arXiv subjects

Li Zhaoping

Publications and source records attributed to Li Zhaoping.

7 recordsLinked to original sources

arXiv2026

What are the functions of primary visual cortex (V1)?

Although Hubel and Wiesel established decades ago how individual V1 neurons transform retinal inputs, functions of V1 as a whole are being discovered only recently. First, V1 acts as a motor cortex for exogenously guiding saccades by constructing a bottom-up saliency map of the visual field. Second, V1 initiates a processing bottleneck: a massive reduction of visual information begins at its output to downstream areas. Third, downstream recognition is limited by impoverished information, V1 supports ongoing recognition by providing additional information queried by top-down feedback from downstream areas, directed predominantly to central visual field representations. These V1 functions underpin a framework in which vision is mainly looking and seeing through the bottleneck. Looking selects a fraction of visual information into the bottleneck, largely by saccades that center selected contents at gaze. Seeing recognizes the selected contents. Looking and seeing rely mainly on processing in the peripheral and central visual fields.

q-bio.NC↗

arXiv2026

Vision as looking and seeing through a bottleneck

Progress in vision research has been slower downstream than upstream of primary visual cortex (V1). Traditional frameworks have largely overlooked a central constraint: only a tiny fraction of retinal input is recognized. Thus, to a first approximation, vision is better formulated as looking and seeing through a bottleneck. Looking, mainly by the peripheral visual field, selects visual information to enter this bottleneck, largely via gaze shifts that center selected contents at fovea. Seeing, mainly by the central visual field, recognizes this content. Converging evidence suggests that V1 initiates the bottleneck and contributes to looking by generating a bottom-up saliency map that guides saccades exogenously, and that top-down feedback along the visual pathway, targeting mainly the representation of the central visual field, refines seeing. Progress will accelerate through falsifiable theories that explicitly link behavior with neural substrates, and by experimental designs that avoid forced fixation and precisely track gaze.

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arXiv2025

Conduction velocity of intracortical axons in monkey primary visual cortex grows with distance: implications for computation

A critical visual computation is to construct global scene properties from activities of early visual cortical neurons which have small receptive fields. Such a computation is enabled by contextual influences, through which a neuron's response to visual inputs is influenced by contextual inputs outside its classical receptive fields. Accordingly, neurons can signal global properties including visual saliencies and figure-ground relationships. Many believe that intracortical axons conduct signals too slowly to bring the contextual information from receptive fields of other neurons. A popular opinion is that much of the contextual influences arise from feedback from higher visual areas whose neurons have larger receptive fields. This paper re-examines pre-existing data to reveal these unexpected findings: the conduction speed of V1 intracortical axons increases approximately linearly with the conduction distance, and is sufficiently high for conveying the contextual influences. Recognizing the importance of intracortical contribution to critical visual computations should enable fresh progress in answering long-standing questions.

q-bio.NC↗

arXiv2025

Vision: looking and seeing through our brain's information bottleneck

Our brain recognizes only a tiny fraction of sensory input, due to an information processing bottleneck. This blinds us to most visual inputs. Since we are blind to this blindness, only a recent framework highlights this bottleneck by formulating vision as mainly looking and seeing. Looking selects a tiny fraction of visual information for progression through the bottleneck, mainly by shifting gaze to center an attentional spotlight. Seeing decodes, i.e., recognizes, objects within the selected information. Since looking often occurs before seeing and evokes limited awareness, humans have the impression of seeing whole scenes clearly. According to the new framework, the bottleneck starts from the output of the primary visual cortex (V1) to downstream brain areas. This is motivated by the evidence-backed V1 Saliency Hypothesis (V1SH) that V1 creates a saliency map of the visual field to guide looking. Massive visual information loss downstream from V1 makes seeing vulnerable to ambiguity and illusions (errors). To overcome this, feedback from downstream to upstream areas such as V1 queries for additional relevant information. An integral part of this framework is the central-peripheral dichotomy (CPD) theory proposing that vision in the peripheral and central visual fields are specialized for looking (deciding where to shift the gaze) and seeing, respectively, and that the feedback query to aid seeing is mainly directed to the central visual field. This V1SH-Bottleneck-CPD framework predicts that the peripheral visual field, lacking feedback queries, is more vulnerable to illusions, and that such illusions become visible in the central visual field when the feedback query is compromised. We present theoretical predictions, experimental confirmations, a Feedforward-Feedback-Verify-and-reWeight (FFVW) algorithm for seeing through the bottleneck.

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arXiv2024

Imperceptible Gaze Guidance Through Ocularity in Virtual Reality

We introduce to VR a novel imperceptible gaze guidance technique from a recent discovery that human gaze can be attracted to a cue that contrasts from the background in its perceptually non-distinctive ocularity, defined as the relative difference between inputs to the two eyes. This cue pops out in the saliency map in the primary visual cortex without being overtly visible. We tested this method in an odd-one-out visual search task using eye tracking with 15 participants in VR. When the target was rendered as an ocularity singleton, participants' gaze was drawn to the target faster. Conversely, when a background object served as the ocularity singleton, it distracted gaze from the target. Since ocularity is nearly imperceptible, our method maintains user immersion while guiding attention without noticeable scene alterations and can render object's depth in 3D scenes, creating new possibilities for immersive user experience across diverse VR applications.

cs.HC↗

arXiv2014

Primary visual cortex as a saliency map: parameter-free prediction of behavior from V1 physiology

It has been hypothesized that neural activities in the primary visual cortex (V1) represent a saliency map of the visual field to exogenously guide attention. This hypothesis has so far provided only qualitative predictions and their confirmations. We report this hypothesis' first quantitative prediction, derived without free parameters, and its confirmation by human behavioral data. The hypothesis provides a direct link between V1 neural responses to a visual location and the saliency of that location to guide attention exogenously. In a visual input containing many bars, one of them saliently different from all the other bars which are identical to each other, saliency at the singleton's location can be measured by the shortness of the reaction time in a visual search task to find the singleton. The hypothesis predicts quantitatively the whole distribution of the reaction times to find a singleton unique in color, orientation, and motion direction from the reaction times to find other types of singletons. The predicted distribution matches the experimentally observed distribution in all six human observers. A requirement for this successful prediction is a data-motivated assumption that V1 lacks neurons tuned simultaneously to color, orientation, and motion direction of visual inputs. Since evidence suggests that extrastriate cortices do have such neurons, we discuss the possibility that the extrastriate cortices play no role in guiding exogenous attention so that they can be devoted to other functional roles like visual decoding or endogenous attention.

q-bio.NC↗

arXiv2004

Mathematical Analysis and Simulations of the Neural Circuit for Locomotion in Lamprey

We analyze the dynamics of the neural circuit of the lamprey central pattern generator (CPG). This analysis provides insights into how neural interactions form oscillators and enable spontaneous oscillations in a network of damped oscillators, which were not apparent in previous simulations or abstract phase oscillator models. We also show how the different behaviour regimes (characterized by phase and amplitude relationships between oscillators) of forward/backward swimming, and turning, can be controlled using the neural connection strengths and external inputs.

q-bio.NC↗