scholarly journals Variability of perceptual multistability: from brain state to individual trait

2012 ◽  
Vol 367 (1591) ◽  
pp. 988-1000 ◽  
Author(s):  
Andreas Kleinschmidt ◽  
Philipp Sterzer ◽  
Geraint Rees
Keyword(s):  
Sensory Input ◽  
Parietal Lobe ◽  
Individual Variability ◽  
Brain State ◽  
Perceptual Inference ◽  
External Stimulation ◽  
Switching Behaviour ◽  
Individual Trait ◽  
The Individual ◽  
The Brain

Few phenomena are as suitable as perceptual multistability to demonstrate that the brain constructively interprets sensory input. Several studies have outlined the neural circuitry involved in generating perceptual inference but only more recently has the individual variability of this inferential process been appreciated. Studies of the interaction of evoked and ongoing neural activity show that inference itself is not merely a stimulus-triggered process but is related to the context of the current brain state into which the processing of external stimulation is embedded. As brain states fluctuate, so does perception of a given sensory input. In multistability, perceptual fluctuation rates are consistent for a given individual but vary considerably between individuals. There has been some evidence for a genetic basis for these individual differences and recent morphometric studies of parietal lobe regions have identified neuroanatomical substrates for individual variability in spontaneous switching behaviour. Moreover, disrupting the function of these latter regions by transcranial magnetic stimulation yields systematic interference effects on switching behaviour, further arguing for a causal role of these regions in perceptual inference. Together, these studies have advanced our understanding of the biological mechanisms by which the brain constructs the contents of consciousness from sensory input.

scholarly journals A theory of cortical responses

2005 ◽  
Vol 360 (1456) ◽  
pp. 815-836 ◽  
Author(s):  
Karl Friston
Keyword(s):  
Free Energy ◽  
Perceptual Learning ◽  
Hierarchical Models ◽  
Empirical Bayes ◽  
Sensory Input ◽  
Theoretical Treatment ◽  
Perceptual Inference ◽  
Repetition Suppression ◽  
Cortical Responses ◽  
The Brain

This article concerns the nature of evoked brain responses and the principles underlying their generation. We start with the premise that the sensory brain has evolved to represent or infer the causes of changes in its sensory inputs. The problem of inference is well formulated in statistical terms. The statistical fundaments of inference may therefore afford important constraints on neuronal implementation. By formulating the original ideas of Helmholtz on perception, in terms of modern-day statistical theories, one arrives at a model of perceptual inference and learning that can explain a remarkable range of neurobiological facts. It turns out that the problems of inferring the causes of sensory input (perceptual inference) and learning the relationship between input and cause (perceptual learning) can be resolved using exactly the same principle. Specifically, both inference and learning rest on minimizing the brain's free energy, as defined in statistical physics. Furthermore, inference and learning can proceed in a biologically plausible fashion. Cortical responses can be seen as the brain’s attempt to minimize the free energy induced by a stimulus and thereby encode the most likely cause of that stimulus. Similarly, learning emerges from changes in synaptic efficacy that minimize the free energy, averaged over all stimuli encountered. The underlying scheme rests on empirical Bayes and hierarchical models of how sensory input is caused. The use of hierarchical models enables the brain to construct prior expectations in a dynamic and context-sensitive fashion. This scheme provides a principled way to understand many aspects of cortical organization and responses. The aim of this article is to encompass many apparently unrelated anatomical, physiological and psychophysical attributes of the brain within a single theoretical perspective. In terms of cortical architectures, the theoretical treatment predicts that sensory cortex should be arranged hierarchically, that connections should be reciprocal and that forward and backward connections should show a functional asymmetry (forward connections are driving, whereas backward connections are both driving and modulatory). In terms of synaptic physiology, it predicts associative plasticity and, for dynamic models, spike-timing-dependent plasticity. In terms of electrophysiology, it accounts for classical and extra classical receptive field effects and long-latency or endogenous components of evoked cortical responses. It predicts the attenuation of responses encoding prediction error with perceptual learning and explains many phenomena such as repetition suppression, mismatch negativity (MMN) and the P300 in electroencephalography. In psychophysical terms, it accounts for the behavioural correlates of these physiological phenomena, for example, priming and global precedence. The final focus of this article is on perceptual learning as measured with the MMN and the implications for empirical studies of coupling among cortical areas using evoked sensory responses.

