Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: Prospective, multicentre cohort study

Study question What are the diagnostic yield and accuracy of early computed tomography (CT) angiography followed by magnetic resonance imaging/angiography (MRI/MRA) and digital subtraction angiography (DSA) in patients with non-traumatic intracerebral haemorrhage? Methods This prospective diagnostic study enrolled 298 adults (18-70 years) treated in 22 hospitals in the Netherlands over six years. CT angiography was performed within seven days of haemorrhage. If the result was negative, MRI/MRA was performed four to eight weeks later. DSA was performed when the CT angiography or MRI/MRA results were inconclusive or negative. The main outcome was a macrovascular cause, including arteriovenous malformation, aneurysm, dural arteriovenous fistula, and cavernoma. Three blinded neuroradiologists independently evaluated the images for macrovascular causes of haemorrhage. The reference standard was the best available evidence from all findings during one year's follow-up. Study answer and limitations A macrovascular cause was identified in 69 patients (23%). 291 patients (98%) underwent CT angiography; 214 with a negative result underwent additional MRI/MRA and 97 with a negative result for both CT angiography and MRI/MRA underwent DSA. Early CT angiography detected 51 macrovascular causes (yield 17%, 95% confidence interval 13% to 22%). CT angiography with MRI/MRA identified two additional macrovascular causes (18%, 14% to 23%) and these modalities combined with DSA another 15 (23%, 18% to 28%). This last extensive strategy failed to detect a cavernoma, which was identified on MRI during follow-up (reference strategy). The positive predictive value of CT angiography was 72% (60% to 82%), of additional MRI/MRA was 35% (14% to 62%), and of additional DSA was 100% (75% to 100%). None of the patients experienced complications with CT angiography or MRI/MRA; 0.6% of patients who underwent DSA experienced p

Predatory developmental environments shape loser behaviour in animal contests

Meuthen D, Bakker TCM, Thünken T. Predatory developmental environments shape loser behaviour in animal contests. Behaviour. 2019;156(15):1519-1532.High predation risk during development induces phenotypic changes in animals. However, little is known about how these plastic responses affect signalling and competitiveness during contests. Herein, we have studied the consequences of anti-predator plasticity during the intra-sexual competition of Pelvicachromis taeniatus, a cichlid fish with mutual mate choice. We staged contests between adult size-matched siblings of the same sex derived from different environments: one fish was regularly exposed to conspecific alarm cues since the larval stage (simulating predator presence), the other fish to control conditions. Rearing environment did not affect the winner of contests or total aggression within a fight. However, contest behaviour differed between treatments. The effects were especially pronounced in alarm cue-exposed fish that lost a contest: they generally displayed lower aggression than winners but also lower aggression than losers of the control treatment. Thus, perceived predator presence modulates intra-sexual competition behaviour by increasing the costs associated with fighting

UV matters in shoaling decisions

Shoaling behaviour in fish is influenced by numerous factors, such as familiarity, kinship, group size and shoal composition. Grouping decisions are based on both olfactory and visual cues. The visual system of many vertebrates is extended into the ultraviolet (UV) wave range as in three-spined sticklebacks (Gasterosteus aculeatus, L.). We investigated whether the presence or absence of UV wavelengths has an influence on shoaling behaviour in this species. Reproductively non-active three-spined sticklebacks were given the choice between two shoals, equal in numbers of individuals, which could be seen either through a UV-transmitting [UV(+)] or a UV-blocking [UV(−)] filter. Test fish preferred to join the shoal seen under UV(+) conditions. Due to differences in quantal flux between the UV(+) and UV(−) filters used, control experiments with neutral-density optical filters were performed in order to clarify the role of luminance. Here, test fish spent significantly more time near shoals that were seen in a darker environment, suggesting a potential trade-off between UV radiation and lower brightness during shoal choice. To our knowledge, these results demonstrate for the first time that shoaling decisions are influenced by UV wavelengths

Parental investment in relation to offspring quality in the biparental cichlid fish Pelvicachromis taeniatus

Thünken T, Meuthen D, Bakker TCM, Kullmann H. Parental investment in relation to offspring quality in the biparental cichlid fish Pelvicachromis taeniatus. Animal Behaviour. 2010;80(1):69-74.Theory predicts that parents should adjust their parental investment to the reproductive value of the brood. Previous studies have mainly investigated the relationship between brood size, brood age and the intensity of care. However, the impact of brood quality traits such as the offspring’s average body size on parental investment has received relatively little attention. We examined the parental response to brood quality in the biparentally brood-caring cichlid fish Pelvicachromis taeniatus. We manipulated offspring quality by manipulating the food availability for the free-swimming fry and measured the parental response over 4 weeks. Generally, care decreased over the 4 weeks suggesting that parents adjust care to decreasing offspring vulnerability. However, parents of relatively low-quality broods, that is, of broods with relatively small average individual body size, showed a greater reduction in care than parents of high-quality broods resulting in a significant difference in care provided in the fourth week. The result suggests that parents adjust their care to brood quality and supports the predictions of the parental investment theory. Furthermore, mothers of high-quality fry were significantly more aggressive towards their partner than mothers of low-quality fry. This result is discussed in the context of parental response to brood value. Generally, females invested more in brood care than males

High perceived predation risk during development affects mutual mate choice in a cichlid fish

Meuthen D, Baldauf SA, Bakker TCM, Thünken T. High perceived predation risk during development affects mutual mate choice in a cichlid fish. Animal Behaviour. 2019;158:227-237

Inbreeding avoidance through non-random mating in sticklebacks

Negative effects of inbreeding are well documented in a wide range of animal taxa. Hatching success and survival of inbred offspring is reduced in many species and inbred progeny are often less attractive to potential mates. Thus, individuals should avoid mating with close kin. However, experimental evidence for inbreeding avoidance through non-random mating in vertebrates is scarce. Here, we show that gravid female three-spined sticklebacks (Gasterosteus aculeatus) when given the choice between a courting familiar brother and a courting unfamiliar non-sib prefer to mate with the non-sib and thus avoid the disadvantages of incest. We controlled for differences in males' body size and red intensity of nuptial coloration. Thus, females adjust their courting behaviour to the risk of inbreeding