Physiology of Astroglia.

Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.

Relationships between higher-level functional capacity and dental health behaviors in community-dwelling older adults.

OBJECTIVE: The aim of the present study was to elucidate relationships between higher-level functional capacity and dental health behaviours in community-dwelling older adults. BACKGROUND: In ageing society, it is necessary to promote oral health in the elderly, because good oral health is a significant contributing factor to good general health. Higher-level functional capacity has been considered a crucial factor for successful independent living in the elderly. We hypothesised that functional capacity is a significant indicator of dental health behaviours. METHODS: Three hundred and thirty-eight adults aged 65 years or older were enrolled in this study. Higher-level functional capacity was evaluated using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-index). Univariate and multivariate models were constructed with dental health behaviours, such as regular visits to a dentist, brushing frequency and use of extra cleaning devices, as the dependent variable, and the total TMIG-index score and its subcategory scores as the principal independent variable. RESULTS: Univariate logistic regression analysis demonstrated a significant correlation between low TMIG-index and 'intellectual activity' subcategory scores to lack of regular visits to a dentist and not using extra cleaning devices. Using a multivariate model, significant relationships remained after adjusting for a number of variables including demographics, medical status, lifestyle and number of remaining teeth. CONCLUSION: Intellectual activity of higher-level functional capacity may be an accurate indicator of dental health behaviours in community-dwelling older adults. Intellectual activity should be taken into consideration to effectively promote oral health behaviours and oral hygiene in elderly persons living independently.

[Hygiene requirements for the level of intellectual intensivity loads in foreign language learning].

The material of this article provides information about the basics of hygiene conditions and nature of intellectual loads of students of secondary schools in the perception of information in a foreign language. Are the most favorable conditions for the successful training of perception and assimilation of information supplied in the course of the learning process in one foreign language or some more different ones? It was found that the process of perception and assimilation of educational information in foreign languages is associated with some degree of mental and emotional stress of students. At the same time, the effectiveness of the learning process depends on the degree of stress. Certain parameters of the psychological and emotional stress students usually have a stimulating effect on their central nervous system. Another level, the psychological and emotional stress of students on the contrary, causes a braking effect of functional activity of the relevant structures of the central nervous system of students and reduces the effectiveness of training.

["Brain reading": achievements, perspectives and ethical problems].

The new trend in brain research designated as brain reading is considered. This research deals with decoding the informational content of the brain processing via its physiological parameters. Such studies are based on rather complicated methods of mathematical analysis. Single records rather than averaged data are used to reveal their content. Three main streams of studies are distinguished, i.e. the object classification, the emotion recognition and brainotyping. Particularly, the studies directed to recognizing the type of thinking via EEG spectra, carried out in the author's laboratory, are reviewed. The possible outcome of the brain reading technique is considered. Finally it is argued that in the future, the broad application of this technique needs to be controlled with some ethical rules.

[Time and space distribution of coincident impulses in closed neural circuits in the sensorimotor cortex of the rabbit (the rhythmical defensive dominanta)].

In the course of analysis of the conjugate unit activity of simultaneously recorded neurons in the sensorimotor cortex of rabbits, 22 closed neural circuits consisting of 3 or 4 neurons were considered. In the model of the defensive dominanta, 1-3 weeks after imposing rhythmic (2 s) activity to a rabbit, the distribution of coincident impulses was analyzed in real time. It was found out that the events when the coincident impulses of neural pairs were generated with two-second intervals could be shifted in time and space over a closed circuit of neurons in one direction. Two-second intervals between the coincident impulses of the neighboring pairs could be conjugate, i.e. the end of one interval in one pair coincided with the beginning of a two-second interval in the next pair. Conjugate intervals of the neighboring neural pairs could promote a pass-through of the information on the stimulus properties over the closed neuronal circuit, thus completing a full cycle. The longest passes-through lasted from 10 and 12 s. Also, more intricate variants of the information transfer were revealed. Thus, not only passes-through of the two- second intervals between the neuronal pairs were observed, but also, coincident impulses repeatedly occurred with this interval in some of the pairs of the circuits. The longest transitions lasted 16 and 22 s.

[The problems of studying the effects of far long-duration space mission factors on the higher nervous activity in model experiments with animals].

The article presents the analysis of difficulty with studying the CNS functional changes caused by ionizing radiations solely and in combination with the other spaceflight factors, and discusses optional methods of modeling the basic elements of operator's work in experiments with animals, primates specifically, as well as of data extrapolation on humans.

[Peculiarities of modifying influence of the factors forming the functional status of the central nervous system on dynamics of the rat higher nervous activity disturbances totally exposed to electron and gamma-radiation at a dose of 100 Gy].

The dynamics of using a stabilized motor defensive conditioned reflex of active avoidance in "shuttle-box" in rats after the total influence of high energy electrons and gamma-rays at a dose of 100 Gy and a modifying influence of the two most important factors forming the functional status of the central nervous system: the stage of the conditioned reflex consolidation and typological peculiarities of the higher nervous activity have been investigated. The influence of both types of ionizing radiation has been shown to cause far more profound disturbances of non consolidated conditioned reflexes in comparison with the automatized conditioned reflexes and provoke an inverted picture of disturbances in the animals with opposed peculiarities of the higher nervous activity. The qualitative picture of the dynamics of disturbances that are caused by these types of radiation is identical. In summary, the studied conditions that form the functional status of the central nervous system determine the nature of neuroradiation syndrome to a greater extent than differences in the effectiveness of these types of radiation.