scholarly journals A novel dynamic brain network in arousal for brain states and emotion analysis

2021 ◽  
Vol 18 (6) ◽  
pp. 7440-7463
Author(s):  
Yunyuan Gao ◽  
◽  
Zhen Cao ◽  
Jia Liu ◽  
Jianhai Zhang ◽  
...  
Keyword(s):  
Parietal Lobe ◽  
Brain Networks ◽  
Brain Network ◽  
Brain State ◽  
High Arousal ◽  
Emotion Analysis ◽  
Significant Difference ◽  
Brain States ◽  
The Brain ◽  
Channel Norm

<abstract> <sec><title>Background</title><p>Brain network can be well used in emotion analysis to analyze the brain state of subjects. A novel dynamic brain network in arousal is proposed to analyze brain states and emotion with Electroencephalography (EEG) signals.</p> </sec> <sec><title>New Method</title><p>Time factors is integrated to construct a dynamic brain network under high and low arousal conditions. The transfer entropy is adopted in the dynamic brain network. In order to ensure the authenticity of dynamics and connections, surrogate data are used for testing and analysis. Channel norm information features are proposed to optimize the data and evaluate the level of activity of the brain.</p> </sec> <sec><title>Results</title><p>The frontal lobe, temporal lobe, and parietal lobe provide the most information about emotion arousal. The corresponding stimulation state is not maintained at all times. The number of active brain networks under high arousal conditions is generally higher than those under low arousal conditions. More consecutive networks show high activity under high arousal conditions among these active brain networks. The results of the significance analysis of the features indicates that there is a significant difference between high and low arousal.</p> </sec> <sec><title>Comparison with Existing Method(s)</title><p>Compared with traditional methods, the method proposed in this paper can analyze the changes of subjects' brain state over time in more detail. The proposed features can be used to quantify the brain network for accurate analysis.</p> </sec> <sec><title>Conclusions</title><p>The proposed dynamic brain network bridges the research gaps in lacking time resolution and arousal conditions in emotion analysis. We can clearly get the dynamic changes of the overall and local details of the brain under high and low arousal conditions. Furthermore, the active segments and brain regions of the subjects were quantified and evaluated by channel norm information.This method can be used to realize the feature extraction and dynamic analysis of the arousal dimension of emotional EEG, further explore the emotional dimension model, and also play an auxiliary role in emotional analysis.</p> </sec> </abstract>

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 SPECIFIC MORPHOMETRIC FEATURES OF SUPERIOR SAGITTAL SINUS IN ADULTS

2019 ◽  
Vol 18 (4) ◽  
pp. 63-66
Author(s):  
Yu. M. Vovk ◽  
S. V. Bondarenko
Keyword(s):  
Sagittal Plane ◽  
Superior Sagittal Sinus ◽  
Individual Variability ◽  
Head Shape ◽  
Sagittal Sinus ◽  
Convex Part ◽  
Morphometric Features ◽  
Parasagittal Plane ◽  
The Individual ◽  
The Brain

In order to determine the individual peculiarity of the shape, size, position and relations of the upper sagittal sinus, depending on the type of structure of the head in adults, craniometry and morphometry of the head sinuses were performed. The most significant venous collector of the brain is the upper sagittal sinus, which is located in the sagittal plane along the ridge of the lattice to the inner occipital projection. This formation is characterized by a triangular shape. The upper wall is formed by the leaves of the convex part of the solid membrane, and the two lateral walls by splitting the sickle of the cerebellum in the parasagittal plane. In adults, the upper wall contacts the inner surface of the parietal and occipital bones of the cranial vault. According to our data, the upper sagittal sinus has a specific range of variability depending on age, sex and head shape. The range of individual variability of the structure of the upper sagittal sinus was determined, which is characterized by the greatest values of length and height in adults, irrespective of gender with dolichomorphic head shape (narrow-headed) and increase in latitudinal parameters in people with meso- and brachymorphic head (middle and wide).

scholarly journals Structure of the Upper and Lower Surfaces of Human Corpus Callosum

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Olga Boiagina ◽  
Keyword(s):  
Corpus Callosum ◽  
Digital Camera ◽  
Lower Surface ◽  
Structural Features ◽  
Mean Value ◽  
Individual Variability ◽  
Cerebral Hemispheres ◽  
The Difference ◽  
The Individual ◽  
The Brain

