Fake or Fantasy: Rapid Dissociation between Strategic Content Monitoring and Reality Filtering in Human Memory

Abstract

Memory verification is crucial for meaningful behavior. Orbitofrontal damage may impair verification and induce confabulation and inappropriate acts. The strategic retrieval account explains this state by deficient monitoring of memories' precise content, whereas the reality filter hypothesis explains it by a failure of an orbitofrontal mechanism suppressing the interference of memories that do not pertain to reality. The distinctiveness of these mechanisms has recently been questioned. Here, we juxtaposed these 2 mechanisms using high-resolution evoked potentials in healthy subjects who performed 2 runs of a continuous recognition task which contained pictures that precisely matched or only resembled previous pictures. We found behavioral and electrophysiological dissociation: Strategic content monitoring was maximally challenged by stimuli resembling previous ones, whereas reality filtering was maximally challenged by identical stimuli. Evoked potentials dissociated at 200-300 ms: Strategic monitoring induced a strong frontal negativity and a distinct cortical map configuration, which were particularly weakly expressed in reality filtering. Recognition of real repetitions was expressed at 300-400 ms, associated with ventromedial prefrontal activation. Thus, verification of a memory's concordance with the past (its content) dissociates from the verification of its concordance with the present. The role of these memory control mechanisms in the generation of confabulations and disorientation is discussed.

An Electrophysiological Dissociation between Orbitofrontal Reality Filtering and Context Source Monitoring

“…These are the stimuli on which reality confusing patients, who produced confabulations and were disoriented, failed; they had a specific increase of false positives in response to Dis2 stimuli (Nahum et al, 2012;Schnider, Ptak, et al, 2000;Schnider & Ptak, 1999;Schnider et al, 1996aSchnider et al, , 1996b. Processing of these stimuli activated the posterior medial orbitofronal cortex (Schnider, Treyer, et al, 2000) and induced a specific frontal positivity at 200-300 msec in previous evoked potential studies ( Wahlen et al, 2011;Schnider et al, 2002).…”

“…Previous studies have shown that reality filtering and recognition effects can be seized over frontal, central, and posterior electrode sites (Wahlen et al, 2011;Schnider et al, 2002), but that the precise optimal electrode position may vary. We, therefore, grouped electrodes into ROIs for the analysis: frontal, central, and posterior ROIs (as in the previous studies), to which we added a central right and central left ROIs.…”

“…As additional constraints, the duration of a given scalp topography had to be ≥20 msec. Clusters that correlated ≥90% were merged (Wahlen et al, 2011). The number of maps explaining the averaged data set was determined by cross validation and the Krzanowski-Lai criterion (Pascual-Marqui et al, 1995).…”

“…For this study, we composed a continuous recognition task that combined the challenges of context source monitoring (verification of picturesʼ previous visual context) and reality filtering. We recorded high-density evoked potentials in healthy participants to address the following questions: (1) Does reality filtering within a task, which simultaneously challenges context source monitoring, again induce the frontal positivity and relative absence of an electrocortical map configuration at 200-300 msec that was previously observed in different reality filtering tasks (Wahlen, Nahum, Gabriel, & Schnider, 2011;Schnider et al, 2002)? (2) Does context source monitoring performed within a continuous recognition task share a common early process with reality filtering or is it expressed only after 400 msec, as in most traditional source monitoring tasks (Addante et al, 2012;Mollison & Curran, 2012;Leynes & Phillips, 2008;Vallesi & Shallice, 2006;Johnson, Kounios, et al, 1997;Wilding & Rugg, 1996)?…”

Children’s sense of reality: The development of orbitofrontal reality filtering

“…Recent studies have shown that this process is rapid (200-300 ms after stimulus presentation; Schnider, Valenza, Morand, & Michel, 2002), and that it dissociates from other memory control processes like context source memory (BouzerdaWahlen, Nahum, Liverani, Guggisberg, & Schnider, 2014;Johnson, Kounios, & Nolde, 1997;Mitchell & Johnson, 2009), strategic retrieval monitoring (BouzerdaWahlen, Nahum, Ptak, & Schnider, 2013;Gilboa et al, 2006;Wahlen, Nahum, Gabriel, & Schnider, 2011) and temporal order memory (Liverani et al, 2015). These processes are laborious and have different signatures in evoked potential studies (Bouzerda-Wahlen et al, 2014;Liverani et al, 2015;Wahlen et al, 2011). Orbitofrontal reality filtering is also different from reality monitoring, the ability to distinguish between the memory of a thought and a memory of a perception experienced in the past (Johnson & Raye, 1981).…”