Variation In Behavioral Responses Research Articles

Use of human invasive SEEG and non-invasive EEG recordingsin vivo towards tDCS dose individualization

Transcranial direct current stimulation (tDCS) is a type of non-invasive neuromodulatory rehabilitative therapy that has been the focus of many recent studies in a variety of disease conditions, e.g., stroke, spinal cord injury (SCI), depression, etc. However, one hurdle for success is the variability in behavioral outcomes across different subjects. One reason for such inter-individual variability is differences in tDCS-generated electric fields (EF) inside the brain of each subject and thus the resulting tDCS-modulated neural activity. We believe a solid understanding of in vivo tDCS-generated EF and neurophysiological reactivity to tDCS is crucial to eventually minimize the variability in tDCS-related behavioral (e.g., Fugl-Meyer Motor Scale) and physiological (e.g., transcranial magnetic stimulation or TMS-evoked motor potentials or MEP) responses. Importantly, it would help us formulate dose individualization based on personal characteristics for tDCS, as already occurred for other neuromodulatory techniques, e.g., repetitive TMS (rTMS), and likely improve outcomes by decreasing inter-individual variability in recovery. This abstract will present, for the first time, tDCS-generated EF and tDCS-modulated changes in brain activity at subcortical level using stereoelectroencephalography (SEEG) with simultaneous scalp electroencephalography (EEG). We will use our finding to explore the possibility of using non-invasive EEG to individualize tDCS dose and montage in clinical setting.

Mixed effects of an introduced ecosystem engineer on the foraging behavior and habitat selection of predators.

Invasive ecosystem engineers both positively and negatively affect their recipient ecosystems by generating novel habitats. Many studies have focused on alterations to ecosystem properties and to native species diversity and abundance caused by invasive engineers. However, relatively few studies have documented the extent to which behaviors of native species are affected. The red seaweed Gracilaria vermiculophylla (Rhodophyta) invaded estuaries of the southeastern United States within the last few decades and now provides abundant aboveground vegetative cover on intertidal mudflats that were historically devoid of seaweeds. We hypothesized that G.vermiculophylla would affect the foraging behavior of native shorebirds positively for birds that target seaweed-associated invertebrates or negatively for birds that target prey on or within the sediment now covered with seaweed. Visual surveys of mudflats >1ha in size revealed that more shorebirds occurred on mudflats with G.vermiculophylla relative to mudflats without G.vermiculophylla. This increased density was consistent across 7 of 8 species, with the one exception being the semipalmated plover Charadrius semipalmatus. A regression-based analysis indicated that while algal presence predicted shorebird density, densities of some bird species depended on sediment composition and infaunal invertebrate densities. At smaller spatial scales (200m2 and <1m2 ), experimental removals and additions of G.vermiculophylla and focal observations showed strong variation in behavioral response to G.vermiculophylla among bird species. Birds preferentially foraged in bare mud (e.g., C.semipalmatus), in G.vermiculophylla (e.g., Arenaria interpres), or displayed no preference for either habitat (e.g., Tringa semipalmata). Thus, while the presence of the invasive ecosystem engineer on a mudflat appeared to attract greater numbers of these predators, shorebird species differed in their behavioral responses at the smaller spatial scales that affect their foraging. Our research illuminates the need to account for species identity, individual behavior, and scale when predicting the impacts of invasive species on native communities.

Zebrafish “personality” influences sensitivity to magnetic fields

How animals integrate different sensory information for orientation is a complex process involving interactions between a variety of internal and external factors. Due to this complexity, each component of a suite of factors is typically studied in isolation. Here, we examine how an internal factor (personality of fish) influences the response of zebrafish (Danio rerio) to the magnetic field, while swimming in a flow chamber. Our previous work demonstrated that the orientation to the water current (rheotaxis) of zebrafish individuals is influenced by variations of the magnetic field only when fish are part of a shoal. In this study, we evaluated the rheotactic behavior of 20 fish, grouped in shoals of “proactive” or “reactive” individuals, under magnetic fields of different directions. We found that the magnetic field influenced at which water speed rheotaxis was elicited in zebrafish with “reactive” personality, but not in those with “proactive” personality. These results suggest that fish personality influences response to or weighing of sensory inputs and provides some insight on the variation in behavioral responses to environmental stimuli in both laboratory and natural settings.

