Prefrontal Cortex Lesions Impair Object-Spatial Integration

How and where object and spatial information are perceptually integrated in the brain is a central question in visual cognition. Single-unit physiology, scalp EEG, and fMRI research suggests that the prefrontal cortex (PFC) is a critical locus for object-spatial integration. To test the causal participation of the PFC in an object-spatial integration network, we studied ten patients with unilateral PFC damage performing a lateralized object-spatial integration task. Consistent with single-unit and neuroimaging studies, we found that PFC lesions result in a significant behavioral impairment in object-spatial integration. Furthermore, by manipulating inter-hemispheric transfer of object-spatial information, we found that masking of visual transfer impairs performance in the contralesional visual field in the PFC patients. Our results provide the first evidence that the PFC plays a key, causal role in an object-spatial integration network. Patient performance is also discussed within the context of compensation by the non-lesioned PFC

The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

Speech Cues Contribute to Audiovisual Spatial Integration

Speech is the most important form of human communication but ambient sounds and competing talkers often degrade its acoustics. Fortunately the brain can use visual information, especially its highly precise spatial information, to improve speech comprehension in noisy environments. Previous studies have demonstrated that audiovisual integration depends strongly on spatiotemporal factors. However, some integrative phenomena such as McGurk interference persist even with gross spatial disparities, suggesting that spatial alignment is not necessary for robust integration of audiovisual place-of-articulation cues. It is therefore unclear how speech-cues interact with audiovisual spatial integration mechanisms. Here, we combine two well established psychophysical phenomena, the McGurk effect and the ventriloquist's illusion, to explore this dependency. Our results demonstrate that conflicting spatial cues may not interfere with audiovisual integration of speech, but conflicting speech-cues can impede integration in space. This suggests a direct but asymmetrical influence between ventral ‘what’ and dorsal ‘where’ pathways

Integrating Functional and Diffusion Magnetic Resonance Imaging for Analysis of Structure-Function Relationship in the Human Language Network

The capabilities of magnetic resonance imaging (MRI) to measure structural and functional connectivity in the human brain have motivated growing interest in characterizing the relationship between these measures in the distributed neural networks of the brain. In this study, we attempted an integration of structural and functional analyses of the human language circuits, including Wernicke's (WA), Broca's (BA) and supplementary motor area (SMA), using a combination of blood oxygen level dependent (BOLD) and diffusion tensor MRI.Functional connectivity was measured by low frequency inter-regional correlations of BOLD MRI signals acquired in a resting steady-state, and structural connectivity was measured by using adaptive fiber tracking with diffusion tensor MRI data. The results showed that different language pathways exhibited different structural and functional connectivity, indicating varying levels of inter-dependence in processing across regions. Along the path between BA and SMA, the fibers tracked generally formed a single bundle and the mean radius of the bundle was positively correlated with functional connectivity. However, fractional anisotropy was found not to be correlated with functional connectivity along paths connecting either BA and SMA or BA and WA. for use in diagnosing and determining disease progression and recovery

The Canada Lynx (Lynx canadensis) of Isle Royale: over-harvest, climate change, and the extirpation of an island population

In the 1930s, the Canada Lynx (Lynx canadensis) was extirpated from Isle Royale, a 535-km2 island located in western Lake Superior, 22 km from the Ontario and Minnesota shorelines. The first half of the 20th century was a time of change on Isle Royale as Caribou (Rangifer tarandus) disappeared, Coyotes (Canis latrans) briefly appeared, Moose (Alces americanus), Grey Wolves (Canis lupus), and Red Foxes (Vulpes vulpes) became established, and the habitat was altered by fire, logging, and over-browsing. Although these changes may have contributed to the demise of the Canada Lynx, our results suggest that over-harvest was a primary cause. Assuming a peak carrying capacity of 75 Canada Lynx and harvest rates comparable to those reported from 1890–1935, a population viability analysis indicated that the island population had a 0% chance of surviving 50 years. The analysis also indicated that, even in the absence of harvest, the population had only a 14% chance of persistence for 250 years. However, when 10 Canada Lynx were added to the modeled population every 10th year, the probability of persistence increased to 100%. Our analyses suggest that the island’s Canada Lynx population maintained itself by periodic immigration across an ice bridge; therefore, natural recolonization should be possible. However, the probability of ice-bridge formation has declined from 0.8 in the winter of 1958–59 to 0.1 in 2012–13, likely as a result of climate change. The Isle Royale situation exemplifies another impact of climate change and the possible need to augment populations to mitigate the loss of connectivity

