Using fMRI to distinguish components of the multiple object tracking task

Abstract

Multiple object tracking (MOT) has proven to be a powerful technique for studying sustained selective attention. However, surprisingly little is known about its underlying neural mechanisms. Previous fMRI investigations have identified several brain areas thought to be involved in MOT, but there were disagreements between the studies, none distinguished between the act of tracking targets and the act of attending targets, and none attempted to determine which of these brain areas interact with each other. Here we address these three issues. First, using more observers and a random effects analysis, we show that some of the previously identified areas may not play a specific role in MOT. Second, we show that the frontal eye fields (FEF), the anterior intraparietal sulcus (AIPS), the superior parietal lobule (SPL), the posterior intraparietal sulcus (PIPS) and the human motion area (MT+) are differentially activated by the act of tracking, as distinguished from the act of attention. Finally, by using an algorithm modified from the computer science literature, we were able to map the interactions between these brain areas.

Expansion of MT Neurons Excitatory Receptive Fields during Covert Attentive Tracking

“…Finally, our results provide neuronal correlates of previously reported increases in ERPs and BOLD-signal amplitude during tracking (Culham et al, 1998;Drew et al, 2009;Howe et al, 2009;Doran and Hoffman, 2010). Furthermore, they support behavioral reports linking attention and tracking performance (Yantis, 1992;Sears and Pylyshyn, 2000;Cavanagh and Alvarez, 2005;Tombu and Seiffert, 2008;Iordanescu et al, 2009;Niebergall et al, 2010).…”

“…A single or multiple moving spotlights of attention may highlight tracked objects and enhance their neuronal representations in visual cortex. Supporting this hypothesis, previous studies of multiple-object tracking (MOT) in humans have demonstrated that visual event-related potentials (ERPs) and BOLD signals evoked by attentively tracked objects are enhanced relative to those evoked by distracters (Culham et al, 1998;Drew et al, 2009;Howe et al, 2009;Doran and Hoffman, 2010). The mechanisms of these effects at the level of single visual neurons remain poorly understood.…”

Attentional trade-offs maintain the tracking of moving objects across saccades

“…Using functional MRI in humans, Culham et al (1998) showed that attentive tracking of moving objects activated FEF and the intraparietal sulcus (IPS; the human homologue of LIP) more than twice as much as passive viewing of the same stimuli. Attentional load strongly modulates the activation in IPS but very little in FEF (Culham et al 2001;Jovicich et al 2001;Howe et al 2009;Jahn et al 2012). This difference has been interpreted to suggest that IPS is directly involved in tracking, whereas FEF may perform more general tasks such as the control of eye movements during tracking (Culham et al 2001;Howe et al 2009).…”

Exhausting attentional tracking resources with a single fast-moving object

“…On the other hand, at stationary and slow speeds where behavioral performance is at ceiling, perhaps not all the resource is deployed. The uncertainty regarding this point makes it difficult to interpret an fMRI study that contrasted stationary with moving targets (Howe et al, 2009). …”