Exploratory Study of rTMS Neuromodulation Effects on Electrocortical Functional Measures of Performance in an Oddball Test and Behavioral Symptoms in Autism.

There is no accepted pathology to autism spectrum disorders (ASD) but research suggests the presence of an altered excitatory/inhibitory (E/I) bias in the cerebral cortex. Repetitive transcranial magnetic stimulation (rTMS) offers a non-invasive means of modulating the E/I cortical bias with little in terms of side effects. In this study, 124 high functioning ASD children (IQ > 80, <18 years of age) were recruited and assigned using randomization to either a waitlist group or one of three different number of weekly rTMS sessions (i.e., 6, 12, and 18). TMS consisted of trains of 1.0 Hz frequency pulses applied over the dorsolateral prefrontal cortex (DLPFC). The experimental task was a visual oddball with illusory Kanizsa figures. Behavioral response variables included reaction time and error rate along with such neurophysiological indices such as stimulus and response-locked event-related potentials (ERP). One hundred and twelve patients completed the assigned number of TMS sessions. Results showed significant changes from baseline to posttest period in the following measures: motor responses accuracy [lower percentage of committed errors, slower latency of commission errors and restored normative post-error reaction time slowing in both early and later-stage ERP indices, enhanced magnitude of error-related negativity (ERN), improved error monitoring and post-error correction functions]. In addition, screening surveys showed significant reductions in aberrant behavior ratings and in both repetitive and stereotypic behaviors. These differences increased with the total number of treatment sessions. Our results suggest that rTMS, particularly after 18 sessions, facilitates cognitive control, attention and target stimuli recognition by improving discrimination between task-relevant and task-irrelevant illusory figures in an oddball test. The noted improvement in executive functions of behavioral performance monitoring further suggests that TMS has the potential to target core features of ASD.

Shell colour, temperature, (micro)habitat structure and predator pressure affect the behaviour of Cepaea nemoralis

Although shell colour polymorphism of the land snail Cepaea nemoralis is a well-known phenomenon, proximate and ultimate factors driving its evolution remain uncertain. Polymorphic species show variation in behavioural responses to selective forces. Therefore, we estimated effects of various environmental factors (temperature, humidity, food availability, (micro)habitat structure and predatory pressure) on behavioural response (frequency of locomotion, climbing and hiding) of C. nemoralis morphs, in experimental and natural conditions. In the experimental part of study, the frequency of locomotion was negatively affected by temperature and the presence of food and positively influenced by the presence of light. Morphs significantly differed in behavioural responses to environmental variability. Pink mid-banded and yellow five-banded morphs climbed less often and hide in shelter more often than yellow and pink unbanded individuals when temperature was low and food was absent. Snails fed most often at moderate temperature compared to low and high temperatures. Field investigations partially confirmed differences among morphs in frequency of climbing, but not in terms of probability of hiding in sheltered sites. In natural colonies, temperature and (micro)habitat structure significantly affected frequency of climbing as well as hiding in shelter. Snails more often hid in sheltered sites where thrushes preyed on Cepaea. Tendency of unbanded morphs to climb trees may have evolved under avian predatory pressure as thrushes forage on a ground. Tendency of banded morphs to hide in sheltered sites may reflect prey preferences for cryptic background. The results implicate that differential behaviour of C. nemoralis morphs compensate for their morphological and physiological limitations of adaptation to habitat.

