Adaptation of physiology and behavior to seasonal changes in the environment are for many organisms essential for survival. Most of our knowledge about the underlying mechanisms comes from... Show moreAdaptation of physiology and behavior to seasonal changes in the environment are for many organisms essential for survival. Most of our knowledge about the underlying mechanisms comes from research on photoperiodic regulation of reproduction in plants, insects and mammals. However, even humans, who mostly live in environments with minimal seasonal influences, show annual rhythms in physiology (e.g., immune activity, brain function), behavior (e.g., sleep–wake cycles) and disease prevalence (e.g., infectious diseases). As seasonal variations in environmental conditions may be drastically altered due to climate change, the understanding of the mechanisms underlying seasonal adaptation of physiology and behavior becomes even more relevant. While many species have developed specific solutions for dedicated tasks of photoperiodic regulation, we find a number of common principles and mechanisms when comparing insect and mammalian systems: (1) the circadian system contributes to photoperiodic regulation; (2) similar signaling molecules (VIP and PDF) are used for transferring information from the circadian system to the neuroendocrine system controlling the photoperiodic response; (3) the hormone melatonin participates in seasonal adaptation in insects as well as mammals; and (4) changes in photoperiod affect neurotransmitter function in both animal groups. The few examples of overlap elaborated in this perspective article, as well as the discussion on relevance for humans, should be seen as encouragement to unravel the machinery of seasonal adaptation in a multitude of organisms. Show less
This paper examines how a translocal approach could enrich conceptualisations of human mobility in the context of the current climate regime. Drawing on the concept of ‘translocal legalities’, it... Show moreThis paper examines how a translocal approach could enrich conceptualisations of human mobility in the context of the current climate regime. Drawing on the concept of ‘translocal legalities’, it is argued that a socio-legal and translocal analysis could inform the existing analyses of climate-related mobility. Through the case of post-cyclone Idai relocations in Mozambique, it demonstrates the need to capture multi-faced and multi-level aspects of climate-related mobility. This involves different degrees of adaptation but also inevitable losses and damages that defy conventional categorisation into economic or non-economic. A translocal approach, which is empirically grounded in local realities, but also takes into account national and international level developments, can enable a more nuanced understanding of climate-related relocations. It provides insights into both the adaptation and loss and damage aspects in their full complexities and thereby brings about a more informed perspective on human mobility in the current climate regime. Show less
Despite the introduction of many new sound-coding strategies speech perception outcomes in cochlear implant listeners have leveled off. Computer models may help speed up the evaluation of new sound... Show moreDespite the introduction of many new sound-coding strategies speech perception outcomes in cochlear implant listeners have leveled off. Computer models may help speed up the evaluation of new sound-coding strategies, but most existing models of auditory nerve responses to electrical stimulation include limited temporal detail, as the effects of longer stimulation, such as adaptation, are not well-studied. Measured neural responses to stimulation with both short (400 ms) and long (10 min) duration highrate (5kpps) pulse trains were compared in terms of spike rate and vector strength (VS) with model outcomes obtained with different forms of adaptation. A previously published model combining biophysical and phenomenological approaches was adjusted with adaptation modeled as a single decaying exponent, multiple exponents and a power law. For long duration data, power law adaptation by far outperforms the single exponent model, especially when it is optimized per fiber. For short duration data, all tested models performed comparably well, with slightly better performance of the single exponent model for VS and of the power law model for the spike rates. The power law parameter sets obtained when fitted to the long duration data also yielded adequate predictions for short duration stimulation, and vice versa. The power law function can be approximated with multiple exponents, which is physiologically more viable. The number of required exponents depends on the duration of simulation; the 400 ms data was well-replicated by two exponents (23 and 212 ms), whereas the 10-minute data required at least seven exponents (ranging from 4 ms to 600 s). Adaptation of the auditory nerve to high-rate electrical stimulation can best be described by a power-law or a sum of exponents. This gives an adequate fit for both short and long duration stimuli, such as CI speech segments. (C) 2020 The Authors. Published by Elsevier B.V. Show less
The ventral tegmental area dopamine (VTA-DA) mesolimbic circuit processes emotional, motivational, and social reward associations together with their more demanding cognitive aspects that involve... Show moreThe ventral tegmental area dopamine (VTA-DA) mesolimbic circuit processes emotional, motivational, and social reward associations together with their more demanding cognitive aspects that involve the mesocortical circuitry. Coping with stress increases VTA-DA excitability, but when the stressor becomes chronic the VTA-DA circuit is less active, which may lead to degeneration and local microglial activation. This switch between activation and inhibition of VTA-DA neurons is modulated by e.g. corticotropin-releasing hormone (CRH), opioids, brain-derived neurotrophic factor (BDNF), and the adrenal glucocorticoids. These actions are coordinated with energy-demanding stress-coping styles to promote behavioral adaptation. The VTA circuits show sexual dimorphism that is programmed by sex hormones during perinatal life in a manner that can be affected by glucocorticoid exposure. We conclude that insight in the role of stress in VTA-DA plasticity and connectivity, during reward processing and stress-coping, will be helpful to better understand the mechanism of resilience to breakdown of adaptation. Show less
