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Fundamentals
Published in Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam, Introduction to Computational Health Informatics, 2019
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam
Predictive coding is based upon predicting the value of a pixel based on neighboring pixels and past changes. It is a two-step process: 1) predicting the value using neighboring pixels and 2) taking the difference between the actual value and predicted value to calculate the prediction-error. This prediction-error value is small and is encoded. The image is reconstructed using the prediction-error and the predicted value.
Psychological and neurobiological processes in coping with pain
Published in Philip N. Murphy, The Routledge International Handbook of Psychobiology, 2018
Charlotte Krahé, Aikaterini Fotopoulou
Taken together, the above findings suggest that positively intentioned real or imagined interactions seem to attenuate pain (especially when interpersonally relevant). The direction of effects, particularly for more ambiguous interactions, seems to depend on individual differences in attachment style. Empathy from the social partner also seems to play a role in these effects. Considering these findings and drawing on attachment theory and principles of predictive coding theory, we proposed an integrative framework within which the role of social interactions on pain may be understood (see Krahé et al., 2013, for details; see also Decety & Fotopoulou, 2015). In particular, we put forward the idea that social interactions may influence pain by acting as social, predictive signals of contextual safety or threat, both in regard to noxious stimuli and the social environment in which they occur. Further, the perception of social interactions themselves (e.g., individual differences in attachment style) was argued to influence these signals. While behavioural findings may be understood within such a framework, it is vital to support them with research offering insights at a different level of explanation, namely studies investigating the neurobiological mechanisms underlying effects of social interactions on pain. Candidate neural regions such as a “salience network” processing threats to the body – involved in weighting the importance of safety and threat and integrating these with social contextual factors – as well as neurobiological pathways related to attachment, such as those involving oxytocin, have already briefly been mentioned and will be explored in more detail in the next section.
Pre-Clinical Approaches and Methods on Alzheimer’s Disease
Published in Atanu Bhattacharjee, Akula Ramakrishna, Magisetty Obulesu, Phytomedicine and Alzheimer’s Disease, 2020
S. R. Chandra, Pooja Mailankody
Reisberg (1985), using a global deterioration scale (GDS), predicted that SCD + grade 2 GDS is not normal and grade 3 MCI, grade 4 MCI and higher were associated with dementia. SCD is associated more with depression (Bolla et al.), and depression influences hippocampal volume (Gurvits et al.), suggesting a complex interaction between these three states. The outcome studies have limitation in terms of early dementias, and whether MCI were excluded or not is not clear. Geerlings reported three times greater risk of developing dementia within 3.5 years of being diagnosed as MCI, whereas John and Montgomery and Wang et al. reported that it does not. Cross-sectional studies revealed a greater decline with MCI. Cognitive tests are difficult to quantify between SCD and non-SCD. Biological assessment with quantitative encephalography (qEEG) showed increased θ, whereas voxel-based morphometric studies reported grey matter differences in medial temporal, frontal, and other neocortices. A smaller hippocampus in SCD was reported by van den Filler. Positron emission tomography (PET) studies reported decreased cerebral metabolism of glucose in the parietotemporal and parahippocampal regions. Subjects who had SCD in conjunction with the apolipoprotein E ε4 (APOEε4) allele had greater changes. Higher cortisol levels were reported by Wolf et al. Functional magnetic resonance imaging (fMRI) studies have revealed no change in performance during tasks but observed differences in functional brain activation between SCD and non-SCD subjects. When semantically related words were used, increased activation of the lateral prefrontal cortex was seen and led to compensatory theory, classifying it to be compensation for decay of the hippocampal memory system elsewhere. Testing of the episodic memory and valuation system revealed decreased preference for future-oriented tasks, attenuating attention, and subjective evaluation systems. The phenomenon of “Negative Subsequent” is postulated to be the cause of increased activation of failed recall. Dedifferentiation theory argues that loss of specialization results in diffuse brain activation, but how this hyperactivity contributes to SCD is not clear. Homeostasis breakdown theory says that it could be associated with loss of comprehensive temporal dynamics. Prediction error theory describes brain functions as a statistical optimization engine, and makes implicit predictions of inputs actively making inferences, instead of passively recording. Predictive coding is the principle by which there is a comparison of internally generated predictions with external reality. Awareness of subtle errors can occur in multiple domains, causing SCD. Homeostasis breakdown occurs and compensatory functions act for some time. but these can lead to glutamate excitotoxicity and cell death. Depression is a common characteristic of SCD and there is probably a complex interaction between depression, SCD, MCI, and dementia. Outcome studies are not clear if MCI were excluded. The longer the follow-up, the longer the conversion period.
