scholarly journals A global framework for a systemic view of brain modeling

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Frederic Alexandre
Keyword(s):  
Instrumental Conditioning ◽  
The Body ◽  
Posterior Cortex ◽  
Reciprocal Relationships ◽  
Brain Modeling ◽  
Brain Theory ◽  
Habitual Behavior ◽  
Definition Of ◽  
The Brain ◽  
Specific Contribution

AbstractThe brain is a complex system, due to the heterogeneity of its structure, the diversity of the functions in which it participates and to its reciprocal relationships with the body and the environment. A systemic description of the brain is presented here, as a contribution to developing a brain theory and as a general framework where specific models in computational neuroscience can be integrated and associated with global information flows and cognitive functions. In an enactive view, this framework integrates the fundamental organization of the brain in sensorimotor loops with the internal and the external worlds, answering four fundamental questions (what, why, where and how). Our survival-oriented definition of behavior gives a prominent role to pavlovian and instrumental conditioning, augmented during phylogeny by the specific contribution of other kinds of learning, related to semantic memory in the posterior cortex, episodic memory in the hippocampus and working memory in the frontal cortex. This framework highlights that responses can be prepared in different ways, from pavlovian reflexes and habitual behavior to deliberations for goal-directed planning and reasoning, and explains that these different kinds of responses coexist, collaborate and compete for the control of behavior. It also lays emphasis on the fact that cognition can be described as a dynamical system of interacting memories, some acting to provide information to others, to replace them when they are not efficient enough, or to help for their improvement. Describing the brain as an architecture of learning systems has also strong implications in Machine Learning. Our biologically informed view of pavlovian and instrumental conditioning can be very precious to revisit classical Reinforcement Learning and provide a basis to ensure really autonomous learning.

scholarly journals A global framework for a systemic view of brain modeling

2020 ◽  
Author(s):  
Frédéric Alexandre
Keyword(s):  
Computational Neuroscience ◽  
Instrumental Conditioning ◽  
Cognitive Architecture ◽  
The Body ◽  
Clear Understanding ◽  
Posterior Cortex ◽  
Reciprocal Relationships ◽  
Brain Modeling ◽  
Definition Of ◽  
The Brain

Abstract Background: The brain is a complex system, due to the heterogeneity of its structure, the diversity of the functions in which it participates and to its reciprocal relationships with the body and the environment. Researchers in cognitive computational neuroscience generally focused on one specific task, lack this global view and a clear understanding of how their model is inserted in a global cognitive architecture. A systemic description of the brain is presented here, as a general framework where specific models in computational neuroscience can be integrated and associated with global information flows and cognitive functions. Results: In an enactive view, this framework integrates the fundamental organization of the brain in sensorimotor loops with the internal and the external worlds, answering four fundamental questions (what, why, where and how). Our survival-oriented definition of behavior gives a prominent role to pavlovian and instrumental conditioning, augmented during phylogeny by the specific contribution of other kinds of learning, related to semantic memory in the posterior cortex, episodic memory in the hippocampus and working memory in the frontal cortex. Conclusions: This framework highlights that responses can be prepared in different ways, from pavlovian reflexes and habitual behavior to deliberations for goal-directed planning and reasoning, and explains that these different kinds of responses coexist, collaborate and compete for the control of behavior. It also lays emphasis on the fact that cognition can be described as a dynamical system of interacting memories, some acting to provide information to others, to replace them when they are not efficient enough, or to help for their improvement. Describing the brain as an architecture of learning systems has also strong implications in Machine Learning. Our biologically informed view of pavlovian and instrumental conditioning can be very precious to revisit classical Reinforcement Learning and provide a basis to ensure really autonomous learning.

scholarly journals Awakening: Predicting external stimulation to force transitions between different brain states

