Search

Background The effects of climate change, loss of pastureland to other land usage and presence of large carnivores are the main reasons for the increase in supplementary feeding of semi-domesticated reindeer (Rangifer tarandus tarandus) in Fennoscandia over the last decades. Feeding might expose reindeer to stress and increased animal-to-animal contact, leading to an increased risk of infectious disease transmission, like infectious keratoconjunctivitis (IKC). As it can develop rapidly and be very painful, IKC is described as an important animal welfare concern and a potential source of economic loss. The aim of this study was to investigate the current presence of IKC and potential associations between IKC and supplementary feeding through an online questionnaire survey, distributed among reindeer herders in Norway and Sweden in 2021.Results: Infectious keratoconjunctivitis was common, with 54 (71%) of the 76 herders that responded having observed clinical signs during the past 10 years. These signs were mainly observed as increased lacrimation, causing “wet cheeks”, but also as keratitis and conjunctivitis. Winter, followed by autumn, were the seasons in which IKC was observed most. The herders reported several measures, such as slaughter and isolation of affected reindeer, to counteract the spread of disease. The herding year 2019/2020 was associated with reports of outbreaks of IKC in herds as well as being the herding year where most herders (80%) had performed supplementary feeding. A significant association was found between IKC and feeding performed in an enclosure (odds ratio = 15.20), while feeding on free range areas had a non-significant, negative, relationship with the appearance of IKC outbreaks (odds ratio = 0.29). Finally, there was a trend in the data suggesting that IKC affected calves especially.Conclusions: Infectious keratoconjunctivitis is a common disease, mainly observed in winter and autumn. It has mild to moderately severe clinical signs. Our results imply that IKC is associated with stress and feeding situations and that calves might be more susceptible than adults, however, this needs to be confirmed with further studies, preferably on an individual animal level.

The ability to manipulate objects with limbs has evolved repeatedly among land tetrapods. Several selective forces have been proposed to explain the emergence of forelimb manipulation, however, work has been largely restricted to mammals, which prevents the testing of evolutionary hypotheses in a comprehensive evolutionary framework. In birds, forelimbs have gained the exclusive function of flight, with grasping transferred predominantly to the beak. In some birds, the feet are also used in manipulative tasks and appear to share some features with manual grasping and prehension in mammals, but this has not been systematically investigated. Here we use large online repositories of photographs and videos to quantify foot manipulative skills across a large sample of bird species (>1000 species). Our results show that a complex interaction between niche, diet and phylogeny drive the evolution of manipulative skill with the feet in birds. Furthermore, we provide strong support for the proposition that an arboreal niche is a key element in the evolution of manipulation in land vertebrates. Our systematic comparison of foot use in birds provides a solid base for understanding morphological and neural adaptations for foot use in birds, and for studying the convergent evolution of manipulative skills in birds and mammals.

Fast gamma oscillations, generated within the retina, and transmitted to the cortex via the lateral geniculate nucleus (LGN), are thought to carry information about stimulus size and continuity. This hypothesis relies mainly on studies carried out under anesthesia and the extent to which it holds under more naturalistic conditions remains unclear. Using multi-electrode recordings of spiking activity in the retina and the LGN of the cat, we show that visually driven gamma oscillations are absent for awake states and are highly dependent on halothane (or isoflurane). Under ketamine, responses were non-oscillatory, as in the awake condition. Response entrainment to the monitor refresh was commonly observed up to 120 Hz and was superseded by the gamma oscillatory responses induced by halothane. Given that retinal gamma oscillations are contingent upon halothane anesthesia and absent in the awake cat, such oscillations should be considered artifactual, thus playing no functional role in vision.

