Projection-specific anatomy, physiology and behaviour in the mouse superior colliculus

The superior colliculus (SC) projects to other brain centres through multiple pathways, which are thought to be important in rapid, visually guided behaviours. Projections to the visual thalamus and the periaqueductal gray have been hypothesised to be important for visually-guided defensive behaviour, however, the extent to which these projections are anatomically and functionally distinct remains poorly understood. Further still, our understanding of the influence of these pathways on visually-guided defensive responses is incomplete. We tested the anatomical localisation and segregation of the SC cells projecting to each target using dual retrograde tracing. Through injecting CTB protein conjugated to different fluorophores into the visual thalamus and periaqueductal gray, we found intermingled yet separate SC populations projecting to each target. We took advantage of the intermingled yet separate nature of the two SC output pathways to measure their functional properties. Injecting retrogradelytransported cre virus into either the visual thalamus or periaqueductal gray, we gated expression of GCaMP7s in the SC. We implanted a lens above the SC and measured the global, calcium-dependent fluorescent signal while presenting visual stimuli to head-fixed mice free to run on a treadmill. Employing different visual stimuli, we observed that while there was shared visual tuning between the two SC output pathways, they exhibited different dynamics and responses to the animal’s own movement. Finally, we performed behavioural experiments to better understand the roles each pathway might play in defensive behavioural responses. Our results inform theories about the neural pathways that allow mice to produce defensive responses to visual threats

Functional Organisation of the Mouse Superior Colliculus

The superior colliculus (SC) is a highly conserved area of the mammalian midbrain that is widely implicated in the organisation and control of behaviour. SC receives input from a large number of brain areas, and provides outputs to a large number of areas. The convergence and divergence of anatomical connections with different areas and systems provides challenges for understanding how SC contributes to behaviour. Recent work in mouse has provided large anatomical datasets, and a wealth of new data from experiments that identify and manipulate different cells within SC, and their inputs and outputs, during simple behaviours. These data offer an opportunity to better understand the roles that SC plays in these behaviours. However, some of the observations appear, at first sight, to be contradictory. Here we review this recent work and hypothesise a simple framework which can capture the observations, that requires only a small change to previous models. Specifically, the functional organisation of SC can be explained by supposing that three largely distinct circuits support three largely distinct classes of simple behaviours–arrest, turning towards, and the triggering of escape or capture. These behaviours are hypothesised to be supported by the optic, intermediate and deep layers, respectively

Visual spatial location influences selection of instinctive behaviours in mouse

Visual stimuli can elicit instinctive approach and avoidance behaviours. In mouse, vision is known to be important for both avoidance of an overhead threat and approach toward a potential terrestrial prey. The stimuli used to characterize these behaviours, however, vary in both spatial location (overhead or near the ground plane) and visual feature (rapidly expanding disc or slowly moving disc). We therefore asked how mice responded to the same visual features presented in each location. We found that a looming black disc induced escape behaviour when presented overhead or to the side of the animal, but the escapes produced by side-looms were less vigorous and often preceded by freezing behaviour. Similarly, small moving discs induced freezing behaviour when presented overhead or to the side of the animal, but side sweeps also elicited approach behaviours, such that mice explored the area of the arena near where the stimulus had been presented. Our observations therefore show that mice combine cues to the location and features of visual stimuli when selecting among potential behaviours

Mapping senior leaders’ perceptions of the impact of local and national covid-19 closure/lockdown policies on schools and vulnerable young people and those at risk of exclusion. Report of findings

A report of intellectual output 1. Erasmus+ Project Co-MAP: Collaborative, Community mapping of young people's learning experiences during COVID-19. Mapping senior leaders’ perceptions of the impact of local and national covid-19 closure/lockdown policies on schools and vulnerable young people and those at risk of exclusio

Global-scale evidence for the refractory nature of riverine black carbon

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Nature Geoscience 11 (2018): 584-588, doi:10.1038/s41561-018-0159-8.Wildfires and incomplete combustion of fossil fuel produce large amounts of black carbon. Black carbon production and transport are essential components of the carbon cycle. Constraining estimates of black carbon exported from land to ocean is critical, given ongoing changes in land use and climate, which affect fire occurrence and black carbon dynamics. Here, we present an inventory of the concentration and radiocarbon content (∆14C) of particulate black carbon for 18 rivers around the globe. We find that particulate black carbon accounts for about 15.8 ± 0.9% of river particulate organic carbon, and that fluxes of particulate black carbon co-vary with river-suspended sediment, indicating that particulate black carbon export is primarily controlled by erosion. River particulate black carbon is not exclusively from modern sources but is also aged in intermediate terrestrial carbon pools in several high-latitude rivers, with ages of up to 17,000 14C years. The flux-weighted 14C average age of particulate black carbon exported to oceans is 3,700 ± 400 14C years. We estimate that the annual global flux of particulate black carbon to the ocean is 0.017 to 0.037 Pg, accounting for 4 to 32% of the annually produced black carbon. When buried in marine sediments, particulate black carbon is sequestered to form a long-term sink for CO2.A.C. acknowledges financial support from the University of Zurich Forschungskredit Fellowship and the University of Zurich (grant No. STWF-18-026). M.R., S.A. and M.S. acknowledge support from the University Research Priority Projection Global Change and Biodiversity (URPP-GCB). M.Z. acknowledges support from the National Natural Science Foundation of China (No. 41521064). T.E. acknowledges support from the Swiss National Science Foundation (“CAPS-LOCK” and “CAPS-LOCK2” #200021_140850). V.G. acknowledges financial support from an Independent Study Award from the Woods Hole Oceanographic Institution