2019 ◽  
Vol 116 (36) ◽  
pp. 18088-18097 ◽  
Author(s):  
Gustavo Deco ◽  
Josephine Cruzat ◽  
Joana Cabral ◽  
Enzo Tagliazucchi ◽  
Helmut Laufs ◽  
...  
Keyword(s):  
Fundamental Problem ◽  
Effective Connectivity ◽  
Brain State ◽  
Whole Brain ◽  
External Stimulation ◽  
Neuropsychiatric Diseases ◽  
Brain Modeling ◽  
Brain States ◽  
Definition Of ◽  
The Brain

A fundamental problem in systems neuroscience is how to force a transition from one brain state to another by external driven stimulation in, for example, wakefulness, sleep, coma, or neuropsychiatric diseases. This requires a quantitative and robust definition of a brain state, which has so far proven elusive. Here, we provide such a definition, which, together with whole-brain modeling, permits the systematic study in silico of how simulated brain stimulation can force transitions between different brain states in humans. Specifically, we use a unique neuroimaging dataset of human sleep to systematically investigate where to stimulate the brain to force an awakening of the human sleeping brain and vice versa. We show where this is possible using a definition of a brain state as an ensemble of “metastable substates,” each with a probabilistic stability and occurrence frequency fitted by a generative whole-brain model, fine-tuned on the basis of the effective connectivity. Given the biophysical limitations of direct electrical stimulation (DES) of microcircuits, this opens exciting possibilities for discovering stimulation targets and selecting connectivity patterns that can ensure propagation of DES-induced neural excitation, potentially making it possible to create awakenings from complex cases of brain injury.

scholarly journals The Soul and Personal Identity. Derek Parfit’s Arguments in the Substance Dualist Perspective

Perichoresis ◽  
2017 ◽  
Vol 15 (2) ◽  
pp. 3-23
Author(s):  
Dmytro Sepetyi
Keyword(s):  
Personal Identity ◽  
Human Life ◽  
The Body ◽  
Psychological Profile ◽  
Temporal Continuity ◽  
Brain Theory ◽  
Body Theory ◽  
Humean Theory ◽  
The Brain ◽  
Humean View

AbstractThis paper re-evaluates Derek Parfit’s attack on the commonly held view that personal identity is necessarily determinate and that it is what matters. In the first part we first argue against the Humean view of personal identity; secondly, we classify the remaining alternatives into three kinds: the body theory and the brain theory, the quasi-Humean theory, and the soul theory, and thirdly we deploy Parfit’s arguments and related considerations to the point that none of the materialistic alternatives is consistent with the commonly held view. This leaves us with the alternative: either we accept the radical and highly implausible materialistic view Parfit calls ‘Reductionism’, or we accept the view that we are nonphysical indivisible entities—Cartesian egos, or souls. The second part of the paper discusses Parfit’s objections against the Cartesian view: that there is no reason to believe in the existence of such nonphysical entities; that if such entities exist, there is no evidence that they are enduring (to span a human life); that even if they exist and are enduring, they are irrelevant for the psychological profile and temporal continuity of a person; that experiments with ‘brain-splitted’ patients provide strong evidence against the Cartesian view. We argue that these objections are in part mistaken, and that the remaining (sound) part is not strong enough to make the Cartesian view less plausible than Reductionism.

scholarly journals Brain More Resistant to Energy Restriction Than Body: A Systematic Review

2021 ◽  
Vol 15 ◽  
Author(s):  
Marie Sprengell ◽  
Britta Kubera ◽  
Achim Peters
Keyword(s):  
Systematic Review ◽  
Magnetic Resonance ◽  
Caloric Restriction ◽  
High Energy ◽  
The Body ◽  
Energy Concentration ◽  
High Energy Phosphates ◽  
Decision Algorithm ◽  
Brain Theory ◽  
The Brain

