Causal Evidence for Expression of Perceptual Expectations in Category-Selective Extrastriate Regions

• Published in: Current biology 2019-08, Vol.29 (15), p.2496-2500.e3
• Main Authors: Gandolfo, Marco, Downing, Paul Edward
• Format: Article
• Language: English
• Subjects: category-selective brain regions; extrastriate body area; occipital place area; perceptual expectations; pre-stimulus brain activity; transcranial magnetic stimulation
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2019.06.024

Expectations about a visual event shape the way it is perceived [1–4]. For example, expectations induced by valid cues signaling aspects of a visual target can improve judgments about that target, relative to invalid cues [5, 6]. Such expectation effects are thought to arise via pre-activation of a template in neural populations that represent the target [7, 8] in early sensory areas [9] or in higher-level regions. For example, category cues (“face” or “house”) modulate pre-target fMRI activity in associated category-selective brain regions [10, 11]. Further, a relationship is sometimes found between the strength of template activity and success in perceptual tasks on the target [12–14]. However, causal evidence linking pre-target activity with expectation effects is lacking. Here we provide such evidence, using fMRI-guided online transcranial magnetic stimulation (TMS). In two experiments, human volunteers made binary judgments about images of either a body or a scene. Before each target image, a verbal cue validly or invalidly indicated a property of the image, thus creating perceptual expectations about it. To disrupt these expectations, we stimulated category-selective visual brain regions (extrastriate body area, EBA; occipital place area, OPA) during the presentation of the cue. Stimulation ended before the target images appeared. We found a double dissociation: TMS to EBA during the cue period removed validity effects only in the body task, whereas stimulating OPA removed validity effects only in the scene task. Perceptual expectations are expressed by the selective activation of relevant populations within brain regions that encode the target. •Expectations influence perception of visual events•Anticipatory activity in category-specific regions expresses expectations•Disruption of this activity removes effects of cues on discrimination performance Gandolfo and Downing demonstrate that perceptual expectations about an upcoming visual stimulus are expressed in the brain activity of category-selective brain regions: online transcranial magnetic brain stimulation over such regions selectively removes the behavioral effects of predictive verbal pre-cues on perceptual discrimination tasks.