Biology subjects

Rosselli, F. B.

Publications and source records attributed to Rosselli, F. B..

4 recordsLinked to original sources

bioRxiv2026

Rapid estimation of receptive fields across stages of the early visual system

Estimating receptive fields in large neural populations is often limited by experimental time: stimuli with theoretically favorable statistics for receptive-field estimation may, in practice, evoke too few informative spikes in neurons with high specificity for structured features, requiring impracticably long recordings. Therefore, we asked whether a structured stimulus could broadly engage neural populations across stages of the early visual system while permitting a tractable and interpretable reverse-correlation analysis. To address this question, we developed "reverse correlation against stimulus elements (RCASE)", an analysis framework for stimuli that can be represented frame by frame through the presence or absence of specific stimulus elements. We then designed such a stimulus consisting of random moving objects (RMO) and compared RMO/RCASE with conventional spike-triggered averaging using a dense binary white noise (WN/STA) stimulus across different stages of the early visual system of the mouse, namely the retina, the nucleus of the optic tract, the superior colliculus and the primary visual cortex, and in the primate retina. To distinguish the contributions of spatial and temporal scales, motion, stimulus structure, and analysis choice, we additionally compared against WN/STA with different square sizes and frame rates, spike-triggered covariance analysis, as well as random static objects and spatially correlated cloud stimuli. RMO evoked stronger and more reliable responses than WN in the mouse retina and across the investigated mouse visual areas. RMO/RCASE yielded discernible receptive fields for a substantially larger proportion of neurons and in a fraction of the recording time. Although the stimulus objects featured localized moving contrast edges, this advantage was not restricted to direction-selective cell populations. In the primate retina, in contrast, WN/STA approached the performance of RMO/RCASE. RMO/RCASE also supported simultaneous estimation of stimulus direction, speed, and color tuning. Our approach enables rapid and interpretable functional characterization of large populations of visual neurons, enabling to simultaneously recover receptive fields and feature tuning, whenever a low-dimensional feature space can be specified beforehand.

neuroscience↗

bioRxiv2026

Mice and humans use ambiguous local motion to stabilize gaze

Animals need to infer properties of the environment that are only ambiguously encoded by neurons in the sensory periphery. In vision, local edge motion seen through small receptive fields does not uniquely specify the direction of global or object motion. Can these ambiguous local motion signals drive behavior directly, or must the ambiguity first be resolved? We addressed this question in reflexive gaze stabilization by tracing motion signals from the retina through the nucleus of the optic tract (NOT) to eye movements, combining retinal and in vivo electrophysiology, computational modelling, and eye tracking in mice and humans. By using stimuli that dissociate local edge motion from global, object motion, we found that NOT cell responses were strongly biased towards local motion and were largely explained by linear pooling of retinal inputs. This effect propagated to behavior: eye movements followed local motion, to the point that changing the edge orientation of vertically moving objects produced horizontal eye movements. Humans showed a qualitatively similar bias, which increased when central vision was masked. Thus, ambiguous local motion signals can drive effective behavior; a conserved sensorimotor strategy in which visually guided behavior relies on a heuristic rather than an accurate reconstruction of the external world.

neuroscience↗

bioRxiv2024

Action potential propagation speed compensates for traveling distance in the human retina

Neural information processing requires accurately timed action potentials arriving from presynaptic neurons at the postsynaptic neuron. However, axons of ganglion cells in the human retina feature low axonal conduction speeds and vastly different lengths, which poses a challenge to the brain for constructing a temporally coherent image over the visual field. Combining results from microelectrode array recordings, human behavioral measurements, transmission electron microscopy, and mathematical modelling of the retinal nerve fiber layer, we demonstrate that axonal propagation speeds compensate for variations in axonal length across the human retina including the fovea. The human brain synchronizes the arrival times of action potentials at the optic disc by increasing the diameters of longer axons, which increases their propagation speeds.

neuroscience↗

bioRxiv2018

Evidence of ventral stream computations in rat lateral extrastriate cortex

In rodents, the progression of extrastriate areas located laterally to primary visual cortex (V1) has been assigned to a putative object-processing pathway (homologous to the primate ventral stream), based on anatomical considerations. Recently, we found functional support for such attribution (Tafazoli et al., 2017), by showing that this cortical progression is specialized for coding object identity despite view changes - the hallmark property of a ventral-like pathway. Here, we sought to clarify what computations are at the base of such specialization. To this aim, we performed multi-electrode recordings from V1 and laterolateral area LL (at the apex of the putative ventral-like hierarchy) of male adult rats, during the presentation of drifting gratings and noise movies. We found that the extent to which neuronal responses were entrained to the phase of the gratings sharply dropped from V1 to LL, along with the quality of the receptive fields inferred through reverse correlation. Concomitantly, the tendency of neurons to respond to different oriented gratings increased, while the sharpness of orientation tuning declined. Critically, these trends are consistent with the nonlinear summation of visual inputs that is expected to take place along the ventral stream, according to the predictions of hierarchical models of ventral computations and a meta-analysis of the monkey literature. This suggests an intriguing homology between the mechanisms responsible for building up shape selectivity and transformation tolerance in the visual cortex of primates and rodents, reasserting the potential of the latter as models to investigate ventral stream functions at the circuitry level.\n\nSignificance StatementDespite the growing popularity of rodents as models of visual functions, it remains unclear whether their visual cortex contains specialized modules for processing shape information. To addresses this question, we compared how neuronal tuning evolves from rat primary visual cortex (V1) to a downstream visual cortical region (area LL) that previous work has implicated in shape processing. In our experiments, LL neurons displayed a stronger tendency to respond to drifting gratings with different orientations, while maintaining a sustained response across the whole duration of the drift cycle. These trends match the increased complexity of pattern selectivity and the augmented tolerance to stimulus translation found in monkey visual temporal cortex, thus revealing a homology between shape processing in rodents and primates.

neuroscience↗