Biology subjects

Duckworth, J.

Publications and source records attributed to Duckworth, J..

6 recordsLinked to original sources

bioRxiv2026

Neurons entrain and shape an intrinsic arteriole rhythm that distributes blood across the cortical mantle

The cerebral arteriole network distributes blood across cortex through branches whose diameters oscillate near a frequency fvaso ~ 0.1 Hz. We asked whether the spatiotemporal pattern of these vaso-oscillations reflects neuronal entrainment of an intrinsic vascular oscillation. Three findings support this: First, suppressing endothelial hyperpolarization left resting-state oscillations intact but weakened the vascular response to neural activity, showing that vasomotion originates within the arteriole network rather than following neuronal drive. Second, arterioles amplify sensory drive selectively rather than faithfully: neural activity near 0.1 Hz is resonantly enhanced to form a strong peak in the vascular response. Third, neuronal frequency sets spatial reach, and areas compete: when two neighboring cortical areas are driven simultaneously, the one nearer fvaso captures more vascular territory. Neurons therefore entrain an intrinsic vascular rhythm and stimulation frequency governs how vasomotion distributes blood, shapes functional brain images, and may influence interstitial fluid transport.

neuroscience↗

bioRxiv2026

Ultralow frequency vaso-oscillations in human cerebral arteries are independent from Mayer waves

This study tests the hypothesis that vasomotion, an [~] 0.1 Hz oscillation in arteriole diameter, is generated by intrinsic oscillations within the arterioles that perfuse the brain, and not by external drive from systemic blood pressure oscillations (Mayer waves). During cardio-pulmonary bypass that transiently eliminated systemic blood pressure oscillations in 14 patients, we observed that vasomotor oscillations persist with normal amplitudes and frequencies over the one- to three-hour time course of surgery. In contrast, [~] 0.1 Hz oscillations in peripheral blood pressure were predominantly absent. This implies that cerebral arterioles generate their own rhythmic vaso-dynamics, although we cannot discount that vasomotion can phase-lock with [~] 0.1 Hz systemic physiological rhythms in the awake, healthy state. We discuss the impact of this finding on the role of vasomotion in modulating the perfusion of blood and the transport of interstitial fluid in the brain.

neuroscience↗

bioRxiv2026

Cortical vasodynamics exhibit multiscale propagation structure in the awake mouse

Spontaneous vasomotor rhythms and fluctuations are recognized contributors to functional MRI (fMRI) signals. Yet the spatial evolution of vasomotor contributions, which bear on the interpretation of fMRI signals in terms of functionally connected brain regions, remains unresolved. To clarify this issue, we analyze the 0.01 - 0.20 Hz space-frequency modes of 14T cerebral blood volume (CBV)-weighted fMRI across the awake mouse cortex. High-resolution CBV-fMRI identified single-vessel-aligned, frequency-specific modes of vasodynamic propagation, and ultra-fast CBV-fMRI enabled mapping of phase-gradients along tangential and radial axes. Tangential gradients extended maps of vasomotor traveling waves across the entire cortical mantle, with a median speed of 0.9 - 1.3 mm/s. Radial gradients revealed approximately three-fold slower changes in timing that support lamina-dependent regulation of perfusion. Region-specific differences in propagation speed and direction occur across cortical areas and between mice. These findings reframe vascular fluctuations as a feature of brain-wide physiology, as opposed to residual noise.

neuroscience↗

bioRxiv2026

A hypoxia-sensitive medullary nucleus modulates cerebral blood flow via a disynaptic pathway to cortex

The RVLM (rostral ventral lateral medulla) region of the brainstem is implicated as a controller of both systemic and cerebral blood flow (CBF). Past studies leave open the question of how the RVLM stabilizes CBF in awake animals. Here, we focus on CBF regulation by the adenergic subpopulation of RVLM neurons (RVLMD{beta}h). Hypoxic challenge increases the variability of the activity of RVLMD{beta}h neurons along with increased CBF. Experimental photoactivation of RVLMD{beta}h neurons leads to rapid vasodilation of pial arterioles across the cortical mantle and increased CBF, which is only then followed by an increase in cortical activity. No significant changes in systemic physiology are observed. Virus tracing establishes disynaptic pathways from the RVLM to neocortex with predominant relays involving the lateral hypothalamus and the zona incerta subthalamic nuclei. Chemogenetic inhibition of those nuclei led to a 70 % reduction in the ability of photoactivated RVLMD{beta}h neurons to induce cortical vasodilation and increase CBF. In toto, these findings reveal a major RVLM subcortical pathway to drive transcortical increases in CBF and represent an adaptive mechanism to inform the cerebral vasculature about environmental shifts in pO2.

