann, et al. 2007).”

“18 and imagination [13,28,33,34] allows us not only to share our memories with others, but also to 424 invent and share imaginary events with others.”

“There is certainly evidence linking the hippocampus to processing of scenes (e.g., Aly et al., 2013; Barense et al., 2010; Bird et al., 2010; Hassabis et al., 2007a; Preston et al., 2010; Stern et al., 2001; Summerfield et al., 2010), but we cannot understand the significance of this evidence in the absence of well-ar…”

“…et al., 2010), self–other distinction (Ruby and Decety, 2001), the contemplation of others' (Mar, 2011) and one's own (Lombardo et al., 2009) mind states, as well as scene construction processes when envisioning past, fictitious , and future events (Hassabis et al., 2007; Spreng et al., 2009).”

“…of spatial contexts, and similar networks seem to be involved in remembering past episodes and imagining novel scenes or future events (Addis et al., 2007; Bar, 2007; Buckner and Carroll, 2007; Hassabis et al., 2007; Szpunar et al., 2007) (for review and discussion, see Schacter et al., 2007).”

“…et al., 2009) mental states, mental navigation of the body in space (Maguire et al., 1997), semantic processing (Binder et al., 2009), as well as scene construction processes when envisioning past, fictitious, and future events (Hassabis et al., 2007; Spreng et al., 2009; Bzdok et al., 2013).”

“…pointing performance and hippocampal volume was partially (but incompletely) mediated by perspective taking ability, suggesting that part of the advantage of a larger right hippocampus is an enhanced ability to construct an egocentric scene from an arbitrary vantage point (Hassabis et al., 2007).”

“Recollection in the BB-model results in visuo-spatial imagery of a coherent scene from a single viewpoint and direction, that is it implements a process of scene construction (Burgess et al., 2001a; Byrne et al., 2007; Schacter et al., 2007; Hassabis et al., 2007; Buckner, 2010) at the neuronal level.”

“Also in line with the current hypothesis concerning the CMS regions is a recent study by Hassabis et al. (2007).”

“…memory recall, selfrepresentation, and future thinking (Addis et al., 2007; D'Argembeau et al., 2007; Daselaar et al., 2008; Gilboa et al., 2004; Hassabis et al., 2007a; Johnson et al., 2002; Maguire, 2001a; Northoff et al., 2006; Schacter et al., 2007; Sugiura et al., 2005; Svoboda et al.,…”

“…the surrounding posterior cingulate is not just involved in visualspatial navigation, but also a component of the DMN, thought to be involved in self-consciousness, reflective self-awareness, episodic memory and imagination (Cavanna and Trimble, 2006; Hassabis et al., 2007; Utevsky et al., 2014).”

“…during the construction of episodic simulations has been a consistent result in the episodic memory and future thinking literature (Okuda et al., 2003; Szpunar et al., 2007, Hassabis et al., 2007; Weiler et al., 2010; Addiset al. 2007; Addis et al, 2009; Addis, Cheng, Roberts, & Schacter, 2011).”

“of RSC in response to the most permanent landmarks, this may help to explain the ubiquity of RSC activations in fMRI studies not only involving scenes and navigation, but also autobiographical memory [46,47] and thinking about the future [76,77].”

“This distinction was subsequently affirmed at the neural level, where both the imagination and the viewing of single SD objects (indoor and outdoor) evoked activity within brain regions classically associated with the perception or imagination of full scenes (Epstein and Kanwisher, 1998; Aguirre and D’Esposito, 1999;…”

“Moreover, Addis and Schacter (2008) found that while posterior hippocampal activity correlated with the amount of detail comprising both past and future events, anterior hippocampal activity correlated only with the amount of detail comprising future events.”

“Most of these regions have been associated with episodic memory retrieval and recent studies suggest that they form a functional subsystem of the DN that supports the construction of detailed mental representations of specific events—episodic simulation or scene construction processes [Andrews-Hanna et al., 2010, 2014…”

“) [7–9].”

“On the basis that scene construction engages the hippocampus during imagination (Hassabis, Kumaran, Vann, et al. 2007, Hassabis, Kumaran, and Maguire 2007), we hypothesized that, in neurologically healthy participants, simply perceiving scenes (without a comparison or discrimination task) may…”

“[68] documented an imagination network which was commonly activated by recall of both real and (previously) imagined memories, and also by newly imagined scenarios.”

“Theta activity appears in the hippocampal formation (Greenstein, Pavlides, & Winson, 1988 , cited in Klimesche, 1996 ; Larson, Wong, & Lynch, 1986 ), an area important in novelty detection (Knight, 1996 ), and in imagining fictitious scenes (Hassabis, Kumaran, & Maguire, 2007 ).”

“…of the hippocampus in both allocentric and sequential egocentric strategies is in agreement with the theoretical proposition of its role in episodic memory and more precisely in its role in spatiotemporal organization of events (Mizumori et al., 1999; Eichenbaum, 2001; Hassabis et al., 2007).”

“…previous research has suggested may support self-referential simulations (for a review see Buckner et al., 2008), and the MTL network associated with declarative memory (Kahn et al., 2008; Vincent et al., 2006) and scene construction (Andrews-Hanna et al., 2010; also see Hassabis et al., 2007).”

“…conceiving of others’ viewpoints (theory of mind), social cognition, mental navigation, deductive and inductive reasoning, and mind-wandering [Binder et al., 2009; Buckner and Carroll, 2007; Buckner et al., 2008; Gusnard, 2005; Hassabis et al., 2007; Legrand and Ruby, 2009; Spreng et al., 2009].”