The reactive scope model—a new model integrating homeostasis, allostasis, and stress

Romero, L. M., Dickens, M. J., & Cyr, N. E. (2009). The reactive scope model—a new model integrating homeostasis, allostasis, and stress. Hormones and behavior55(3), 375-389.

Abstract

Allostasis, the concept of maintaining stability through change, has been proposed as a term and a model to replace the ambiguous term of stress, the concept of adequately or inadequately coping with threatening or unpredictable environmental stimuli. However, both the term allostasis and its underlying model have generated criticism. Here we propose the Reactive Scope Model, an alternate graphical model that builds on the strengths of allostasis and traditional concepts of stress yet addresses many of the criticisms. The basic model proposes divergent effects in four ranges for the concentrations or levels of various physiological mediators involved in responding to stress. (1) Predictive Homeostasis is the range encompassing circadian and seasonal variation — the concentrations/levels needed to respond to predictable environmental changes. (2) Reactive Homeostasis is the range of the mediator needed to respond to unpredictable or threatening environmental changes. Together, Predictive and Reactive Homeostasis comprise the normal reactive scope of the mediator for that individual. Concentrations/levels above the Reactive Homeostasis range is (3) Homeostatic Overload, and concentrations/levels below the Predictive Homeostasis range is (4) Homeostatic Failure. These two ranges represent concentrations/levels with pathological effects and are not compatible with long-term (Homeostatic Overload) or short-term (Homeostatic Failure) health. Wear and tear is the concept that there is a cost to maintaining physiological systems in the Reactive Homeostasis range, so that over time these systems gradually lose their ability to counteract threatening and unpredictable stimuli. Wear and tear can be modeled by a decrease in the threshold between Reactive Homeostasis and Homeostatic Overload, i.e. a decrease in reactive scope. This basic model can then be modified by altering the threshold between Reactive Homeostasis and Homeostatic Overload to help understand how an individual’s response to environmental stressors can differ depending upon factors such as prior stressors, dominance status, and early life experience. We illustrate the benefits of the Reactive Scope Model and contrast it with the traditional model and with allostasis in the context of chronic malnutrition, changes in social status, and changes in stress responses due to early life experiences. The Reactive Scope Model, as an extension of allostasis, should be useful to both biomedical researchers studying laboratory animals and humans, as well as ecologists studying stress in free-living animals.

Vividness, Consciousness, and Mental Imagery: Making the Missing Links across Disciplines and Methods

Guest Editor: Amedeo D’Angiulli

https://www.mdpi.com/journal/brainsci/special_issues/Vividness_Consciousness_Imagery

All articles can be accessed freely online.

Marks, D.F. I Am Conscious, Therefore, I Am: Imagery, Affect, Action, and a
General Theory of Behavior. Brain Sci. 2019, 9(5), 107;
https://doi.org/10.3390/brainsci9050107.
Views: 2082, Downloads: 1277, Citations: 2, Altmetrics: 2
https://www.mdpi.com/2076-3425/9/5/107

Lefebvre, E.; D’Angiulli, A. Imagery-Mediated Verbal Learning Depends on
Vividness–Familiarity Interactions: The Possible Role of Dualistic Resting
State Network Activity Interference. Brain Sci. 2019, 9(6), 143;
https://doi.org/10.3390/brainsci9060143.
Views: 1537, Downloads: 645, Citations: 0, Altmetrics: 5
https://www.mdpi.com/2076-3425/9/6/143

Pinna, B.; Conti, L. The Limiting Case of Amodal Completion: The Phenomenal
Salience and the Role of Contrast Polarity. Brain Sci. 2019, 9(6), 149;
https://doi.org/10.3390/brainsci9060149.
Views: 1307, Downloads: 701, Citations: 2, Altmetrics: 1
https://www.mdpi.com/2076-3425/9/6/149

Craver-Lemley, C.; Reeves, A. Taste Modulator Influences Rare Case of
Color-Gustatory Synesthesia. Brain Sci. 2019, 9(8), 186;
https://doi.org/10.3390/brainsci9080186.
Views: 1041, Downloads: 907, Citations: 0, Altmetrics: 0
https://www.mdpi.com/2076-3425/9/8/186

