Retinotopic connectivity maps are robust to large eye movements and optical blur

Retinotopic mapping can reveal the multiple retinotopically organized visual field maps in human visual cortex. Unfortunately, the requirement for controlled stimuli and maintaining fixation precludes its use in groups with atypical eye movements or limited acuity, including individuals at either end of the life span and those with visual conditions, such as nystagmus, amblyopia, or a large refractive error. Consequently, this severely limits the conclusions we can draw about normal and abnormal visual processing. Here we present a novel data-driven method to estimate connective fields (CF), fine-grained maps of the functional connectivity between brain areas. We correlate the response of each brain voxel with all the responses within the primary visual cortex (V1). Using a probabilistic atlas of V1, we then determine the location and size of this correlation profile in visual space. This generates detailed retinotopic maps of extrastriate cortex comparable to conventional population receptive field (pRF) modelling. We further show that an inhibitory CF region often surrounds the facilitatory CF. The visual field extent of this inhibition falls off with cortical magnification. Importantly, because CF analysis requires no knowledge about the visual stimulus, this obviates the controlled stimulus conditions in standard mapping studies. We show that CF maps are much more robust to the presence of large eye movements and myopic defocus than pRF mapping. Moreover, using a gaze-contingent video game as stimulus we can produce maps extending considerably further into the visual periphery than is possible with conventional experiments. Our data-driven CF procedure can help advance the understanding of visual cortical architecture, both in healthy controls and disorders. Due to its ease-of-use and flexibility it also shows great potential to broaden the user base of retinotopic mapping to clinical settings to include those for whom conventional retinotopic mapping is difficult or outright impossible.