Examining the role of the temporo-parietal network in memory, imagery, and viewpoint transformations

Abstract

The traditional view of the medial temporal lobe (MTL) focuses on its role in episodic memory. However, some of the underlying functions of the MTL can be ascertained from its wider role in supporting spatial cognition in concert with parietal and prefrontal regions. The MTL is strongly implicated in the formation of enduring allocentric representations (e.g., O'Keefe, 1976; King et al., 2002; Ekstrom et al., 2003). According to our BBB model (Byrne et al., 2007), these representations must interact with head-centered and body-centered representations in posterior parietal cortex via a transformation circuit involving retrosplenial areas. Egocentric sensory representations in parietal areas can then cue the recall of allocentric spatial representations in long-term memory and, conversely, the products of retrieval in MTL can generate mental imagery within a parietal “window.” Such imagery is necessarily egocentric and forms part of visuospatial working memory, in which it can be manipulated for the purpose of planning/imagining the future. Recent fMRI evidence (Lambrey et al., 2012; Zhang et al., 2012) supports the BBB model. To further test the model, we had participants learn the locations of objects in a virtual scene and tested their spatial memory under conditions that impose varying demands on the transformation circuit. We analyzed how brain activity correlated with accuracy in judging the direction of an object (1) from visuospatial working memory (we assume transient working memory due to the order of tasks and the absence of change in viewpoint, but long-term memory retrieval is also possible), (2) after a rotation of viewpoint, or (3) after a rotation and translation of viewpoint (judgment of relative direction). We found performance-related activity in both tasks requiring viewpoint rotation (ROT and JRD, i.e., conditions 2 and 3) in the core medial temporal to medial parietal circuit identified by the BBB model. These results are consistent with the predictions of the BBB model, and shed further light on the neural mechanisms underlying spatial memory, mental imagery and viewpoint transformations.

Relationship Between Response Time and the Alpha Attenuation of Congruence Judgments in Two-Model Imagery

“…This finding is also consistent with the results of Roberts and Bell's study, which reported that the response amplitude in the right parietal lobe in both men and women was larger than that in other brain areas during the performance of a complex three-dimensional block design mental rotation task (Roberts and Bell, 2003). According to Overney, et al (2005), Overnry and Blanke (2009), and Dhindsa, et al (2014), the left posterior parietal lobe is strongly activated during mental rotation and mental transmission involving the body part of another person compared to the observer's own body part. Consequently, in the current study, the results obtained in the mental rotation task involving wooden dolls suggested that the participants' judgments did not involve their own body image.…”

EEG correlates of spatial orientation in the human retrosplenial complex

“…Studies on spatial navigation demonstrated the involvement of the RSC in various kinds of navigation tasks (Maguire, 2001;Spiers and Maguire, 2006;Vann et al, 2009), especially in tasks requiring transformation of egocentric and allocentric information into alternative reference frames (Byrne et al, 2007;Vann et al, 2009;Zhang et al, 2012;Dhindsa et al, 2014). Previous studies also showed modulations of the alpha frequency band (8-13 Hz) during spatial navigation in or near RSC .…”

“…The use of an egocentric SRF, in contrast primarily involves the parietal cortex which integrates self-motion cues from the visual, vestibular, and kinesthetic systems (Bremmer et al, 2001;Cohen and Andersen, 2002;Seubert et al, 2008). The retrosplenial complex (RSC), comprising the caudal cingulate cortex (BA 29 and 30) as well as part of the medial parietal cortex (BA 23 and 31), plays an important role in the exchange and integration of egocentric and allocentric information (Byrne et al, 2007;Vann et al, 2009;Zhang et al, 2012;Dhindsa et al, 2014) and in computing heading directions based on local landmarks (Marchette et al, 2014).…”

The Cognitive Architecture of Spatial Navigation: Hippocampal and Striatal Contributions

“…These responses may allow determination of the location of visual objects relative to the body or in a world-referenced frame (Pouget and Sejnowski, 1997). In particular, area 7a, which contains neurons with world-referenced gain fields (Snyder et al, 1998), projects to the parahippocampal gyrus and presubiculum and so may allow translation between egocentric parietal representations and allocentric medial temporal representations (Burgess et al, 2001;Wilber et al, 2014), potentially mediated by retrosplenial cortex (Byrne et al, 2007;Dhindsa et al, 2014;Lambrey et al, 2012). The distinction between egocentric and allocentric representations is useful in outlining the cognitive architecture of navigation.…”