Individual differences in mental imagery modulate effective connectivity of scene-selective regions during resting state

Impoverished recall of sensory details along infrequently travelled routes in aphantasia

Visual imagery is important for recalling environmental details, but individuals with aphantasia are reported to show intact spatial memory. We investigated spatial memories of previously experienced environments in individuals with and without aphantasia using self-report and route description tasks. Aphantasic participants (n = 113) and controls (n = 110) completed questionnaires on spatial navigation, memory, anxiety, and mood. A subgroup (aphantasic: n = 65, control: n = 72) completed a route description task assessing memory for details along frequently and infrequently travelled routes. Aphantasic participants did not differ significantly from controls on self-reported navigation ability or strategies. Both groups recalled similar numbers of spatial, entity, and sensory details when describing frequently travelled routes. However, aphantasic participants recalled fewer sensory details for infrequently travelled routes. This finding was corroborated by nominally lower ratings on self-reported memory for object locations and new routes. Findings suggest that spatial memory, including sensory content, remains intact in aphantasia for frequent routes. Impoverished sensory details for infrequent routes indicates that individuals with aphantasia may rely on compensatory strategies, like semanticization, for frequently experienced environments. This suggests that spatial memory for real-world environments involve dissociable processes, some of which are independent of imagery.

Precuneus activation correlates with the vividness of dynamic and static imagery: an fMRI study

Introduction

Visual mental imagery (VMI) is a cognitive function that significantly impacts various aspects of daily life. However, the neural correlates of VMI vividness remain unclear, especially underlying different VMI types. Therefore, the current functional magnetic resonance imaging (fMRI) study aimed to investigate the neural mechanisms underlying static (SI) and dynamic VMI (DI), focusing on the role of precuneus especially in the imagery vividness.

Methods

The study involved 24 participants recruited from ShanghaiTech University. After excluding four participants due to excessive movements, data from 20 participants were analyzed. Each participant completed the Chinese version of the Vividness of Visual Imagery Questionnaire (VVIQ) to assess their imagery vividness abilities. During fMRI scanning, participants were asked to imagine SI and DI scenarios in response to auditory stimuli. High-resolution fMRI data were acquired using a 3T scanner, and a General Linear Model (GLM) was applied to analyze blood oxygenation level-dependent (BOLD) signals, focusing on the precuneus's role in imagery vividness.

Results

The results revealed that the left precuneus was found activated in both SI and DI tasks. Moreover, the left precuneus activation was positively correlated with VVIQ score. On the other hand, greater activation in the right precuneus was found during dynamic than static imagery as well as more extensive neural engagements; the right precuneus activation was further detected significantly correlated with individual VVIQ scores.

Discussion

The study's findings offered fresh insights into the cognitive and neural processes subserving VMI. By revealing the distinct roles of the left and right precuneus in imagery vividness, this research contributed to a more nuanced understanding of VMI and its neural basis.

The Action Cycle Theory of Perception and Mental Imagery

The Action Cycle Theory (ACT) is an enactive theory of the perception and a mental imagery system that is comprised of six modules: Schemata, Objects, Actions, Affect, Goals and Others' Behavior. The evidence supporting these six connected modules is reviewed in light of research on mental imagery vividness. The six modules and their interconnections receive empirical support from a wide range of studies. All six modules of perception and mental imagery are influenced by individual differences in vividness. Real-world applications of ACT show interesting potential to improve human wellbeing in both healthy people and patients. Mental imagery can be applied in creative ways to make new collective goals and actions for change that are necessary to maximize the future prospects of the planet.

Unrestricted eye movements strengthen effective 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 underlying, directional, connectivity between the MTL memory system and oculomotor system associated with constructing vivid mental representations of scenes.