Biology subjects

Ladyka-Wojcik, N.

Publications and source records attributed to Ladyka-Wojcik, N..

5 recordsLinked to original sources

bioRxiv2025

Neural signatures of recollection are sensitive to memory quality and specific event features

Episodic memories reflect a bound representation of multimodal features that can be recollected with varying levels of precision. Recent fMRI investigations have demonstrated that the precision and content of information retrieved from memory engage a network of posterior medial temporal and parietal regions co-activated with the hippocampus. Yet, comparatively little is known about how memory content and precision affect common neural signatures of memory captured by electroencephalography (EEG), where recollection has been associated with changes in event-related potential (ERP) and oscillatory measures of neural activity. Here, we used a multi-feature paradigm previously reported in Cooper & Ritchey (2019) with continuous measures of memory, in conjunction with scalp EEG, to characterize the content and quality of information that drives ERP and oscillatory markers of episodic memory. A common signature of memory retrieval in left posterior regions, called the late positive component (LPC), was sensitive to overall memory quality and also to precision of recollection for spatial features. Analysis of oscillatory markers during recollection revealed that alpha/beta desynchronization was modulated by overall memory quality and also by individual features in memory. Importantly, we found evidence of a relationship between these two neural markers of memory retrieval, suggesting that they may represent complementary aspects of the recollection experience. These findings demonstrate how time-sensitive and dynamic processes identified with EEG correspond to overall episodic recollection, and also to the retrieval of precise features in memory.

neuroscience↗

bioRxiv2025

Effective connectivity between the medial temporal lobes and early visual cortex modulated by unrestricted viewing predicts memory retrieval and gaze reinstatement

Memory and gaze behavior are intricately linked, guiding one another to extract information and create mental representations of our environment for subsequent retrieval. Recent findings from functional neuroimaging and computational modeling suggest that reciprocal interactions between the extended hippocampal system and visuo-oculomotor regions are functionally relevant for building these mental representations during visual exploration. Yet, evidence for the directionality of information flow during encoding within this reciprocal architecture in humans is limited. In the current study, we used dynamic causal modeling (DCM) to give a non-invasive account for the directional influences between these systems when new memories are created. Here, we provide novel evidence demonstrating how unrestricted, naturalistic visual exploration induces changes in this connectivity. Subsequent memory retrieval performance was also predicted by the pattern of connectivity modulated by unrestricted visual exploration, identifying the mechanism underlying a rich history of previous work linking increased gaze behavior during encoding to later memory. Together, these findings suggest that gaze behavior shapes the ways in which brain dynamics within and between the hippocampal system and early visual cortex unfold during encoding in humans. Importantly, these directional interactions support the building of coherent, lasting mental representations.

neuroscience↗

bioRxiv2022

Multimodal Object Representations Rely on Integrative Coding

Combining information from multiple senses is essential to object recognition. Yet how the mind combines sensory input into coherent multimodal representations - the multimodal binding problem - remains poorly understood. Here, we applied multi-echo fMRI across a four-day paradigm, in which participants learned 3-dimensional multimodal object representations created from well-characterized visual shape and sound features. Our novel paradigm decoupled the learned multimodal object representations from their baseline unimodal shape and sound features, thus tracking the emergence of multimodal concepts as they were learned by healthy adults. Critically, the representation for the whole object was different from the combined representation of its individual parts, with evidence of an integrative object code in anterior temporal lobe structures. Intriguingly, the perirhinal cortex - an anterior temporal lobe structure - was by default biased towards visual shape, but this initial shape bias was attenuated with learning. Pattern similarity analyses suggest that after learning the perirhinal cortex orthogonalized combinations of visual shape and sound features, transforming overlapping feature input into distinct multimodal object representations. These results provide evidence of integrative coding in the anterior temporal lobes that is distinct from the distributed sensory features, advancing the age-old question of how the mind constructs multimodal objects from their component features.

neuroscience↗

bioRxiv2021

Unrestricted eye movements strengthen causal connectivity from hippocampal to oculomotor regions during scene construction

Scene construction is a key component of memory recall, navigation, and future imagining, and relies on the medial temporal lobes (MTL). A parallel body of work suggests that eye movements may enable the imagination and construction of scenes, even in the absence of external visual input. There are vast structural and functional connections between regions of the MTL and those of the oculomotor system. However, the directionality of connections between the MTL and oculomotor control regions, and how it relates to scene construction, has not been studied directly in human neuroimaging. In the current study, we used dynamic causal modeling (DCM) to interrogate effective connectivity between the MTL and oculomotor regions using a scene construction task in which participants eye movements were either restricted (fixed-viewing) or unrestricted (free-viewing). By omitting external visual input, and by contrasting free- versus fixed- viewing, the directionality of neural connectivity during scene construction could be determined. As opposed to when eye movements were restricted, allowing free viewing during construction of scenes strengthened top-down connections from the MTL to the frontal eye fields, and to lower-level cortical visual processing regions, suppressed bottom-up connections along the visual stream, and enhanced vividness of the constructed scenes. Taken together, these findings provide novel, non-invasive evidence for the causal architecture between the MTL memory system and oculomotor system associated with constructing vivid mental representations of scenes. HighlightsO_LIThe role of eye movements in mentally constructing scene imagery was investigated C_LIO_LIRestricting eye movements impaired vividness of constructed scene imagery C_LIO_LIMaking eye movements strengthened connectivity from memory to oculomotor regions C_LI

neuroscience↗

bioRxiv2019

Recollection and prior knowledge recruit the left angular gyrus during recognition

The human angular gyrus (AG) is implicated in recollection, or our ability to retrieve detailed memory content from a specific study episode. Parallel work also highlights a key role of the AG in the representation of general knowledge and semantics. How these two lines of research converge remains unclear. The present fMRI experiment used a remember-know paradigm with famous and non-famous faces to test whether activity in the AG could be modulated by both task-specific recollection and general prior knowledge in the same participants. Increased BOLD activity in the left AG was observed during both recollection in the absence of prior knowledge (i.e., recollected > non-recollected or correctly rejected non-famous faces) and when prior knowledge was accessed in the absence of recollection (i.e., famous > non-famous correct rejections). This pattern was unique to the left AG, and was not present in any other regions of the lateral inferior parietal lobe. Furthermore, the response profile of the left AG was consistent with accounts of recollection strength. Recollection-related activity was greater for faces with longer exposures at encoding than those with shorter exposures and was greater for stimuli with prior knowledge than those without, despite prior knowledge being incidental to the recognition decision. Therefore, the left AG is recruited during the access of both task-specific recollection and general prior knowledge, with greater activity as the amount of retrieved information increases, irrespective of its episodic or semantic nature. Significance StatementThe human angular gyrus (AG) is often implicated in our ability to remember past events. A separate line of research examining our ability to represent general knowledge has also highlighted the AG as a core region of interest. To reconcile these separate views of AG function, we used fMRI to test whether the human left AG was sensitive to remembering details from a specific study episode (i.e., recollection) or more general prior knowledge, within the same participants. Overall, activity in the left AG was sensitive to both recollection and prior knowledge, suggesting any complete functional account of the left AG during retrieval must consider its sensitivity to both kinds of mnemonic representations.

neuroscience↗