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Functional Magnetic Resonance Imaging (fMRI) of the Visual Cortex with Wide-View Retinotopic Stimulation
Published on: December 8, 2023
Continuous mapping of the cortical object vision pathway using traveling waves in object space
Elfi Goesaert1, Hans P Op de Beeck
1Laboratory of Experimental Psychology, University of Leuven (K.U.Leuven), Tiensestraat 102, 3000 Leuven, Belgium.
Neuroimage
|December 2, 2009
Summary
Researchers adapted visual cortex mapping techniques to study complex objects like faces and buildings. They found that specific brain areas activate for faces and buildings, but not in a continuous map, challenging previous models.
Area of Science:
- Neuroscience
- Cognitive Science
- Visual Perception
Background:
- High-level visual cortex organization is often studied using discrete object categories like faces and buildings.
- Lower visual cortex levels are studied using phase-encoding techniques with gradual stimuli, creating traveling waves and time delays.
- These techniques relate cortical location time delays to stimulus preference.
Purpose of the Study:
- To extend phase-encoding techniques to investigate higher-order visual object properties.
- To map the organization of high-level visual regions for complex object representations.
- To test for continuous representations across the ventral visual stream.
Main Methods:
- Developed gradual morphing sequences transitioning between faces and buildings.
- Utilized phase-encoding with contracting/expanding rings containing natural scene elements.
- Measured time-locked activation in face-selective (FFA) and place-selective (PPA) regions.
Main Results:
- Activation in the fusiform face area (FFA) and parahippocampal place area (PPA) was time-locked to face-like and building-like stimuli in morphs, respectively.
- FFA and PPA activity also time-locked to foveal and eccentric ring stimuli, confirming prior findings.
- Crucially, the cortical area between FFA and PPA showed no modulation related to morph position or retinotopic eccentricity, contradicting large-scale continuous maps.
Conclusions:
- Phase-encoding techniques are effective for studying high-level visual regions and complex object properties.
- The ventral visual stream's organization for faces and buildings may not be a large-scale continuous map.
- Findings suggest a more complex, potentially non-continuous, organization for high-level visual object representation.
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