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).”

“Based on these findings, it was suggested that midline regions may help to distinguish actual experiences from imagined ones (see also Hassabis et al., 2007).”

“…activated in neuroimaging studies of constructed experience (Abraham, Schubotz, & von Cramon, 2008; Addis et al., 2007; Botzung et al., 2008; Hassabis et al., 2007; Okuda et al., 2003; Szpunar & McDermott, 2008); see Figure 1 for lesion tracings and the Supplementary Materials for detailed…”

“…as episodic retrieval and future imagining, thus accounting for the neural overlap between execution of these functions and activity of the DMN [Andrews-Hanna et al., 2014b; Binder et al., 2009; Buckner and Carroll, 2007; Cabeza and Moscovitch, 2013; Hassabis et al., 2007; Schacter, et al., 2012].”

“…constructing mental representations of scenes (Maguire and Mullally, 2013; Zeidman and Maguire, 2016), imagining the future (Schacter et al., 2012; Hassabis et al., 2007), decision-making (McCormick et al., 2016; Mullally and Maguire, 2014) and even mind-wandering (Karapanagiotidis et al., 2017).”

“Moreover, anterior mPFC and the PCC have also been reported when recalling real events relative to imagining fictitious events [13].”

“Here, we investigate the hypothesis that imagination consists of at least two distinct processes: a constructive process, by which a novel future event is mentally formed, often by combining specific aspects of past experience (Addis et al., 2007; Hassabis et al., 2007; Schacter et al., 2007), and an evaluative proces…”

“Following each mental replay attempt, participants pressed a button indicating on a scale of 1–4 (“1” = poor memory and “4” = excellent memory) the vividness and accuracy of their attempt to replay the cued video clip (Chadwick, Hassabis, & Maguire, 2011 ; Hassabis, Kumaran, & Maguire, 2007 ).”

“…any event, whether or not located in subjective time, such as the ability to generate and visualize coherent spatial contexts (“scene construction”; Hassabis et al., 2007b), and to recover and integrate the journal homepage:…”

“26) reflecting stronger demands on visual processing and visual control [43].”

“Because medial temporal lobe structures are crucial for declarative and associative memory processes and for the detailed construction of mental images [19,39,65], we assume that pain patients, because of their greater amount of pain experience, generated more detailed and vivid mental scenes for pain descriptors in r…”

“…cognitive processes – including autobiographical memory (e.g. (Bonnici et al., 2012); Maguire (2014); (Nieuwenhuis and Takashima, 2011)), imagination (Hassabis et al., 2007), spatial navigation (Doeller et al., 2008)), goal-directed decision making (Roy et al., 2012), schema-based memory formation…”

“…in the construction of atemporal scenes resonates with functional neuroimaging studies in which the centrality of the hippocampus, albeit particularly on the right hand side, has been emphasised (Hassabis et al., 2007a; Mullally et al., 2012a; Mullally et al., 2014; Summerfield et al., 2010).”

“Previous research suggests hippocampal activation can be expected during memories this recent (~2 weeks; Hassabis et al., 2007).”

“However, neither interpretation of the function of the posterior cingulate could explain the observed decrease in its activation during imagery tasks in our study: first, because in introspection tasks like retrieval and imagery the DMN network is expected to show activation rather than the reverse (Laird et al., 2011…”

“The right hippocampus may be driven by initial spatial or relational processing of complex visual scenes (Hassabis et al., 2007; Binder et al., 2005; Köhler et al., 2005), the spatial context of recalled/imagined episodes being retrieved early in the construction process (Weiler et al.”

“…2014 | Volume 8 | Article 818 | 2 The precuneus has also been linked to episodic memory retrieval (Shallice et al., 1994), processing of mental imagery (Hassabis et al., 2007; Johnson et al., 2007; Burgess, 2008), and visuo-spatial memory functions (Vincent et al., 2006; Epstein et al., 2007).”

“In the current experiment, this was achieved by asking participants to both remember past and imagine future events, as both tasks have been associated with the construction of elaborate mental scenes (e.g., Hassabis et al., 2007).”

“…construction of a visual scene in absence of the appropriate external stimulus, a cognitive process which is called 'mental imagery' (Thomas, 2010) and is a subcomponent of scene construction, the process of mentally generating and maintaining a complex and coherent scene (Hassabis et al., 2007).”