Haustein, S.; Vellino, A.; D’Angiulli, A. Insights from a Bibliometric
Analysis of Vividness and Its Links with Consciousness and Mental Imagery.
Brain Sci. 2020, 10(1), 41;
https://doi.org/10.3390/brainsci10010041.
Views: 810, Downloads: 300, Citations: 0, Altmetrics: 1
https://www.mdpi.com/2076-3425/10/1/41

van der Helm, P.A. Dubious Claims about Simplicity and Likelihood: Comment on
Pinna and Conti (2019). Brain Sci. 2020, 10(1), 50;
https://doi.org/10.3390/brainsci10010050.
Views: 699, Downloads: 234, Citations: 1, Altmetrics: 0
https://www.mdpi.com/2076-3425/10/1/50

Pinna, B.; Conti, L. On the Role of Contrast Polarity: In Response to van der
Helm’s Comments. Brain Sci. 2020, 10(1), 54;
https://doi.org/10.3390/brainsci10010054.
Views: 657, Downloads: 243, Citations: 0, Altmetrics: 0
https://www.mdpi.com/2076-3425/10/1/54

Thorudottir, S.; Sigurdardottir, H.M.; Rice, G.E.; Kerry, S.J.; Robotham,
R.J.; Leff, A.P.; Starrfelt, R. The Architect Who Lost the Ability to
Imagine: The Cerebral Basis of Visual Imagery. Brain Sci. 2020, 10(2), 59;
https://doi.org/10.3390/brainsci10020059.
Views: 2817, Downloads: 972, Citations: 0, Altmetrics: 56
https://www.mdpi.com/2076-3425/10/2/59

Brain Sciences (ISSN 2076-3425) is a journal published by MDPI AG, Basel,
Switzerland

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Sleep function and synaptic homeostasis

Tononi, G., & Cirelli, C. (2006). Sleep function and synaptic homeostasis. Sleep medicine reviews10(1), 49-62.

Summary

This paper reviews a novel hypothesis about the functions of slow wave sleep—the synaptic homeostasis hypothesis. According to the hypothesis, plastic processes occurring during wakefulness result in a net increase in synaptic strength in many brain circuits. The role of sleep is to downscale synaptic strength to a baseline level that is energetically sustainable, makes efficient use of gray matter space, and is beneficial for learning and memory. Thus, sleep is the price we have to pay for plasticity, and its goal is the homeostatic regulation of the total synaptic weight impinging on neurons. The hypothesis accounts for a large number of experimental facts, makes several specific predictions, and has implications for both sleep and mood disorders

Consciousness without a cerebral cortex

Merker, B. (2007). Consciousness without a cerebral cortex: A challenge for neuroscience and medicine. Behavioral and brain sciences30(1), 63-81.

Abstract:

A broad range of evidence regarding the functional organization of the vertebrate brain – spanning from comparative neurology to experimental psychology and neurophysiology to clinical data – is reviewed for its bearing on conceptions of the neural organization of consciousness. A novel principle relating target selection, action selection, and motivation to one another, as a means to optimize integration for action in real time, is introduced. With its help, the principal macrosystems of the vertebrate brain can be seen to form a centralized functional design in which an upper brain stem system organized for conscious function performs a penultimate step in action control. This upper brain stem system retained a key role throughout the evolutionary process by which an expanding forebrain – culminating in the cerebral cortex of mammals – came to serve as a medium for the elaboration of conscious contents. This highly conserved upper brainstem system, which extends from the roof of the midbrain to the basal diencephalon, integrates the massively parallel and distributed information capacity of the cerebral hemispheres into the limited-capacity, sequential mode of operation required for coherent behavior. It maintains special connective relations with cortical territories implicated in attentional and conscious functions, but is not rendered nonfunctional in the absence of cortical input. This helps explain the purposive, goal-directed behavior exhibited by mammals after experimental decortication, as well as the evidence that children born without a cortex are conscious. Taken together these circumstances suggest that brainstem mechanisms are integral to the constitution of the conscious state, and that an adequate account of neural mechanisms of conscious function cannot be confined to the thalamocortical complex alone.

Keywords: action selection; anencephaly; central decision making; consciousness; control architectures; hydranencephaly; macrosystems; motivation; target selection; zona incerta

The conscious id

Solms, M. (2013). The conscious id. Neuropsychoanalysis15(1), 5-19.

