The accessibility of the vertebrate retina has provided the opportunity to assess various parameters of the visual abilities of a range of species. This thin but complex extension of the brain achieves a large proportion of the necessary visual processing of an optical image before information is delivered to the brain as neural impulses. Studies of the retina as a wholemount or a flattened sheet of neural tissue are abundant due to the large amount of information that can be analysed, as follows: the level of summation or convergence; the coverage, stratification and potential sites of synaptic connections; the spatial resolving power; the arrangement of neuronal arrays or mosaics; electrophysiological access for the recording of responses to visual stimuli; the spatial arrangement of cell dendritic fields; location of retinal ‘blind spots’ (optic nerve, falciform process and pecten); topographic differences in retinal cell sampling; spectral filters, and reflective structures. The present study examines all aspects of the wholemount technique, including enucleation, fixation, retinal extraction, flattening, staining, visualization of labelled cells and stereological mapping of cell density. Uniquely, it highlights the crucial technical and often species-specific differences encountered when examining a range of vertebrate taxa (fishes, reptiles, birds and mammals). This broad comparative approach will enable future studies to overcome technical difficulties, thus permitting larger conceptual questions to be posed regarding the diversity of visual tasks across phylogenetic boundaries.

Our research assessed the prevalence of secondary traumatic stress (STS) among mental health providers working with military patients. We also investigated personal, work-related, and exposure-related correlates of STS. Finally, using meta-analysis, the mean level of STS symptoms in this population was compared with the mean level of these symptoms in other groups. Participants (N = 224) completed measures of indirect exposure to trauma (i.e., diversity, volume, frequency, ratio), appraisal of secondary exposure impact, direct exposure to trauma, STS, and work characteristics. The prevalence of STS was 19.2%. Personal history of trauma, complaints about having too many patients, and more negative appraisals of the impact caused by an indirect exposure to trauma were associated with higher frequency of STS symptoms. A meta-analysis showed that the severity of intrusion, avoidance, and arousal symptoms of STS was similar across various groups of professionals indirectly exposed to trauma (e.g., mental health providers, rescue workers, social workers).

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Many species of fish rely on their visual systems to interact with conspecifics and these interactions can lead to collective behavior. Individual-based models have been used to predict collective interactions; however, these models generally make simplistic assumptions about the sensory systems that are applied without proper empirical testing to different species. This could limit our ability to predict (and test empirically) collective behavior in species with very different sensory requirements. In this study, we characterized components of the visual system in two species of cyprinid fish known to engage in visually dependent collective interactions (zebrafish Danio rerio and golden shiner Notemigonus crysoleucas) and derived quantitative predictions about the positioning of individuals within schools. We found that both species had relatively narrow binocular and blind fields and wide visual coverage. However, golden shiners had more visual coverage in the vertical plane (binocular field extending behind the head) and higher visual acuity than zebrafish. The centers of acute vision (areae) of both species projected in the fronto-dorsal region of the visual field, but those of the zebrafish projected more dorsally than those of the golden shiner. Based on this visual sensory information, we predicted that: (a) predator detection time could be increased by >1,000% in zebrafish and >100% in golden shiners with an increase in nearest neighbor distance, (b) zebrafish schools would have a higher roughness value (surface area/volume ratio) than those of golden shiners, (c) and that nearest neighbor distance would vary from 8 to 20 cm to visually resolve conspecific striping patterns in both species. Overall, considering between-species differences in the sensory system of species exhibiting collective behavior could change the predictions about the positioning of individuals in the group as well as the shape of the school, which can have implications for group cohesion. We suggest that more effort should be invested in assessing the role of the sensory system in shaping local interactions driving collective behavior.

The TOMM and CVLT-II are sensitive to the potential impact of current financial compensation seeking and prior psychiatric history on neuropsychological test performance after TBI.

These results should help direct future research with regard to investigation of risk factors for equine MRSA infection in community and hospital populations.

Little is known as to how visual systems and visual behaviors vary within guilds in which species share the same micro-habitat types but use different foraging tactics. We studied different dimensions of the visual system and scanning behavior of Carolina chickadees, tufted titmice, and white-breasted nuthatches, which are tree foragers that form heterospecific flocks during the winter. All species had centro-temporally located foveae that project into the frontal part of the lateral visual field. Visual acuity was the highest in nuthatches, intermediate in titmice, and the lowest in chickadees. Chickadees and titmice had relatively wide binocular fields with a high degree of eye movement right above their short bills probably to converge their eyes while searching for food. Nuthatches had narrower binocular fields with a high degree of eye movement below their bills probably to orient the fovea toward the trunk while searching for food. Chickadees and titmice had higher scanning (e.g., head movement) rates than nuthatches probably due to their wider blind areas that limit visual coverage. The visual systems of these three species seem tuned to the visual challenges posed by the different foraging and scanning strategies that facilitate the partitioning of resources within this guild.

Vertebrates possess different types of retinal specializations that vary in number, size, shape, and position in the retina. This diversity in retinal configuration has been revealed through topographic maps, which show variations in neuron density across the retina. Although topographic maps of about 300 vertebrates are available, there is no method for characterizing retinal traits quantitatively. Our goal is to present a novel method to standardize information on the position of the retinal specializations and changes in retinal ganglion cell (RGC) density across the retina from published topographic maps. We measured the position of the retinal specialization using two Cartesian coordinates and the gradient in cell density by sampling ganglion cell density values along four axes (nasal, temporal, ventral, and dorsal). Using this information, along with the peak and lowest RGC densities, we conducted discriminant function analyses (DFAs) to establish if this method is sensitive to distinguish three common types of retinal specializations (fovea, area, and visual streak). The discrimination ability of the model was higher when considering terrestrial (78%-80% correct classification) and aquatic (77%-86% correct classification) species separately than together. Our method can be used in the future to test specific hypotheses on the differences in retinal morphology between retinal specializations and the association between retinal morphology and behavioral and ecological traits using comparative methods controlling for phylogenetic effects.