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Lauri Oksama, Lauri Nummenmaa, Jukka Hyönä; Cortical circuit for tracking dynamic object locations and identities. Journal of Vision 2015;15(12):224. doi: 10.1167/15.12.224.
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© 2017 Association for Research in Vision and Ophthalmology.
During real-world vision observers often need to attend and track several moving objects. Sometimes the objects also have different identities (such as individual players in a football game), thus the observer needs to bind the object identities to their movement trajectories to know where each object is currently located. It has been proposed that dynamic identity-location binding is based on serial attention shifting with the help of working memory (Oksama & Hyönä, 2008). However, the brain mechanisms supporting tracking of object locations (multiple object tracking; MOT) and their identities (multiple identity tracking; MIT) have remained unresolved. Here we reveal cortical circuits supporting MIT and MOT while viewing moving objects with distinct identities. Twenty-four participants tracked identities (MIT) or locations (MOT) of 0, 2 or 4 moving targets while their haemodynamic brain activation was measured with functional magnetic resonance imaging (fMRI). Concurrent eye tracking revealed that participants made more saccades in the MIT versus MOT condition. Both MIT and MOT tasks engaged similar components of the dorsal attention system, yet MIT task resulted in increased activity in frontocortical circuits supporting working memory and temporal areas involved in object recognition, as quantified on separate localizer scans. Additional activations were observed in intraparietal regions involved in attention shifting. Only the latter regions’ activity was modulated by the number of saccades made during trials, suggesting that eye movements do not confound frontal and temporal responses. We conclude that MIT task relies on interactions between executive functions and ventral visual areas.
Meeting abstract presented at VSS 2015
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