Owls constitute a diverse group of raptors, active at different times of the day with distinct light conditions that might be associated with multiple visual adaptations. We investigated whether shifts in the spectral sensitivity of the L cone visual pigment, as inferred by analysis of gene structure, could be one such adaptive mechanism. Using Sanger sequencing approach, we characterized the long wavelength-sensitive (LWS) opsin gene expressed in the retina of five owl species, specifically chosen to represent distinct patterns of activity. Nocturnality was epitomized by the American barn owl (Tyto furcata), the striped owl (Asio clamator), and the tropical screech owl (Megascops choliba); diurnality, by the ferruginous pygmy owl (Glaucudium brasilianum); and cathemerality, by the burrowing owl (Athene cunicularia). We also analyzed the presence of the L cone in the retinas of four species of owl (T. furcata, A. cunicularia, G. brasilianum and M. choliba) using immnunohistochemistry. Five critical sites for the spectral tuning of the LWS opsin (164, 181, 261, 269, and 292) were analyzed and compared to the sequence of other birds. The sequence of A. cunicularia showed a substitution on residue 269, with the presence of an alanine instead threonine, which generates an estimated maximum absorption (λmax) around 537 nm. No other variation was found in the spectral tuning sites of the LWS opsin, among the other species, and the λmax was estimated at around 555 nm. The presence of L cones in the retinas of the four species of owls was revealed using immunohistochemistry and we observed a reduced number of L cones in T. furcata compared to A. cunicularia, G. brasilianum and M. choliba.

Neste artigo é descrito um sistema com potencial para identificar a privação do sono, que, com base no levantamento bibliográfico realizado, ainda não foi abordado na literatura. Este sistema integra simultaneamente duas metodologias, o teste de vigilância psicomotora (Psychomotor vigilance test, PVT) e a pupilometria, que se destacam no estudo da privação do sono. Entretanto, para atender às peculiaridades destas metodologias, permitindo que coexistam em um único sistema, algumas adaptações foram realizadas em seus procedimentos. Esta integração poderá garantir não só a complementariedade de indicadores que torna a identificação da privação do sono mais robusta, assim como estabelecer a equalização do estado psicofisiológico do sujeito, o que não é possível em testes realizados com defasagem temporal. Neste estudo, a validação das métricas do sistema foi realizada com sujeitos em estado de alerta. Os resultados mostraram-se coerentes com a literatura. Entretanto, algumas métricas apresentam um deslocamento em seus valores médios, que segundo as avaliações realizadas são determinadas pelas exigências técnicas do sistema. Os resultados obtidos nesta avaliação, somados à crescente demanda de ferramentas de aplicação em larga escala e que possam ser utilizadas além dos limites laboratoriais para estudos em distúrbios e privação do sono, apontam este sistema como uma potencial ferramenta. Entretanto, será necessário o estabelecimento de um experimento rigoroso, para avaliar se os indicadores oriundos das métricas do sistema permitem a identificação robusta da privação do sono.

TO COME.

The transformation of spatial (SF) and temporal frequency (TF) tuning functions from broad-band/low-pass to narrow band-pass profiles is one of the key emergent properties of neurons in the mammalian primary visual cortex (V1). The mechanisms underlying such transformation are still a matter of ongoing debate. With the aim of providing comparative insights into the issue, we analyzed various aspects of the spatiotemporal tuning dynamics of neurons in the visual wulst of four awake owls. The wulst is the avian telencephalic target of the retinothalamofugal pathway and, in owls, bears striking functional analogy with V1. Most neurons in our sample exhibited fast and large-magnitude adaptation to the visual stimuli with response latencies very similar to those reported for V1. Moreover, latency increased as a function of stimulus SF but not TF, which suggests that parvo- and magno-like geniculate inputs could be converging onto single wulst neurons. No net shifts in preferred SF or TF were observed along the initial second of stimulation, but bandwidth decreased roughly during the first 200 ms after response latency for both stimulus dimensions. For SF, this occurred exclusively as a consequence of low-frequency suppression, whereas suppression was observed both at the low- and high-frequency limbs of TF tuning curves. Overall these results indicate that SF and TF tuning curves in the wulst are shaped by both feedforward and intratelencephalic suppressive mechanisms, similarly to what seems to be the case in the mammalian striate cortex.