[Displays of individually-typological features of animals and the person at a choice of strategy of goal-direction behavior].

In work the hypothesis according to which different forms of goal-directed behavior develop depending on the basis of the undervaluation/supervaluation of reinforcement by brain abilities at the conditions of its achievement uncertainty. From these positions such opposite biological characteristics of the subject, as impulsiveness/self-control, care/propensity to risk on which basis there are individually typological features in behavior of the person and animals are considered. In the article, our experimental data on animals and the persons by behavioral techniques and results of last years on research of neural networks of animal cortical and subcortical brain structures depending on the strategy in choice behavior are also analyzed.

[Prognosis of acute encephalopathy].

The prognosis in children with acute encephalopathy who were achieved rehabilitation in our rehabilitation center was presented. Main sequelae was motor disturbance 25%, mental deterioration 90%, higher cortical dysfunction 80% and epilepsy 70%. The patients were divided into 5 groups according to the clinical courses at the onset: cases with metabolic disorders, cases with cytokine storms, cases with status convultics, cases with severe refractory status epilepticus, and cases with the main symptom of decreased consciousness. Typical cases of each group were showed with their brain MRI and single photon emission cerebral tomography (SPECT). In cases with metabolic disorders and cytokine storms, the sequelae were generally severe. In cases with status convulticus, main sequelae was mental deterioration. In cases with severe refractory status epileptics, most contraversial problem was epilepsy. In cases with the main symptom of decreased consciousness, higher cortical dysfunction was the main problem.

Neural reuse: a fundamental organizational principle of the brain.

An emerging class of theories concerning the functional structure of the brain takes the reuse of neural circuitry for various cognitive purposes to be a central organizational principle. According to these theories, it is quite common for neural circuits established for one purpose to be exapted (exploited, recycled, redeployed) during evolution or normal development, and be put to different uses, often without losing their original functions. Neural reuse theories thus differ from the usual understanding of the role of neural plasticity (which is, after all, a kind of reuse) in brain organization along the following lines: According to neural reuse, circuits can continue to acquire new uses after an initial or original function is established; the acquisition of new uses need not involve unusual circumstances such as injury or loss of established function; and the acquisition of a new use need not involve (much) local change to circuit structure (e.g., it might involve only the establishment of functional connections to new neural partners). Thus, neural reuse theories offer a distinct perspective on several topics of general interest, such as: the evolution and development of the brain, including (for instance) the evolutionary-developmental pathway supporting primate tool use and human language; the degree of modularity in brain organization; the degree of localization of cognitive function; and the cortical parcellation problem and the prospects (and proper methods to employ) for function to structure mapping. The idea also has some practical implications in the areas of rehabilitative medicine and machine interface design.

[Modern approaches to human cognitive activity enhancement].

Recent literature on human cognitive activity enhancement is reviewed and summarized. Two classes of pharmacological approaches are picked out, i.e. modern aspects of traditional substance utilization and application of specially developed drugs. Among non-pharmacological approaches a number of psychological, physiological, behavioral and biophysical methods to improve human cognition, memory and learning are analyzed. The most attention is paid to non-drug approaches that utilize bioelectric processes of the individual including characteristics of its brain electrical activity--electroencephalogram (EEG) to enhance different aspects of cognitive functioning. Some promising lines of these investigations are delineated.

Extending the functional cerebral systems theory of emotion to the vestibular modality: a systematic and integrative approach.

Throughout history, vestibular and emotional dysregulation have often manifested together in clinical settings, with little consideration that they may have a common basis. Regarding vestibular mechanisms, the role of brainstem and cerebellar structures has been emphasized in the neurological literature, whereas emotion processing in the cerebral hemispheres has been the focus in psychology. A conceptual model is proposed that links research in the 2 disparate fields by means of a functional cerebral systems framework. The claim is that frontal regions exert regulatory control over posterior systems for sensation and autonomic functions in a dense, interconnected network. Impairment at levels within the system is expected to influence vestibular and cognitive processes depending on the extent of frontal regulatory capacity. M. Kinsbourne's (1980) shared cerebral space model specifies the conditions under which dysfunction of the vestibular modality will influence higher cognitive levels. A position on laterality and associative relations within the right hemisphere is proposed to explain links among dizziness, nausea, and negative emotion.

Provocative and inhibitory effects of a video-EEG neuropsychologic protocol in juvenile myoclonic epilepsy.

