Biology subjects

Baldassano, C.

Publications and source records attributed to Baldassano, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Hippocampal and cortical oscillations support the encoding of event memories during movie watching

Remembering temporally-extended experiences requires integrating information over time into coherent event representations that can be stored and later retrieved. Oscillatory dynamics may provide a flexible mechanism to support these operations by coordinating communication across regions and organizing neural activity in time. Yet most evidence for the oscillatory basis of episodic encoding comes from discrete-stimulus paradigms, leaving unclear whether these mechanisms can help organize memory during continuous experience. Using iEEG recorded while participants watched a 50-min film, we measured how power, synchrony and phase alignment support memory formation at the beginning, middle, and end of the events. At event onset, remembered events showed reduced gamma power with increased hippocampal-frontal synchrony, indicating that successful events begin with transient long-range coordination rather than heightened local processing. Within an event, memory was predicted by the direction of change, with recalled events showing increases in temporal gamma power and hippocampal-temporal gamma synchrony, consistent with the progressive binding of incoming information into a developing event representation. At the end of an event, memory was supported by an increase in hippocampal theta power and phase resetting. Temporal gamma power was likewise elevated and hippocampal-temporal gamma synchrony increased, suggesting that information bound locally over the course of the event might be transmitted to the hippocampus as the event closes. Frontal beta power decreased at the same moment, consistent with disruption of the outgoing event model. Naturalistic memory formation therefore does not rest on a sustained encoding state, but on the appropriate temporal coordination and stability of oscillatory states across brain regions and event phases, in which stable oscillatory states support ongoing representation while transient, boundary-driven reorganization of hippocampal-cortical networks switches the system between consolidating the completed event and encoding the next.

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bioRxiv2025

The Hippocampus Rapidly Integrates Sequence Representations During Novel Multistep Predictions

Memories for temporally extended sequences can be used adaptively to predict future events on multiple timescales, a function that relies on the hippocampus. For such predictions to be useful, they should be updated when environments change. We investigated how and when new learning shapes hippocampal representations of temporally extended sequences, and how this updating relates to flexible predictions about future events. Human participants learned sequences of environments in immersive virtual reality. They then learned novel environment transitions connecting previously separate sequences. During subsequent fMRI, participants predicted multiple steps into the future in both the newly connected sequence and control sequences that remained separate. The hippocampus integrated representations of the connected sequence, such that activity patterns became more similar across trials for the connected sequence vs. the unconnected sequences. These integrated sequence representations in the hippocampus emerged soon after learning, incorporated representations of the initial sequences as well as new activity patterns not previously present in either sequence, and predicted participants ability to update their predictions in behavior. Together, these results advance our understanding of how structured knowledge dynamically emerges in service of adaptive behavior.

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bioRxiv2025

Repeated Viewing of a Narrative Movie Changes Event Timescales in The Brain

Many everyday experiences share a recurring structure: routines, familiar routes, rewatched films, and replayed songs. How do repeated encounters with such structure alter the brains representations of events? We hypothesized that, with repeated viewing of a film clip, event representations in the brain may adapt by becoming either finer (more detailed) or coarser (more generalized). To test this hypothesis, we analyzed data from 30 human participants (12 males, 18 females) who underwent functional magnetic resonance imaging (fMRI) while watching three 90-second clips from "The Grand Budapest Hotel" six times each. We used hidden Markov models and pattern similarity analysis applied to searchlights across the brain to quantify the strength of event structure at different timescales for each clip presentation. We then tested how event structure strength changed at both slow and fast timescales with repeated viewings. Most brain regions exhibited stability in the strength of event structure at both slow and fast timescales. Other regions, however, showed flexible event representations that became more or less granular across repeated clip presentations. Notably, several brain regions exhibited consistent changes in the strength of event structure at a slow timescale across different movie clips. Furthermore, in lateral occipital cortex and middle temporal gyrus, slow timescale structure was correlated with subsequent memory for the clips. These results highlight that event dynamics in the brain are not fixed, but can change flexibly with experience. Significance StatementMany day-to-day experiences recur over time, as we retrace the same route to work or listen to our favorite song on repeat. We asked how increasing familiarity with an experience changes the brains representations of it. Individuals repeatedly watched film clips while undergoing fMRI. We examined how the brains temporal representations of events in the clips changed with repeated viewing. As clips became familiar, some brain regions exhibited fine-tuned event representations that divided film clips into smaller events. Other brain regions showed coarser event representations that grouped previously distinct events. The strength of event structure at a coarse timescale was correlated with memory. These results show that the brain flexibly changes how it represents events as they become more familiar.

