scholarly journals Investigation, modelling and quantification of the brain response to external stimuli

2010 ◽  
Author(s):  
Seetharaman Karthik
2021 ◽  
Vol 18 (5) ◽  
pp. 051003
Author(s):  
Jimmy Petit ◽  
José Rouillard ◽  
François Cabestaing

Abstract A brain–computer interface (BCI) aims to derive commands from the user’s brain activity in order to relay them to an external device. To do so, it can either detect a spontaneous change in the mental state, in the so-called ‘active’ BCIs, or a transient or sustained change in the brain response to an external stimulation, in ‘reactive’ BCIs. In the latter, external stimuli are perceived by the user through a sensory channel, usually sight or hearing. When the stimulation is sustained and periodical, the brain response reaches an oscillatory steady-state that can be detected rather easily. We focus our attention on electroencephalography-based BCIs (EEG-based BCI) in which a periodical signal, either mechanical or electrical, stimulates the user skin. This type of stimulus elicits a steady-state response of the somatosensory system that can be detected in the recorded EEG. The oscillatory and phase-locked voltage component characterising this response is called a steady-state somatosensory-evoked potential (SSSEP). It has been shown that the amplitude of the SSSEP is modulated by specific mental tasks, for instance when the user focuses their attention or not to the somatosensory stimulation, allowing the translation of this variation into a command. Actually, SSSEP-based BCIs may benefit from straightforward analysis techniques of EEG signals, like reactive BCIs, while allowing self-paced interaction, like active BCIs. In this paper, we present a survey of scientific literature related to EEG-based BCI exploiting SSSEP. Firstly, we endeavour to describe the main characteristics of SSSEPs and the calibration techniques that allow the tuning of stimulation in order to maximise their amplitude. Secondly, we present the signal processing and data classification algorithms implemented by authors in order to elaborate commands in their SSSEP-based BCIs, as well as the classification performance that they evaluated on user experiments.


2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Hamidreza Namazi ◽  
Vladimir V. Kulish

Human brain response is the result of the overall ability of the brain in analyzing different internal and external stimuli and thus making the proper decisions. During the last decades scientists have discovered more about this phenomenon and proposed some models based on computational, biological, or neuropsychological methods. Despite some advances in studies related to this area of the brain research, there were fewer efforts which have been done on the mathematical modeling of the human brain response to external stimuli. This research is devoted to the modeling and prediction of the human EEG signal, as an alert state of overall human brain activity monitoring, upon receiving external stimuli, based on fractional diffusion equations. The results of this modeling show very good agreement with the real human EEG signal and thus this model can be used for many types of applications such as prediction of seizure onset in patient with epilepsy.


Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 286
Author(s):  
Soheil Keshmiri

Recent decades have witnessed a substantial progress in the utilization of brain activity for the identification of stress digital markers. In particular, the success of entropic measures for this purpose is very appealing, considering (1) their suitability for capturing both linear and non-linear characteristics of brain activity recordings and (2) their direct association with the brain signal variability. These findings rely on external stimuli to induce the brain stress response. On the other hand, research suggests that the use of different types of experimentally induced psychological and physical stressors could potentially yield differential impacts on the brain response to stress and therefore should be dissociated from more general patterns. The present study takes a step toward addressing this issue by introducing conditional entropy (CE) as a potential electroencephalography (EEG)-based resting-state digital marker of stress. For this purpose, we use the resting-state multi-channel EEG recordings of 20 individuals whose responses to stress-related questionnaires show significantly higher and lower level of stress. Through the application of representational similarity analysis (RSA) and K-nearest-neighbor (KNN) classification, we verify the potential that the use of CE can offer to the solution concept of finding an effective digital marker for stress.


Author(s):  
M. S. Chafi ◽  
V. Dirisala ◽  
G. Karami ◽  
M. Ziejewski

In the central nervous system, the subarachnoid space is the interval between the arachnoid membrane and the pia mater. It is filled with a clear, watery liquid called cerebrospinal fluid (CSF). The CSF buffers the brain against mechanical shocks and creates buoyancy to protect it from the forces of gravity. The relative motion of the brain due to a simultaneous loading is caused because the skull and brain have different densities and the CSF surrounds the brain. The impact experiments are usually carried out on cadavers with no CSF included because of the autolysis. Even in the cadaveric head impact experiments by Hardy et al. [1], where the specimens are repressurized using artificial CSF, this is not known how far this can replicate the real functionality of CSF. With such motivation, a special interest lies on how to model this feature in a finite element (FE) modeling of the human head because it is questionable if one uses in vivo CSF properties (i.e. bulk modulus of 2.19 GPa) to validate a FE human head against cadaveric experimental data.


2021 ◽  
Author(s):  
Tatsuya Osaki ◽  
Yoshiho Ikeuchi

AbstractMacroscopic axonal connections in the human brain distribute information and neuronal activity across the brain. Although this complexity previously hindered elucidation of functional connectivity mechanisms, brain organoid technologies have recently provided novel avenues to investigate human brain function by constructing small segments of the brain in vitro. Here, we describe the neural activity of human cerebral organoids reciprocally connected by a bundle of axons. Compared to conventional organoids, connected organoids produced significantly more intense and complex oscillatory activity. Optogenetic manipulations revealed that the connected organoids could re-play and recapitulate over time temporal patterns found in external stimuli, indicating that the connected organoids were able to form and retain temporal memories. Our findings suggest that connected organoids may serve as powerful tools for investigating the roles of macroscopic circuits in the human brain – allowing researchers to dissect cellular functions in three-dimensional in vitro nervous system models in unprecedented ways.