Revisiting the Role of Aquatic Plants in Beaver Habitat Selection

© 2018 University of Notre Dame. All Rights Reserved. Beaver (Castor canadensis) can help to restore wetlands and mitigate the effects of climate change on hydrological regimes in some areas. Therefore, ongoing resource management efforts seek to promote the presence and persistence of beaver populations. The long-term success of such endeavors requires an understanding of what conditions are conducive to sustaining beaver populations, often in landscapes with degraded forest resources. Available information about beaver habitat suitability is largely based on short-term studies in stream habitats that do not consider aquatic plant suitability, even though aquatic plants may comprise over half of beavers\u27 annual diets. In the present study, we assess whether the availability of woody plants, conditions conducive to the availability of aquatic vascular plants (macrophytes), and/or other features of basin morphology are associated with the persistence and density of beaver occupancy in 23 lakes over a 50-y period. We incorporate field-based study that includes all species of macrophytes, to extend previous work that focused specifically on water lily species (Nymphaea spp., Nuphar spp.). Lake perimeter (a function of sinuosity and surface area) and total macrophyte cover were associated with the persistence and density of beaver occupancy in lakes. Each factor independently explained ∼70% (R2adj) of the variation in the persistence of beaver occupancy. Percent cover of floating-leaved macrophytes was a leading predictor of beaver colony density in lakes, independently explaining 72% (R2adj) of the variation. Brasenia schreberi appeared particularly valuable to sustaining beaver in smaller lakes. Several lakes with abundant Brasenia supported high colony densities and long-term colony occupancy. Where feasible, beaver restoration efforts may increase the probability of success by facilitating beaver access to lakes that host key rhizomatous macrophyte species

A first genetic assessment of the newly introduced Isle Royale gray wolves (Canis lupus)

The gray wolf (Canis lupus) population of Isle Royale National Park suffered an extreme population decline where by 2017 only two wolves that were both half-siblings and a father-daughter pair remained with low probability of producing viable young. This precipitous decline was in part due to the negative fitness consequences associated with inbreeding. To restore the Isle Royale ecosystem 19 gray wolves were translocated in 2018 and 2019. The founders were translocated from Grand Portage, MN (n = 4), western Upper Peninsula, MI (n = 4), Jostle Lake, ON (n = 3), and Michipicoten Island, ON (n = 8), and genotyped using 18 microsatellite loci. Allelic richness and heterozygosity of translocated Isle Royale founders was similar to reference populations. Population structure assigned the Isle Royale founders to gray wolves with little evidence of admixture from eastern wolves (Canis lycaon cf). In addition, we confirmed wolves translocated from Michipicoten Island were a single family-group. Through simulation and empirical analysis of the new Isle Royale founders we projected a loss in genetic variation over the next 50 years and an increase in inbreeding. However, varying levels of immigration may allow the retention of some genetic variation. Our findings indicate Isle Royale founders are genetically diverse and representative of the Great Lakes region, but the numerical dominance of a single family group may have negative implications for retaining genetic diversity and success of establishment for specific wolves, reinforcing the importance of continued monitoring of genetic fitness

A voice region in the monkey brain

For vocal animals, recognizing species-specific vocalizations is important for survival and social interactions. In humans, a voice region has been identified that is sensitive to human voices and vocalizations. As this region also strongly responds to speech, it is unclear whether it is tightly associated with linguistic processing and is thus unique to humans. Using functional magnetic resonance imaging of macaque monkeys (Old World primates, Macaca mulatta) we discovered a high-level auditory region that prefers species-specific vocalizations over other vocalizations and sounds. This region not only showed sensitivity to the ‘voice‘ of the species, but also to the vocal identify of conspecific individuals. The monkey voice region is located on the superior-temporal plane and belongs to an anterior auditory what pathway. These results establish functional relationships with the human voice region and support the notion tha t, for different primate species, the anterior temporal regions of the brain are adapted for recognizing communication signals from conspecifics