scholarly journals Plasticity versus stability across the human cortical visual connectome

2019 ◽  
Author(s):  
Koen V. Haak ◽  
Christian F. Beckmann

AbstractWhether and how the balance between plasticity and stability varies across the brain is an important open question. Within a processing hierarchy, it is thought that plasticity is increased at higher levels of cortical processing, but direct quantitative comparisons between low- and high-level plasticity have not been made so far. Here, we addressed this issue for the human cortical visual system. By quantifying plasticity as the complement of the heritability of functional connectivity, we demonstrate a non-monotonic relationship between plasticity and hierarchical level, such that plasticity decreases from early to mid-level cortex, and then increases further of the visual hierarchy. This non-monotonic relationship argues against recent theory that the balance between plasticity and stability is governed by the costs of the “coding-catastrophe”, and can be explained by a concurrent decline of short-term adaptation and rise of long-term plasticity up the visual processing hierarchy.

Cephalalgia ◽  
1999 ◽  
Vol 19 (8) ◽  
pp. 718-724 ◽  
Author(s):  
W Wang ◽  
G-P Wang ◽  
X-L Ding ◽  
Y-H Wang

Migraine sufferers potentiate their visual evoked potentials (VEPs) from a short period of 2 min to a longer period of 15 min. As a lack of habituation is linked to higher level arousal, we thus hypothesized that short-term VEP potentiation might be correlated with an arousal-related personality trait. We therefore carried out short-term VEPs, Plutchik-van Praag's Depression Inventory, Zuckerman's Sensation-Seeking Scales (Form V), and Zuckerman-Kuhlman's Personality Questionnaire in 26 healthy subjects, 22 patients suffering from migraine without aura between attacks, 13 episodic and 20 chronic tension-type headaches. The chronic tension-type headache sufferers showed increased depression compared with other groups, which might be a consequence of the headache itself. Migraines, however, showed steeper habituation slopes of N1-P1 and P1-N2, decreased thrill and adventure-seeking, and general sensation-seeking man healthy controls; in addition, the habituation slope of P1-N2 was positively correlated with experience-seeking in migraine. The short-term VEP potentiation and the decreased thrill and adventure-seeking and general sensation-seeking in migraine might be related to a high level of cortical arousal and a low 5HT neurotransmission. In compliance with the long-term VEP study, the positive correlation between the P1-N2 habituation slope and experience-seeking in migraine suggests a continuous metabolic overload for the brain interictally, which can trigger the activation of a migraine attack.


2021 ◽  
Vol 39 (4) ◽  
pp. 1-33
Author(s):  
Fulvio Corno ◽  
Luigi De Russis ◽  
Alberto Monge Roffarello

In the Internet of Things era, users are willing to personalize the joint behavior of their connected entities, i.e., smart devices and online service, by means of trigger-action rules such as “IF the entrance Nest security camera detects a movement, THEN blink the Philips Hue lamp in the kitchen.” Unfortunately, the spread of new supported technologies makes the number of possible combinations between triggers and actions continuously growing, thus motivating the need of assisting users in discovering new rules and functionality, e.g., through recommendation techniques. To this end, we present , a semantic Conversational Search and Recommendation (CSR) system able to suggest pertinent IF-THEN rules that can be easily deployed in different contexts starting from an abstract user’s need. By exploiting a conversational agent, the user can communicate her current personalization intention by specifying a set of functionality at a high level, e.g., to decrease the temperature of a room when she left it. Stemming from this input, implements a semantic recommendation process that takes into account ( a ) the current user’s intention , ( b ) the connected entities owned by the user, and ( c ) the user’s long-term preferences revealed by her profile. If not satisfied with the suggestions, then the user can converse with the system to provide further feedback, i.e., a short-term preference , thus allowing to provide refined recommendations that better align with the original intention. We evaluate by running different offline experiments with simulated users and real-world data. First, we test the recommendation process in different configurations, and we show that recommendation accuracy and similarity with target items increase as the interaction between the algorithm and the user proceeds. Then, we compare with other similar baseline recommender systems. Results are promising and demonstrate the effectiveness of in recommending IF-THEN rules that satisfy the current personalization intention of the user.