2020 ◽  
Author(s):  
Katja Junttila ◽  
Anna-Riikka Smolander ◽  
Reima Karhila ◽  
Anastasia Giannakopoulou ◽  
Maria Uther ◽  
...  

Learning is increasingly assisted by technology. Digital games may be useful for learning, especially in children. However, more research is needed to understand the factors that induce gaming benefits to cognition. In this study, we investigated the effectiveness of digital game-based learning approach in children by comparing the learning of foreign speech sounds and words in a digital game or a non-game digital application with equal amount of exposure and practice. To evaluate gaming-induced plastic changes in the brain function, we used the mismatch negativity (MMN) brain response that reflects the activation of long-term memory representations for speech sounds and words. We recorded auditory event-related potentials (ERPs) from 37 school-aged Finnish-speaking children before and after playing the “Say it again, kid!” (SIAK) language-learning game where they explored game boards, produced English words aloud, and got stars as feedback from an automatic speech recognizer to proceed in the game. The learning of foreign speech sounds and words was compared in two conditions embedded in the game: a game condition and a non-game condition with the same speech production task but lacking visual game elements and feedback. The MMN amplitude increased between the pre-measurement and the post-measurement for the word trained with the game but not for the word trained with the non-game condition, suggesting that the gaming intervention enhanced learning more than the non-game intervention. The results indicate that digital game-based learning can be beneficial for children’s language learning and that gaming elements per se, not just practise time, support learning.


2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Chuanfu Li ◽  
Jun Yang ◽  
Jinbo Sun ◽  
Chunsheng Xu ◽  
Yuanqiang Zhu ◽  
...  

In recent years, neuroimaging studies of acupuncture have explored extensive aspects of brain responses to acupuncture in finding its underlying mechanisms. Most of these studies have been performed on healthy adults. Only a few studies have been performed on patients with diseases. Brain responses to acupuncture in patients with the same disease at different pathological stages have not been explored, although it may be more important and helpful in uncovering its underlying mechanisms. In the present study, we used fMRI to compare brain responses to acupuncture in patients with Bell’s palsy at different pathological stages with normal controls and found that the brain response to acupuncture varied at different pathological stages of Bell’s palsy. The brain response to acupuncture decreased in the early stages, increased in the later stages, and nearly returned to normal in the recovered group. All of the changes in the brain response to acupuncture could be explained as resulting from the changes in the brain functional status. Therefore, we proposed that the brain response to acupuncture is dependent on the brain functional status, while further investigation is needed to provide more evidence in support of this proposition.


PEDIATRICS ◽  
1951 ◽  
Vol 7 (2) ◽  
pp. 269-293
Author(s):  
CHARLES C. CHAPPLE

A study has been made of the known phenomena which affect the biologic organism. Certain correlations have been found and other correlations are logically inferred. The common grounds of anatomic structures, the anatomic responses to endocrine stimuli, the interrelationships and interdependencies of the endocrines and external stimuli have been followed and have been related to cellular permeability and hyaluronic acid. Cellular phases, including the rhythmic alternations in physiologic functions, have been delineated and their importance stressed. Further, the probability is advanced that this rhythmicity originates physiologically in the brain but that the brain itself is capable of receiving transmissions from within and without the body, and disseminating them, again rhythmically, in normal or altered amplitude and frequency. Further experimental evidence of these correlations and their practical extrapolations into drug actions and the therapy of infections and metabolic disease will be reported and will include clinical, animal and in vitro studies. At present, the following conclusions seem justified: 1. No component of the body is capable of independent action. 2. Action in any component is reflected, according to its magnitude and directness of application, upon all the body. 3. All such actions are mediated by the brain. 4. There is a dynamic, rhythmic cyclicity in physiologic action which can be altered in amplitude and frequency. 5. These rhythms are alternations of cellular tenseness and relaxation. 6. The concomitants of the tense phase are compactness, impermeability, electric conductivity and contraction of all cells, and these characteristics might be described collectively as the factors operative in maturing the cell. The concomitants of the relaxed phase are laxness, permeability, electric resistance and expansion of all cells and are factors of growth. 7. The phase of tenseness is accompanied by an increase in certain hormonal activities and that of relaxation by an increase in others. 8. The hormones may be causes of the phase or the results of it. 9. Infectious disease cannot act as an extraneous agent capable of bringing its own engine into such a highly integrated mechanism but must act on the body through its ability to affect one of the body's mechanisms. 10. Drugs must act through the same channels available to disease. 11. Foods may contain, in addition to their caloric content, components capable of stimulating either the phase of cellular expansion or cellular compaction, particularly foods from the reproductive systems of plants or animals (milk, eggs, cereal, for example). 12. Vitamins each stimulate one phase and should be evaluated in terms of positive actions. 13. Inherent growth and maturation factors are not of fixed capacity in an individual but beyond certain limits must be supplied him or applied to him constantly. 14. The hormone most manifest in the tense phase is estrogen and so may be considered the maturation factor, and the one most manifest in the phase of relaxation or cell division is progesterone, which may be considered the growth factor.


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