Distinct Functional Network Connectivity for Abstract and Concrete Mental Imagery

Mental imagery shapes emotions in people's decisions related to risk taking

This research investigates the specific effects of mental imagery on people's emotional responses and risk-taking decisions. We present findings across four studies, including three experiments, that highlight emotions as a mediator between the valence of mental images related to risk and subsequent risk-taking propensity. Our research identifies two key factors that moderate this relationship: the category of cognitive process (analytical thinking vs. visual mental imagery) and the vividness of mental imagery. In Study 1, we found an effect of the valence of mental images on the intensity of emotional reactions, which in turn were linked to risk-taking willingness. Positive imagery corresponded with stronger positive emotions and increased declared risk taking. The experimental Study 2 provided causal evidence for these associations, showing that participants positively imagining risk-related behaviors reported more intense positive feelings and a greater inclination to take risks than those imagining risk taking in a negative manner. Subsequent preregistered experiments (Studies 3 and 4) corroborated our central hypothesis that mental imagery is a distinct driver of emotional responses in risk-related decision making and showed potential boundary conditions for this effect. Study 3 emphasized that decisions influenced by mental imagery had greater emotional strength than those based on analytical reasoning. The final Study 4 demonstrated that vividness of mental imagery further moderates this effect: more vivid images led to stronger emotions, thus affecting risk-taking propensity. These results underscore the significance of emotions in decision making, particularly when decisions are based on mental imagery rather than analysis, and point to the amplifying effect of image vividness on emotional and decision-making processes.

Structural and functional neural substrates underlying the concreteness effect

The concreteness effect refers to the advantage in speed and accuracy of processing concrete words over abstract words. Previous studies have shown that the processing of the two types of words is mediated by distinct neural mechanisms, but these studies were mainly conducted with task-based functional magnetic resonance imaging. This study investigates the associations between the concreteness effect and grey matter volume (GMV) of brain regions as well as resting-state functional connectivity (rsFC) of these identified regions. The results show that the GMV of left inferior frontal gyrus (IFG), right middle temporal gyrus (MTG), right supplementary motor area and right anterior cingulate cortex (ACC) negatively correlates with the concreteness effect. The rsFC of the left IFG, the right MTG and the right ACC with the nodes, mainly in default mode network, frontoparietal network and dorsal attention network positively correlates with the concreteness effect. The GMV and rsFC jointly and respectively predict the concreteness effect in individuals. In conclusion, stronger connectivity amongst functional networks and higher coherent engagement of the right hemisphere predict a greater difference in the verbal memory of abstract and concrete words.

Overlapping connectivity patterns during semantic processing of abstract and concrete words revealed with multivariate Granger Causality analysis

. Abstract, unlike concrete, nouns refer to notions beyond our perception. Even though there is no consensus among linguists as to what exactly constitutes a concrete or abstract word, neuroscientists found clear evidence of a "concreteness" effect. This can, for instance, be seen in patients with language impairments due to brain injury or developmental disorder who are capable of perceiving one category better than another. Even though the results are inconclusive, neuroimaging studies on healthy subjects also provide a spatial and temporal account of differences in the processing of abstract versus concrete words. A description of the neural pathways during abstract word reading, the manner in which the connectivity patterns develop over the different stages of lexical and semantic processing compared to that of concrete word processing are still debated. We conducted a high-density EEG study on 24 healthy young volunteers using an implicit categorization task. From this, we obtained high spatio-temporal resolution data and, by means of source reconstruction, reduced the effect of signal mixing observed on scalp level. A multivariate, time-varying and directional method of analyzing connectivity based on the concept of Granger Causality (Partial Directed Coherence) revealed a dynamic network that transfers information from the right superior occipital lobe along the ventral and dorsal streams towards the anterior temporal and orbitofrontal lobes of both hemispheres. Some regions along these pathways appear to be primarily involved in either receiving or sending information. A clear difference in information transfer of abstract and concrete words was observed during the time window of semantic processing, specifically for information transferred towards the left anterior temporal lobe. Further exploratory analysis confirmed a generally stronger connectivity pattern for processing concrete words. We believe our study could guide future research towards a more refined theory of abstract word processing in the brain.