neuroscience↗

bioRxiv2024

Temporal and spatial variability in availability bias has consequences for marine bird abundance estimates during the non-breeding season

O_LITo effectively monitor how marine ecosystems are being reshaped by anthropogenic pressures, we require understanding of species abundances and distributions. Due to their socio-economic and ecological value, predatory species are often at the forefront of survey efforts. However, survey data are only valuable if they can reliably be converted into estimates of underlying distributions. C_LIO_LIWe consider at-sea surveys of marine predators that often inform ecological impact assessments of offshore windfarms. These surveys are subject to a form of detection bias called availability bias whereby individuals which are submerged below the surface are consequently unavailable for detection. Although correction factors are commonly used in these surveys, they are currently based on limited data that may not be species-, time-, or area-specific. Here, we use time-depth-recorder data to investigate variation in marine bird availability bias. C_LIO_LIWe found that the proportion of diving marine birds submerged below the sea surface during daylight hours, and therefore unavailable to be counted during surveys, varied by species, month, and area. For three of our focal species wintering around northwest Europe (Atlantic puffin, common guillemot, razorbill) our results were different to comparable values previously used to correct for the availability bias, whereas no correction factors are regularly used for the fourth species (red-throated diver). We now present availability bias correction factors that are species- and month-specific to the areas the study populations use during their non-breeding seasons: the North Sea, the north and west coasts of the UK, the Baltic Sea, and Icelandic coastal waters. C_LIO_LISynthesis and applications: Variation in the proportion of daylight hours that marine birds spent submerged lead to differences in availability bias correction factors, thereby impacting estimations of their abundances. We encourage use of correction factors that use data from the species, marine area, and month during which surveys are conducted to provide more accurate abundance estimates. Using more relevant correction factors will result in increasingly accurate abundance and distribution estimates of diving marine birds, with relevance for a range of applications including planning for offshore windfarm developments, the designation and monitoring of protected areas, and understanding environmental change. C_LI

ecology↗

bioRxiv2021

Age and infectious dose significantly affect disease progression after RHDV2 infection in naive domestic rabbits

Rabbit haemorrhagic disease virus 2 (RHDV2 or GI.2, referring to any virus with lagovirus GI.2 structural genes) is a recently emerged calicivirus that causes generalised hepatic necrosis and disseminated intravascular coagulation leading to death in susceptible lagomorphs (rabbits and hares). Previous studies investigating the virulence of RHDV2 have reported conflicting results, with case fatality rates ranging from 0% to 100% even within a single study. Lagoviruses are of particular importance in Australia and New Zealand where they are used as biocontrol agents to manage wild rabbit populations; wild rabbits threaten over 300 native species and result in economic impacts in excess of $200 million AUD to Australian agricultural industries. It is critically important that any pest control method is both highly effective (i.e., virulent, in the context of viral biocontrols) and has minimal animal welfare impacts. To determine whether RHDV2 might be a suitable candidate biocontrol agent, we investigated the virulence and disease progression of a naturally occurring Australian recombinant RHDV2 in both 5-week-old and 11-week-old New Zealand White laboratory rabbits after either high or low dose oral infection. Objective measures of disease progression were recorded through continuous body temperature monitoring collars, continuous activity monitors, and twice daily observations. We observed a 100% case fatality rate in both infected kittens and adult rabbits after either high dose or low dose infection. Clinical signs of disease, such as pyrexia, weight loss, and reduced activity, were evident in the late stages of infection. Clinical disease, i.e., welfare impacts, were limited to the period after the onset of pyrexia, lasting on average 12 hours and increasing in severity as disease progressed. These findings confirm the high virulence of this RHDV2 variant in naive rabbits. While age and infectious dose significantly affected disease progression, the case fatality rate was consistently 100% under all conditions tested.

microbiology↗