The Role of Temporal Synchrony as a Binding Cue for Visual Persistence in Early Visual Areas: An fMRI Study

Abstract

We examined the role of temporal synchrony-the simultaneous appearance of visual features-in the perceptual and neural processes underlying object persistence. When a binding cue (such as color or motion) momentarily exposes an object from a background of similar elements, viewers remain aware of the object for several seconds before it perceptually fades into the background, a phenomenon known as object persistence. We showed that persistence from temporal stimulus synchrony, like that arising from motion and color, is associated with activation in the lateral occipital (LO) area, as measured by functional magnetic resonance imaging. We also compared the distribution of occipital cortex activity related to persistence to that of iconic visual memory. Although activation related to iconic memory was largely confined to LO, activation related to object persistence was present across V1 to LO, peaking in V3 and V4, regardless of the binding cue (temporal synchrony, motion, or color). Although persistence from motion cues was not associated with higher activation in the MT+ motion complex, persistence from color cues was associated with increased activation in V4. Taken together, these results demonstrate that although persistence is a form of visual memory, it relies on neural mechanisms different from those of iconic memory. That is, persistence not only activates LO in a cue-independent manner, it also recruits visual areas that may be necessary to maintain binding between object elements.

Recognition of letters displayed as briefly flashed dot patterns

“…Some activation was seen in V1, V3A/B and hV4. Ferber et al (2003) found an increased hemodynamic response in LO from movement-triggered persistence that lasted a few seconds, and Wong et al (2009) were able to produce similar effects by briefly displaying a segmented figure upon a background of random line segments.…”

Figure–Ground Representation and Its Decay in Primary Visual Cortex

“…Previous studies defined persistence-related fMRI responses as those that were greater in the persist condition as compared with the vanish condition following the offset of figure motion, because the stimuli in the two conditions are identical during the motion phase (Strother et al, 2011;Wong et al, 2009;Ferber et al, 2003Ferber et al, , 2005Large et al, 2005). As in these previous studies, whole-brain analyses revealed persistence-related responses in LO (but not adjacent MT+) in all subjects, for all annulus sizes (persist > vanish; always p < 10 −3 ).…”

“…Interestingly, neither of these studies observed decreases in V1 fMRI responses, which one would expect if background suppression is crucial to perceived figure-ground segmentation. Several other fMRI studies reported increased figure-ground fMRI activity in extrastriate visual areas (Wong, Aldcroft, Large, Culham, & Vilis, 2009;Ferber, Humphrey, & Vilis, 2003Large, Aldcroft, & Vilis, 2005;Schira, Fahle, Donner, Kraft, & Brandt, 2004), but these studies also failed to observe fMRI responses corresponding to background suppression in V1. This is surprising because perceived figure-ground boundaries automatically engage attentional mechanisms (Egeth & Yantis, 1997), which are known to produce concomitant enhancement and suppression of neural responses in V1, even in the absence of visual stimulation (Silver, Ress, & Heeger, 2007;Kastner, Pinsk, De Weerd, Desimone, & Ungerleider, 1999).…”

“…In addition to V1, we measured fMRI responses in lateral occipital cortex (LO), which mediates shape perception (Kourtzi & Kanwisher, 2000) and represents figures rather than backgrounds (Appelbaum et al, 2006;Goh et al, 2004). Previous studies observed figureground fMRI responses in LO using stimuli similar to ours University of Western Ontario (Strother et al, 2011;Wong et al, 2009;Ferber et al, 2003Ferber et al, , 2005Large et al, 2005), but these studies were not designed to delineate V1 fMRI responses to a figure and its surrounding background.…”

In and out of consciousness: Sustained electrophysiological activity reflects individual differences in perceptual awareness

“…A number of functional neuroimaging studies have attempted to identify the neural substrates subserving persistence during SFM (Ferber, Humphrey, & Vilis, 2005;Large, Aldcroft, & Vilis, 2005;Strother et al, 2011;Wong, Aldcroft, Large, Culham, & Vilis, 2009). These studies have revealed that perceptual persistence is associated with sustained activation in the ventral visual pathway, particularly in the object-sensitive lateral occipital complex (LOC; Ferber et al, 2005;Large et al, 2005), as well as in the primary visual cortex (Strother et al, 2011).…”