Plasticity and personality of parental care in the clown anemonefish

Characterizing individual variation in parental care is critical to understanding how selection shapes and maintains patterns of care, yet little is known about how individual parents vary in their responses to the environment. Reaction norms, functions that describe how phenotypes change across an environmental gradient, provide an elegant framework for studying individual variation in behavioural responses. We use a reaction norm approach to investigate how studying plasticity, which describes variation within an individual through time, and personality, which describes repeatable variation among individuals, together explain individual variation in the parental behaviour of the anemonefish Amphiprion percula. More specifically, we test how resource availability influences individual parental responses to the environment and discuss the consequences for our understanding of plasticity and personality in parental care. Breeding pairs of A. percula were fed either a high or a low food ration and their parental behaviours were monitored. Individuals exhibited plasticity in parental behaviour across the two resource environments. Furthermore, individuals were repeatable in their behaviour through time, as evidenced by significant among-individual variation in intercept. Finally, the slope and elevation of individual reaction norms varied, revealing a level of variation not captured at the population level and providing insight into the potential mechanisms generating individual variation.

Distinct effects of two separately applied stressors on behavior in the red flour beetle

Stress is ubiquitous in nature and organisms have evolved mechanisms to cope with it. Stress responses nevertheless vary based on the type of stress, its duration, magnitude, and the organism’s physiological status. We studied here the effect of two separately applied stress types, differing also in their duration, on various behavioral responses of the red flour beetle (Tribolium castaneum). The two stress types applied were short-term cold stress and long-term low protein stress. The behavioral response variables were movement activity, preference to move along the test arena edges, latency to emerge from shelter, and preference for dark microhabitat, measured at two stages of the beetles’ lives, as young adults after eclosion and one month later. Behavioral responses were stress-specific. Cold-stressed beetles moved over the longest distances but were also the most reluctant to leave an accessible shelter. We interpret this to mean that cold-stressed beetles were the most active under unfavorable conditions and least bold under more favorable, protected conditions. As beetles aged, their movement activity decreased and latency to emerge from shelter increased. Non-stressed beetles were the most consistent in their behavior across all behavioral tests. This finding is similar to those in previous studies and suggests that moderate stress reduces behavioral consistency. While all beetles gained mass during the study period, the two stress types led to different patterns of body mass increase, which was more moderate for cold-stressed than for protein-stressed beetles.

Variable sensory perception in autism.

Autism is associated with sensory and cognitive abnormalities. Individuals with autism generally show normal or superior early sensory processing abilities compared to healthy controls, but deficits in complex sensory processing. In the current opinion paper, it will be argued that sensory abnormalities impact cognition by limiting the amount of signal that can be used to interpret and interact with environment. There is a growing body of literature showing that individuals with autism exhibit greater trial-to-trial variability in behavioural and cortical sensory responses. If multiple sensory signals that are highly variable are added together to process more complex sensory stimuli, then this might destabilise later perception and impair cognition. Methods to improve sensory processing have shown improvements in more general cognition. Studies that specifically investigate differences in sensory trial-to-trial variability in autism, and the potential changes in variability before and after treatment, could ascertain if trial-to-trial variability is a good mechanism to target for treatment in autism.

Financial self-efficacy: a determinant of financial inclusion

PurposeThe purpose of this paper is to examine the relationship between financial self-efficacy (FSE) and financial inclusion (FI) among individual financial consumers in Uganda.Design/methodology/approachUsing a quantitative approach and cross-sectional research design, a sample of 400 individuals from urban Central and rural Northern Uganda was drawn. SPSS and AMOS™ 21, regression analysis and structural equation models were used to establish the hypothesized relationship between FSE and FI.FindingsThe results suggest a strong positive and significant relationship between FSE and FI. The results further suggest that other variables which were controlled for, such as age and gender, had significant influence on an individual’s usage of formal financial services.Research limitations/implicationsThe study was assessed using both potential and actual consumers of financial services collectively. However, if separately assessed, possibly there would be a variation in behavioral responses toward FI.Practical implicationsFormal financial service providers need to enhance individuals’ levels of confidence in management of finances and utilization of formal financial products and services, so that the financial consumers can realize the changes in financial behavior and consequently FI.Social implicationsThe enhancement of individuals’ level of confidence in evaluating the available financial service options will guide them to take financial decisions that will improve their livelihood.Originality/valueThe results contribute toward the limited empirical and theoretical evidence for FSE and FI from a behavioral demand-side perspective.

