RESEARCH ARTICLE


Bottom-up Retinotopic Organization Supports Top-down Mental Imagery



Ruey-Song Huang1, *, Martin I. Sereno2, 3, 4
1 Institute for Neural Computation, University of California, San Diego, La Jolla, CA 92093, USA
2 Department of Cognitive Science, University of California, San Diego, La Jolla, CA 92093, USA
3 Cognitive, Perceptual, and Brain Sciences, University College London, London WC1H 0AP, United Kingdom
4 Department of Psychological Sciences, Birkbeck College, University of London, London WC1E 7HX, United Kingdom


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© Huang and Sereno; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Institute for Neural Computation, University of California, San Diego, 9500 Gilman Drive #0559, La Jolla, CA 92093-0559, USA; Tel/Fax: (858) 822-5977; E-mail: rhuang@ucsd.edu


Abstract

Finding a path between locations is a routine task in daily life. Mental navigation is often used to plan a route to a destination that is not visible from the current location. We first used functional magnetic resonance imaging (fMRI) and surface-based averaging methods to find high-level brain regions involved in imagined navigation between locations in a building very familiar to each participant. This revealed a mental navigation network that includes the precuneus, retrosplenial cortex (RSC), parahippocampal place area (PPA), occipital place area (OPA), supplementary motor area (SMA), premotor cortex, and areas along the medial and anterior intraparietal sulcus. We then visualized retinotopic maps in the entire cortex using wide-field, natural scene stimuli in a separate set of fMRI experiments. This revealed five distinct visual streams or ‘fingers’ that extend anteriorly into middle temporal, superior parietal, medial parietal, retrosplenial and ventral occipitotemporal cortex. By using spherical morphing to overlap these two data sets, we showed that the mental navigation network primarily occupies areas that also contain retinotopic maps. Specifically, scene-selective regions RSC, PPA and OPA have a common emphasis on the far periphery of the upper visual field. These results suggest that bottom-up retinotopic organization may help to efficiently encode scene and location information in an eye-centered reference frame for top-down, internally generated mental navigation. This study pushes the border of visual cortex further anterior than was initially expected.

Keywords: fMRI, mental navigation, retinotopic maps, five visual streams, far periphery.