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bioRxiv2025

Music-evoked reactivation during continuous perception is associated with enhanced subsequent recall of naturalistic events

Music is a potent cue for recalling personal experiences, yet the neural basis of music-evoked memory remains elusive. We address this question by using the full-length film Eternal Sunshine of the Spotless Mind to examine how repeated musical themes reactivate previously encoded events in cortex and shape next-day recall. Participants in an fMRI study viewed either the original film (with repeated musical themes) or a no-music version. By comparing neural activity patterns between these groups, we found that music-evoked reactivation of neural patterns linked to earlier scenes in the default mode network was associated with improved subsequent recall. This relationship was specific to the music condition and persisted when we controlled for a proxy measure of initial encoding strength (spatial intersubject correlation), suggesting that music-evoked reactivation may play a role in making event memories stick that is distinct from what happens at initial encoding.

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bioRxiv2024

Binding items to contexts through conjunctive neural representations with the Method of Loci

Schematic prior knowledge can provide a powerful scaffold for episodic memories, yet the neural mechanisms underlying this scaffolding process are still poorly understood. A crucial step of the scaffolding process is the way in which details of a new episode are connected to an existing schema, forming a robust memory representation that can be easily accessed in the future. A unique testbed for studying this binding process is a mnemonic technique called the Method of Loci (MoL), in which people meaningfully connect items to be remembered with a well-learned list of imagined loci. We collected fMRI data from participants in 3 longitudinal sessions while they were enrolled in a month-long MoL training course, all of whom showed dramatic improvements in their ability to remember lists of 20 or 40 words. We obtained neural patterns when the loci and objects are presented by themselves, when they are combined into an integrated representation at encoding, and when the integrated representation was subsequently retrieved, as well as verbal descriptions from the participants about the way they associated each item to each locus. We found that in default mode network regions, including medial prefrontal cortex (mPFC), the combined representations of loci and items are highly conjunctive: the unified locus-item representation was substantially different from a linear combination of the isolated locus and item representation, reflecting the addition of new integrative details specific to each combined pair. The conjunctive component of the representation reflected the particular creative details generated by individual participants and increased over time as participants gained expertise in MoL. Our findings reveal a critical role for the default mode network in creating meaningful connections between new information and well-learned schematic contexts.

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bioRxiv2024

How sturdy is your memory palace? Reliable room representations predict subsequent reinstatement of placed objects

What are the neural properties that make spatial contexts effective scaffolds for storing and accessing memories? We hypothesized that spatial locations with stable and distinctive (i.e., reliable) neural representations would best support memory for new experiences. To test this, participants learned the layout of a custom-built 23-room virtual reality (VR) "memory palace" that they explored using a head-mounted display. The next day, participants underwent whole-brain fMRI while watching videos of the rooms, allowing us to measure the reliability of the neural activity pattern associated with each room. Participants then returned to VR to encode 23 objects placed in each of the 23 rooms and later recalled the rooms and objects during fMRI. We found that our room reliability measure (computed prior to encoding) predicted object reinstatement during recall across cortex; this was driven not only by group-level reliability across participants, but also idiosyncratic reliability within participants. Moreover, this effect did not arise through enhanced retrieval of reliable rooms during recall, since the relationship between reliability and object reinstatement remained significant when controlling for room reinstatement during retrieval; this suggests that, instead, room reliability promotes improved binding of rooms to objects at encoding. Together, these results showcase how the quality of the neural repre-sentation of a spatial context can be quantified and used to audit its utility as a memory scaffold for future experiences.