The avian visual wulst is hodologically equivalent to the mammalian primary visual cortex (V1). In contrast to most birds, owls have a massive visual wulst, which shares striking functional similarities with V1. To provide a better understanding of how motion is processed within this area, we used sinusoidal gratings to characterize the spatiotemporal frequency and speed tuning profiles of 131 neurones recorded from awake burrowing owls. Cells were found to be clearly tuned to both spatial and temporal frequencies, and in a way that is similar to what has been reported in the striate cortex of primates and carnivores. Our results also suggest the presence of spatial frequency tuning domains in the wulst. Speed tuning was assessed by several methods devised to measure the degree of dependence between spatial and temporal frequency tuning. Although many neurones were found to be independently tuned, a significant proportion of cells showed at least some degree of dependence, compatible with the idea that some kind of initial transformation towards an explicit representation of speed is being carried out by the owl wulst. Interestingly, under certain constraints, a higher incidence of spatial frequency-invariant speed tuned profiles was obtained by combining our experimentally measured responses using a recent cortical model of speed tuning. Overall, our findings reinforce the notion that, like V1, the owl wulst is an important initial stage for motion processing, a function that is usually attributed to areas of the tectofugal pathway in lateral-eyed birds.

The avian retinothalamofugal pathway reaches the telencephalon in an area known as visual wulst. A close functional analogy between this area and the early visual cortex of mammals has been established in owls. The goal of the present study was to assess quantitatively the directional selectivity and motion integration capability of visual wulst neurones, aspects that have not been previously investigated. We recorded extracellularly from a total of 101 cells in awake burrowing owls. From this sample, 88% of the units exhibited modulated directional responses to sinusoidal gratings, with a mean direction index of 0.74 +/- 0.03 and tuning bandwidth of 28 +/- 1.16 degrees . A direction index higher than 0.5 was observed in 66% of the cells, thereby qualifying them as direction selective. Motion integration was tested with moving plaids, made by adding two sinusoidal gratings of different orientations. We found that 80% of direction-selective cells responded optimally to the motion direction of the component gratings, whereas none responded to the global motion of plaids, whose direction was intermediate to that of the gratings. The remaining 20% were unclassifiable. The strength of component motion selectivity rapidly increased over a 200 ms period following stimulus onset, maintaining a relatively sustained profile thereafter. Overall, our data suggest that, as in the mammalian primary visual cortex, the visual wulst neurones of owls signal the local orientated features of a moving object. How and where these potentially ambiguous signals are integrated in the owl brain might be important for understanding the mechanisms underlying global motion perception.

Visual responses in the cortex and lateral geniculate nucleus (LGN) are often associated with synchronous oscillatory patterning. In this short review, we examine the possible relationships between subcortical and cortical synchronization mechanisms. Our results obtained from simultaneous multi–unit recordings show strong synchronization of oscillatory responses between retina, LGN and cortex, indicating that cortical neurons can be synchronized by oscillatory activity relayed through the LGN. This feed–forward synchronization mechanism operating in the 60 to 120 Hz frequency range was observed mostly for static stimuli. In response to moving stimuli, by contrast, cortical synchronization was independent of oscillatory inputs from the LGN, with oscillation frequency in the range of 30 to 60 Hz. The functional implications of synchronization of activity from parallel channels are discussed, in particular its significance for signal transmission and cortical integration processes.

The normal maturation of the auditory space map in the deeper layers of the ferret superior colliculus (SC) depends on signals provided by the superficial visual layers, but it is unknown where or how these signals influence the developing auditory responses. Here we report that tracer injections in the superficial layers label axons with en passant and terminal boutons, both in the deeper layers of the SC and in their primary source of auditory input, the nucleus of the brachium of the inferior colliculus (nBIC). Electron microscopy confirmed that biocytin-labelled SC axons form axodendritic synapses on nBIC neurons. Injections of biotinylated dextran amine in the nBIC resulted in anterograde labelling in the deeper layers of the SC, as well as retrogradely labelled superficial and deep SC neurons, whose distribution varied systematically with the rostrocaudal placement of the injection sites in the nBIC. Topographical order in the projection from the SC to the ipsilateral nBIC was confirmed using fluorescent microspheres. We demonstrated the existence of functional SC-nBIC connections by making whole-cell current-clamp recordings from young ferret slices. Both monosynaptic and polysynaptic EPSPs were generated by electrical stimulation of either the superficial or deep SC layers. In addition to unimodal auditory units, both visual and bimodal visual-auditory units were recorded in the nBIC in vivo and their incidence was higher in juvenile ferrets than in adults. The SC-nBIC circuit provides a potential means by which visual and other sensory or premotor signals may be delivered to the nBIC to calibrate the representation of auditory space.