10.29007/cfr2 ◽  
2018 ◽  
Author(s):  
Zunoon Parambath ◽  
Nilupa Udawatta

Recession is considered as a major threat to the economy as it slows down economic activities. The property development sector is extremely responsive to these economic conditions. Thus, it is crucial to understand causes, effects and strategies for property developers to survive in a recession without any ill effects. Thus, this research aimed to develop a framework for property developers to identify appropriate survival strategies in recession. A comprehensive literature review was conducted in this research to achieve the above mentioned aim. The results of this study indicated that recession prompts negative impacts on property development sector resulting in unemployment, lower demand, production and revenue, decline in resources and high level of competition. According to the results, the survival strategies were classified into short-term and long-term strategies. The short term strategies include: implementing management tactics, cut down of operating costs, keeping financing lines set up, timely repayment of debts, setting vital new objectives for the future, undertaking shorter time span developments, specialisation in favoured market, renegotiating deals and contracts. The long-term strategies include retrenchment, restructuring, investment and ambidextrous strategies. Similarly, attention should be paid to predict any changes in the economic environment that can influence property development activities and it is necessary to carefully evaluate investment activities to increase sales, profits and market shares of property developers. Preparing for a crisis is doubtlessly the ideal approach as it can facilitate both survival and growth. Thus, the property developers can implement these suggested strategies in their businesses to enhance their practices.


Author(s):  
Valentina Tocchioni ◽  
Alessandra Petrucci ◽  
Alessandra Minello

In the last years, there has been a large increase in high-educated and high-skilled people’s mobility as a consequence of the internationalization and globalization, the weakening of research and university systems of sending countries (the “brain drain” process), the increase in skilled demand and improvements in higher education of host countries (the “brain gain” process). At the micro-level, academic mobility has positive consequences on occupational prospects and careers of researchers, both in the short- and long- run. Nevertheless, numerous research studies have demonstrated the challenges of engaging in international academic mobility for people with caring responsibilities, particularly women. Using Italian data on occupational conditions of PhDs collected in 2018 by Istat and modelling multinomial logistic regression analyses, we intend to verify if female researchers are associated with a lower international mobility irrespective their field of study, and the extent to which gender interacts differently in the various fields of study in affecting the probability of moving abroad after PhD qualification. Also, the distinction between long-term and short-term mobility, which has been mainly neglected in the literature concentrating on longer stays, has taken into account. In this respect, short-term mobility is a potentially high-value investment that may be pursued also by those researchers and scientists who cannot move for longer periods, such as women with caring responsibilities. In the literature, it is acknowledged that an experience abroad during early career may have positive effects on future occupational prospects. With our work, we intend to shed light on potential disparities on moving abroad that may exist among researchers in their early career by gender, and which could contribute to leave behind women in academia.


Meditation refers to a state of mind of relaxation and concentration, where generally the mind and body is at rest. The process of meditation reflects the state of the brain which is distinct from sleep or typical wakeful states of consciousness. Meditative practices usually involve regulation of emotions and monitoring of attention. Over the past decade there has been a tremendous increase in an interest to study the neural mechanisms involved in meditative practices. It could also be beneficial to explore if the effect of meditation is altered by the number of years of meditation practice. Functional Magnetic Resonance Imaging (fMRI) is a very useful imaging technique which can be used to perform this analysis due to its inherent benefits, mainly it being a non-invasive technique. Functional activation and connectivity analysis can be performed on the fMRI data to find the active regions and the connectivity in the brain regions. Functional connectivity is defined as a simple temporal correlation between anatomically separate, active neural regions. Functional connectivity gives the statistical dependencies between regional time series. It is a statistical concept and is quantified using metrics like Correlation. In this study, a comparison is made between functional connectivity in the brain regions of long term meditation practitioners (LTP) and short-term meditation practitioners (STP) to see the differences and similarities in the connectivity patterns. From the analysis, it is evident that in fact there is a difference in connectivity between long term and short term practitioners and hence continuous practice of meditation can have long term effects.


2021 ◽  
Vol 7 (3D) ◽  
pp. 450-457
Author(s):  
Dmitry V. Pashchenko ◽  
Dmitry A. Trokoz ◽  
Alexey I. Martyshkin ◽  
Elena A. Balzannikova

This article discusses one of the main problems of user identification by keyboard handwriting - short-term changes in the keystroke dynamics of users in connection with its psychophysical state, as well as changes over a long time associated with the formation of keystroke dynamics by a new user or when switching to a new device. A method for determining the phase of working capacity by the time characteristics of the keystroke dynamics is proposed.


