Odor stimuli: not just chemical identity

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When Two Become One: The Limits of Causality Analysis of Brain Dynamics

Biological systems often consist of multiple interacting subsystems, the brain being a prominent example. To understand the functions of such systems it is important to analyze if and how the subsystems interact and to describe the effect of these interactions. In this work we investigate the extent to which the cause-and-effect framework is applicable to such interacting subsystems. We base our work on a standard notion of causal effects and define a new concept called natural causal effect. This new concept takes into account that when studying interactions in biological systems, one is often not interested in the effect of perturbations that alter the dynamics. The interest is instead in how the causal connections participate in the generation of the observed natural dynamics. We identify the constraints on the structure of the causal connections that determine the existence of natural causal effects. In particular, we show that the influence of the causal connections on the natural dynamics of the system often cannot be analyzed in terms of the causal effect of one subsystem on another. Only when the causing subsystem is autonomous with respect to the rest can this interpretation be made. We note that subsystems in the brain are often bidirectionally connected, which means that interactions rarely should be quantified in terms of cause-and-effect. We furthermore introduce a framework for how natural causal effects can be characterized when they exist. Our work also has important consequences for the interpretation of other approaches commonly applied to study causality in the brain. Specifically, we discuss how the notion of natural causal effects can be combined with Granger causality and Dynamic Causal Modeling (DCM). Our results are generic and the concept of natural causal effects is relevant in all areas where the effects of interactions between subsystems are of interest

The Impact of Leadership Style on The Job Satisfaction, Turnover Perceptions, and Performance of Staff Accountants in Large Public Accounting Firms

190 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1975.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Longitudinal resting-state functional magnetic resonance imaging in a mouse model of metastatic bone cancer reveals distinct functional reorganizations along a developing chronic pain state

Functional neuroimaging has emerged as attractive option for characterizing pain states complementing behavioral readouts or clinical assessment. In particular, resting-state functional magnetic resonance imaging (rs-fMRI) enables monitoring of functional adaptations across the brain, for example, in response to chronic nociceptive input. We have used rs-fMRI in a mouse model of chronic pain from breast cancer-derived tibial bone metastases to identify pain-induced alterations in functional connectivity. Combined assessment of behavioral readouts allowed for defining a trajectory as model function for extracting pain-specific functional connectivity changes from the fMRI data reflective of a chronic pain state. Cingulate and prefrontal cortices as well as the ventral striatum were identified as predominantly affected regions, in line with findings from clinical and preclinical studies. Inhibition of the peripheral bone remodeling processes by antiosteolytic therapy led to a reduction of pain-induced network alterations, emphasizing the specificity of the functional readouts for a developing chronic pain state

Prospective Administration of Anti-NGF Treatment Effectively Suppresses Functional Connectivity Alterations Following Cancer-Induced Bone Pain in Mice

Cancer-induced bone pain is abundant among advanced stage cancer patients and arises from a primary tumor in the bone or skeletal metastasis of common cancer types such as breast, lung or prostate cancer. Recently, antibodies targeting nerve growth factor (NGF) have been shown to effectively relieve neuropathic and inflammatory pain states in mice and in humans. While efficacy has been shown in mice on a behavioral level, effectiveness in preventing pain-induced functional rearrangements in the central nervous system has not been shown. Therefore we assessed longitudinal whole-brain functional connectivity using resting-state fMRI in a mouse model of cancer-induced bone pain. We found functional connectivity between major hubs of ascending and descending pain pathways such as the periaqueductal gray, amygdala, thalamus as well as cortical somatosensory regions to be affected by a developing cancer pain state. These changes could be successfully prevented through prospective administration of a monoclonal anti-NGF antibody (mAb911). This indicates efficacy of anti-NGF treatment to prevent pain-induced adaptations in brain functional networks following persistent nociceptive input from cancer-induced bone pain. Additionally, it highlights the suitability of resting-state fMRI readouts as an indicator of treatment response on the basis of longitudinal functional network changes

Data for research article "The interaction of path integration and terrestrial visual cues in navigating desert ants: what can we learn from path characteristics?"