The dynamic, accurate measurement of pupil size is extremely valuable for studying a large number of neuronal functions and dysfunctions. Despite tremendous and well-documented progress in image processing techniques for estimating pupil parameters, comparatively little work has been reported on practical hardware issues involved in designing image acquisition systems for pupil analysis. Here, we describe and validate the basic features of such a system which is based on a relatively compact, off-the-shelf, low-cost FireWire digital camera. We successfully implemented two configurable modes of video record: a continuous mode and an event-triggered mode. The interoperability of the whole system is guaranteed by a set of modular software components hosted on a personal computer and written in Labview. An offline analysis suite of image processing algorithms for automatically estimating pupillary and eyelid parameters were assessed using data obtained in human subjects. Our benchmark results show that such measurements can be done in a temporally precise way at a sampling frequency of up to 120Hz and with an estimated maximum spatial resolution of 0.03mm. Our software is made available free of charge to the scientific community, allowing end users to either use the software as is or modify it to suit their own needs.

This paper gives an overview of the markets and applications for permanent and temporary bonding technologies.

The understanding of how neurons interact in the visual cortex and what types of neurons are responsable for each interaction are still open questions. In order to analyse such problem, the spiking activity of neurons in the central visual pathway of awake owls was analyzed with Principal Component Analysis (PCA) and clustering techniques. Further analysis using kernel representation revealed the existence of two large groups of neurons with distinguishable behavior.

Light emitting diodes (LEDs) are extensively used as light sources to investigate visual and visually related function and dysfunction. Here, we describe the design of a compact, low-cost, stand-alone LED-based system that enables the configuration, storage and presentation of elaborate visual stimulation paradigms. The core functionality of this system is provided by a microcontroller whose ultra-low power consumption makes it well suited for long lasting battery applications. The effective use of hardware resources is managed by multi-layered architecture software that provides an intuitive and user-friendly interface. In the configuration mode, different stimulation sequences can be created and memorized for ten channels, independently. LED-driving current output can be set either as continuous or pulse modulated, up to 500 Hz, by duty cycle adjustments. In run mode, multiple-channel stimulus sequences are automatically applied according to the pre-programmed protocol. Steady state visual evoked potentials were successfully recorded in five subjects with no visible electromagnetic interferences from the stimulator, demonstrating the efficacy of combining our prototyped equipment with electrophysiological techniques. Finally, we discuss a number of possible improvements for future development of our project.

