Goal-Directed Visual Processing Differentially Impacts Human Ventral and Dorsal Visual Representations

Abstract

Recent studies have challenged the ventral/"what" and dorsal/"where" two-visual-processing-pathway view by showing the existence of "what" and "where" information in both pathways. Is the two-pathway distinction still valid? Here, we examined how goal-directed visual information processing may differentially impact visual representations in these two pathways. Using fMRI and multivariate pattern analysis, in three experiments on human participants (57% females), by manipulating whether color or shape was task-relevant and how they were conjoined, we examined shape-based object category decoding in occipitotemporal and parietal regions. We found that object category representations in all the regions examined were influenced by whether or not object shape was task-relevant. This task effect, however, tended to decrease as task-relevant and irrelevant features were more integrated, reflecting the well-known object-based feature encoding. Interestingly, task relevance played a relatively minor role in driving the representational structures of early visual and ventral object regions. They were driven predominantly by variations in object shapes. In contrast, the effect of task was much greater in dorsal than ventral regions, with object category and task relevance both contributing significantly to the representational structures of the dorsal regions. These results showed that, whereas visual representations in the ventral pathway are more invariant and reflect "what an object is," those in the dorsal pathway are more adaptive and reflect "what we do with it." Thus, despite the existence of "what" and "where" information in both visual processing pathways, the two pathways may still differ fundamentally in their roles in visual information representation.

Spatiotemporal Analysis of Category and Target-related Information Processing in the Brain during Object Detection

“…4). As was previously observed (Vaziri-Pashkam et al, 2017), the task-and category-related information were dominant in the frontoparietal and occipitotemporal cortices, respectively. The current study, extended these results by investigating the flow of task-and category-related information in the brain and showed that the processing of target-related information was initiated on prefrontal areas and the information was sent to posterior brain areas probably for facilitated decision-making and recognition (Bar et al, 2006;Summerfield et al, 2006).…”

“…In order to gain a deeper insight into the spatiotemporal dynamics of object and task processing, a recent study, which fused MEG with functional magnetic resonance imaging (fMRI), found that a sequence of overlapping and separate structures along the frontoparietal and occipitotemporal cortices undertook task processing (Hebart et al, 2018). This observation was on par with previous findings which suggested that task processing was distributed along both the dorsal and ventral visual streams (Vaziri-Pashkam and Xu, 2017). They found a late effect of task when decoded the brain signals with ignorable influence of task on object representations (Hebart et al, 2018).…”

“…In order to recognize an object and initiate the relevant motor action, the brain must process a combination of the information provided by the external stimulus and the internal task goals. While majority of classical studies have considered 'object recognition' as a feed-forward brain process (DiCarlo et al, 2012;VanRullen, 2012), recent studies have argued against this view by providing evidence on the significant influence of top-down task-dependent processes on bottom-up sensorydriven inputs (Harel et al, 2011;Bar et al, 2001;Bar et al, 2006;Vaziri-Pashkam and Xu, 2017). The effects of task are generally imposed on sensory processing by mechanisms generally referred to as prediction (Summerfield et al, 2006), expectation (Puri et al, 2009;Meijs et al, 2018;Manahova et al, 2018) and most importantly attention (Stokes et al, 2009;Spyropoulos et al, 2018;Rohenkohl and Nobre, 2011;Battistoni et al, 2017;Summerfield and Egner, 2009;Paneri and Gregoriou, 2017).…”

Parietal representations of stimulus features are amplified during memory retrieval and flexibly aligned with top-down goals

“…Substantial evidence from electrophysiological (Toth and Assad, 2002;Freedman and Assad, 2006;Ibos and Freedman, 2014) and BOLD Erez and Duncan, 2015;Bracci et al, 2017;Vaziri-Pashkam and Xu, 2017;Long and Kuhl, 2018) measurements indicates that LPC representations of perceptual events are influenced by top-down goals. Our results provide novel evidence that, in dorsal LPC, specific features of a remembered stimulus are dynamically strengthened or weakened according to the current goal.…”

Human frontoparietal cortex represents behaviorally-relevant target status during invariant object recognition

“…In particular, adaptive coding properties have been demonstrated in a set of parietal and frontal regions that are collectively referred to as the Multiple-Demand (MD) network (Duncan, 2010;Fedorenko, Duncan, & Kanwisher, 2013;Mitchell et al, 2016). Some sub-regions of the MD network have been previously shown to encode information about abstract task rules and response mappings (Harel, Kravitz, & Baker, 2014;Waskom, Kumaran, Gordon, Rissman, & Wagner, 2014;Woolgar, Thompson, Bor, & Duncan, 2011), as well as representations of relevant visual object properties (Y. Erez & Duncan, 2015;Jackson, Rich, Williams, & Woolgar, 2017;Vaziri-Pashkam & Xu, 2017). Though its role in invariant target recognition has not yet been tested, based on these coding properties, the MD network may play an important role in recognizing relevant objects during search, especially when successful search relies on flexibly updating the set of features that define the current target.…”