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

Abstract

Successful navigation relies on the ability to identify, perceive, and correctly process the spatial structure of a scene. It is well known that visual mental imagery plays a crucial role in navigation. Indeed, cortical regions encoding navigationally relevant information are also active during mental imagery of navigational scenes. However, it remains unknown whether their intrinsic activity and connectivity reflect the individuals' ability to imagine a scene. Here, we primarily investigated the intrinsic causal interactions among scene-selective brain regions such as Parahipoccampal Place Area (PPA), Retrosplenial Complex, and Occipital Place Area (OPA) using Dynamic Causal Modelling for resting-state functional magnetic resonance data. Second, we tested whether resting-state effective connectivity parameters among scene-selective regions could reflect individual differences in mental imagery in our sample, as assessed by the self-reported Vividness of Visual Imagery Questionnaire. We found an inhibitory influence of occipito-medial on temporal regions, and an excitatory influence of more anterior on more medial and posterior brain regions. Moreover, we found that a key role in imagery is played by the connection strength from OPA to PPA, especially in the left hemisphere, since the influence of the signal between these scene-selective regions positively correlated with good mental imagery ability. Our investigation contributes to the understanding of the complexity of the causal interaction among brain regions involved in navigation and provides new insight in understanding how an essential ability, such as mental imagery, can be explained by the intrinsic fluctuation of brain signal.

Keywords: Dynamic Causal Modelling; Imagery; Navigation; Resting-state; Scene-selective regions; fMRI.

Fig. 1

Anatomical location of regions of interest. Nodes of each region are displayed in different colours: the Parahippocampal Place Area (PPA) is represented in sky-blue colour; Retro-splenial complex (RSC) is represented in green and Occipital Place Area (OPA) is shown in pink colour. The edges between regions represent the connections separately modelled for each hemisphere in the Dynamic Causal Modelling (DCM) analysis. Regions of each hemisphere, left (L) and right (R) were visualized using the BrainNet Viewer (Xia et al. 2013)

Fig. 2

PEB results of intrinsic effective connectivity. A-matrices of intrinsic effective connectivity in the left and right hemisphere are shown in panel A and panel B, respectively. Parameters with posterior probability higher than 95% are shown and are marked in bold type. Non suprathreshold parameters values are also reported in non-bold type in matrices. Connection strengths are displayed from pale red to dark red (i.e., excitatory), and from pale blue to blue (i.e., inhibitory). Schematic representations of A-matrices parameter results are also shown: red solid arrows represent excitatory connections and blue solid arrows represent inhibitory connections. Regions of interest are labelled as follows: Occipital Place Area (OPA), Parahippocampal Place Area (PPA) and Retrosplenial Complex (RSC)

Fig. 3

Effect of the Vivideness of Visual Imagery Questionnaire (VVIQ) on each connectivity parameter. Parameters with posterior probability higher than 95% are shown (pp > 0.95) whereas non-suprathreshold parameter values are labelled with “n.s.”. A positive relation between connectivity parameter and VVIQ is shown from yellow to dark red, and a negative relation is shown from turquoise to dark blue. On the right of the panels, a schematic representation for each hemisphere is also provided. Red solid line represents a positive relation between the outgoing connectivity and VVIQ scores whereas the blue solid line represents a negative relation between the outgoing connectivity and VVIQ scores. Dotted lines display parameter values with a posterior probability between 0.85 and 0.95 threshold: Connection strength from left OPA to left PPA is equal to -0.011 (pp = 0.94) and connection strength from left OPA to left RSC is equal to 0.009 (pp = 0.85)