The avian retinothalamofugal pathway reaches the telencephalon in an area known as visual wulst. A close functional analogy between this area and the early visual cortex of mammals has been established in owls. The goal of the present study was to assess quantitatively the directional selectivity and motion integration capability of visual wulst neurones, aspects that have not been previously investigated. We recorded extracellularly from a total of 101 cells in awake burrowing owls. From this sample, 88% of the units exhibited modulated directional responses to sinusoidal gratings, with a mean direction index of 0.74 +/- 0.03 and tuning bandwidth of 28 +/- 1.16 degrees . A direction index higher than 0.5 was observed in 66% of the cells, thereby qualifying them as direction selective. Motion integration was tested with moving plaids, made by adding two sinusoidal gratings of different orientations. We found that 80% of direction-selective cells responded optimally to the motion direction of the component gratings, whereas none responded to the global motion of plaids, whose direction was intermediate to that of the gratings. The remaining 20% were unclassifiable. The strength of component motion selectivity rapidly increased over a 200 ms period following stimulus onset, maintaining a relatively sustained profile thereafter. Overall, our data suggest that, as in the mammalian primary visual cortex, the visual wulst neurones of owls signal the local orientated features of a moving object. How and where these potentially ambiguous signals are integrated in the owl brain might be important for understanding the mechanisms underlying global motion perception.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico A percepção visual é altamente influenciada pela contexto, ou seja, a forma como os elementos de uma cena se organizam no espaço e no tempo. A modulação contextual pode ser definida como a informação da periferia do campo receptivo que modifica as respostas do neurônio. Dentre outros, o contraste acromático é um importante atributo das imagens conhecido por modular a resposta dos neurônios. Tendo em vista isso, investigamos o efeito do contraste local na modulação contextual por meio de registros extracelulares de neurônios do wulst visual das corujas. A resposta ao contraste de 31 neurônios do wulst visual das corujas Tyto furcata foram descritas utilizando gabors estacionários como estímulos. A maioria dessas células exibiram um comportamento monotônico a medida que a intensidade do contraste aumentava. Quatro modelos matemáticos (linear, potência, logarítmico e taxa hiperbólica), foram empregados para ajustar as curvas de resposta ao contraste de cada neurônio. De acordo com a qualidade do ajuste (R2), o modelo de taxa hiperbólica revelou-se como melhor descritor para 78% dos neurônios do wulst, porém quando critério de informação de Akaike foi empregado essa tendência se extinguiu. Portanto, o perfil da resposta ao contraste mostrou-se relativamente variável de célula para célula. A despeito dessa variação, os resultados revelaram que uma parte significativa dos neurônios exibiram um perfil linear (39%), embora modelo linear não seja o melhor descritor. Os resultados confirmaram que a modulação centro-contorno é engendrada pela rede neurônios presente no wulst, as quais apresentaram um grau de supressão considerável (Média=0.35). Foi possível observar que os efeitos modulatórios tendem a ser mais fortes quando os estímulos são posicionados na zona terminal de maneira colinear, sugerindo que a saliência do contorno seja engendrada no wulst visual. Além disso, constatou-se uma tendência à facilitação em baixos contrastes e supressão em altos contrastes. A heterogeneidade de respostas dos neurônios revelaram que o tipo de efeito modulatório depende do contraste e da conformação espacial dos atributos. Evidentemente, os resultados deste estudo não nos permite afirmar que o processamento da saliência visual acontece no wulst de corujas Tyto furcata. Todavia, os efeitos facilitatórios encontrados confirmam a importância de se explorar esse fenômeno de forma minuciosa, pois talvez seja ele limitado a uma camada ou a população específica de neurônios do wulst visual que receba retroalimentação de regiões com correspondência funcional a áreas extraestriadas de mamíferos, ou ainda que as operações engajadas na a saliência visual ocorram de forma não conhecida no wulst visual. The visual perception is greatly influenced by the context, that is the manner which elements of a scene are organised into space and time. Contextual modulation is defined as the information of the receptive field periphery that modifies neuron responses. The achromatic contrast is an important property of images known to modulate neuron responses. Here we have investigated the effect of local contrast in contextual modulation by recording extra-celular signals from single neuron within the wulst. First, we described the contrast response of 31 neurons from the visual wulst of barn owls using stationary gabor patches as stimulus. We have shown that most cells exhibit a monotonic behaviour as the contrast intensity increases. Second, we applied four mathematical models (linear, power, logarithmic and hyperbolic ratio) to adjust each cell’s contrast response. According to the goodness-of-fit (R2), the hyperbolic ratio seemed to be the best describer of 78% of wulst neurons, but since the Akaike’s information criterion was employed this tendency has ceased. So we concluded that the contrast response profile was considerably variable from cell to cell. In despite of this variation, our findings reveal that a significant part of neurons (39%) exhibited linear behaviour. The results show support for previous findings that contextual modulation is engendered by the network of wulst neurons, which exhibit considerable degree of suppression (mean = 0.35). We observed that modulatory effects tend to be stronger when stimuli are collinear and placed at the end-zone suggesting that contour saliency is engendered in the visual wulst. In addition, we also noticed a tendency to facilitation effects at low contrast and suppression at high contrast conditions.The heterogeneity of the neurons responses revealed that the modulatory effects depends on the contrast and the spatial conformation of attributes. Obviously, these results does not allow us to state that processing of visual saliency happens within the visual wulst of Tyto furcata. However, facilitatory effects found in this work confirm the importance of exploring this phenomenon in detail, because its occurrence may be limited to a specific layer or population of neurons in the visual wulst that receive feedback from regions with functional correspondence extrastriatal areas of mammal brains, otherwise the operations engaged in the visual saliency must occur in a undisclosed manner within the visual wulst. Key-words: Barn owl, contrast response, contextual modulation, visual wulst.

