Changes in Events Alter How People Remember Recent Information

Observers spontaneously segment larger activities into smaller events. For example, “washing a car” might be segmented into “scrubbing,” “rinsing,” and “drying” the car. This process, called event segmentation, separates “what is happening now” from “what just happened.” In this study, we show that event segmentation predicts activity in the hippocampus when people access recent information. Participants watched narrative film and occasionally attempted to retrieve from memory objects that recently appeared in the film. The delay between object presentation and test was always 5 sec. Critically, for some of the objects, the event changed during the delay whereas for others the event continued. Using fMRI, we examined whether retrieval-related brain activity differed when the event changed during the delay. Brain regions involved in remembering past experiences over long periods, including the hippocampus, were more active during retrieval when the event changed during the delay. Thus, the way an object encountered just 5 sec ago is retrieved from memory appears to depend in part on what happened in those 5 sec. These data strongly suggest that the segmentation of ongoing activity into events is a control process that regulates when memory for events is updated

Medial Temporal Lobe Volume Predicts Elders’ Everyday Memory

Deficits in memory for everyday activities are common complaints among healthy and demented older adults. The medial temporal lobes and dorsolateral prefrontal cortex are both affected by aging and early-stage Alzheimer’s disease, and are known to influence performance on laboratory memory tasks. We investigated whether the volume of these structures predicts everyday memory. Cognitively healthy older adults and older adults with mild Alzheimer’s-type dementia watched movies of everyday activities and completed memory tests on the activities. Structural MRI was used to measure brain volume. Medial temporal but not prefrontal volume strongly predicted subsequent memory. Everyday memory depends on segmenting activity into discrete events during perception, and medial temporal volume partially accounted for the relationship between performance on the memory tests and performance on an event-segmentation task. The everyday-memory measures used in this study involve retrieval of episodic and semantic information as well as working memory updating. Thus, the current findings suggest that during perception, the medial temporal lobes support the construction of event representations that determine subsequent memory

The Hippocampal Film Editor: Sensitivity and Specificity to Event Boundaries in Continuous Experience.

The function of the human hippocampus is normally investigated by experimental manipulation of discrete events. Less is known about what triggers hippocampal activity during more naturalistic, continuous experience. We hypothesized that the hippocampus would be sensitive to the occurrence of event boundaries, that is, moments in time identified by observers as a transition between events. To address this, we analyzed functional MRI data from two groups: one (n = 253, 131 female) who viewed an 8.5 min film and another (n = 15, 6 female) who viewed a 120 min film. We observed a strong hippocampal response at boundaries defined by independent observers, which was modulated by boundary salience (the number of observers that identified each boundary). In the longer film, there were sufficient boundaries to show that this modulation remained after covarying out a large number of perceptual factors. This hypothesis-driven approach was complemented by a data-driven approach, in which we identified hippocampal events as moments in time with the strongest hippocampal activity. The correspondence between these hippocampal events and event boundaries was highly significant, revealing that the hippocampal response is not only sensitive, but also specific to event boundaries. We conclude that event boundaries play a key role in shaping hippocampal activity during encoding of naturalistic events.SIGNIFICANCE STATEMENT Recent years have seen the field of human neuroscience research transitioning from experiments with simple stimuli to the study of more complex and naturalistic experience. Nonetheless, our understanding of the function of many brain regions, such as the hippocampus, is based primarily on the study of brief, discrete events. As a result, we know little of what triggers hippocampal activity in real-life settings when we are exposed to a continuous stream of information. When does the hippocampus "decide" to respond during the encoding of naturalistic experience? We reveal here that hippocampal activity measured by fMRI during film watching is both sensitive and specific to event boundaries, identifying a potential mechanism whereby event boundaries shape experience by modulation of hippocampal activity

Hippocampal activity patterns carry information about objects in temporal context

The hippocampus is critical for human episodic memory, but its role remains controversial. One fundamental question concerns whether the hippocampus represents specific objects or assigns context-dependent representations to objects. Here, we used multivoxel pattern similarity analysis of fMRI data during retrieval of learned object sequences to systematically investigate hippocampal coding of object and temporal context information. Hippocampal activity patterns carried information about the temporal positions of objects in learned sequences, but not about objects or temporal positions in random sequences. Hippocampal activity patterns differentiated between overlapping object sequences and between temporally adjacent objects that belonged to distinct sequence contexts. Parahippocampal and perirhinal cortex showed different pattern information profiles consistent with coding of temporal position and object information, respectively. These findings are consistent with models proposing that the hippocampus represents objects within specific temporal contexts, a capability that might explain its critical role in episodic memory

Tapahtumasegmentaation aivovasteet hippokampuksessa ja aivokuorella äänitarinan kuuntelun aikana