The corpus callosum in the interval between the cerebral hemispheres is a plate of white matter, uneven in thickness, in which two surfaces are distinguished - the upper and lower ones, bent according to its lateral profile. The objective of the study was to study the individual variability of location of the lateral and medial longitudinal strips on the upper surface of the corpus callosum, as well as structural features of its lower surface. The material was the brain of men and women (10 specimens each) of the second period of adulthood, who died for the causes not related to the pathology of the central nervous system. After two weeks of fixation in a 10% formalin solution, the brain was prepared by separating the cerebral hemispheres and other parts of the brain from the corpus callosum, resulting in exposure of its upper and lower surface, which was photographed using a digital camera. As evidenced by the obtained data, the width of the trunk of the corpus callosum in men varies from 9 to 16 mm, whereas in women the difference between the minimum (11.0 mm) and the maximum (20.0 mm) values is greater than in men, when in fact there is only small difference of the arithmetic mean value. Thus, we offer to consider the lateral longitudinal strips to be the boundaries of the corpus callosum hemispherical part and the distance between them determines the width of this formation, which in average is 13.0 ± 2.5 mm in men and 14.4 ± 2.7 mm in women. In the meantime, the nature of the individual variability of the width of the corpus callosum trunk in women is more diverse than in men.

scholarly journals Gene, the Sexual Brain, and Cognition: Machine-Predicted Brain Sex Score Explains Individual Differences in Cognitive Development and Genetic Influence.

2021 ◽  
Author(s):  
Kakyeong Kim ◽  
Yoonjung Yoonie Joo ◽  
Gun Ahn ◽  
Hee-Hwan Wang ◽  
Seo-Yoon Moon ◽  
...  
Keyword(s):  
Cognitive Development ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Individual Variability ◽  
Brain Morphometry ◽  
Sex Development ◽  
Polygenic Scores ◽  
The Individual ◽  
Individual And Sex Differences ◽  
The Brain

Sex impacts the development of the brain and cognition differently across individuals. We investigated the biological underpinnings of the individual variability of sexual dimorphism in the brain and its impact on cognitive development. In prepubertal children (N=9,658, ages 9~10 years old; the Adolescent Brain Cognitive Development study), we tested whether the individual difference in brain sex development was related to that in cognitive development, known to be influenced by genetic factors. We estimated an individual’s brain sex score from machine learning models trained on brain morphometry and diffusion white matter connectomes that accurately classified the biological sex with a test ROC-AUC of 93.32%. A greater brain sex score correlated significantly with greater intelligence (Pfdr&lt;0.001, ηp2=0.034~0.050; adjusted for covariates) and higher cognitive genome-wide polygenic scores (GPSs) (Pfdr&lt;0.001, ηp2&lt;0.005). Structural equation models revealed that the GPS-intelligence association was modulated by the brain sex score, such that a brain with a higher maleness score (or a lower femaleness score) mediated a positive GPS effect on intelligence (indirect effects=0.006~0.009; P=0.002~0.022; sex-stratified analysis). The novel gene-brain-cognition relationship reported in this study presents a biological pathway to the individual and sex differences in the brain and cognitive development in preadolescence.

scholarly journals Spontaneous Fluctuations in Oscillatory Brain State Cause Differences in Transcranial Magnetic Stimulation Effects Within and Between Individuals

2021 ◽  
Vol 15 ◽  
Author(s):  
Shanice E. W. Janssens ◽  
Alexander T. Sack
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Signal Propagation ◽  
Individual Variability ◽  
Brain State ◽  
State Dependent ◽  
Oscillatory State ◽  
Transcranial Alternating Current Stimulation ◽  
The Individual ◽  
Spontaneous Fluctuations