Male song sparrows have elevated testosterone in response to neighbors versus strangers

Upon hearing a conspecific signal, animals must assess their relationship with the signaller and respond appropriately. Territorial animals usually respond more aggressively to strangers than neighbors in a phenomenon known as the “dear enemy effect”. This phenomenon likely evolved because strangers represent a threat to an animal's territory tenure and parentage, whereas neighbors only represent a threat to an animal's parentage because they already possess a territory (providing territory boundaries are established and stable). Although the dear enemy effect has been widely documented using behavioral response variables, little research has been conducted on the physiological responses of animals to neighbors versus strangers. We sought to investigate whether the dear enemy effect is observed physiologically by exposing territorial male song sparrows (Melospiza melodia) to playback simulating a neighbor or a stranger, and then collecting blood samples to measure plasma testosterone levels. We predicted that song sparrows would exhibit increased testosterone levels after exposure to stranger playback compared to neighbor playback, due to the role testosterone plays in regulating aggression. Contrary to our prediction, we found that song sparrows had higher testosterone levels after exposure to neighbor playback compared to stranger playback. We discuss several explanations for our result, notably that corticosterone may regulate the dear enemy effect in male song sparrows and this may inhibit plasma testosterone. Future studies will benefit from examining corticosterone in addition to testosterone, to better understand the hormonal underpinnings of the dear enemy effect.

Pace Yourself: Intraindividual Variability in Context Use Revealed by Self-paced Event-related Brain Potentials.

Event-related brain potentials (ERPs) have revealed multiple mechanisms by which contextual constraints impact language processing. At the same time, little work has examined the trial-to-trial dynamics of context use in the brain. In the current study, we probed intraindividual variability in behavioral and neural indices of context processing during reading. In a concurrent self-paced reading and ERP paradigm, participants read sentences that were either strongly or weakly constraining completed with an expected or unexpected target word. Our findings revealed substantial within-subject variability in behavioral and neural responses to contextual constraints. First, context-based amplitude reductions of the N400, a component linked to semantic memory access, were largest among trials eliciting the slowest RTs. Second, the RT distribution of unexpected words in strongly constraining contexts was positively skewed, reflecting an increased proportion of very slow RTs to trials that violated semantic predictions. Among those prediction-violating trials eliciting faster RTs, a late sustained anterior positivity was observed. However, among trials producing the differentially slowed RTs to prediction violations, we observed a markedly earlier effect of constraint in the form of an anterior N2, a component linked to conflict resolution and the cognitive control of behavior. The current study provides the first neurophysiological evidence for the direct role of cognitive control functions in the volitional control of reading. Collectively, our findings suggest that context use varies substantially within individual participants and that coregistering behavioral and neural indices of online sentence processing offers a window into these single-item dynamics.

Mobbing behaviour in a passerine community increases with prevalence in predator diet

Mobbing behaviour against predators is well documented but less is known about the factors influencing variation in behavioural response between prey species. We conducted a series of playback experiments to examine how the mobbing responses of prey species differed according to their relative risk of predation by the Eurasian Pygmy Owl Glaucidium passerinum, a predator of passerines. We found that mobbing among 22 passerine prey species was positively correlated with their prevalence in the Pygmy Owl diet. To compare mobbing behaviour between two seasons, we conducted playback experiments during spring (breeding season) and autumn (non‐breeding season). Contrary to previous studies, we found that mobbing intensity was greater during autumn than in spring. Our study shows a differential mobbing response of 22 species to the calls from one predator species and underscores the importance of considering seasonal variation in mobbing behaviour. Mobbing response differences observed among bird species strongly suggest different cooperation behaviour at the community level.

Association between Attention and Heart Rate Fluctuations in Pathological Worriers.

