The evolutionary origins of the Global Neuronal Workspace in vertebrates

The Global Neuronal Workspace theory of consciousness offers an explicit functional architecture that relates consciousness to cognitive abilities such as perception, attention, memory, and evaluation. We show that the functional architecture of the Global Neuronal Workspace, which is based mainly on human studies, corresponds to the cognitive-affective architecture proposed by the Unlimited Associative Learning theory that describes minimal consciousness. However, we suggest that when applied to basal vertebrates, both models require important modifications to accommodate what has been learned about the evolution of the vertebrate brain. Most importantly, comparative studies suggest that in basal vertebrates, the Global Neuronal Workspace is instantiated by the event memory system found in the hippocampal homolog. This proposal has testable predictions and implications for understanding hippocampal and cortical functions, the evolutionary relations between memory and consciousness, and the evolution of unified perception.

Memory footprint: Predictors of flashbulb and event memories of the 2016 Euro Cup final

Two years after Portugal won the UEFA European Championship, we examined what the Portuguese remember of this momentous occasion. We investigated if flashbulb memories (FBMs) and event memories (EMs) were determined by distinct factors, and whether EM was a predictor of FBM. Participants responded to an online questionnaire about their FBM, EM and set of predictors. Structural equation modeling revealed that FBM and EM were associated with different pathways. Interest in football predicted importance which triggered emotional intensity which predicted personal rehearsal, a direct determinant of FBMs. On the other pathway, interest determined knowledge about football, the main predictor of EMs. Importantly, EM was a causal determinant of FBM which shows that the memory trace for the original event enhances memory for the reception context. The findings suggests that even though the two types of memories are determined by independent factors, they interact very closely.

How suspense and surprise enhance subsequent memory: the case of the 2016 United States Presidential Election

We examined whether the retroactive enhancement effect - i.e., improved memory accuracy for event details occurring before a surprising moment - would be present in participants' memory for details in their private lives following a surprising and suspenseful public event. To equate event type across participants, we selected when they first learned the outcome of the 2016 US Presidential Election. Participants self-divided into those who viewed the outcome as positive, negative, or neutral, while we experimentally divided them into those whose memory was assessed 6 or 12 months post-election. We assessed their accuracy for details surrounding the election and their phenomenological experience of learning the outcome, including emotional tension, our operationalisation of suspense. We found participants' memory characteristics were strongly related to their level of tension and shock, irrespective of valence. We also observed uniformly high accuracy regarding details about the weather participants experienced in their ZIP codes on election day. While these results intimated about the presence of retroactive enhancement, Experiment 2 examined the effect more directly by comparing participants' memory for the 2016 Election with two other politically-relevant events that provoked less tense reactions. The results revealed retroactive enhancement is dependent upon experiencing a surprising moment amidst a suspenseful event.

The Eyes Are More Eloquent Than Words: Anticipatory Looking as an Index of Event Memory in Alzheimer's Disease

Alzheimer's disease (AD) is a disorder in which individuals experience a difficulty in maintaining event memory for when, where, who, and what. However, verbal deficiency, one of the other symptoms of AD, may prevent a precise diagnosis of event memory because existing tests are based on verbal instructions by the tester and verbal response from patient. Therefore, non-verbal methods are essential to evaluate event memory in AD. The present study, using eye tracking, investigated whether AD patients deployed anticipatory looking to target acts related to future events based on previous experience when an identical video was presented to them twice. The results revealed the presence of anticipatory looking, although AD patients were unable to verbally report the content of the video. Our results illustrate that AD patients have a one-time event memory better than previously thought.

Remembering facts versus feelings in the wake of political events

Amid rising political polarisation, inaccurate memory for facts and exaggerated memories of grievances can drive individuals and groups further apart. We assessed whether people with more accurate memories of the facts concerning political events were less susceptible to bias when remembering how events made them feel. Study 1 assessed participants' memories concerning the 2016 U.S. presidential election (N = 571), and included 33 individuals with Highly Superior Autobiographical Memory (HSAM). Study 2 assessed participants' memories concerning the 2018 referendum on abortion in Ireland (N = 733). Participants rated how happy, angry, and scared they felt days after these events. Six months later, they recalled their feelings and factual information. In both studies, participants overestimated how angry they had felt but underestimated happiness and fear. Adjusting for importance, no association was found between the accuracy of memory for facts and feelings. Accuracy in remembering facts was predicted by media exposure. Accuracy in remembering feelings was predicted by consistency over time in feelings and appraisals about past events. HSAM participants in Study 1 remembered election-related facts better than others, but not their feelings. Thus, having a good grasp of the facts did not protect against bias in remembering feelings about political events.

