Biology subjects

Goffaux, V.

Publications and source records attributed to Goffaux, V..

5 recordsLinked to original sources

bioRxiv2024

Impact of a transient neonatal visual deprivation on the development of the ventral occipito-temporal cortex in humans

How does experience shape the development of visual brain regions? We demonstrate that a transient period of visual deprivation early in life in humans leads to permanent alteration in the function of the early visual cortex (EVC), while leaving the categorical coding of downstream ventral occipito-temporal cortex (VOTC) mostly unaffected. We used fMRI to characterize the brain response to five categories (faces, bodies, objects, buildings and words) in a rare group of cataract-reversal individuals who experienced a transient period of blindness early in life, and in matched participants with typical visual development. We show that the encoding of low-level visual properties is impaired in EVC in cataract-reversal participants, while the categorical response in the VOTC is preserved. When altering the visual properties of our stimuli to mimic in controls the deficit of EVC response of the cataract, we observe a cascading alteration of the categorical coding from EVC to VOTC that is not observed in the cataract-reversal group. Our results show that a typical visual categorical organization develops in VOTC despite a period of visual deprivation early in life and in the presence of impaired processing in EVC. A deep neural network exposed to a visual diet that emulates the experience of our participants reproduced our brain observations within an artificial system. These findings emphasize how specific visual regions are differently affected by a period of visual deprivation early in life, with information encoded in EVC being permanently affected, while the categorical coding in VOTC shows resilience to deprivation.

neuroscience↗

bioRxiv2024

Shared spatial selectivity in early visual cortex and face-selective brain regions

Face recognition relies on dedicated brain regions that are widely considered to show unique selectivity, including a disproportionate vulnerability to face inversion and a relative invariance to stimulus location. This proposed spatial invariance contrasts with accounts of common visuospatial coding whereby high-level category-selective areas inherit spatial properties from earlier regions. Critically, early regions (V1-V3) show characteristic retinotopic variations, with greater cortical sampling along the horizontal than vertical meridian and in the lower than upper field, mirroring established behavioural advantages for face recognition at these locations. We examined whether face-selective regions (OFA, pFus, mFus) share these spatial anisotropies, and whether these properties could drive the observed variations in face recognition. Using wide-field retinotopic mapping with upright and inverted faces ({+/-}21{degrees} eccentricity), we estimated population receptive fields (pRFs) and visual-field coverage. Though pRFs were substantially larger in face-selective regions than in V1-V3, pRF sizes did not vary in line with behavioural anisotropies. In contrast, both early and face-selective regions showed higher pRF numbers and greater visual-field coverage along the horizontal meridian and in the lower field. These sampling differences provide a plausible neural substrate for behavioural anisotropies in face recognition. We also show that pRF numbers in mFus were greater for upright than inverted faces, likely contributing to the perceptual advantage for upright faces. Together, our findings indicate that variations in visual-field sampling within face-selective cortex parallel those of early visual areas, supporting a hierarchical model in which the spatial selectivity of category-selective areas is built on that of earlier regions. Significance statementHigh-level face-selective cortex is often treated as functionally and spatially distinct from early visual areas. We show instead that these regions all share systematic patterns of spatial biases. Using population receptive field (pRF) analyses, both early and face-selective regions showed greater sampling (higher pRF numbers) and increased visual-field coverage along the horizontal than vertical meridian, and in the lower than upper visual field, matching the pattern of anisotropies in face-recognition performance. This relationship was absent for pRF sizes, indicating that behavioural anisotropies are more closely linked to sampling density and coverage. This common pattern of spatial sampling embeds specialised face-processing systems within a hierarchical network in which high-level regions retain fundamental aspects of visuospatial organisation from early visual cortex.

neuroscience↗

bioRxiv2023

The resolution of face perception varies systematically across the visual field

Visual abilities tend to vary predictably across the visual field - for simple low-level stimuli, visibility is better along the horizontal vs. vertical meridian and in the lower vs. upper visual field. In contrast, face perception abilities have been reported to show either distinct or entirely idiosyncratic patterns of variation in peripheral vision, suggesting a dissociation between the spatial properties of low- and higher-level vision. To assess this link more clearly, we extended methods used in low-level vision to develop an acuity test for face perception, measuring the smallest size at which facial gender can be reliably judged in peripheral vision. In 3 experiments, we show the characteristic inversion effect, with better acuity for upright faces than inverted, demonstrating the engagement of high-level face-selective processes in peripheral vision. We also observe a clear advantage for gender acuity on the horizontal vs. vertical meridian and a smaller-but-consistent lower- vs. upper-field advantage. These visual field variations match those of low-level vision, indicating that higher-level face processing abilities either inherit or actively maintain the characteristic patterns of spatial selectivity found in early vision. The commonality of these spatial variations throughout the visual hierarchy means that the location of faces in our visual field systematically influences our perception of them.

neuroscience↗

bioRxiv2023

Backward masking reveals coarse-to-fine dynamics in human V1

Natural images exhibit luminance variations aligned across a broad spectrum of spatial frequencies (SFs). It has been proposed that, at early stages of processing, the coarse signals carried by the low SF (LSF) of the visual input are sent rapidly from primary visual cortex (V1) to ventral, dorsal and frontal regions to form a coarse representation of the input, which is later sent back to V1 to guide the processing of fine-grained high SFs (i.e., HSF). We used functional resonance imaging (fMRI) to investigate the role of human V1 in the coarse-to-fine integration of visual input. We disrupted the processing of the coarse and fine content of full-spectrum human face stimuli via backward masking of selective SF ranges (LSFs: <1.75cpd and HSFs: >1.75cpd) at specific times (50, 83, 100 or 150ms). In line with coarse-to-fine proposals, we found that (1) the selective masking of stimulus LSF disrupted V1 activity in the earliest time window, and progressively decreased in influence, while (2) an opposite trend was observed for the masking of a stimulus HSF. This pattern of activity was found in V1, as well as in ventral (i.e. the Fusiform Face area, FFA), dorsal and orbitofrontal regions. We additionally presented participants with contrast negated stimuli. While contrast negation significantly reduced response amplitudes in the FFA, as well as coupling between FFA and V1, coarse-to-fine dynamics were not affected by this manipulation. The fact that V1 response dynamics to strictly identical stimulus sets differed depending on the masked scale adds to growing evidence that V1 role goes beyond the early and quasi-passive transmission of visual information to the rest of the brain. It instead indicates that V1 may yield a spatially registered common forum or blackboard that integrates top-down inferences with incoming visual signals through its recurrent interaction with high-level regions located in the inferotemporal, dorsal and frontal regions.

neuroscience↗

bioRxiv2021

Information redundancy across spatial scales modulates early visual cortical processing

Visual images contain redundant information across spatial scales where low spatial frequency contrast is informative towards the location and likely content of high spatial frequency detail. Previous research suggests that the visual system makes use of those redundancies to facilitate efficient processing. In this framework, a fast, initial analysis of low-spatial frequency (LSF) information guides the slower and later processing of high spatial frequency (HSF) detail. Here, we used multivariate classification as well as time-frequency analysis of MEG responses to the viewing of intact and phase scrambled images of human faces to demonstrate that the availability of redundant LSF information, as found in broadband intact images, correlates with a reduction in HSF representational dominance in both early and higher-level visual areas as well as a reduction of gamma-band power in early visual cortex. Our results indicate that the cross spatial frequency information redundancy that can be found in all natural images might be a driving factor in the efficient integration of fine image details.

neuroscience↗