pRF-Guide: Measured Receptive Fields Guide fMRI-to-Image Reconstruction

Learned neural readouts can infer spatial assignments from fMRI, leaving unclear whether independently measured retinotopy contributes additional information. We introduce pRF-Guide, which reweights response-dependent attention with quality-weighted population receptive-field footprints. Matched training controls separate the effect of a structured prior from that of its correct voxel correspondence. Across four NSD participants and three training seeds, true geometry improves reconstructed-image spatial cosine by 0.0039 over a retrained shuffled prior, with favorable participant means throughout. A separately refitted single-participant study supports the contribution of joint footprint–scale correspondence, while fixed-weight interventions on pRF centers and widths further link measured geometry to reconstruction outcomes. Measured retinotopic correspondence contributes information beyond learned spatial capacity, but does not uniformly improve every reconstruction component or metric.