Top-down modulation of visual feature processing: The role of the inferior frontal junction

Abstract

Distinct areas within the visual association cortex are specialized for representing specific stimulus features, such as V4 for color and V5/hMT+ for motion. Recent studies have demonstrated that areas associated with attended features exhibit enhanced cortical activity, whereas those associated with ignored features elicit reduced activity. However, the source of this attentional (or top-down) modulation remains uncertain. A network of fronto-parietal cortical regions has been proposed as the prime candidate underlying this top-down modulation. Here, we evaluate whether there are distinct or overlapping top-down network regions for attention to different stimulus features. To this end, we explored functional magnetic resonance imaging (fMRI) functional connectivity data, electroencephalographic (EEG) source localization, and phase coherence that were obtained while participants attended or ignored motion and color stimuli. Functional connectivity analysis indicated that attention to color relies strongly on prefrontal regions, whereas attention to motion recruits both prefrontal and parietal areas. Although these networks are generally topologically segregated, both color and motion processes recruit right inferior frontal junction (IFJ). However, the IFJ may be more critical for color processing, as only connectivity with V4 predicted the degree of attentional modulation. Source localization at the time range of attentional modulation of the event related potential corroborated the role of the right IFJ and indicated that feature-based, top-down modulation occurs early during processing (< 200 ms post-stimulus onset). Furthermore, long-distance alpha (8-12 Hz) phase coherence between the IFJ and visual cortices may serve as a mechanism underlying anticipatory, top-down modulation of color feature processing.

Feature-Specific Attentional Priority Signals in Human Cortex

“…A domain-general organization of attention priority signals is corroborated by previous studies that have directly compared brain activity between spatial and feature-based attention tasks (Wojciulik and Kanwisher, 1999;Giesbrecht et al, 2003;Egner et al, 2008), as well as between attention to different feature dimensions (Zanto et al, 2010). These studies have shown that primarily similar brain areas in the dorsal attention network show increased activity during different types of attention tasks.…”

“…Some domain specificity has also been suggested by subtle activity differences among different types of attention tasks (Wojciulik and Kanwisher, 1999;Giesbrecht et al, 2003;Egner et al, 2008;Zanto et al, 2010). Indeed, our wholebrain analyses resulted in some differences between maps for motion and color, suggesting some domain specificity outside of the topographic and functionally defined areas we studied in the regionbased analyses.…”

Lifespan age differences in working memory: A two-component framework

“…Long-range synchronization is also increased during WM tasks (Palva et al, 2005) and sustained interareal phase synchrony among visual and frontoparietal regions during the retention interval is strengthened with load (Palva et al, 2010). In a similar vein, Zanto et al (2010b) observed higher alpha band phase-locking between frontal and posterior regions of interest (ROI) for to-be remembered versus to-be-ignored items, suggesting that alpha phase coherence may serve as a mechanism of anticipatory top-down control. This assumption was corroborated by related evidence showing that perturbing PFC function via repetitive TMS disrupts the attentional modulation of alpha phase coherence (Rihs et al, 2009).…”

Domain-general involvement of the posterior frontolateral cortex in time-based resource-sharing in working memory: An fMRI study

“…This might also explain why, in our more sensitive model-based analysis, only the right IFJ was revealed in both tasks. Recently, Zanto et al (2010) reported that top-down modulation of motion elicits bilateral IFJ connectivity while top-down modulation of color preferentially engages right IFJ connectivity. Thus, like in our study, only the right IFJ was recruited across different types of information.…”

“…Recently, Zanto et al, (2010Zanto et al, ( , 2011 showed that the IFJ acts as a control region that mediates the causal connection between top-down modulation in the service of attentional goals and subsequent WM performance. They proposed that updating relevant task representations may occur via goal-directed biasing of neural activity in distal cortical regions and found that this neural biasing optimizes WM performance.…”