Tapahtumasegmentaatio jäsentää sekä arkista kokemustamme että muistiamme. Parhaillaan meneillään olevan tapahtuman hahmotus ja prosessointi tapahtuu todennäköisesti aivokuorella, mutta ilman toimivaa hippokampusta tilanteesta ei voi syntyä pysyvää muistoa. On olennainen kysymys, missä kohtaa ja miten hippokampus osallistuu tapahtumien prosessointiin ja mieleen painamiseen. Aiemmin on magneettikuvaustutkimuksin osoitettu, että hippokampus reagoi tapahtumien välisiin rajoihin aktivaatiopiikein. On ehdotettu, että ne ilmentäisivät aistimodaliteetista riippumattoman tason prosessia, jossa hippokampus kokoaa yhteen ja vahvistaa koetun tilanteen kokonaisrepresentaation, jotta se voidaan painaa muistiin. Aiemmat tutkimukset on kuitenkin toteutettu yksinomaan audiovisuaalisilla ärsykkeillä, ja koska hippokampuksen tiedetään osallistuvan myös visuaaliseen prosessointiin, ei ole täysin selvää, etteivätkö havaitut aktivaatiot voisi selittyä alemman, aistitietoa käsittelevän tason prosesseilla. Tämän kysymyksen ratkaisemiseksi tässä tutkimuksessa selvitettiin reagoiko hippokampus tapahtumarajoihin puhtaasti auditiivisessa ärsykkeessä. Ärsykkeenä oli 71-minuuttinen tarinallinen äänikirja, jonka osallistujat kuuntelivat passiivisesti fMRI-rekisteröinnin aikana, ja jonka tapahtumarajat määriteltiin kokeellisesti erillisen koehenkilöryhmän avulla. Aivokuvausaineisto analysoitiin aivoalueittain sekä hippokampuksesta että eksploratiivisesti myös kaikilta aivokuoren alueilta. Hippokampuksen havaittiin reagoivan tapahtumarajoihin aktivaatiopiikein. Aivokuorella voimakkaasti reagoivia alueita olivat mm. posteriorinen mediaalinen aivokuori, ventromediaalinen prefrontaalialue, parahippokampaalinen poimu sekä etummainen pihtipoimu. Monien näistä alueista uskotaan osallistuvan meneillään olevan tapahtuman mallintamiseen ja hahmottamiseen, ja osa mahdollisesti osallistuu huomion siirtämiseen sisäisen ja ulkoisen välillä. Etummaisen pihtipoimun tiedetään osallistuvan odotusten ja havaintojen välisten konfliktien monitorointiin, mikä saattaisi tukea teoriaa, jonka mukaan segmentaatio olisi riippuvaista havaituista ennustevirheistä. Tätä ei kuitenkaan tämän tutkimuksen perusteella voida varmasti päätellä, vaan asiaa tulisi tutkia tarkemmin. Tämän tutkimuksen tulokset tukevat näkemystä, jonka mukaan hippokampuksen lisääntynyt toiminta tapahtumarajoilla liittyy korkean tason abstraktiin segmentaatioon ja mahdollisesti episodisen muiston luomiseen. Tämä prosessi mahdollisesti tapahtuu yhteistyössä aivokuoren aktiivisten alueiden kanssa, mutta kausaaliset suhteet ja informaation kulku näiden alueiden välillä on selvitettävä myöhemmissä tutkimuksissa.Event segmentation structures our experience as well as our memories. The representation of the currently ongoing event is likely dependent on a network of cortical areas, but the ability to retain a memory of the event requires an intact hippocampus. It is thus a relevant question how and when this hippocampal episodic encoding happens. It has previously been shown that the hippocampus is sensitive to event boundaries and responds to them with transient fMRI activation peaks. It has been proposed that these hippocampal end-of-event activations represent a high-level, modality-independent process of sharpening or “printing out” of the memory trace of the situation. However, the studies reporting hippocampal peaks have been conducted on audio-visual stimuli, so it is unclear whether these results generalise to narratives without a visual component, as the hippocampus is known to support visual processing as well as episodic encoding. In this study I aim to answer this question by analysing fMRI data from participants experiencing a purely auditory narrative. The stimulus was a 71-minute-long audio book, and it was segmented behaviourally by a separate group of participants with a naïve intuitive segmentation paradigm. The data was analysed with a region of interest (ROI) analysis in the hippocampus, as well as in an exploratory manner on all areas from a cortical atlas. The hippocampus was found to respond significantly to event boundaries in the story. Strong responses were also found in areas of the posterior medial cortex (PMC), as well as in ventromedial prefrontal cortex (vmPFC), parahippocampal gyrus, anterior cingulate (ACC) and the insula. Many of these are known to be involved in representing the event model, and some with switching between internal and external processing modes. ACC in particular is known to be involved in conflict monitoring – this might link with the proposal that segmentation in general is driven by prediction error and would merit further study. I conclude that the hippocampus does detect and respond to event boundaries in a naturalistic auditory narrative, which is in line with the “print out” hypothesis and implies that these activations are related to domain-general episodic encoding. The increased hippocampal processing is likely to happen in collaboration with cortical areas involved in signalling change and representing the working event model. However, the causal connections between these areas during the boundary-related processing cascade needs to be elaborated in future studies

Is There a Higher-Order Mechanism that Explains Performance Across Prediction Tasks?

