Disruption of Foveal Space Impairs Discrimination of Peripheral Objects.

Kimberly B. Weldon,Anina N. Rich,Mark A. Williams,Alexandra Woolgar

doi:10.3389/fpsyg.2016.00699

Abstract

Visual space is retinotopically mapped such that peripheral objects are processed in a cortical region outside the region that represents central vision. Despite this well-known fact, neuroimaging studies have found information about peripheral objects in the foveal confluence, the cortical region representing the fovea. Further, this information is behaviorally relevant: disrupting the foveal confluence using transcranial magnetic stimulation impairs discrimination of peripheral objects at time-points consistent with a disruption of feedback. If the foveal confluence receives feedback of information about peripheral objects to boost vision, there should be behavioral consequences of this phenomenon. Here, we tested the effect of foveal distractors at different stimulus onset asynchronies (SOAs) on discrimination of peripheral targets. Participants performed a discrimination task on target objects presented in the periphery while fixating centrally. A visual distractor presented at the fovea ~100 ms after presentation of the targets disrupted performance more than a central distractor presented at other SOAs. This was specific to a central distractor; a peripheral distractor at the same time point did not have the same effect. These results are consistent with the claim that foveal retinotopic cortex is recruited for extra-foveal perception. This study describes a new paradigm for investigating the nature of the foveal feedback phenomenon and demonstrates the importance of this feedback in peripheral vision.

Highlights

The traditional model of visual object recognition is a primarily feedforward process in which visual input is processed in successive stages that correspond to the functional architecture of the ventral visual stream (Riesenhuber and Poggio, 1999)
In Experiment 1, we found that a visual distractor presented at fixation at +117 ms stimulus onset asynchronies (SOAs) disrupted behavioral performance more than distractors presented at other non-simultaneous SOAs
We observe a “recovery” in perceptual discrimination ability if the distractor is presented later in the course of a trial, suggesting that the behavioral disruption at +117 ms SOA is not a result of displaying a distractor object any time after stimulus onset, but reflects a critical timecourse for the disruption of the feedback phenomenon. This paradigm does not speak to the location in the brain involved in the interference with visual processing, but based on the collective work of Williams et al (2008) and Chambers et al (2013), we infer that it occurs at the foveal confluence

Summary

Introduction

The traditional model of visual object recognition is a primarily feedforward process in which visual input is processed in successive stages that correspond to the functional architecture of the ventral visual stream (Riesenhuber and Poggio, 1999). Recent evidence from studies using transcranial magnetic stimulation (TMS) point to the crucial role of feedback signals from high to low visual areas, for example in perceptual completion (Wokke et al, 2012), conscious perception of motion (Silvanto et al, 2005), and scene categorization (Koivisto et al, 2011). Established theories propose that feedback acts by modulating or anticipating pre-activated feedforward visual input (Supèr et al, 2001; DiCarlo et al, 2012).

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