Reminders activate the prefrontal-medial temporal cortex and attenuate forgetting of event memory

Replicas of an aspect of an experienced event can serve as effective reminders, yet little is known about the neural basis of such reminding effects. Here we examined the neural activity underlying the memory-enhancing effect of reminders 1 week after encoding of naturalistic film clip events. We used fMRI to determine differences in network activity associated with recently reactivated memories relative to comparably aged, non-reactivated memories. Reminders were effective in facilitating overall retrieval of memory for film clips, in an all-or-none fashion. Prefrontal cortex and hippocampus were activated during both reminders and retrieval. Peak activation in ventro-lateral prefrontal cortex (vPFC) preceded peak activation in the right hippocampus during the reminders. For film clips that were successfully retrieved after 7 days, pre-retrieval reminders did not enhance the quality of the retrieved memory or the number of details retrieved, nor did they more strongly engage regions of the recollection network than did successful retrieval of a non-reminded film clip. These results suggest that reminders prior to retrieval are an effective means of boosting retrieval of otherwise inaccessible episodic events, and that the inability to recall certain events after a delay of a week largely reflects a retrieval deficit, rather than a storage deficit for this information. The results extend other evidence that vPFC drives activation of the hippocampus to facilitate memory retrieval and scene construction, and show that this facilitation also occurs when reminder cues precede successful retrieval attempts. The time course of vPFC-hippocampal activity during the reminder suggests that reminders may first engage schematic information meditated by vPFC followed by a recollection process mediated by the hippocampus.

Highly emotional vicarious memories

Vicarious memories are memories that people have in reference to events that they have not directly experienced, rather heard second-hand. Little research has investigated vicarious memory; when it has, it has predominantly focused on vicarious trauma. The purpose of this study was to compare vicarious memories with personal memories. University students (N = 142) completed an in-person interview in which they recalled four memories: a highly positive personal memory, a highly negative personal memory, a highly positive vicarious memory and a highly negative vicarious memory. Personal and vicarious memory reports were compared and contrasted in terms of memory qualities, memory functions and event centrality. The results indicate that vicarious and personal memory reports share many phenomenological and functional properties. Although to a lesser degree than personal memories, vicarious memories do influence decision-making and problem-solving. Current models of episodic memory only include events that individuals have directly experienced. The current study adds to a growing body of literature which suggests that current models of episodic memory are too restrictive and should expand to include vicarious memory reports.

Evidence that an episodic mode of thinking facilitates encoding of perceptually rich memories for naturalistic events relative to a gist-based mode of thinking

Several studies have demonstrated that an episodic specificity induction (ESI) can influence cognitive abilities that involve episodic processes at retrieval. To better understand the downstream implications of an "episodic mode of thinking," we investigate whether an ESI influences encoding of new events. In a between-subjects design, participants were given an ESI or gist (control) induction. In an ostensibly unrelated task, participants then were shown film clips of naturalistic events. After a filled delay, participants were given a surprise memory test, which required narrative recollection of the film clips. Participants who received the ESI generated narratives that contained more perceptual details specifically. Relative to gist thinking, an episodic mode of thinking appears to facilitate encoding of perceptually rich memories for naturalistic events.

The Primacy of Spatial Context in the Neural Representation of Events

Some theories of episodic memory hypothesize that spatial context plays a fundamental role in episodic memory, acting as a scaffold on which episodes are constructed. A prediction based on this hypothesis is that spatial context should play a primary role in the neural representation of an event. To test this hypothesis in humans, male and female participants imagined events, composed of familiar locations, people, and objects, during an fMRI scan. We used multivoxel pattern analysis to determine the neural areas in which events could be discriminated based on each feature. We found that events could be discriminated according to their location in areas throughout the autobiographical memory network, including the parahippocampal cortex and posterior hippocampus, retrosplenial cortex, posterior cingulate cortex, precuneus, and medial prefrontal cortex. Events were also discriminable based on person and object features, but in fewer regions. Comparing classifier performance in regions involved in memory for scenes and events demonstrated that the location of an event was more accurately classified than the person or object involved. These results support theories that suggest that spatial context is a prominent defining feature of episodic memory.SIGNIFICANCE STATEMENT Remembered and imagined events are complex, consisting of many elements, including people, objects, and locations. In this study, we sought to determine how these types of elements differentially contribute to how the brain represents an event. Participants imagined events consisting of familiar locations, people, and objects (e.g., kitchen, mom, umbrella) while their brain activity was recorded with fMRI. We found that the neural patterns of activity in brain regions associated with spatial and episodic memory could distinguish events based on their location, and to some extent, based on the people and objects involved. These results suggest that the spatial context of an event plays an important role in how an event is represented in the brain.

Who was that masked man? Conjoint representations of intrinsic motions with actor appearance

Motion plays an important role in recognising animate creatures. This research supports a distinction between intrinsic and extrinsic motions in their relationship to identifying information about the characters performing the motions. Participants viewed events involving costumed human characters. Intrinsic motions involved relative movements of a character's body parts, whereas extrinsic motions involved movements with respect to external landmarks. Participants were later tested for recognition of the motions and who had performed them. The critical test items involved familiar characters performing motions that had previously been performed by other characters. Participants falsely recognised extrinsic conjunction items, in which characters followed the paths of other characters, more often than intrinsic conjunction items, in which characters moved in the manner of other characters. In contrast, participants falsely recognised new extrinsic motions less often than new intrinsic motions, suggesting that they remembered extrinsic motions but had difficulty remembering who had performed them. Modelling of receiver operating characteristics indicated that participants discriminated old items from intrinsic conjunction items via familiarity, consistent with conjoint representations of intrinsic motion and identity information. In contrast, participants used recollection to distinguish old items from extrinsic conjunction items, consistent with separate but associated representations of extrinsic motion and identity information.