2020 ◽  
Vol 34 (05) ◽  
pp. 9571-9578 ◽  
Author(s):  
Wei Zhang ◽  
Yue Ying ◽  
Pan Lu ◽  
Hongyuan Zha

Personalized image caption, a natural extension of the standard image caption task, requires to generate brief image descriptions tailored for users' writing style and traits, and is more practical to meet users' real demands. Only a few recent studies shed light on this crucial task and learn static user representations to capture their long-term literal-preference. However, it is insufficient to achieve satisfactory performance due to the intrinsic existence of not only long-term user literal-preference, but also short-term literal-preference which is associated with users' recent states. To bridge this gap, we develop a novel multimodal hierarchical transformer network (MHTN) for personalized image caption in this paper. It learns short-term user literal-preference based on users' recent captions through a short-term user encoder at the low level. And at the high level, the multimodal encoder integrates target image representations with short-term literal-preference, as well as long-term literal-preference learned from user IDs. These two encoders enjoy the advantages of the powerful transformer networks. Extensive experiments on two real datasets show the effectiveness of considering two types of user literal-preference simultaneously and better performance over the state-of-the-art models.


Author(s):  
Н.Б. Панкова

В лекции рассмотрены общие представления об адаптации, основанные на классических работах Г. Селье, Ф.З. Меерсона, Н.А. Агаджаняна, а также особенности адаптивного ответа развивающегося организма. Рассмотрены механизмы срочной адаптации как мобилизации функциональных резервов организма. В качестве одного из механизмов долговременной адаптации представлена эпигенетическая регуляция, которая позволяет выбрать и реализовать программу экспрессии генов - в соответствии с этапом онтогенетического развития, или средовым окружением. В качестве ещё одного механизма долговременной адаптации рассмотрено воздействие на генетический материал. Приведены примеры формирования адаптивного ответа организма на физико-химические и климатогеографические стрессорные факторы. Отдельно проанализированы механизмы адаптивного ответа организма детей на факторы образовательной среды. The lecture addresses general ideas about adaptation based on classic studies by H. Selye, F.Z. Meerson, and N.A. Agadzhanyan and features of the adaptive response in a developing body. Mobilization of the functional reserve is considered as a mechanism of short-term adaptation. Epigenetic regulation is presented as one of mechanisms for long-term adaptation, which allows selecting and implementing a gene expression program consistent with the stage of ontogenetic development or the environment. Another mechanism of long-term adaptation is influence on the genome. The lecture provides examples of adaptation to physicochemical and climatic geographical stress factors. Mechanisms of the adaptive response to factors of the educational environment in children are analyzed separately.


2004 ◽  
Vol 287 (2) ◽  
pp. R465-R471 ◽  
Author(s):  
Richard A. Galbraith ◽  
Ilean Hodgdon ◽  
Michele S. Grimm ◽  
Margaret A. Vizzard

The anorectic cobalt protoporphyrin (CoPP) is known to elicit short-term hypophagia and long-term weight loss through unknown mechanisms in the brains of experimental animals. The goal of this work was to determine 1) if the prolonged duration of action of CoPP is related to its prolonged retention within the brain; and 2) with the use of immunohistochemical detection of Fos, the product of the early-immediate gene c-fos, which cells are activated after exposure to CoPP. These studies were carried out in male rats after intracerebroventricular administration of CoPP, 0.4 μmol/kg body wt, given under light halothane anesthesia. Residence of CoPP in the brain was determined by residual counts in dissected brains of 57CoPP-injected rats. Fos immunoreactivity was mapped in coronal sections of rat brains 4–6 h after injection with CoPP. The results showed that 57CoPP was retained in the hypothalamus preferentially compared with the cortex of the brain and could be detected in the hypothalamus for in excess of 5 wk. Fos activation was increased by CoPP, detected predominantly in neuronal rather than glial cells, and was markedly more robust in the hypothalamus than in other brain areas. Thus CoPP remains in the hypothalamus for prolonged periods and activates Fos expression in the hypothalamus.


SIMULATION ◽  
1964 ◽  
Vol 3 (6) ◽  
pp. 46-51
Author(s):  
W. Ross Adey ◽  
N.V. Findler

It is attempted in this paper to give a mathematical description of the short-term memory. Instead of using the microscopic properties of individual neu rons, such as the number of interconnections, neuron density, threshold value, etc., the cerebral cortex is regarded as a "neuron gas" that is a vast conglomer ate of neurons with statistically distributed charac teristics. Stimuli from the environment cause the receptor neurons to emit virtual electromagnetic waves into the brain. A self-optimizing process of the brain tis sue is here described by which the useful, informa tion-carrying energy reaching the long-term memory tends to maximum. It is emphasized that in the following a brain model is described and the physical processes in volved may have no direct equivalent in reality.


Sign in / Sign up

Export Citation Format

Share Document