Recent data suggests that several psychopathological conditions are associated with alterations in the variability of behavioral and physiological responses. Pathological worry, defined as the cognitive representation of a potential threat, has been associated with reduced variability of heart beat oscillations (i.e., decreased heart rate variability; HRV) and lapses of attention indexed by reaction times (RTs). Clinical populations with attention deficit show RTs oscillation around 0.05 and 0.01 Hz when performing a sustained attention task. We tested the hypothesis that people who are prone to worry do it in a predictable oscillating pattern revealed through recurrent lapses in attention and concomitant oscillating HRV. Sixty healthy young adults (50% women) were recruited: 30 exceeded the clinical cut-off on the Penn State Worry Questionnaire (PSWQ; High-Worry, HW); the remaining 30 constituted the Low-Worry (LW) group. After a diagnostic assessment, participants performed two 15-min sustained attention tasks, interspersed by a standardized worry-induction procedure. RTs, HRV and moods were assessed. The analyses of the frequency spectrum showed that the HW group presents a significant higher and constant peak of RTs oscillation around 0.01 Hz (period 100 s) after the induction of worry, in comparison with their baseline and with the LW group that was not responsive to the induction procedure. Physiologically, the induction significantly reduced high-frequency HRV and such reduction was associated with levels of self-reported worry. Results are coherent with the oscillatory nature of the default mode network (DMN) and further confirm an association between cognitive rigidity and autonomic nervous system inflexibility.

Cortical stimulation parameters for functional mapping

PurposeThere is significant variation in how patients respond to cortical electrical stimulation. It has been hypothesized that individual demographic and pathologic factors, such as age, sex, disease duration, and MRI findings, may explain this discrepancy. The purpose of our study is to identify specific patient characteristics and their effect on cortical stimulation, and discover the extent of variation in behavioral responses that exists among patients with epilepsy. MethodWe retrospectively analyzed data from 92 patients with medically intractable epilepsy who had extra-operative cortical electrical stimulation. Mapping records were evaluated and information gathered about demographic data, as well as the thresholds of stimulation for motor, sensory, speech, and other responses; typical seizure behavior; and the induction of afterdischarges. ResultsNinety-two patient cortical stimulation mapping reports were analyzed. The average of the minimum thresholds for motor response was 4.15mA±2.67. The average of the minimum thresholds for sensory response was 3.50mA±2.15. The average of the minimum thresholds for speech response was 4.48mA±2.42. The average of the minimum thresholds for afterdischarge was 4.33mA±2.37. Most striking were the degree of variability and wide range of thresholds seen between patients and within the different regions of the same patient. ConclusionWide ranges of thresholds exist for the different responses between patients and within different regions of the same patient. With multivariate analysis in these series, no clinical or demographic factors predicted physiological response or afterdischarge threshold levels.

Towards an evidence-based model of fear of cancer recurrence for breast cancer survivors

PurposeIn order to understand the multidimensional mechanism of fear of cancer recurrence (FCR) and to identify potential targets for interventions, it is important to empirically test the theoretical model of FCR. This study aims at assessing the validity of Lee-Jones et al.’s FCR model.MethodsA total of 1205 breast cancer survivors were invited to participate in this study. Participants received a questionnaire booklet including questionnaires on demographics and psychosocial variables including FCR. Data analysis consisted of the estimation of direct and indirect effects in mediator models.ResultsA total of 460 women (38 %) participated in the study. Median age was 55.8 years (range 32–87). Indirect effects of external and internal cues via FCR were found for all mediation models with limited planning for the future (R2 = .28) and body checking (R2 = .11–.15) as behavioral response variables, with the largest effects for limited planning for the future. A direct relation was found between feeling sick and seeking professional advice, not mediated by FCR.ConclusionsIn the first tested models of FCR, all internal and external cues were associated with higher FCR. In the models with limited planning for the future and body checking as behavioral response, an indirect effect of cues via FCR was found supporting the theoretical model of Lee-Jones et al.Implications for Cancer SurvivorsAn evidence-based model of FCR may facilitate the development of appropriate interventions to manage FCR in breast cancer survivors.