Why do we remember? The communicative function of episodic memory

Episodic memory has been analyzed in a number of different ways in both philosophy and psychology, and most controversy has centered on its self-referential, 'autonoetic' character. Here, we offer a comprehensive characterization of episodic memory in representational terms, and propose a novel functional account on this basis. We argue that episodic memory should be understood as a distinctive epistemic attitude taken towards an event simulation. On this view, episodic memory has a metarepresentational format and should not be equated with beliefs about the past. Instead, empirical findings suggest that the contents of human episodic memory are often constructed in the service of the explicit justification of such beliefs. Existing accounts of episodic memory function that have focused on explaining its constructive character through its role in 'future-oriented mental time travel' neither do justice to its capacity to ground veridical beliefs about the past nor to its representational format. We provide an account of the metarepresentational structure of episodic memory in terms of its role in communicative interaction. The generative nature of recollection allows us to represent and communicate the reasons for why we hold certain beliefs about the past. In this process, autonoesis corresponds to the capacity to determine when and how to assert epistemic authority in making claims about the past. A domain where such claims are indispensable are human social engagements. Such engagements commonly require the justification of entitlements and obligations, which is often possible only by explicit reference to specific past events.

Perirhinal cortical inactivation impairs object-in-place memory and disrupts task-dependent firing in hippocampal CA1, but not in CA3

Objects and their locations can associatively define an event and a conjoint representation of object-place can form an event memory. Remembering how to respond to a certain object in a spatial context is dependent on both hippocampus and perirhinal cortex (PER). However, the relative functional contributions of the two regions are largely unknown in object-place associative memory. We investigated the PER influence on hippocampal firing in a goal-directed object-place memory task by comparing the firing patterns of CA1 and CA3 of the dorsal hippocampus between conditions of PER muscimol inactivation and vehicle control infusions. Rats were required to choose one of the two objects in a specific spatial context (regardless of the object positions in the context), which was shown to be dependent on both hippocampus and PER. Inactivation of PER with muscimol (MUS) severely disrupted performance of well-trained rats, resulting in response bias (i.e., choosing any object on a particular side). MUS did not significantly alter the baseline firing rates of hippocampal neurons. We measured the similarity in firing patterns between two trial conditions in which the same target objects were chosen on opposite sides within the same arm [object-in-place (O-P) strategy] and compared the results with the similarity in firing between two trial conditions in which the rat chose any object encountered on a particular side [response-in-place (R-P) strategy]. We found that the similarity in firing patterns for O-P trials was significantly reduced with MUS compared to control conditions (CTs). Importantly, this was largely because MUS injections affected the O-P firing patterns in CA1 neurons, but not in CA3. The results suggest that PER is critical for goal-directed organization of object-place associative memory in the hippocampus presumably by influencing how object information is associated with spatial information in CA1 according to task demand.

Disambiguation of similar object-place paired associations and the roles of the brain structures in the medial temporal lobe

Amnesic patients who have damage in the hippocampus and in associated areas in the medial temporal lobe suffer from remembering specific events that may or may not share similar objects and locations. Computational models, behavioral studies, and physiological findings all suggest that neural circuits in the hippocampus are suitable for representing seemingly similar events as distinctively different individual event memories. This article offers a selective review on this particular function of the hippocampus and its associates areas such as the perirhinal cortex, mostly centering upon lesion studies and physiological studies using animals. We also present recent experimental results showing that the dentate gyrus subfield of the hippocampus and perirhinal cortex are particularly important for discriminating similar paired associates between same objects and different locations, or vice versa.

Functionally dissociating aspects of event memory: the effects of combined perirhinal and postrhinal cortex lesions on object and place memory in the rat

Reciprocal interactions between the hippocampus and the perirhinal and parahippocampal cortices form core components of a proposed temporal lobe memory system. For this reason, the involvement of the hippocampus in event memory is thought to depend on its connections with these cortical areas. Contrary to these predictions, we found that NMDA-induced lesions of the putative rat homologs of these cortical areas (perirhinal plus postrhinal cortices) did not impair performance on two allocentric spatial tasks highly sensitive to hippocampal dysfunction. Remarkably, for one of the tasks there was evidence of a facilitation of performance. The same cortical lesions did, however, disrupt spontaneous object recognition and object discrimination reversal learning but spared initial acquisition of the discrimination. This pattern of results reveals important dissociations between different aspects of memory within the temporal lobe. Furthermore, it shows that the perirhinal-postrhinal cortex is not a necessary route for spatial information reaching the hippocampus and that object familiarity-novelty detection depends on different neural substrates than do other aspects of event memory.