Electrically evoked compound action potentials (eCAPs) are measurements of the auditory nerve's response to electrical stimulation. ECAP amplitudes during pulse trains can exhibit temporal... Show moreElectrically evoked compound action potentials (eCAPs) are measurements of the auditory nerve's response to electrical stimulation. ECAP amplitudes during pulse trains can exhibit temporal alternations. The magnitude of this alternation tends to diminish over time during the stimulus. How this pattern relates to the temporal behavior of nerve fibers is not known. We hypothesized that the stochasticity, refractoriness, adaptation of the threshold and spike-times influence pulse-train eCAP responses. Thirty thousand auditory nerve fibers were modeled in a three-dimensional cochlear model incorporating pulse-shape effects, pulse-history effects, and stochasticity in the individual neural responses. ECAPs in response to pulse trains of different rates and amplitudes were modeled for fibers with different stochastic properties (by variation of the relative spread) and different temporal properties (by variation of the refractory periods, adaptation and latency). The model predicts alternation of peak amplitudes similar to available human data. In addition, the peak alternation was affected by changing the refractoriness, adaptation, and relative spread of auditory nerve fibers. As these parameters are related to factors such as the duration of deafness and neural survival, this study suggests that the eCAP pattern in response to pulse trains could be used to assess the underlying temporal and stochastic behavior of the auditory nerve. As these properties affect the nerve's response to pulse trains, they are of uttermost importance to sound perception with cochlear implants. (C) 2019 Elsevier B.V. All rights reserved. Show less
Armisen, D.; Rajakumar, R.; Friedrich, M.; Benoit, J.B.; Robertson, H.M.; Panfilio, K.A.; ... ; Khila, A. 2018
This thesis presents a series of translational research studies to explore topics of importance to a patient stakeholder community--Duchenne and Becker muscular dystrophy. The overarching objective... Show moreThis thesis presents a series of translational research studies to explore topics of importance to a patient stakeholder community--Duchenne and Becker muscular dystrophy. The overarching objective was to inform a patient/family foundation's interventions and policy and advocacy approaches. Results from a longitudinal study on mothers__ wellbeing support the need for systematic exploration of caregivers__ unmet support needs, especially those related to coping with DMD-related uncertainty and fear. Efforts to improve mothers__ adaptation should focus on fostering resilience and enhancing benefit finding. A study on treatment preferences and disease impact that used Best-Worst Scaling found that caregivers were willing to accept a serious or fatal risk when balanced with a non-curative treatment, even absent lifespan improvement. Parents__ most pressing worries were about symptom progression and access to medical care. The final qualitative studies highlight the complexity of clinical trial decision making, especially for rare, progressive pediatric disorders, where participants equated doing __nothing__ with doing harm. Parents developed intentions to participate in trials before the informed consent process. Parents__ decisions were strongly influenced by the anticipation of individual benefit. The adaptive optimism engendered by the availability of trial was highly valued by both parents and clinicians on trial teams. Show less
In medical decision making decisions are made by using cost-utility analyses. Utilities, in cost-utility analyses, are benefits in health estimated by comparing preferences for health states to... Show moreIn medical decision making decisions are made by using cost-utility analyses. Utilities, in cost-utility analyses, are benefits in health estimated by comparing preferences for health states to perfect health and death. Whose__ utilities are used, those given by patients__ or by members of the general public, does matter. Previous research has shown that utilities given by patients are higher compared to those given by members of the public. The main objective of this thesis was to examine mechanisms that have been suggested to explain this gap between health state utilities. Most mechanisms suggested to influence this gap were only marginally explanatory except for focusing illusion and adaption. The public has the tendency to focus on the negative aspects of a health state. On the other hand patients adapt to their illness and take this adaptation into account. Due to focusing illusion of members of the public utilities will become lower whereas adaptation will lead to higher utilities. Whose utilities should be used in decision making depends on whose utilities are most valid. Utilities shaped by focusing illusion are biased however it is a matter of discussion if adaptation leads to invalid utilities. Show less
This thesis deals with the adaptation and acculturation of immigrant adolescents in junior vocational education. The adaptation of immigrant adolescents fits the notion of an 'immigrant paradox'.... Show moreThis thesis deals with the adaptation and acculturation of immigrant adolescents in junior vocational education. The adaptation of immigrant adolescents fits the notion of an 'immigrant paradox'. Maintaining aspects of the ethnic culture was found positively related to immigrant adolescents' adaptation. Show less