Abstract

Two aspects of the body are represented in the brain, and they are represented differently. The most important difference is that the brain regions for the two aspects of the body are associated with different aspects of consciousness. Very broadly speaking, the brainstem mechanisms derived from the autonomic body are associated with affective consciousness, and the cortical mechanisms derived from the sensorimotor body are associated with cognitive consciousness. Moreover, the upper brainstem is intrinsically conscious whereas the cortex is not; it derives its consciousness from the brainstem. These facts have substantial implications for psychoanalytic metapsychology because the upper brainstem (and associated limbic structures) performs the functions that Freud attributed to the id, while the cortex (and associated forebrain structures) performs the functions he attributed to the ego. This means that the id is the fount of consciousness and the ego is unconscious in itself. The basis for these conclusions, and some of their implications, are discussed here in a preliminary fashion. Keywords: affect; cognition; conscious; ego; id; unconscious

Mentalizing homeostasis: The social origins of interoceptive inference

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Fotopoulou, A., & Tsakiris, M. (2017). Mentalizing homeostasis: The social origins of interoceptive inference. Neuropsychoanalysis19(1), 3-28.
Is the self already relational in its very bodily foundations? The question of whether our mental life is initially and primarily shaped by embodied dimensions of the individual or by interpersonal relations is debated in many fields, including psychology, philosophy, psychoanalysis, and more recently, cognitive neuroscience. In this interdisciplinary target article, we put forward the radical claim that even some of the most minimal aspects of selfhood, namely the feeling qualities associated with being an embodied subject, are fundamentally shaped by embodied interactions with other people in early infancy and beyond. Such embodied interactions allow the developing organism to mentalize its homeostatic regulation. In other words, embodied interactions contribute directly to the building of mental models of the infant’s physiological states, given the need to maintain such states within a given dynamic range despite internal or external perturbations. Specifically, our position rests on the following three propositions: (1) the progressive integration and organization of sensory and motor signals constitutes the foundations of the minimal self, a process which we have linked to contemporary, computational models of brain function and named “embodied mentalization”; (2) interactions with other people are motivated and constrained by the same principles that govern the “mentalization” of sensorimotor signals in the individual – and hence the mentalization of one’s body can include signals from other bodies in physical proximity and interaction, especially in interaction with particular bodies. (3) Crucially, given the dependency of humans in early infancy, there is a “homeostatically necessary” plethora of such embodied “proximal” interactions, especially as regards interoception. Collectively, such experiences of proximal intercorporeality “sculpt” the mentalization process and hence the constitution of the minimal self, including the progressive sophistication of mental distinctions between “subject-object,” “self-other” and even “pleasure-pain.” Finally, we explore notions of cardiac and more broadly interoceptive awareness as later, cognitive acquisitions that allow us to progressively solidify such distinctions, as well as understand and empathise with other people.
Keywords:
self; affect; emotion; awareness; social cognition; touch; interoception; intersubjectivity; embodiment; skin ego; minimal self

Homeostasis in Neuroscience

 

Some commentaries from the neurosciences point of view about the relations between citizens and public agencies

A. F. Rocha, State University of Campinas, Brazil

Research on Artificial and Natural Intelligence

Summary

The success story continues making Nudge well read and much applied. The key message is that people are irrational on their decision making and need to be guided by policy markers, which are able to have useful insights from Psychology and Behavioral Economics about how to elaborate choice structures to rationalize people’s financial behavior. Inertia is one popular of these insights and refers to the tendency of humans to procrastinate in making choices. This tendency is acknowledged but not understood and explained. The same occurs with other reported insights. In contrast, the present paper proposes any decision guaranteeing the individual biological; psychological and social homeostasis are rational despite being or not the expected decision supported by any formal model. Most of the important human decisions are about keeping homeostasis within boundaries promoting well being, hence resulting from complex analyses of benefits; risks and costs from both the personal and social point of view as carried out by two different Personal and Social Decision Networks. Rational choice selects, therefore, high beneficial goods or services for promoting homeostasis at lowest risk and cost from both personal and social point of views. A decision neural model for decision making is presented and used to illustrate how rational choices are computed to guarantee individual homeostasis, and to propose that individuals seem to be irrational because the proposed economic formal theories take into consideration just the policy maker point of view disregarding the individual needs.

Keywords: Decision Making, Brain, Economic Psychology, Behavioral Economy, Neurosciences, Nudge

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