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bioRxiv2024

Neural and behavioral reinstatement jointly reflect retrieval of narrative events

When recalling past events, patterns of gaze position and neural activity resemble those observed during the original experience. We hypothesized that these two phenomena, known as gaze reinstatement and neural reactivation, are linked through a common process that underlies the reinstatement of past experiences during memory retrieval. Here, we tested this proposal based on the viewing and recall of a narrative movie, which we assessed through fMRI, deep learningbased gaze prediction, and language modeling of spoken recall. In line with key predictions, gaze behavior adhered to the same principles as neural activity; it was event-specific, robust across individuals, and generalized across viewing and recall. Additionally, gaze-dependent brain activity overlapped substantially across tasks. Collectively, these results suggest that retrieval engages mechanisms that direct our eyes during natural vision, reflecting common constraints within the functional organization of the nervous system. Moreover, they highlight the importance of considering behavioral and neural reinstatement together in our understanding of remembering.

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bioRxiv2024

Neural and verbal responses to attachment-schema narratives differ based on past and current caregiving experiences

We investigated how past and current caregiving experiences impacted emotional event processing by examining inter-subject functional correlation in 7- to 15-year-olds during narrative movies depicting separation and reunion. Early adversity impacted amygdala interactions with the hippocampus, but medial prefrontal-amygdala connectivity and the content of later recall was shaped by attachment security to current caregivers. This suggests that current attachment can have a redemptive effect on attachment schemas formed in early childhood.

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bioRxiv2023

Neocortico-hippocampal ripple-based coordination during naturalistic encoding

Ripples are fast oscillatory events widely recognized as crucial markers for memory consolidation and neural plasticity. These transient bursts of activity are thought to coordinate information transfer between the hippocampus and neocortical areas, providing a temporal framework that supports the stabilization and integration of new memories. However, their role in human memory encoding during naturalistic scenarios remains unexplored. Here, we recorded intracranial electrophysiological data from ten epilepsy patients watching a movie. Ripples were analyzed in the hippocampus and in neocortical regions (i.e., temporal and frontal cortex). Our results revealed a differential dynamical pattern of ripple occurrence during encoding. Enhanced hippocampal ripple recruitment was observed at event boundaries, reflecting hippocampal involvement in event segmentation, whereas higher ripple rates were seen within an event for cortical electrodes with higher ripple occurrence at the temporal cortex reflecting weather an event was later recalled. These findings shed light on the neural mechanisms underlying memory encoding and provide insights into the potential role of ripples in the encoding of an event, suggesting an impact in the formation of long-term memories of distinct episodes.

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bioRxiv2023

Top-down attention shifts behavioral and neural event boundaries in narratives with overlapping event scripts

Understanding and remembering the complex experiences of everyday life relies critically on prior schematic knowledge about how events in our world unfold over time. How does the brain construct event representations from a library of schematic scripts, and how does activating a specific script impact the way that events are segmented in time? We developed a novel set of 16 audio narratives, each of which combines one of four location-relevant event scripts (restaurant, airport, grocery store, lecture hall) with one of four socially-relevant event scripts (breakup, proposal, business deal, meet cute), and presented them to participants in an fMRI study and a separate online study. Responses in angular gyrus, parahippocampal gyrus, and subregions of medial prefrontal cortex (mPFC) were driven by both location and social script information, showing that these regions can track schematic sequences from multiple domains. For some stories participants were primed to attend to one of the two scripts, by training them to listen for and remember specific script-relevant episodic details. Activating a location-related event script shifted the timing of subjective event boundaries to align with script-relevant changes in the narratives, and this behavioral shift was mirrored in the timing of neural responses, with mPFC event boundaries (identified using a Hidden Markov Model) aligning to location-relevant rather than socially-relevant boundaries when participants were location primed. Our findings demonstrate that neural event dynamics are actively modulated by top-down goals, and provide new insight into how narrative event representations are constructed through the activation of temporally-structured prior knowledge.