<p><b>Raw data for article appearing in the Journal of Experimental Biology</b></p><p>Data shows the coordinates of paths that ants took in 3 separate experiments. Experiment 1: Walking speeds of ants during homing paths and nest searches. Experiment 2: Observing ants’ responses to visual novelty. Experiment 3: Observing interactions between path integration and visual guidance.</p> <p> </p> <p>Path coordinates are provided as Matlab files (see XtransfSmoothed and YtransfSmoothed in path structure) when extracted from high-speed movies. You will need access to the Matlab environment to view these files. Path coordinates are provided as text documents when extracted from paper recordings. </p><p><br></p><p><b>Abstract from research paper</b></p><p>Ant foragers make use of multiple navigational cues to navigate through the world and the combination of innate navigational strategies and the learning of environmental information is the secret of their navigational success. We present here detailed information about the paths of <i>Cataglyphis fortis</i> desert ants navigating by an innate strategy, namely path integration. Firstly, we observe that the ants’ walking speed decreases significantly along their homing paths, such that they slow down just before reaching the goal, and maintain a slower speed during subsequent search paths. Interestingly, this drop in walking speed is independent of absolute home-vector length and depends on the proportion of the home vector that was completed. Secondly, we find that ants are influenced more strongly by novel or altered visual cues the further along their homing path they are. These results suggest that path integration modulates speed along the homing path in a way that might help ants search for, utilise or learn environmental information at important locations. Ants walk more slowly and sinuously when encountering novel or altered visual cues and occasionally stop and scan the world, this might indicate the re-learning of visual information.</p><p><br></p

Dynamic measurement of tumor vascular permeability and perfusion using a hybrid system for simultaneous magnetic resonance and fluorescence imaging

PURPOSE: Assessing tumor vascular features including permeability and perfusion is essential for diagnostic and therapeutic purposes. The aim of this study was to compare fluorescence and magnetic resonance imaging (MRI)-based vascular readouts in subcutaneously implanted tumors in mice by simultaneous dynamic measurement of tracer uptake using a hybrid fluorescence molecular tomography (FMT)/MRI system. PROCEDURE: Vascular permeability was measured using a mixture of extravascular imaging agents, GdDOTA and the dye Cy5.5, and perfusion using a mixture of intravascular agents, Endorem and a fluorescent probe (Angiosense). Dynamic fluorescence reflectance imaging (dFRI) was integrated into the hybrid system for high temporal resolution. RESULTS: Excellent correspondence between uptake curves of Cy5.5/GdDOTA and Endorem/Angiosense has been found with correlation coefficients R > 0.98. The two modalities revealed good agreement regarding permeability coefficients and centers-of-gravity of the imaging agent distribution. CONCLUSION: The FMT/dFRI protocol presented is able to accurately map physiological processes and poses an attractive alternative to MRI for characterizing tumor neoangiogenesis

Multimodal influences on learning walks in desert ants (Cataglyphis fortis)

Ants are excellent navigators using multimodal information for navigation. To accurately localise the nest at the end of a foraging journey, visual cues, wind direction and also olfactory cues need to be learnt. Learning walks are performed at the start of an ant’s foraging career or when the appearance of the nest surrounding has changed. We investigated here whether the structure of such learning walks in the desert ant Cataglyphis fortis takes into account wind direction in conjunction with the learning of new visual information. Ants learnt to travel back and forth between their nest and a feeder, and we then introduced a black cylinder near their nest to induce learning walks in regular foragers. By doing this across days with different wind directions, we were able to probe how ants balance different sensory modalities. We found that (1) the ants’ outwards headings are influenced by the wind direction with their routes deflected such that they will arrive downwind of their target, (2) a novel object along the route induces learning walks in experienced ants and (3) the structure of learning walks is shaped by the wind direction rather than the position of the visual cue

Data for research article 'Multimodal influences on learning walks in desert ants (Cataglyphis fortis)'

Data for paper published in the Journal of Comparative Physiology A (published June 2020).Data contains paths from recorded ants during the experiments. Files can be opened with TextEdit (on a Macintosh) or WordPad (Windows).For details please see the README.txt and view the experiment methods in the published paper. Abstract:Ants are excellent navigators using multimodal information for navigation. To accurately localise the nest at the end of a foraging journey, visual cues, wind direction and also olfactory cues need to be learnt. Learning walks are performed at the start of an ant’s foraging career or when the appearance of the nest surrounding has changed. We investigated here whether the structure of such learning walks in the desert ant Cataglyphis fortis takes into account wind direction in conjunction with the learning of new visual information. Ants learnt to travel back and forth between their nest and a feeder, and we then introduced a black cylinder near their nest to induce learning walks in regular foragers. By doing this across days with different wind directions, we were able to probe how ants balance different sensory modalities. We found that (1) the ants’ outwards headings are influenced by the wind direction with their routes deflected such that they will arrive downwind of their target, (2) a novel object along the route induces learning walks in experienced ants and (3) the structure of learning walks is shaped by the wind direction rather than the position of the visual cue. </p

Accounting : Principles and applications

417 tr. ; 27 cm