Explore the vast range of titles available.

Information that is shared across brains is encoded in idiosyncratic fine-scale functional topographies. Hyperalignment captures shared information by projecting pattern vectors for neural responses and connectivities into a common, high-dimensional information space, rather than by aligning topographies in a canonical anatomical space. Individual transformation matrices project information from individual anatomical spaces into the common model information space, preserving the geometry of pairwise dissimilarities between pattern vectors, and model cortical topography as mixtures of overlapping, individual-specific topographic basis functions, rather than as contiguous functional areas. The fundamental property of brain function that is preserved across brains is information content, rather than the functional properties of local features that support that content. In this Perspective, we present the conceptual framework that motivates hyperalignment, its computational underpinnings for joint modeling of a common information space and idiosyncratic cortical topographies, and discuss implications for understanding the structure of cortical functional architecture.

Poikilothermic disease vectors can respond to altered climates through spatial changes in both population size and phenology. Quantitative descriptors to characterize, analyze and visualize these dynamic responses are lacking, particularly across large spatial domains. In order to demonstrate the value of a spatially explicit, dynamic modeling approach, we assessed spatial changes in the population dynamics of Ixodes scapularis, the Lyme disease vector, using a temperature-forced population model simulated across a grid of 4 × 4 km cells covering the eastern United States, using both modeled (Weather Research and Forecasting (WRF) 3.2.1) baseline/current (2001–2004) and projected (Representative Concentration Pathway (RCP) 4.5 and RCP 8.5; 2057–2059) climate data. Ten dynamic population features (DPFs) were derived from simulated populations and analyzed spatially to characterize the regional population response to current and future climate across the domain. Each DPF under the current climate was assessed for its ability to discriminate observed Lyme disease risk and known vector presence/absence, using data from the US Centers for Disease Control and Prevention. Peak vector population and month of peak vector population were the DPFs that performed best as predictors of current Lyme disease risk. When examined under baseline and projected climate scenarios, the spatial and temporal distributions of DPFs shift and the seasonal cycle of key questing life stages is compressed under some scenarios. Our results demonstrate the utility of spatial characterization, analysis and visualization of dynamic population responses—including altered phenology—of disease vectors to altered climate.

Omnivory is ubiquitous in ecological communities. Yet, we lack a consensus of how plant alternative resources impact the ability of omnivores to suppress prey populations. Previous work suggests that plant alternative resources can increase, decrease, or have no effect on the magnitude of omnivore—prey interactions. This discrepancy may arise from (1) the ability of omnivore populations to respond to plant alternative resources and (2) identity-specific effects of plant alternative resources. We used a meta-analysis to examine how omnivore population responses and the identity of plant alternative resources affect (1) omnivore predation rates (mainly reported as per capita predation rate) and (2) omnivore impacts on prey population density. Plant alternative resources reduced omnivore predation rate regardless of identity. The suppression of the predation rate by flowers and flowering plants was magnified when pollen alone was tested as the alternative resource. Surprisingly, plant alternative resource availability reduced prey density, suggesting that omnivore predation increased with plant alternative resources. This discrepancy (plant alternative resources not only decreased omnivore predation rates but also decreased prey density) resulted from experimental differences in the ability of omnivore populations to respond to plant alternative resources. In the presence of plant alternative resources, allowing omnivore population responses decreased prey density, while not allowing population responses increased prey density. Because omnivores commonly suppress prey density in the presence of plant alternative resources when population responses of omnivores are allowed, the effectiveness of biological control may depend upon the availability of such resources and the facilitation of population responses.

Comparative analyses that link information on species' traits, environmental change, and organism response have rarely identified unambiguous trait correlates of vulnerability. We tested if species' traits could predict local-scale changes in dung beetle population response to three levels of forest conversion intensity within and across two biogeographic regions (the Neotropics and Afro-Eurasian tropics). We combined biodiversity surveys, a global molecular phylogeny, and information on three species' traits hypothesized to influence vulnerability to forest conversion to examine (1) the consistency of beetle population response across regions, (2) if species' traits could predict this response, and (3) the cross-regional consistency of trait-response relationships. Most beetle populations declined following any degree of forest conversion; these declines were strongest for Neotropical species. The relationship between traits and population trend was greatly influenced by local and biogeographic context. We discuss the ability of species' traits to explain population trends and suggest several ways to strengthen trait-response models.

