Browsing by Author "Burles, Clayton Ford"

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    Disambiguating the Role of the Retrosplenial Complex in Human Navigation
    (2018-06-14) Burles, Clayton Ford; Iaria, Giuseppe; Protzner, Andrea B.; MacMaster, Frank P.
    The role of the human retrosplenial cortex in spatial orientation and navigation has been obscured by a long history of ambiguous localization, beginning as early as Brodmann’s original depiction which intentionally overrepresented it’s extent. While some modern atlases of the brain exclude this region, many include a surprisingly generous delineation; this has resulted in a very large area of the medial parietal cortex implicitly viewed as being equipotentially involved in spatial orientation and navigation. In this thesis, I provide novel evidence of a more precise paradigm by which we can understand the role of the ‘retrosplenial cortex’, i.e. the posterior cingulate, in spatial orientation and navigation. First, from fMRI activity evoked in a novel spatial task, but subsequently from a meta-analysis of the literature more generally, we have identified that ventral portions of the posterior cingulate are relatively more engaged in encoding spatial information, whereas dorsal portions are more involved in recalling and computing spatial information or representations. Not simply descriptive, this delineation proved valuable in characterizing the neural correlates of a lifelong developmental condition in which individuals get lost on a daily basis in very familiar surroundings, a condition known as Developmental Topographical Disorientation (DTD). In fact, we identified that the dorsal posterior cingulate displays far greater differences then the ventral posterior cingulate in functional connectivity between individuals with DTD and healthy controls; these findings would not have been uncovered with traditional delineations of the retrosplenial cortex. Other studies will undoubtedly benefit from appreciating these functional subregions when analyzing or interpreting activity within the posterior cingulate evoked by spatial orientation tasks. A clear understanding of the neural correlates of spatial orientation and navigation in humans will benefit greatly from future research validating this posterior cingulate delineation, as well as extending increasingly meticulous attention to the location of activity evoked in the posterior cingulate and other brain regions.
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    The Development of a Practical Measure of Environmental-Scale Spatial Ability: the Spatial Configuration Task
    (2014-01-29) Burles, Clayton Ford; Iaria, Giuseppe
    The ability to orient and navigate throughout an environment is a fundamental yet complex cognitive skill. This ability may be valuable in certain academic fields (Hegarty, Crookes, Dara-Abrams, & Shipley, 2010) and military occupations (Shanmugaratnam & Parush, 2012), and an assessment of these environmental-scale spatial skills for use in selection or training would be valuable. With this in mind, a new task (the Spatial Configuration Task) was developed and it’s suitability for group testing environmental-scale spatial skills was assessed. The Spatial Configuration Task was demonstrated to be reliable (test-retest reliability r = .814), valid (significantly correlated with the Cognitive Map Formation and Use Tasks; r =-.414, r = .339 respectively), and practical (average duration of 9.69 minutes). This task may have useful applications in selection as well as research, as there are few standardized measures of environmental-scale spatial ability suitable for mass testing.