Biology subjects

Shipp, S.

Publications and source records attributed to Shipp, S..

3 recordsLinked to original sources

bioRxiv2026

Seeing the world in a grain of sand: Fine global and local representations in foveal and parafoveal vision

Foveal vision enables primates to perceive small objects with remarkable precision by resolving both fine-global form and fine-local detail. Yet current coarse-to-fine and local-to-global frameworks, derived largely from parafoveal recordings and large-object representations, posit that V1 encodes local detail whereas IT represents global form, leaving the neuronal basis of foveal object representation unresolved. Here we show that fine-global form and fine-local detail are encoded parallelly as early as V1 and preserved across V2, V4 and IT at both foveal (1{degrees}-2{degrees}) and parafoveal (2{degrees}-6{degrees}) retinal eccentricities. Coarse-global features dominate parafoveal vision and higher cortical areas. Response latencies revealed a rapid processing sequence, with 2-6 ms separating coarse-global, fine-local, and fine-global processing within parafoveal V1, V2 and V4. These findings establish a cortical neuronal framework to resolve fine-global form of small objects in foveal vision along primate ventral visual stream, supporting fine-scale perception during reading and fine object recognition. Highlights O_LIFoveal two-photon imaging across V1, V2, V4, and IT C_LIO_LIGlobal and local processing examined across eccentricity C_LIO_LIFine and coarse global representations emerge as early as V1 C_LIO_LIFine global and local representations are preserved from V1 up to IT C_LIO_LITightly timed coarse-to-fine-to-fine processing within each cortex C_LIO_LIFast coarse-global dominates parafoveal and higher cortical areas C_LI

neuroscience↗

bioRxiv2025

Beyond Inheritance: De novo Fast Motion Computation in Primate Visual Cortex

Objects move through space and time, generating sequential visuotopic activations in all sighted animals leading to motion perception of velocity defined by direction and speed. Humans can effortlessly see motion with speeds ranging from 0.25 to 500{degrees}/s. However, direction-selective neurons in the primary visual cortex (V1)--from which all subsequent processing is presumed to derive-- only encode directionality at low speeds. To resolve this paradox, we recorded neuronal responses to moving dots, gratings, and movies across the LGN, V1, MT and MST of the macaque motion pathway. Regardless of cell type and motion stimuli, V1 neurons lost direction selectivity at [~]29{degrees}/s while MT and MST neurons maintained it up to [~]82{degrees}/s and [~]183{degrees}/s, respectively. A cascaded spatiotemporal integration model reveals that at each cortex direction-selective neurons can generate velocity selectivity de novo, by integrating sequential visuotopic activations from preceding areas, irrespective of speed and directionality. By computing velocity anew, the primate brain effectively uses the cortical hierarchy itself to shift gears to efficiently encode slow and fast motion. Thus, five visual areas from the retina into the brains processing hierarchy, external spatiotemporal information is being computed afresh, offering insights for motion processing in other species, modalities and machine vision.

neuroscience↗

bioRxiv2020

Transduction catalysis: doxorubicin accelerates and enhances rAAV-mediated gene expression in the cortex of mouse, cat and monkey

Rapid and efficient gene transduction via recombinant adeno-associated viruses (rAAVs) is highly desirable across many basic and clinical research domains. Here we report vector co-infusion with doxorubicin, a clinical anti-cancer drug, markedly enhanced rAAV-mediated gene expression in the cerebral cortex across mammalian species (cat, mouse, and macaque), acting throughout the time-period examined and detectable at just three days post-transfection. This enhancement showed serotype generality, being common to rAAV serotypes 2, 8, 9 and PHP.eB tested, and was observed both locally, and at remote locations consistent with doxorubicin undergoing retrograde axonal transport. All these effects were observed at doses matching human blood plasma levels in clinical therapy, and lacked detectable cytotoxicity as assessed by cell morphology, activity, apoptosis and behavioral testing. Altogether, this study identifies an effective means to improve the capability and scope of in vivo rAAV applications, accelerating and augmenting gene transduction at doxorubicin concentrations paralleling medical practice. HighlightsO_LIAnti-cancer drug doxorubicin doubles the rate of rAAV-mediated transgene expression C_LIO_LIDoxorubicin enhancement generalizes across rAAV serotypes and animal species C_LIO_LIThe effect is observed in both locally and retrogradely infected cortical neurons C_LIO_LIThe effective dosage is free from appreciable cytotoxicity and matches clinical settings C_LI

neuroscience↗