The gluco-lipostatic theory and its modern variants assume that blood glucose and energy stores are controlled in closed-loop feedback processes. The Selfish Brain theory is based on the same assumptions, but additionally postulates that the brain, as an independent energy compartment, self-regulates its energy concentration with the highest priority. In some clinical situations these two theories make opposite predictions. To investigate one of these situations, namely caloric restriction, we formulated a hypothesis which, if confirmed, would match the predictions of the Selfish Brain theory—but not those of the gluco-lipostatic theory. Hypothesis: Calorie restriction causes minor mass (energy) changes in the brain as opposed to major changes in the body. We conducted a systematic review of caloric-restriction studies to test whether or not the evaluated studies confirmed this hypothesis. We identified 3,157 records, screened 2,804 works by title or abstract, and analyzed 232 by full text. According to strict selection criteria (set out in our PROSPERO preregistration, complying with PRISMA guidelines, and the pre-defined hypothesis-decision algorithm), 8 papers provided enough information to decide on the hypothesis: In animals, high-energy phosphates were measured by 31P-nuclear magnetic resonance, and organ and total body weights were measured by scales, while in humans organ sizes were determined by magnetic resonance imaging. All 8 decidable papers confirmed the hypothesis, none spoke against it. The evidence presented here clearly shows that the most accurate predictions are possible with a theory that regards the brain as independently self-regulating and as occupying a primary position in a hierarchically organized energy metabolism.

scholarly journals Brain Mass (Energy) Resistant to Hyperglycaemic Oversupply: A Systematic Review

2021 ◽  
Vol 15 ◽  
Author(s):  
Marie Sprengell ◽  
Britta Kubera ◽  
Achim Peters
Keyword(s):  
Systematic Review ◽  
Energy Demand ◽  
Energy Content ◽  
The Body ◽  
Mass Energy ◽  
Primary Position ◽  
Brain Mass ◽  
Theoretical Approaches ◽  
Brain Theory ◽  
The Brain

Cerebral energy supply is determined by the energy content of the blood. Accordingly, the brain is undersupplied during hypoglycaemia. Whether or not there is an additional cerebral energy demand that depends upon the energy content of the brain is considered differently in two opposing theoretical approaches. The Selfish-Brain theory postulates that the brain actively demands energy from the body when needed, while long-held theories, the gluco-lipostatic theory and its variants, deny such active brain involvement and view the brain as purely passively supplied. Here we put the competing theories to the test. We conducted a systematic review of a condition in which the rival theories make opposite predictions, i.e., experimental T1DM. The Selfish-Brain theory predicts that induction of experimental type 1 diabetes causes minor mass (energy) changes in the brain as opposed to major glucose changes in the blood. This prediction becomes our hypothesis to be tested here. A total of 608 works were screened by title and abstract, and 64 were analysed in full text. According to strict selection criteria defined in our PROSPERO preannouncement and complying with PRISMA guidelines, 18 studies met all inclusion criteria. Thirteen studies provided sufficient data to test our hypothesis. The 13 evaluable studies (15 experiments) showed that the diabetic groups had blood glucose concentrations that differed from controls by +294 ± 96% (mean ± standard deviation) and brain mass (energy) that differed from controls by −4 ± 13%, such that blood changes were an order of magnitude greater than brain changes (T = 11.5, df = 14, p < 0.001). This finding confirms not only our hypothesis but also the prediction of the Selfish-Brain theory, while the predictions of the gluco-lipostatic theory and its variants were violated. The current paper completes a three-part series of systematic reviews, the two previous papers deal with a distal and a proximal bottleneck in the cerebral brain supply, i.e., caloric restriction and cerebral artery occlusion. All three papers demonstrate that accurate predictions are only possible if one regards the brain as an organ that regulates its energy concentrations independently and occupies a primary position in a hierarchically organised energy metabolism.Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=156816, PROSPERO, identifier: CRD42020156816.