Transcranial magnetic stimulation (TMS) can cause measurable effects on neural activity and behavioral performance in healthy volunteers. In addition, TMS is increasingly used in clinical practice for treating various neuropsychiatric disorders. Unfortunately, TMS-induced effects show large intra- and inter-subject variability, hindering its reliability, and efficacy. One possible source of this variability may be the spontaneous fluctuations of neuronal oscillations. We present recent studies using multimodal TMS including TMS-EMG (electromyography), TMS-tACS (transcranial alternating current stimulation), and concurrent TMS-EEG-fMRI (electroencephalography, functional magnetic resonance imaging), to evaluate how individual oscillatory brain state affects TMS signal propagation within targeted networks. We demonstrate how the spontaneous oscillatory state at the time of TMS influences both immediate and longer-lasting TMS effects. These findings indicate that at least part of the variability in TMS efficacy may be attributable to the current practice of ignoring (spontaneous) oscillatory fluctuations during TMS. Ignoring this state-dependent spread of activity may cause great individual variability which so far is poorly understood and has proven impossible to control. We therefore also compare two technical solutions to directly account for oscillatory state during TMS, namely, to use (a) tACS to externally control these oscillatory states and then apply TMS at the optimal (controlled) brain state, or (b) oscillatory state-triggered TMS (closed-loop TMS). The described multimodal TMS approaches are paramount for establishing more robust TMS effects, and to allow enhanced control over the individual outcome of TMS interventions aimed at modulating information flow in the brain to achieve desirable changes in cognition, mood, and behavior.

scholarly journals Quantification of the biological age of the brain using neuroimaging

2018 ◽  
Author(s):  
James Cole ◽  
Katja Franke ◽  
Nicolas Cherbuin
Keyword(s):  
Individual Variability ◽  
Biological Age ◽  
Accelerated Ageing ◽  
Exciting Field ◽  
Future Directions ◽  
Brain Ageing ◽  
The Individual ◽  
Behavioural Aspects ◽  
Brain Age ◽  
The Brain

The cosmetic and behavioural aspects of ageing become increasingly apparent with the passing years. The individual variability in physical ageing can be immediately observed in people’s face, posture, voice and gait. In contrast, the pace at which our brains age is less obvious, only becoming apparent once substantial neurodegeneration manifests through cognitive decline and dementia. Therefore, a more timely and precise assessment of brain ageing is needed so its determinants and mechanisms can be more effectively identified and ultimately optimised. This chapter describes new approaches aimed at quantifying the biological age of the brain, so-called ‘brain age’; reviews how brain age can be contrasted to chronological age to index risk of premature brain ageing; and explores how brain age can be used to investigate genetic, environmental, health, and lifestyle factors contributing to accelerated ageing. Particular attention is given to the statistical approaches underpinning brain age, evaluating their validity and limitations. The developing brain-age literature covering diverse populations, all stages of life, health and psychopathology, humans and animals, is critically and comprehensively presented. Finally, gaps in our knowledge and unresolved methodological issues are summarised, alongside proposing future directions and highlighting opportunities for further research in this promising and exciting field.

Fit Vs Faint: Assessing Work Causation in “Idiopathic Fall” Cases

2014 ◽  
Vol 19 (5) ◽  
pp. 3-12
Author(s):  
Lorne Direnfeld ◽  
David B. Torrey ◽  
Jim Black ◽  
LuAnn Haley ◽  
Christopher R. Brigham
Keyword(s):  
Blood Flow ◽  
Electrical Activity ◽  
Loss Of Consciousness ◽  
Brain Electrical Activity ◽  
Medical Terminology ◽  
Scientific Analysis ◽  
Medical Causation ◽  
The Individual ◽  
The Brain ◽  
Current Science

Abstract When an individual falls due to a nonwork-related episode of dizziness, hits their head and sustains injury, do workers’ compensation laws consider such injuries to be compensable? Bearing in mind that each state makes its own laws, the answer depends on what caused the loss of consciousness, and the second asks specifically what happened in the fall that caused the injury? The first question speaks to medical causation, which applies scientific analysis to determine the cause of the problem. The second question addresses legal causation: Under what factual circumstances are injuries of this type potentially covered under the law? Much nuance attends this analysis. The authors discuss idiopathic falls, which in this context means “unique to the individual” as opposed to “of unknown cause,” which is the familiar medical terminology. The article presents three detailed case studies that describe falls that had their genesis in episodes of loss of consciousness, followed by analyses by lawyer or judge authors who address the issue of compensability, including three scenarios from Arizona, California, and Pennsylvania. A medical (scientific) analysis must be thorough and must determine the facts regarding the fall and what occurred: Was the fall due to a fit (eg, a seizure with loss of consciousness attributable to anormal brain electrical activity) or a faint (eg, loss of consciousness attributable to a decrease in blood flow to the brain? The evaluator should be able to fully explain the basis for the conclusions, including references to current science.

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