Consciousness in a Rotor? Science and Ethics of Potentially Conscious Human Cerebral Organoids
Published in AJOB Neuroscience, 2023
Federico Zilio, Andrea Lavazza
To observe the synchronization of neural activity with the cardiac input, the most relevant neurocardiac measures used are the heartbeat evoked potential and inter-trial coherence. According to this theory, not only the cortical regions, but also the subcortical ones are relevant for the formation of the central autonomic network, which in turn is involved in the development and maintenance of the brain-gut axis. Furthermore, some versions of the predictive coding theory (Seth, Suzuki, and Critchley 2012); Seth and Tsakiris 2018; particularly related to the embodied theory consider the body (heart, viscera, etc.) as the basis for the sense of self. Indeed, interoceptive monitoring appears to contribute to the predictive regulation of physiological states and physiological integrity, constituting the embodied self in terms of instrumental interoceptive inference. The sense of self-awareness is reached when there is a successful match between informative interoceptive signals from the body and top-down prediction from the brain so that prediction errors are suppressed.
The response set theory of hypnosis reconsidered: toward an integrative model
Published in American Journal of Clinical Hypnosis, 2023
Steven Jay Lynn, Joseph P. Green, Anoushiravan Zahedi, Clément Apelian
The predictive coding model (PCM; Clark, 2013; Friston, 2010) is recognized as one of the most influential theoretical frameworks in cognitive neuroscience (Beni, 2022). The PCM provides useful insights into hypnotic responsiveness and opens the door to a multifactorial, integrative model of hypnosis. The pillar of PCM is that our brain is not a passive recorder but we act as active scientists, constantly testing hypotheses against evidence (Gregory, 1980). Our cognitive hypotheses derive from heuristic models shaped by prior experiences and will be expressed in predictions propagating downward in the nervous system (Adams, Shipp, & Friston, 2013). The constant comparison between predictions and sensory information shapes prediction errors, which are propagated upward in the system (Adams et al., 2013; Clark, 2013). The free-energy principle assumes that any “self-organizing system that resides at equilibrium with its environment must minimize its free energy” by eliminating prediction errors (Friston, 2010, p. 127).
A celebration of Irving Kirsch
Published in American Journal of Clinical Hypnosis, 2023
Anticipated by an earlier statement from White (1941), Kirsch’s most important theoretical work has been the response set theory, which posits that expectancies (or expectations when they are conscious) about suggested behaviors and experiences activate responses consistent with them (Kirsch, 1999). In the longest paper in this issue, “The Response Set Theory of Hypnosis Reconsidered: Toward an Integrative Model,” Kirsch’s most frequent collaborator on hypnosis, and an eminent hypnosis author himself, Steven Jay Lynn, along with Joseph P. Green, Anoushiravan Zahedi, and Clément Apelian (2022, this issue) provide an extensive account of Response Set Theory. They describe how it evolved from a “strong” version in which expectancies fully accounted for the variance of hypnotic responses to a more nuanced one in which expectancies are substantial but not the only contributors to hypnotizability (cf. Spanos, Burnley, & Cross, 1993). In what is likely to be a fruitful proposal, they offer an integrative model that considers multiple variables and includes the recent neuroscientific model of predictive coding in which the brain constantly updates a mental model of reality (see also Kirsch, 2018). Predictive coding was clearly anticipated in the non-brain-centric model of constructivists such as Brunner (e.g., “The organism in perception is in one way or another in a state of expectancy about the environment,” Bruner & Postman, 1949, p. 206), and by neuroscientists (e.g., experience is “an inextricable amalgam of represented anticipation and represented perturbation,” Kinsbourne, 1998, p. 241).