A Review of the Neural and Behavioral Consequences for Unitizing Emotional and Neutral Information

Abstract

A special type of association, called a “unitization,” is formed when pieces of information are encoded as a single representation in memory (e.g., “shirt” and “blue” are encoded as a “blue shirt”; Graf and Schacter, 1989) and typically are later reactivated in memory as a single unit, allowing access to the features of multiple related stimuli at once (Bader et al., 2010; Diana et al., 2011). This review examines the neural processes supporting memory for unitizations and how the emotional content of the material may influence unitization. Although associative binding is typically reliant on hippocampal processes and supported by recollection, the first part of this review will present evidence to suggest that when two items are unitized into a single representation, memory for those bound items may be accomplished on the basis of familiarity and without reliance on the hippocampus. The second part of this review discusses how emotion may affect the processes that give rise to unitizations. Emotional information typically receives a mnemonic benefit over neutral information, but the literature is mixed on whether the presence of emotional information impedes or enhances the associative binding of neutral information (reviewed by Mather, 2007). It has been suggested that the way the emotional and neutral details are related together may be critical to whether the neutral details are enhanced or impeded (Mather, 2007; Mather and Sutherland, 2011). We focus on whether emotional arousal aids or inhibits the creation of a unitized representation, presenting preliminary data, and future directions to test empirically the effects of forming and retrieving emotional and neutral unitizations.

Negative affect impairs associative memory but not item memory

“…Our results are compatible with this view in that item and associative memory were affected in opposite directions. Speculatively, negative emotion might enhance item memory through amygdaladependent processes and modulation of other MTL structures, such as perirhinal cortex (for similar views, see Mather 2007;Murray and Kensinger 2013). In further support of this link, a recent study in rodents demonstrates a potential role for the amygdala in recognition memory, with damage to this structure found to reduce familiarity-type recognition of nonemotional items, while recollection-type processes were spared (Farovik et al 2011).…”

The effects of negative emotion on encoding-related neural activity predicting item and source recognition

“…These subprocesses are often thought to be the core components of recognition memory (Aggleton and Brown, 1999;Düzel et al, 1999;Mandler, 1980;Mecklinger, 2000;Rugg and Curran, 2007;Yonelinas, 1994;Yonelinas and Parks, 2007) and the question whether emotions can differentially modulate them is not fully settled . Some studies have found that emotion can enhance "source memory" performance (Croucher et al, 2011;D'Argembeau and Van der Linden, 2005;Doerksen and Shimamura, 2001;Murray and Kensinger, 2013). These results suggest that emotion can modulate recollection processes, given that source memory tasks require participants to retrieve information belonging to the context in which a central item has been encoded (Koenig and Mecklinger, 2008;Wilding andRugg, 1996, 1997;Yick and Wilding, 2014).…”

Pain anticipation recruits the mesolimbic system and differentially modulates subsequent recognition memory

“…The quadratic effect of shock probability on recollection could also be explained on the basis of studies showing an association between emotional arousal and hippocampusdependent memory dysfunctions (e.g. Murray and Kensinger, 2013;Murty et al, 2011). They suggest that in a state of high emotional arousal (i.e.…”