A matter of hand: Causal links between hand dominance, structural organization of fronto-parietal attention networks, and variability in behavioural responses to transcranial magnetic stimulation

Considerable evidence suggests that, on a group level, human visuospatial attention is asymmetrically organized, with a right-hemispheric dominance. The asymmetrical organization of the superior longitudinal fasciculus (SLF) has been shown to account for the right-hemispheric dominance in visual attention. However, such account is by no means universal, and large individual differences in asymmetrical performance on visuospatial tasks have been reported. Furthermore, the variability in the SLF lateralization has been shown to correlate with behavioural asymmetries. Continuous theta burst stimulation (cTBS) enables to temporarily interfere with cortical activity. cTBS applied over the posterior parietal cortex (PPC) has been previously used to systematically study attentional asymmetries. Interestingly, large individual differences in the effectiveness of stimulation have been reported. In accordance with earlier both animal and human studies, one possible cause underlying these striking individual differences might lie in the structural organization of frontoparietal pathways subserving visuospatial attention. Thus, the current study employed diffusion tractography to examine the relationship between the variability in the structural organization of the SLF and the individual differences in attentional shifts induced by a modified cTBS (cTBSmod; triplets of pulses at 30 Hz, repeated at 6 Hz) applied over the IPS, as measured by a line bisection task. Consistent with previous studies, on a group level, cTBSmod applied over the right intraparietal sulcus (IPS) triggered a rightward bisection bias shift, and there were no significant effects of cTBSmod applied over the left IPS. However, further analyses demonstrated that both handedness and structural variability (as assessed based on hindrance modulated orientational anisotropy) within the middle and the ventral branches of the SLF predicted individual differences in the cTBSmod-induced attentional shifts. Our study thus suggests that the effects of cTBSmod over the IPS may depend on intra-hemispheric interactions between cortical loci controlling visual attention. To conclude, our findings provide converging evidence for the notion put forward previously that inter-individual variability in the structural organization of intra-hemispheric frontoparietal connections has important implications for the functional models of human visual attention. Moreover, we hypothesize that this may also be relevant for the understanding of attentional disorders and their rehabilitation.

Personality matters: Consistency of inter-individual variation in shyness-boldness across non-breeding and pre-breeding season despite a fall in general shyness levels in farmed American mink (Neovison vison)

Individuals of the same species vary consistently in their behaviour across time and context, and this is often referred to as animal personality. In this study, we investigate animal personality based on the definition of personality traits as underlying dispositional factors, which are linked to biological internal factors that are stable and perhaps heritable. Although not directly measurable, these underlying dispositional factors predispose individuals to react through different behavioural patterns. We investigated the shyness-boldness continuum reflected in the consistency across time of the inter-individual variation in behavioural responses towards two different novelty tests: a novel object test representing non-social contexts and a mirror test representing social contexts. Our study animals were 60 farmed American mink (Neovison vison), which were raised in identical housing conditions. We recorded the approach behaviour of the mink towards novelty at two different times: the first time during non-breeding season in December 2013 and the second time during pre-breeding season in February 2014. Behavioural variables were analysed using principal component analyses and our results show consistency in inter-individual variation in shyness measures across seasons. This consistency differed across non-social and social contexts forming two different shyness-boldness dimensions as were also found across context in a previous study. To our knowledge this is the first study to reveal aspects of the shyness-boldness continuum across time and season in the American mink from non-breeding season in December to pre-breeding season in February. Our study confirms the existence of personality in farmed American mink, but interestingly, we saw a shift in the positioning of most individuals from shy to more bold on the shyness continuum when comparing the December measures to the February measures. This shift was further supported by the results of a simple stick test, which indicated a change towards a higher responsiveness towards humans in the pre-breeding season.