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bioRxiv2023

The brain hierarchically represents the past and future during multistep anticipation

Memory for temporal structure enables both planning of future events and retrospection of past events. We investigated how the brain flexibly represents extended temporal sequences into the past and future during anticipation. Participants learned sequences of environments in immersive virtual reality. Pairs of sequences had the same environments in a different order, enabling context-specific learning. During fMRI, participants anticipated upcoming environments multiple steps into the future in a given sequence. Temporal structure was represented in the hippocampus and across higher-order visual regions (1) bidirectionally, with graded representations into the past and future and (2) hierarchically, with further events into the past and future represented in successively more anterior brain regions. In hippocampus, these bidirectional representations were context-specific, and suppression of far-away environments predicted response time costs in anticipation. Together, this work sheds light on how we flexibly represent sequential structure to enable planning over multiple timescales.

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bioRxiv2023

Brain state dynamics reflect emotion transitions induced by music

Our ability to shift from one emotion to the next allows us to adapt our behaviors to a constantly-changing and often uncertain environment. Although previous studies have identified cortical and subcortical regions involved in affective responding, no studies have asked whether and how these regions track and represent transitions between different emotional states and modulate their responses based on the recent emotional context. To this end, we commissioned new musical pieces designed to systematically move participants through different emotional states during fMRI. Using a combination of data-driven (Hidden Markov Modeling) and hypothesis-driven methods, we show that spatiotemporal patterns of activation along the temporoparietal axis reflect transitions between music-evoked emotions. Furthermore, self-reported emotions and the subsequent neural response patterns were sensitive to the emotional context in which the music was heard. The findings highlight the role of temporal and parietal brain regions in not only processing low-level auditory signals, but in linking changes in these signals with our on-going, contextually-dependent emotional responses.

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bioRxiv2021

Neural event segmentation of continuous experience in human infants

How infants experience the world is fundamental to understanding their cognition and development. A key principle of adult experience is that, despite receiving continuous sensory input, we perceive this input as discrete events. Here we investigate such event segmentation in infants and how it differs from adults. Research on event cognition in infants often uses simplified tasks in which (adult) experimenters help solve the segmentation problem for infants by defining event boundaries or presenting discrete actions/vignettes. This presupposes which events are experienced by infants and leaves open questions about the principles governing infant segmentation. We take a different, data-driven approach by studying infant event segmentation of continuous input. We collected whole-brain fMRI data from awake infants (and adults, for comparison) watching a cartoon and used a hidden Markov model to identify event states in the brain. We quantified the existence, timescale, and organization of multiple event representations across brain regions. The adult brain exhibited a known hierarchical gradient of event timescales, from shorter events in early visual regions to longer events in later visual and associative regions. In contrast, the infant brain only represented longer events, even in early visual regions, with no timescale hierarchy. The boundaries defining these infant events only partially overlapped with boundaries defined from adult brain activity and behavioral judgments. These findings suggest that events are organized differently in infants, with longer timescales and more stable neural patterns, even in sensory regions. This may indicate greater temporal integration and reduced temporal precision during dynamic, naturalistic perception. Significance StatementSensory input is continuous and yet humans perceive discrete events. This event segmentation has been studied in adults by asking them to indicate natural breaks in continuous input. This classic parsing task is impossible in infants who cannot understand or follow instructions. We circumvent this barrier by testing how the infant brain parses. We applied a computational model to rare awake fMRI data from infants to identify how their brains transitioned between stable states during a cartoon. Whereas adults showed a gradient in event timescales, from shorter events in sensory regions to longer events in associative regions, infants persistently segmented fewer, longer events across the cortical hierarchy. These findings provide new neuroscientific insight into how infants represent their environment.

