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Updated: Jun 16, 2026

Detecting Pre-Stimulus Source-Level Effects on Object Perception with Magnetoencephalography
Published on: July 26, 2019
Object-sensitive activity reflects earlier perceptual and later cognitive processing of visual objects between 95 and
Haline E Schendan1, Lisa C Lucia
1Psychology Department, Tufts University, 490 Boston Avenue, Medford, MA 02155, USA. Haline_E.Schendan@tufts.edu
This study reveals the timing of brain activity for object recognition using event-related potentials (ERPs). Object-sensitive visual cortex processes intact objects differently from scrambled images, from early figure-ground segregation to later cognitive decisions.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Visual Perception
Background:
- Functional magnetic resonance imaging (fMRI) has identified object-sensitive brain areas, but their temporal activation patterns remain unclear.
- Understanding the time course of visual object recognition is crucial for cognitive neuroscience.
Purpose of the Study:
- To determine the temporal dynamics of object-sensitive cortical activation.
- To integrate event-related potential (ERP) findings with prior fMRI data on visual object cognition.
Main Methods:
- An event-related potential (ERP) study using grayscale images of intact objects and phase-scrambled control stimuli.
- Participants categorized objects and discriminated them from scrambled versions.
- Combined ERP and fMRI data using indirect functional and direct anatomical approaches.
Main Results:
- Object-sensitive activation was observed early (95-175ms) during P100 and VPP/N170 components, linked to figure-ground segregation.
- Later object-sensitive activity occurred after 200ms in the frontocentral N3 complex (200-500ms) and right occipitotemporal P200 (200-300ms), associated with cognitive decisions and perceptual grouping.
- All identified effects localized to extrastriate occipitotemporal cortex.
Conclusions:
- The study successfully mapped the time course of object-sensitive activity in fMRI-defined regions.
- Visual object perception involves distinct temporal stages: figure-ground segregation (95-175ms), perceptual grouping (200-300ms), and object model selection for cognitive decisions (200-530ms).
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