Modulation of frontal effective connectivity during speech

Noninvasive neurostimulation methods such as transcranial direct current stimulation (tDCS) can elicit long-lasting, polarity-dependent changes in neocortical excitability. In a previous concurrent tDCS-fMRI study of overt picture naming, we reported significant behavioural and regionally specific neural facilitation effects in left inferior frontal cortex (IFC) with anodal tDCS applied to left frontal cortex (Holland et al., 2011). Although distributed connectivity effects of anodal tDCS have been modelled at rest, the mechanism by which ‘on-line’ tDCS may modulate neuronal connectivity during a task-state remains unclear. Here, we used Dynamic Causal Modelling (DCM) to determine: (i) how neural connectivity within the frontal speech network is modulated during anodal tDCS; and, (ii) how individual variability in behavioural response to anodal tDCS relates to changes in effective connectivity strength. Results showed that compared to sham, anodal tDCS elicited stronger feedback from inferior frontal sulcus (IFS) to ventral premotor (VPM) accompanied by weaker self-connections within VPM, consistent with processes of neuronal adaptation. During anodal tDCS individual variability in the feedforward connection strength from IFS to VPM positively correlated with the degree of facilitation in naming behaviour. These results provide an essential step towards understanding the mechanism of ‘online’ tDCS paired with a cognitive task. They also identify left IFS as a ‘top-down’ hub and driver for speech change.

Above the Mean: Examining Variability in Behavioral and Neural Responses to Multisensory Stimuli

Even when experimental conditions are kept constant, a robust and consistent finding in both behavioral and neural experiments designed to examine multisensory processing is striking variability. Although this variability has often been considered uninteresting noise (a term that is laden with strong connotations), emerging work suggests that differences in variability may be an important aspect in describing differences in performance between individuals and groups. In the current review, derived from a symposium at the 2015 International Multisensory Research Forum in Pisa, Italy, we focus on several aspects of variability as it relates to multisensory function. This effort seeks to expand our understanding of variability at levels of coding and analysis ranging from the single neuron through large networks and on to behavioral processes, and encompasses a number of the multimodal approaches that are used to evaluate and characterize multisensory processing including single-unit neurophysiology, electroencephalography (EEG), functional magnetic resonance imaging (fMRI), and electrocorticography (ECoG).

From steps to home range formation: species‐specific movement upscaling among sympatric ungulates

Summary Animals move to interact with the environment in order to find food resources and cover. Intrinsic characteristics affecting feeding and antipredatory strategies likely shape variation in movement patterns and home range formation between individuals, populations and species. Browsing herbivores selectively forage on patchily distributed resources in areas with more canopy cover, whereas mixed feeders and grazers feed on more open grasslands and tend to aggregate as an antipredatory strategy. We therefore predicted that at small temporal scales, browsers will show greater net displacements (i.e. typical of searching patterns) than mixed feeders or grazers; but at larger temporal scales, we expect the opposite pattern, since gregarious species will need to use larger areas to feed the whole herd. We also predicted that the feeding/antipredatory strategy will determine the behavioural responses to other environmental factors. To test this, we compared spatial movement patterns at multiple scales (from 20‐min intervals to annual home ranges) of three sympatric, similar‐sized, alpine ungulates which differ in their feeding/antipredatory strategy: roe deer (solitary browsers), mouflon (gregarious grazers) and chamois (intermediate feeders in smaller groups). We used location data from GPS‐collared females of the three species in the French Alps. As predicted, we found that multi‐scale spatial patterns depended on the feeding/antipredatory strategy. Browsers foraged within smaller range areas, searching back and forth. Mixed feeders and, especially, grazers covered larger areas, presumably to satisfy herd needs. The feeding/antipredatory strategies also determined the interspecific variability in behavioural responses to factors such as maternal status, weather, habitat type or human disturbance, supporting our hypothesis. Exploring interspecific variability, we showed how movement behaviour and home range formation vary substantially, even among species within the same guild. This mechanism might be important to maintain intra‐guild multi‐species associations and increase biodiversity, through contributing to niche segregation and, thus, coexistence.