People constantly make predictions about what will happen in the near future. People anticipate how other people around them will act, what other people will say, and what actions will help them achieve the greatest rewards. Because all of these behaviors are typically called prediction, it is easy to make the assumption that performance across all of these types of tasks is driven by the same underlying mechanism. However, there has been little investigation into whether the mechanisms underlying prediction are the same across multiple task modalities. Therefore, in the current study, 226 participants completed four types of tasks that putatively involve prediction to determine whether there is a common factor that can account for performance on these tasks. Fluid and crystallized intelligence were also assessed to ensure that general intelligence did not drive correlations among the tasks. Preliminary evidence from a recent study suggested that people with Posttraumatic Stress Disorder (PTSD) have difficulty with predicting future activity; therefore, participants also completed a questionnaire screening for symptoms of PTSD. Performance across the four prediction tasks was not correlated, and PTSD severity was not significantly correlated with any of the tasks in the study. These results suggest that there is not an integrative prediction mechanism in the brain, but rather that there are multiple prediction systems operating in parallel within the brain. In addition, these results suggest that PTSD may only be associated with a subset, if any, of prediction tasks. Future researchers studying prediction must be careful to investigate performance on various prediction tasks separately, rather than assuming that prediction performance is stable across tasks

Narratives Close the Gap: The Limited Role of Temporal Distance in Binding Events into Coherent Memories

Temporal information has been identified as a powerful influence on memory retrieval. Much of this arise from studies that tend to focus on associations between items. In contrast, real-life experiences consist of discrete events that encompass more than mere associations. While events can be remembered based on temporal proximity, events that are farther apart in time can also be linked together by forming a coherent narrative. Given that daily experiences are multifaceted, it is unclear to what extent prior work generalizes to real-world memories. Here, we sought to determine the influence of temporal features and narrative coherence on memory for lifelike events. Across two experiments, participants listened to a story and later completed recall and temporal judgment tasks. The story consisted of temporally-distant events that could either be meaningfully integrated (i.e., Coherent Narratives), or are depicted in separate, unrelated narratives (i.e., Unrelated Narratives). Each paired event either appeared relatively close together (i.e., Short Lags) or far apart (i.e., Long Lags) in the story. While Coherent Narratives were recalled in greater detail than Unrelated Narratives, conditions of temporal lag did not influence recall performance. Memory performance on temporal judgment tasks, on the other hand, was largely driven by temporal lag and was not affected by narrative coherence. These findings suggest that while time is an integral part of episodic memory, memories for dynamic, lifelike experiences are more anchored to high-level elements such as narrative coherence

Finding a Basic Interpretive Unit through the Human Visual Perception and Cognition-A Comparison between Filmmakers and Audiences

The analysis method and paradigm of film have become a controversial topic in the data-driven era. Film, is not only an attractive industry that can achieve filmmakers’ imagination but has become a perfect stimulus to understand human being’s mental activity. The core research in this study is to examine the impact of filmmaking experience and the role of narrative denoters from filmmakers’ construction to audiences’ interpretation. Based on previous studies and integrating cognitive approaches, the thesis re-explores the nature and essence of film and proposes an alternative term - narrative denoter - which can be used as the indication of message exchanging between filmmakers and audiences. Using a released film that has a complete story to do the experiment, this study investigates the relationship between major, film interpretations, event segmentation, and audience’s preference. The result showed that filmmaking experience does not impact the interpretation of film; however the identification of the narrative denoter played an important role in film perception and cognition; apart from these, the audience’s preference did not correlate with film interpretation. With respect to this result, the narrative denoter can be indicator to demonstrate the message transitions from filmmaker to audience. Suggestions were made for future cognitive film studies on using the narrative denoters as a new analysis unit

Changes in Events Alter How People Remember Recent Information

Observers spontaneously segment larger activities into smaller events. For example, “washing a car” might be segmented into “scrubbing,” “rinsing,” and “drying” the car. This process, called event segmentation, separates “what is happening now” from “what just happened.” In this study, we show that event segmentation predicts activity in the hippocampus when people access recent information. Participants watched narrative film and occasionally attempted to retrieve from memory objects that recently appeared in the film. The delay between object presentation and test was always 5 sec. Critically, for some of the objects, the event changed during the delay whereas for others the event continued. Using fMRI, we examined whether retrieval-related brain activity differed when the event changed during the delay. Brain regions involved in remembering past experiences over long periods, including the hippocampus, were more active during retrieval when the event changed during the delay. Thus, the way an object encountered just 5 sec ago is retrieved from memory appears to depend in part on what happened in those 5 sec. These data strongly suggest that the segmentation of ongoing activity into events is a control process that regulates when memory for events is updated