Application of Scanning Electron Microscopy to Medical Research

1969 ◽  
Vol 27 ◽  
pp. 12-13
Author(s):  
J. D. Hutchison
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Medical Research ◽  
Prosthetic Heart Valve ◽  
School Of Medicine ◽  
Transmission Electron ◽  
Definition Of ◽  
Mechanism Of Failure ◽  
The Brain ◽  
Scanning Electron

When the transmission electron microscope was commercially introduced a few years ago, it was heralded as one of the most significant aids to medical research of the century. It continues to occupy that niche; however, the scanning electron microscope is gaining rapidly in relative importance as it fills the gap between conventional optical microscopy and transmission electron microscopy.IBM Boulder is conducting three major programs in cooperation with the Colorado School of Medicine. These are the study of the mechanism of failure of the prosthetic heart valve, the study of the ultrastructure of lung tissue, and the definition of the function of the cilia of the ventricular ependyma of the brain.

Comparison of Fluorine(18)-fluorodeoxyglucose and Gallium(68)-citrate PET/CT in patients with tuberculosis

2019 ◽  
Vol 58 (05) ◽  
pp. 371-378
Author(s):  
Alfred O. Ankrah ◽  
Ismaheel O. Lawal ◽  
Tebatso M.G. Boshomane ◽  
Hans C. Klein ◽  
Thomas Ebenhan ◽  
...  
Keyword(s):  
Tracer Uptake ◽  
Pet Ct ◽  
The Mean ◽  
18F Fdg ◽  
Definition Of ◽  
Gallium 68 ◽  
Attending Physician ◽  
Pet Scans ◽  
The Brain

Abstract 18F-FDG and 68Ga-citrate PET/CT have both been shown to be useful in the management of tuberculosis (TB). We compared the abnormal PET findings of 18F-FDG- and 68Ga-citrate-PET/CT in patients with TB. Methods Patients with TB on anti-TB therapy were included. Patients had a set of PET scans consisting of both 18F-FDG and 68Ga-citrate. Abnormal lesions were identified, and the two sets of scans were compared. The scan findings were correlated to the clinical data as provided by the attending physician. Results 46 PET/CT scans were performed in 18 patients, 11 (61 %) were female, and the mean age was 35.7 ± 13.5 years. Five patients also had both studies for follow-up reasons during the use of anti-TB therapy. Thirteen patients were co-infected with HIV. 18F-FDG detected more lesions than 68Ga-citrate (261 vs. 166, p < 0.0001). 68Ga-citrate showed a better definition of intracerebral lesions due to the absence of tracer uptake in the brain. The mean SUVmax was higher for 18F-FDG compared to 68Ga-citrate (5.73 vs. 3.01, p < 0.0001). We found a significant correlation between the SUVmax of lesions that were determined by both tracers (r = 0.4968, p < 0.0001). Conclusion Preliminary data shows 18F-FDG-PET detects more abnormal lesions in TB compared to 68Ga-citrate. However, 68Ga-citrate has better lesion definition in the brain and is therefore especially useful when intracranial TB is suspected.

Derrida on Pornography: Putting (It) Up for Sale

Derrida Today ◽  
2013 ◽  
Vol 6 (1) ◽  
pp. 97-114 ◽  
Author(s):  
Christopher Morris
Keyword(s):  
Cultural Studies ◽  
English Translation ◽  
The Body ◽  
The Past ◽  
French Original ◽  
Definition Of ◽  
Critical Discourses ◽  
Academic Debate

Over the past thirty years, academic debate over pornography in the discourses of feminism and cultural studies has foundered on questions of the performative and of the word's definition. In the polylogue of Droit de regards, pornography is defined as la mise en vente that is taking place in the act of exegesis in progress. (Wills's idiomatic English translation includes an ‘it’ that is absent in the French original). The definition in Droit de regards alludes to the word's etymology (writing by or about prostitutes) but leaves the referent of the ‘sale’ suspended. Pornography as la mise en vente boldly restates the necessary iterability of the sign and anticipates two of Derrida's late arguments: that there is no ‘the’ body and that performatives may be powerless. Deriving a definition of pornography from a truncated etymology exemplifies the prosthesis of origin and challenges other critical discourses to explain how pornography can be understood as anything more than ‘putting (it) up for sale’.

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