“No main effects were observed [largest F-statistic: F(1, 39) = 2.”

“Studying how people engage in other critical functions such as imagining and planning for the future (Hassabis and Maguire, 2007, 2009; Hassabis et al., 2007a; Schacter and Addis, 2007), social interactions (Frith, 2007; Frith and Frith, 2006; Frith and Singer, 2008) and also more practical…”

“Thus, in this perspective, we combine many of these findings to suggest that the DMN is at the center of the interaction between the external and internal worlds [62].”

“Hippocampal engagement during scene construction/simulation tasks has been confirmed in fMRI studies of healthy participants (Addis et al. 2007, Hassabis et al. 2007a).”

“Neuroimaging results support the idea that “internal” or self-referential signals occur in the human PFp, especially its medial parts (Gilbert et al., 2006; Burgess et al., 2007; Hassabis et al., 2007; Mason et al., 2007; Raichle and Snyder, 2007; Boorman et al., 2009).”

“The first process is functionally similar to mental imagery (Hassabis et al., 2007b; Schacter and Addis, 2007) while the second process process is functionally similar to the computations that contribute to memory consolidation (Squire and Alvarez, 1995; Nadel and Moscovitch, 1997; Tse et al.,…”

“This interpretation is in line with the established role of spatial processing in creating a viable “context” or space for one to remember (Hassabis et al., 2007; Hassabis et al., 2014; Mullally & Maguire, 2013; Mullally, Vargha-Khadem, & Maguire, 2014).”

“The precuneus and parietal occipital sulcus have long been associated with memory retrieval, imagery and ‘‘attention to internal representations’’ (Fletcher et al., 1995; Burgess et al., 2001b; Maguire, 2001; Wagner et al., 2005; Wallentin et al., 2006; Byrne et al., 2007; Hassabis et al., 2007).”

“Neuroimaging studies with healthy subjects showed that many of the brain regions active when people remember the past are also active when they envision the future (Addis et al., 2007; Buckner and Carroll, 2007; Hassabis et al., 2007a, b).”

“Together, these regions have also been described as the ‘core’ network, reflecting the overlapping contributions of these regions to memory and simulation [5,6].”

“This finding aligns with and extends prior studies suggesting that the MTL may not be involved in future-oriented mental time travel (Hassabis et al. 2007; D’Argembeau et al. 2008; Nyberg et al. 2010).”

“This view is supported by evidence that damage to neural circuitry known to be essential for episodic memory also impairs imagination (Hassabis and Maguire, 2007, 2009; Hassabis et al., 2007; Maguire et al., 2010; Maguire and Hassabis, 2011).”

“Functional imaging studies in healthy samples have suggested that the precuneus subserves self-processing operations (Cavanna and Trimble, 2006; Hassabis et al., 2007; Wolf et al., 2009), including evaluating one’s emotional experiences (Ochsner et al.”

“…that amnesic patients with hippocampal damage also exhibit deficits when imagining future experiences and novel scenes (e.g., Andelman et al. 2010; Hassabis et al. 2007b; Kurzcek et al. 2015; Race et al. 2011; but for evidence of intact future imagining in amnesics, see Squire et al. 2010).”

“Additionally, correlational analysis of the key nodes within the DMN revealed that the posterior cingulate cortex is involved in retrieving and integrating information from other subsystems implicated in selfreferential thoughts and episodic memory (Hassabis et al., 2007; Buckner et al., 2008).”

“The abundance of evidence linking episodic retrieval to mental construction or simulation of future/fictitious events (Hassabis and Maguire 2007, 2009; Hassabis et al. 2007; Schacter and Addis 2007; Schacter et al. 2008; Buckner 2010; Rabin et al. 2010; Szpunar 2010; Viard et al. 2012) has led to a renewed emphasis on…”

“People with destruction of the hippocampus show striking difficulties in recalling past events or imaging future ones (Tulving, 2002; Wearing, 2005; Corkin, 2013), as well as in imagining fictitious scenes (Hassabis et al., 2007)—although impairment of the ability to imagine personal past or future events has also bee…”

“…Rugg and Vil-berg 2013; Spreng et al. 2015; Kim 2016; Murphy et al. 2018), mental simulation and scene construction (Hassabis and Maguire 2007; Hassabis et al. 2007; Spreng and Grady 2010; Gerlach et al. 2011), Theory of Mind (ToM) and social cognition (Saxe and Kanwisher 2003; Rilling et al.…”

“…under the active inference framework have mostly involved the prediction of auditory (Näätänen, 1990), visual (Stagg et al., 2004), or somatosensory stimuli (Akatsuka et al., 2007), or rudimentary event sequences consisting of a succession of objects in scenes (Kumaran and Maguire, 2007).”

