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

Differential eye movements and greater pupil size during mental scene construction in autobiographical recall

There is growing evidence supporting a role for eye movements during autobiographical recall, but their potential functionality remains unclear. We hypothesise that the oculomotor system facilitates the process of mental scene construction, in which complex scenes associated with an autobiographical event are generated and maintained during recall. To explore this, we examined spontaneous eye movements during retrieval of cued autobiographical memories. Participants' verbal descriptions of each memory were recorded in synchronisation with their eye movements and pupil size during recall. For each memory participants described the place (details of the environment where the event took place) and the event (details of what happened). Narratives were analyzed using the Autobiographical Interview procedure, which separated internal spatial (place) and non-spatial (event, thoughts and emotion) details. Eye movements during recall of spatial details had significantly higher fixation duration and smaller saccade amplitude and peak velocity, and a higher number of consecutive unidirectional saccades, in comparison to recall of non-spatial details. Recurrence quantification analysis indicated longer sequences of refixations and more repetitions of the same fixation pattern when participants described spatial details. Recall of spatial details was also associated with significantly greater pupil area. Overall findings are consistent with the spontaneous production of more structured saccade patterns and greater cognitive load during the recall of internal spatial episodic scene details in comparison to episodic non-spatial details. These results are consistent with the oculomotor system facilitating the activation and correct positioning of elements of a complex scene relative to other imagined elements during autobiographical recall.

Internal coupling: Eye behavior coupled to visual imagery

Our eyes do not only respond to visual perception but also to internal cognition involving visual imagery, which can be referred to as internal coupling. This review synthesizes evidence on internal coupling across diverse domains including episodic memory and simulation, visuospatial memory, numerical cognition, object movement, body movement, and brightness imagery. In each domain, eye movements consistently reflect distinct aspects of mental imagery typically akin to those seen in corresponding visual experiences. Several findings further suggest that internal coupling may not only coincide with but also supports internal cognition as evidenced by improved cognitive performance. Available theoretical accounts suggest that internal coupling may serve at least two functional roles in visual imagery: facilitating memory reconstruction and indicating shifts in internal attention. Moreover, recent insights into the neurobiology of internal coupling highlight substantially shared neural pathways in externally and internally directed cognition. The review concludes by identifying open questions and promising avenues for future research such as exploring moderating roles of context and individual differences in internal coupling.

Scene construction in healthy aging - Exploring the interplay between task complexity and oculomotor behaviour

Mounting evidence indicates a close correspondence between episodic memory, mental imagery, and oculomotor behaviour. It remains unclear, however, how oculomotor variables support endogenously driven forms of mental imagery and how this relationship changes across the adult lifespan. In this study we investigated age-related changes in oculomotor signatures during scene construction and explored how task complexity impacts these processes. Younger and cognitively healthy older participants completed a guided scene construction paradigm where scene complexity was manipulated according to the number of elements to be sequentially integrated. We recorded participants' eye movements and collected subjective ratings regarding their phenomenological experience. Overall, older adults rated their constructions as more vivid and more spatially integrated, while also generating more fixations and saccades relative to the younger group, specifically on control trials. Analyses of participants' total scan paths revealed that, in the early stages of scene construction, oculomotor behaviour changed as a function of task complexity within each group. Following the introduction of a second stimulus, older but not younger adults showed a significant decrease in the production of eye movements. Whether this shift in oculomotor behaviour serves a compensatory function to bolster task performance represents an important question for future research.

Scene construction and autobiographical memory retrieval in autism spectrum disorder

Individuals with autism spectrum disorder (ASD) frequently exhibit difficulties in retrieving autobiographical memories (AMs) of specific events from their life. Such memory deficits are frequently attributed to underlying disruptions in self-referential or social cognition processes. This makes intuitive sense as these are hallmarks of ASD. However, an emerging literature suggests that parallel deficits also exist in ASD individuals' ability to reconstruct the rich spatial contexts in which events occur. This is a capacity known as scene construction, and in typically developing individuals is considered a core process in retrieving AMs. In this review, we discuss evidence of difficulties with scene construction in ASD, drawing upon experiments that involve AM retrieval, other forms of mental time travel, and spatial navigation. We also highlight aspects of extant data that cannot be accounted for using purely social explanations of memory deficits in ASD. We conclude by identifying key questions raised by our framework and suggest how they might be addressed in future research.

Understanding the encoding of object locations in small-scale spaces during free exploration using eye tracking

Navigation is instrumental to daily life and is often used to encode and locate objects, such as keys in one's house. Yet, little is known about how navigation works in more ecologically valid situations such as finding objects within a room. Specifically, it is not clear how vision vs. body movements contribute differentially to spatial memory in such small-scale spaces. In the current study, participants encoded object locations by viewing them while standing (stationary condition) or by additionally being guided by the experimenter while blindfolded (walking condition) after viewing the objects. They then retrieved the objects from the same or different viewpoint, creating a 2 × 2 within subject design. We simultaneously recorded participant eye movements throughout the experiment using mobile eye tracking. The results showed no statistically significant differences among our four conditions (stationary, same viewpoint as encoding; stationary, different viewpoint; walking, same viewpoint; walking, different viewpoint), suggesting that in a small real-world space, vision may be sufficient to remember object locations. Eye tracking analyses revealed that object locations were better remembered next to landmarks and that participants encoded items on one wall together, suggesting the use of local wall coordinates rather than global room coordinates. A multivariate regression analysis revealed that the only significant predictor of object placement accuracy was average looking time. These results suggest that vision may be sufficient for encoding object locations in a small-scale environment and that such memories may be formed largely locally rather than globally.

Seeing the future: Connectome strength and network efficiency in visual network predict individual ability of episodic future thinking

Episodic future thinking (EFT) refers to the critical ability that enables people to construct and pre-experience the vivid mental imagery about future events, which impacts on the decision-making for individuals and group. Although EFT is generally believed to have a visual nature by theorists, little neuroscience evidence has been provided to verify this assumption. Here, by employing the approach of connectome-based predictive modeling (CPM) and graph-theoretical analysis, we analyzed resting-state functional brain image from 191 participants to predict their variability of EFT ability (leave-one-out cross-validation), and validated the results by applying different parcellation schemas and feature selection thresholds. At the connectome strength level, CPM-based analysis revealed that EFT ability could be predicted by the connectome strength of visual network. Besides, at the network level, graph-theoretical analysis showed that EFT ability could be predicted by the network efficiency of visual network. Moreover, these findings were replicated using different parcellation schemas and feature selection thresholds. These results robustly and collectively supported that the visual network might be one of the neural substrates underlying EFT ability from a comprehensive perspective of resting-state functional connectivity strength and the neural network. This study provides indications on how the function of visual network supports EFT ability, and enhances our understanding of the EFT ability from a neural basis perspective.