Sob condições não controladas a aquisição de informações visuais é constantemente interrompida por eventos transitórios, tais como o piscar e movimentações de campo visual. A inclusão destes comportamentos em qualquer modelo de processamento visual é de extrema importância. No presente estudo foi utilizada uma abordagem etológica para examinar a dinâmica temporal do piscar, dos movimentos da cabeça e estabilização olhar (fixação) na coruja Athene cunicularia, uma espécie ativa durante o dia. As corujas têm movimentos oculares insignificantes. Desta forma o posicionamento da cabeça pode ser tomado como um indicador confiável do posicionamento dos olhos. Os resultados baseiam-se em 17 horas de filmagens em câmera de vídeo com frequência de amostragem de 25 Hz e 960x600 pixels, entre 0900 e 1600 horas, de um total de nove corujas adultas, alojadas em aviários ao ar livre. Os filmes foram analisados quadro a quadro. Quatro categorias comportamentais foram consideradas para análise: (i) "fixação visual" (caso em que os olhos e a cabeça não se movem por tempo superior a 40 ms, ou seja, acima da taxa de amostragem), (ii) "piscar" (fechamento temporário completo das pálpebras); (iii) "sacada" (movimento de cabeça), e (iv) "fora de vista" (quando nem olho era visível para o observador). Sete animais foram observados em três condições de adiamentos: de manhã (Mn), tarde (Td), à tarde antes de comer (Ta), e em outras duas em condições: "repouso" (R) e "tarefa" (T), quando os animais estavam engajados na uma tarefa de discriminação de imagens. Proximalmente 77% do tempo filmado os animais ficaram visíveis para a câmera filmadora. Em média, 93 % do tempo os animais estavam em fixação visual. Para as fixações foi observada diferença significativa entre os grupos de Mn x Td e R x T (teste t, p > 0,05). A distribuição das durações das fixações foi ampla, variando de 80 a 25.600 ms, e inclinada negativamente com valores médios de 1,840 ms (moda: 480ms). Para corujas em repouso a moda foi de 780 ms e para as corujas em tarefa a moda foi de 240 ms. O piscar durou, em média, 235 ±45 ms (média aritmética ± SD; R: 290 ± 64 ms; T: 180 ± 25 ms). A duração média das movimentações de cabeça tipo sacada foi de 161 ±144 ms (R: 260 ±160 ms; T: 150 ±130 ms). Os animais em repouso piscaram com maior frequência do que os animais em tarefa (média: 7.45/min contra 3.05/min, Wilcoxon, P 0.05). The distribution of gaze durations was broad, ranging from 80 to 25,600ms, and negatively skewed with median values of 1840 ms (mode: 480ms) for resting owls (RO) and 780 ms (mode: 240ms) for discriminating owls (DO). Blink episodes lasted on average 235 ± 45 ms (arithmetic mean ± SD; RO: 290 ± 64 ms; DO: 180 ±25 ms). Mean saccadic gaze-shift duration was 161± 144 ms (RO: 260 ±160 ms; DO: 150±130 ms). RO blinked significantly more often than DO (median: 7.45/min versus 3.05/min, Wilcoxon rank sum, P < 0.001). Independently of the behavioral state of the animal, we also found that around 85% of blinks were concomitant with head movements. However, the fact that most head movements exhibited by DO were not accompanied by blinks as they were seen to be in RO suggests that blinks were not simply triggered by reflexive mechanisms involving corneal stimulation. Our results provide evidence for task-dependent interaction between blink and head movement control mechanisms, a phenomenon that has also been reported in primates.