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bioRxiv2021

Schema representations in distinct brain networks support narrative memory during encoding and retrieval

Schematic prior knowledge can scaffold the construction of event memories during perception and also provide structured cues to guide memory search during retrieval. We measured the activation of story-specific and schematic representations using fMRI while participants were presented with 16 stories and then recalled each of the narratives, and related these activations to memory for specific story details. We predicted that schema representations in mPFC would be correlated with successful recall of story details. In keeping with this prediction, an anterior mPFC region showed a significant correlation between activation of schema representations at encoding and subsequent behavioral recall performance; however, this mPFC region was not implicated in schema representation during retrieval. More generally, our analyses revealed largely distinct brain networks at encoding and retrieval in which schema activation was related to successful recall. These results provide new insight into when and where event knowledge can support narrative memory.

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bioRxiv2021

Developmental changes in story-evoked responses in the neocortex and hippocampus

How does the representation of naturalistic life events change with age? Here we analyzed fMRI data from 414 children and adolescents (5 - 19 years) as they watched a narrative movie. In addition to changes in the degree of inter-subject correlation (ISC) with age in sensory and medial parietal regions, we used a novel measure (between-group ISC) to reveal age-related shifts in the responses across the majority of the neocortex. Over the course of development, brain responses became more discretized into stable and coherent events and shifted earlier in time to anticipate upcoming perceived event transitions, measured behaviorally in an age-matched sample. However, hippocampal responses to event boundaries actually decreased with age, suggesting a shifting division of labor between episodic encoding processes and schematic event representations between the ages of 5 and 19.

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bioRxiv2020

Narratives: fMRI data for evaluating models of naturalistic language comprehension

The "Narratives" collection aggregates a variety of functional MRI datasets collected while human subjects listened to naturalistic spoken stories. The current release includes 345 subjects, 891 functional scans, and 27 diverse stories of varying duration totaling ~4.6 hours of unique stimuli (~43,000 words). This data collection is well-suited for naturalistic neuroimaging analysis, and is intended to serve as a benchmark for models of language and narrative comprehension. We provide standardized MRI data accompanied by rich metadata, preprocessed versions of the data ready for immediate use, and the spoken story stimuli with time-stamped phoneme- and word-level transcripts. All code and data are publicly available with full provenance in keeping with current best practices in transparent and reproducible neuroimaging.

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bioRxiv2020

Decision value signals in the ventromedial prefrontal cortex and anhedonia across mood and psychotic disorders

Deficits in motivation and pleasure are common across many psychiatric disorders, and manifest as symptoms of amotivation and anhedonia, which are prominent features of both mood and psychotic disorders. Here we provide evidence for a shared transdiagnostic mechanism underlying impairments in motivation and pleasure across major depression, bipolar disorder, and schizophrenia. We found that value signals in the ventromedial prefrontal cortex (vmPFC) during decision-making were dampened in individuals with greater motivational and hedonic deficits, regardless of the primary diagnosis. This relationship remained significant while controlling for diagnosis-specific symptoms of mood and psychosis, such as depression as well as positive and negative symptoms. Our results demonstrate that dysfunction in the vmPFC during value-based decision-making is specifically linked to motivational and hedonic impairments across various psychiatric conditions. These findings provide a quantitative neural target for the potential development of novel treatments for amotivation and anhedonia.

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bioRxiv2020

Anticipation of temporally structured events in the brain

1Learning about temporal structure is adaptive because it enables the generation of expectations. We examined how the brain uses experience in structured environments to anticipate upcoming events. During fMRI, individuals watched a 90-second movie clip six times. Using a Hidden Markov Model applied to searchlights across the whole brain, we identified temporal shifts between activity patterns evoked by the first vs. repeated viewings of the movie clip. In many regions throughout the cortex, neural activity patterns for repeated viewings shifted to precede those of initial viewing by up to 15 seconds. This anticipation varied hierarchically in a posterior (less anticipation) to anterior (more anticipation) fashion. We also identified specific regions in which the timing of the brains event boundaries were related to those of human-labeled event boundaries, with the timing of this relationship shifting on repeated viewings. With repeated viewing, the brains event boundaries came to precede human-annotated boundaries by 1-4 seconds on average. Together, these results demonstrate a hierarchy of anticipatory signals in the human brain and link them to subjective experiences of events.

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