“These thoughts may recruit cognitive processes that have been associated with PCC, LTC and IPL such as, scene construction (Hassabis et al., 2007), memory retrieval (Kim, 2012; Wagner et al.”

“, 2002; Kelley et al., 2002). However, as shown above, this experiment demonstrated similar activation patterns and BOLD signal changes in the DMPFC across referential conditions. Which processes does the DMPFC undertake during the referential task? Based on some earlier studies, Northoff & Bermpohl (2004) concluded t…”

“■”

“Further, the only consistent differences that have been observed are in the direction of greater activity for future events than for remembered events (Addis et al. 2007; Hassabis et al. 2007; Szpunar et al. 2007; Addis et al. 2009; Szpunar et al. 2009; Weiler et al. 2010).”

“, 2012) as well as in patients with brain damage or deterioration (Addis et al., 2009b; Hassabis et al., 2007).”

“As the hippocampus plays a role in spatial mental imagery, including the ability to perceive objects or scenes from different perspectives (Hassabis et al., 2007; Bird et al., 2010; Summerfield et al., 2010) which may depend on the complexity of the scene or objects (Kim et al.”

“Findings over the last decade have since linked scenes to the hippocampus in relation to autobiographical memory (Hassabis, Kumaran, & Maguire, 2007; Hassabis & Maguire, 2007) but also widely across cognition, including perception (McCormick et al., 2017; Mullally et al., 2012; Graham et al.,…”

“, (13,15,30,33,38,39,47,51,53,64,65,87,97,101,107,120,125,128,137,140,144)), although fMRI of this region is not without technical challenges.”

“Hassabis and Maguire (2007) recently argued that “scene construction” is a core process that not only underlies our ability to remember the past and to imagine the future, but also supports any task that requires a rich “recollection-like” experience.”

“While P01 (Hassabis et al., 2007; Mullally et al., 2012) and controls (Hassabis, Kumaran, & Maguire, 2007) described scene construction as effortless and natural, Jon reported that he found the process effortful, and describes it as something which he has had to train himself to accomplish (Maguire…”

“These regions may enable the encoding and/or monitoring of dynamic situational relationships with objects (or agents), regardless of the sensory input modality, consistent with their reported roles in mental imagery and episodic memory retrieval (Wakusawa et al, 2009 ; Walther, Caddigan, Fei-Fei, & Beck, 2009 ; Hassab…”

“…significant activation in previous studies that used self-referential paradigms (Zysset et al., 2002; Schmitz et al., 2004; Seger et al., 2004; Yaoi et al., 2009) and known to be involved in the retrieval of episodic or autobiographical memory (Maguire and Mummery, 1999; Hassabis et al., 2007).”

“2009; Neunuebel and Knierim 2014), neuroimaging (Cabeza et al. 2002; Hassabis et al. 2007), lesion (Ergorul and Eichenbaum 2004; Fortin et al.”

“Hence, the present investigation at subnode resolution points to an aberration of multi-modal integration of perceptionaction cycles, more closely linked to DAN and SN function, rather than to imaginationbased thought processes, more closely linked to DMN function (Hassabis et al., 2007; Wang et al., 2017).”

“, 2006; Cabeza and St Jacques, 2007) and studies showing the brain’s ability to distinguish real from imaginary memories (Hassabis et al., 2007) are consistent with this interpretation.”

“Cortical abnormalities in this network suggest that flat affect misattribution may be explained as the failure of self-processing mechanisms (Kircher et al., 2000, 2002; Kjaer et al., 2002; Cavanna and Trimble, 2006; Hassabis et al., 2007; Wolf et al., 2009).”

“Given that episodic simulation and episodic memory draw on many of the same cognitive processes (Atance & O’Neill, 2001; Conway, 2009; Hassabis et al., 2007; Schacter et al., 2012; Szpunar, 2010), it raises the possibility that the effect of affective valence elicited by simulated future events on…”