Open and closed cortico-subcortical loops: A neuro-computational account of access to consciousness in the distractor-induced blindness paradigm.

A neuro-computational model explains how the brain gates information into consciousness, specifically in the distractor-induced blindness task. In this task, participants view rapid streams of colored dots and report intervals of coherent motion preceded by a target color. When distractors (motion intervals before the target color) appear, detection of the target motion declines, especially when the delay between target color and target motion is short. The model proposes that conscious perception requires reverberating activity in cortico-subcortical loops, with basal ganglia pathways either allowing or inhibiting this reverberation. Distractors trigger suppression via the inhibitory hyperdirect pathway, and when a target follows closely, lingering suppression prevents its identification. The model reproduces experimental data on how delay length affects detection probability.

Study at a glance

Abstract

How the brain decides which information to process 'consciously' has been debated over for decades without a simple explanation at hand. While most experiments manipulate the perceptual energy of presented stimuli, the distractor-induced blindness task is a prototypical paradigm to investigate gating of information into consciousness without or with only minor visual manipulation. In this paradigm, subjects are asked to report intervals of coherent dot motion in a rapid serial visual presentation (RSVP) stream, whenever these are preceded by a particular color stimulus in a different RSVP stream. If distractors (i.e., intervals of coherent dot motion prior to the color stimulus) are shown, subjects' abilities to perceive and report intervals of target dot motion decrease, particularly with short delays between intervals of target color and target motion. We propose a biologically plausible neuro-computational model of how the brain controls access to consciousness to explain how distractor-induced blindness originates from information processing in the cortex and basal ganglia. The model suggests that conscious perception requires reverberation of activity in cortico-subcortical loops and that basal-ganglia pathways can either allow or inhibit this reverberation. In the distractor-induced blindness paradigm, inadequate distractor-induced response tendencies are suppressed by the inhibitory 'hyperdirect' pathway of the basal ganglia. If a target follows such a distractor closely, temporal aftereffects of distractor suppression prevent target identification. The model reproduces experimental data on how delays between target color and target motion affect the probability of target detection.