AIM: Protected areas (PAs) are the mainstay of our conservation strategies. While they may succeed in locally preventing species and habitat degradation due to human activities, their ability to mitigate the impacts of climate change on biodiversity is still debated. We assessed whether community and species responses to climate change were related to PAs by testing three main predictions: (1) the thermal adjustment of community composition to temperature changes should be positively related to the proportion of PAs, (2) the species that benefit most from PAs should be less impacted by temperature change, and (3) the species a priori considered the most vulnerable to global change should be even more sensitive to the mitigating effect of PAs. LOCATION: Mainland France. METHODS: Data from a long‐term, large‐scale standardized monitoring programme, recording annual changes in the abundance of 116 breeding bird species in France between 2001 and 2012, were used. Local temporal trends in spring temperature, community reshuffling and bird populations over the country were estimated with a moving window approach (2094 spatial windows). Generalized additive mixed models were then performed to relate these responses to the local proportion of PAs. RESULTS: Most PAs promote community adjustment to temperature changes. At the species scale, our results show that the more a species benefited from PAs, the less vulnerable it was to temperature changes. PAs were also more effective in mitigating the impact of climate change on the less common and northernmost birds. MAIN CONCLUSION: Protected areas do seem to mitigate climate change impacts on species and communities. Our study argues for the use of integrative frameworks at different biological scales to assess the usefulness and relevance of PAs faced with climate change and suggests that PAs remain key effective conservation strategies in a changing climatic world.

Various spike patterns from sensory/motor neurons provide information about the dynamic sensory stimuli. Based on the information theory, neuroscientists have revealed the influence of spike variables on information transmission. Among diverse spike variables, inter-trial heterogeneity, known as jitter, has been observed in physiological neuron activity and responses to artificial stimuli, and it is recognized to contribute to information transmission. However, the relationship between inter-trial heterogeneity and information remains unexplored. Therefore, understanding how jitter impacts the heterogeneity of spiking activities and information encoding is crucial, as it offers insights into stimulus conditions and the efficiency of neural systems. Here, we systematically explored how neural information is altered by number of neurons as well as by each of three fundamental spiking characteristics: mean firing rate (MFR), duration, and cross-correlation (spike time tiling coefficient; STTC). First, we generated groups of spike trains to have specific average values for those characteristics. Second, we quantified the transmitted information rate as a function of each parameter. As population size, MFR, and duration increased, the information rate was enhanced but gradually saturated with further increments in number of cells and MFR. Regarding the cross-correlation level, homogeneous and heterogeneous spike trains (STTC AVG = 0.9 and 0.1) showed the lowest and highest information transmission, respectively. Interestingly however, when jitters were added to mimic physiological noisy environment, the information was reduced by ~ 46% for the spike trains with STTC AVG = 0.1 but rather substantially increased by ~ 63% for the spike trains with STTC AVG = 0.9. Our study suggests that optimizing various spiking characteristics may enhance the robustness and amount of neural information transmitted.

Pulsed infrared neural stimulation (INS, 1875 nm) is an emerging neurostimulation technology that delivers focal pulsed heat to activate functionally specific mesoscale networks and holds promise for clinical application. However, little is known about its effect on excitatory and inhibitory cell types in cerebral cortex. Estimates of summed population neuronal response time courses provide a potential basis for neural and hemodynamic signals described in other studies. Using two-photon calcium imaging in mouse somatosensory cortex, we have examined the effect of INS pulse train application on hSyn neurons and mDlx neurons tagged with GCaMP6s. We find that, in anesthetized mice, each INS pulse train reliably induces robust response in hSyn neurons exhibiting positive going responses. Surprisingly, mDlx neurons exhibit negative going responses. Quantification using the index of correlation illustrates responses are reproducible, intensity-dependent, and focal. Also, a contralateral activation is observed when INS applied. In sum, the population of neurons stimulated by INS includes both hSyn and mDlx neurons; within a range of stimulation intensities, this leads to overall excitation in the stimulated population, leading to the previously observed activations at distant post-synaptic sites.

