Explicit information for category-orthogonal object properties increases along the ventral stream

Abstract

Extensive research has revealed that the ventral visual stream hierarchically builds a robust representation for supporting visual object categorization tasks. We systematically explored the ability of multiple ventral visual areas to support a variety of 'category-orthogonal' object properties such as position, size and pose. For complex naturalistic stimuli, we found that the inferior temporal (IT) population encodes all measured category-orthogonal object properties, including those properties often considered to be low-level features (for example, position), more explicitly than earlier ventral stream areas. We also found that the IT population better predicts human performance patterns across properties. A hierarchical neural network model based on simple computational principles generates these same cross-area patterns of information. Taken together, our empirical results support the hypothesis that all behaviorally relevant object properties are extracted in concert up the ventral visual hierarchy, and our computational model explains how that hierarchy might be built.

Temporally flexible feedback signal to foveal cortex for peripheral object recognition

“…A possible scenario is that the foveal cortex represents the object category and orientation information at different spatial scales, with the object category and orientation information primarily supported at fine and coarse scales, respectively. Using multielectrode recordings from passively fixating macaques, Hong et al (22) recently showed that "category-orthogonal" features of an object, such as orientation, could be linearly decoded from high-level object areas in the ventral stream, and that this information was likely available on a feedforward pass. At one level, our imaging results are consistent in that we found that LOC was sensitive to the category-orthogonal feature of image orientation; however, this was only for stimuli that were in the same category.…”

Extracting Object Identity: Ventral or Dorsal Visual Stream?

“…Differences in anatomical coverage, experimental design, stimuli, and task render their findings difficult to integrate with previous studies showing that facial identity information is present in ventral regions including FFA (Nestor et al, 2011;Anzellotti et al, 2014) and more anterior temporal regions (Kriegeskorte et al, 2007). Jeong and Xu (2016) argue that the ventral face-identity information that these previous studies found may be due to low-level stimulus confounds, or that face-identity information may be present only in anterior temporal cortex, from which their MRI slice coverage precluded measurement.…”

“…Consistent with this proposal is evidence that, in both humans and monkeys, neural activity in the ventral stream contains information about visual object identity and category (Kriegeskorte et al, 2008;Bell et al, 2009) without being modulated by image properties such as object position, viewing angle, size, or context (Li et al, 2009;Rust and DiCarlo, 2010;Anzellotti et al, 2014). However, other evidence suggests that simple visual features (e.g., motion direction) required to categorize stimuli are also represented in dorsal regions (Toth and Assad, 2002;Freedman and Assad, 2006).…”

“…Finally, given that human fMRI studies have found increased IPS activity during spatial attention and eye movements (Müri et al, 1996;Corbetta et al, 1998), future studies should also carefully rule out the possibility that these could have partially driven the IPS results. Systematic differences in saccade distribution or spatial attention might occur if, for example, different individuals carry identity-diagnostic information in different facial features.…”

“…Jeong and Xu (2016) highlight the role of IPS in visual short-term memory (VSTM). Given the diversity of tasks used in previous studies [image-anomalydetection (Kriegeskorte et al, 2007); identification (Nestor et al, 2011); target vs nontarget categorization (Anzellotti et al, 2014)], it will be interesting for future studies to clarify the extent to which IPS results reflect VSTM content. Specifically, the information decoded in IPS may be a visual search template of the frequently presented identity, which is mentally formed by participants during each block as they searched for the oddball stimulus.…”