Effect of Fearful Cue on Population Receptive Field Estimates

Exploring how emotional content alters the functional architecture of early visual areas

Context

Part of my MSc research in the Computational and Biological Vision Lab, Bilkent University, Türkiye

Supervisor: Assoc. Prof. Dr. Hüseyin Boyacı
Period: 10/2016 – 07/2019

Research Question

How does emotional content influence the spatial tuning of neuronal populations in the visual cortex?

Objective:
To test whether visual stimuli with fearful emotional content modulate population receptive field (pRF) properties — such as size and eccentricity — across retinotopic visual areas.

Methods & Experimental Design

Six participants took part in a 3-session fMRI experiment. During each session, participants viewed simultaneously rotating wedge and expanding-contracting ring stimuli, rendered with scrambled, neutral, or fearful images.

Data Processing & Analysis Pipeline:

Raw fMRI data
    → Preprocessing with SPM & FreeSurfer
        → Surface reconstruction and retinotopic mapping
            → pRF modeling with SamSrf toolbox (MATLAB)
                → Parameter estimation: pRF size & center location
                    → Group-level comparison across emotional conditions

Results & Insights

Fearful content led to an increase in pRF size and a shift of receptive field centers toward the eccentric side in both lower (V1–V3) and higher (hV4, V3A) visual areas.
These findings indicate that emotional modulation can occur at the earliest stages of visual processing, not just in high-level regions.
The results support the view that emotion facilitates visual perception by increasing positional tolerance — possibly enabling faster or more flexible detection of relevant stimuli in the visual field.

Outcome & Impact

This study demonstrated that the pRF method, typically used for low-level mapping, can reveal subtle modulatory effects of emotion on spatial tuning in the visual system.
It provided a model-based framework for studying how emotional states interact with visual processing dynamics.

Poster presentation

Turkish Congress of Neuroscience (USK), 04.2019, Trabzon, Turkey. Anatomy. see poster

Keywords: visual perception, emotion, fMRI, pRF modeling, retinotopy, computational neuroscience

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