Forests are major carbon (C) sinks, but their ability to sequester C and thus mitigate climate change, varies with the environment, disturbance regime, and biotic interactions. Herbivory by invasive, nonnative ungulates can have profound ecosystem effects, yet its consequences for forest C stocks remain poorly understood. We determined the impact of invasive ungulates on C pools, both above- and belowground (to 30 cm), and on forest structure and diversity using 26 paired long-term (>20 years) ungulate exclosures and adjacent unfenced control plots located in native temperate rainforests across New Zealand, spanning 36–41° S. Total ecosystem C was similar between ungulate exclosure (299.93 ± 25.94 Mg C ha−1) and unfenced control (324.60 ± 38.39 Mg C ha−1) plots. Most (60%) variation in total ecosystem C was explained by the biomass of the largest tree (mean diameter at breast height [dbh]: 88 cm) within each plot. Ungulate exclusion increased the abundance and diversity of saplings and small trees (dbh ≥2.5, <10 cm) compared with unfenced controls, but these accounted for ~5% of total ecosystem C, demonstrating that a few, large trees dominate the total forest ecosystem C but are unaffected by invasive ungulates at a timescale of 20–50 years. However, changes in understory C pools, species composition, and functional diversity did occur following long-term ungulate exclusion. Our findings suggest that, although the removal of invasive herbivores may not affect total forest C at the decadal scale, major shifts in the diversity and composition of regenerating species will have longer term consequences for ecosystem processes and forest C.

AIM: Avian migration strategies balance the costs and benefits of annual movements between breeding and wintering grounds. If similar constraints affect a large numbers of species, geographical concentrations of migration routes, or migration flyways, may result. Here we provide the first population‐level empirical evaluation of the structure and seasonal dynamics of migration flyways for North American terrestrial birds and their association with atmospheric conditions. LOCATION: Contiguous USA. METHODS: We modelled weekly probability of occurrence for 93 migratory species using spatio‐temporal exploratory models and eBird occurrence data for the combined period 2004 to 2011. We used hierarchical cluster analysis to identify species with shared migration routes based on normalized spatio‐temporal representations of autumn migration. We summarized atmospheric conditions within flyways using nocturnal wind velocity and bearing estimated at three isobaric levels (725, 825 and 925 mbar) for the combined period 2008 to 2011. RESULTS: We identified three migration flyways: an eastern and western flyway whose paths shifted westwards in the spring, and a central flyway whose core boundaries overlapped with the eastern flyway and whose width was more constricted in the autumn. The seasonal shift of the eastern flyway created potentially longer migration journeys in the spring, but this longer route coincides with a low‐level jet stream that may enhance migration speeds. Atmospheric conditions appeared to have a more limited role in the seasonal dynamics of the western flyway. MAIN CONCLUSIONS: Migration routes for terrestrial species in North America can be organized into three broadly defined migration flyways: a geographically distinct flyway located west of the 103rd meridian and two interrelated flyways located east of the 103rd meridian. Seasonal shifts in flyway locations reflect the influence of looped migration strategies that for the eastern flyway can be explained by the trade‐off between minimizing total migration distance while maintaining an association with favourable atmospheric conditions.

•N, N-dimethyltryptamine (DMT), a psychedelic tryptamine acting on 5-HT2A serotonin receptors induces perceptual distortions in visual space.•Inhaled DMT induces strong perceptual effects as shown by the Hallucinogen Rating Scale.•Inhaled DMT leads to increases in visual population receptive field sizes in V1. N, N-dimethyltryptamine (DMT) is a psychedelic tryptamine acting on 5-HT2A serotonin receptors, which is associated with intense visual hallucinatory phenomena and perceptual changes such as distortions in visual space. The neural underpinnings of these effects remain unknown. We hypothesised that changes in population receptive field (pRF) properties in the primary visual cortex (V1) might underlie visual perceptual experience. We tested this hypothesis using magnetic resonance imaging (MRI) in a within-subject design. We used a technique called pRF mapping, which measures neural population visual response properties and retinotopic maps in early visual areas. We show that in the presence of visual effects, as documented by the Hallucinogen Rating Scale (HRS), the mean pRF sizes in V1 significantly increase in the peripheral visual field for active condition (inhaled DMT) compared to the control. Eye and head movement differences were absent across conditions. This evidence for short-term effects of DMT in pRF may explain perceptual distortions induced by psychedelics such as field blurring, tunnel vision (peripheral vision becoming blurred while central vision remains sharp) and the enlargement of nearby visual space, particularly at the visual locations surrounding the fovea. Our findings are also consistent with a mechanistic framework whereby gain control of ongoing and evoked activity in the visual cortex is controlled by activation of 5-HT2A receptors.