Biology subjects

Leavitt, J.

Publications and source records attributed to Leavitt, J..

3 recordsLinked to original sources

bioRxiv2021

The salmon-peloton: hydraulic habitat shifts of adult Atlantic salmon (Salmo salar) due to behaviour thermoregulation

In recent decades there has been an increase in conservation and restoration projects targeting Atlantic salmon (Salmo salar - AS), as populations in eastern Canada decline. Missing however, is an understanding of thermo-hydraulic habitat use by adult AS during summer, and thus the actual benefits of altering in-river physical structures. Here, we illustrated how optical and thermal infrared (TIR) imagery acquired from a UAV can be used in concert with in-situ depth and velocity data to map adult AS and develop models of thermo-hydraulic habitats in the Miramichi River, New Brunswick. We found during optimal thermal conditions (< 19 {degrees}C) proximity to boulders and Froude numbers, a non-dimensional hydraulic metric, were key parameters that characterized adult AS habitat. However, during behavioural thermoregulation events (>19 {degrees}C), proximity to the cool thermal plume and Froude number, a non-dimensional hydraulic parameter, were critical controls on habitat use. We also observed AS formed a distinct geometric formation during behavioural thermoregulation events, and term this formation a thermal-peloton. The primary function of the peloton is undoubtedly to reduce thermally induced stressed; however, we conceptualize the geometry of the peloton attenuates hydraulic-drag, and reduces energetic expenditure of individuals practicing behavioural thermoregulation. These data provide an unrivaled viewpoint of thermo-hydraulic habitat selection by adult AS, and a blue print for restoration work. The use of UAV-based sensors has the potential to instigate a paradigm shift for river sciences. The age of applying hyper-resolution, remote sensing for river science and aquatic ecology is immensely exciting.

ecology↗

bioRxiv2019

Induced illusory body ownership in Borderline Personality Disorder

BackgroundOne aspect of selfhood that may have relevance for Borderline Personality Disorder (BPD) is variation in sense of body ownership. We employed the rubber hand illusion (RHI) to manipulate sense of body ownership in BPD. We extended previous research on illusory body ownership in BPD by testing: 1) two illusion conditions: asynchronous & synchronous stimulation, 2) relationship between Illusion experience and BPD symptoms, and 3) relationship between illusion experience and maladaptive personality traits.\n\nMethodsWe measured illusion strength (questionnaire responses), proprioceptive drift (perceived shift in physical hand position), BPD symptoms (DIB-R score), and maladaptive personality traits (PID-5) in 24 BPD and 21 control participants.\n\nResultsFor subjective illusion strength, we found a main effect of group (BPD > HC, F = 11.94 p = 0.001), and condition (synchronous > asynchronous, F(1,43) = 22.80, p < 0.001). There was a group x condition interaction for proprioceptive drift (F(1,43) = 6.48, p = 0.015) such that people with BPD maintained illusion susceptibility in the asynchronous condition. Borderline symptom severity correlated with illusion strength within the BPD group, and this effect was specific to affective symptoms (r = 0.48, p < 0.01). Across all participants, trait psychoticism correlated with illusion strength (r = 0.44, p < 0.01).\n\nConclusionPeople with BPD are more susceptible to illusory body ownership than controls. This is consistent with the clinical literature describing aberrant physical and emotional experience of self in BPD. A predictive-coding framework holds promise to develop testable mechanistic hypotheses for disrupted bodily self in BPD.\n\nHighlightsO_LIThe rubber hand illusion (RHI) allows measurement of self-disturbance.\nC_LIO_LIPeople with BPD had greater illusion susceptibility and this correlated with affective symptoms.\nC_LIO_LIInteroception stabilizes representations of body ownership, and is impaired in BPD.\nC_LIO_LIIllusion strength correlates with psychotic traits across levels of psychopathology.\nC_LIO_LIPredictive coding frameworks can probe mechanisms of impaired body ownership in psychopathology.\nC_LI

neuroscience↗

bioRxiv2018

Differential valuation and learning from social and non-social cues in Borderline Personality Disorder

BackgroundVolatile interpersonal relationships are a core feature of Borderline Personality Disorder (BPD), and lead to devastating disruption of patients personal and professional lives. Quantitative models of social decision making and learning hold promise for defining the underlying mechanisms of this problem. In this study, we tested BPD and control subject weighting of social versus non-social information, and their learning about choices under stable and volatile conditions. We compared behavior using quantitative models.\n\nMethodsSubjects (n=20 BPD, n=23 control) played an extended reward learning task with a partner (confederate) that requires learning about non-social and social cue reward probability (The Social Valuation Task). Task experience was measured using language metrics: explicit emotions/beliefs, talk about the confederate, and implicit distress (using the previously established marker self-referentiality). Subjects weighting of social and non-social cues was tested in mixed-effects regression models. Subjects learning rates under stable and volatile conditions were modelled (Rescorla-Wagner approach) and group x condition interactions tested.\n\nResultsCompared to controls, BPD subject debriefings included more mentions of the confederate and less distress language. BPD subjects also weighted social cues more heavily, but had blunted learning responses to (non-social and social) volatility.\n\nConclusionsThis is the first report of patient behavior in the Social Valuation Task. The results suggest that BPD subjects expect higher volatility than do controls. These findings lay the groundwork for a neuro-computational dissection of social and non-social belief updating in BPD, which holds promise for the development of novel clinical interventions that more directly target pathophysiology.

neuroscience↗