PURPOSE: Studies suggest that higher cognitive functions could precipitate seizures in juvenile myoclonic epilepsy (JME). The present study aimed to analyze the effects of higher mental activity on epileptiform discharges and seizures in patients with JME and compare them to those of habitual methods of activation. METHODS: Seventy-six patients with JME (41 female) underwent a video-EEG (electroencephalography) neuropsychologic protocol (VNPP) and habitual methods of activation for 4-6 h. RESULTS: Twenty-nine of the 76 (38.2%) presented provocative effect, and inhibition was seen in 28 of 31 (90.3%). A mixed effect was observed in 11 (35.5%), and 30 patients (39.5%) suffered no effect of VNPP. Action-programming tasks were more effective than thinking in provoking epileptiform discharges (23.7% and 11.0% of patients, respectively, p = 0.03). Inhibitory effect was observed equally in the various categories of tasks, except in mental calculation, which had a higher inhibitory rate. Habitual methods of activation were more effective than VNPP in provoking discharges. Anxiety disorders were diagnosed in 24 of 58 patients (41.4%); anxious patients had greater discharge indexes and no significant inhibitory effect on VNPP. DISCUSSION: Praxis exerted the most remarkable provocative effect, in accordance with the motor circuitry hyperexcitability hypothesis in JME. Inhibitory effect, which had no such task specificity, might be mediated by a widespread cortical-thalamic pathway, possibly involving the parietal cortex. The frequent inhibitory effect found under cortical activation conditions, influenced by the presence of anxiety, supports nonpharmacologic therapeutic interventions in JME.

Emergence of functional hierarchy in a multiple timescale neural network model: a humanoid robot experiment.

It is generally thought that skilled behavior in human beings results from a functional hierarchy of the motor control system, within which reusable motor primitives are flexibly integrated into various sensori-motor sequence patterns. The underlying neural mechanisms governing the way in which continuous sensori-motor flows are segmented into primitives and the way in which series of primitives are integrated into various behavior sequences have, however, not yet been clarified. In earlier studies, this functional hierarchy has been realized through the use of explicit hierarchical structure, with local modules representing motor primitives in the lower level and a higher module representing sequences of primitives switched via additional mechanisms such as gate-selecting. When sequences contain similarities and overlap, however, a conflict arises in such earlier models between generalization and segmentation, induced by this separated modular structure. To address this issue, we propose a different type of neural network model. The current model neither makes use of separate local modules to represent primitives nor introduces explicit hierarchical structure. Rather than forcing architectural hierarchy onto the system, functional hierarchy emerges through a form of self-organization that is based on two distinct types of neurons, each with different time properties ("multiple timescales"). Through the introduction of multiple timescales, continuous sequences of behavior are segmented into reusable primitives, and the primitives, in turn, are flexibly integrated into novel sequences. In experiments, the proposed network model, coordinating the physical body of a humanoid robot through high-dimensional sensori-motor control, also successfully situated itself within a physical environment. Our results suggest that it is not only the spatial connections between neurons but also the timescales of neural activity that act as important mechanisms leading to functional hierarchy in neural systems.

The relations between children's communicative perspective-taking and executive functioning.

Two experiments investigated children's communicative perspective-taking ability. In Experiment 1, 4- to 5-year-old children were tested on two referential communication tasks, as well as on measures of inhibitory control, working memory, and cognitive flexibility. Results document children's emergent use of the perspective of their speaking partner to guide their communicative behaviors in both a production and comprehension task. In Experiment 2, 3- to 4-year-old children used a speaker's perspective to guide their interpretation of instructions. In both experiments, egocentric interpretations of speaker requests were negatively correlated with children's inhibitory control skills. Results of these studies demonstrate that young children can differentiate between information that is accessible to the speaker versus privileged knowledge, and use this information to guide their communicative behaviors. Furthermore, the results suggest that children's inhibitory control skills allow them to inhibit their own perspective, enabling them to make use of their communicative partner's perspective.

Brain mechanisms for predictive control by switching internal models: implications for higher-order cognitive functions.

Humans can guide their actions toward the realization of their intentions. Flexible, rapid and precise realization of intentions and goals relies on the brain learning to control its actions on external objects and to predict the consequences of this control. Neural mechanisms that mimic the input-output properties of our own body and other objects can be used to support prediction and control, and such mechanisms are called internal models. We first summarize functional neuroimaging, behavioral and computational studies of the brain mechanisms related to acquisition, modular organization, and the predictive switching of internal models mainly for tool use. These mechanisms support predictive control and flexible switching of intentional actions. We then review recent studies demonstrating that internal models are crucial for the execution of not only immediate actions but also higher-order cognitive functions, including optimization of behaviors toward long-term goals, social interactions based on prediction of others' actions and mental states, and language processing. These studies suggest that a concept of internal models can consistently explain the neural mechanisms and computational principles needed for fundamental sensorimotor functions as well as higher-order cognitive functions.

[Neuropsychological evaluation as a part of the neurological examination].

A systematic evaluation of cognitive function is an integral part of the neurological examination. Behavioral measures could detect functional impairment that is too subtle to be detected by current neurological procedures. Neuropsychological examination should cover both general and specific cognitive processes. The level of general attention or emotional change may affect variety of cognitive processes. Impairment of a functional system due to a focal cerebral damage results in a specific cognitive dysfunction such as aphasia, apraxia, agnosia, etc. Simplified but systematic methods to assess basic neuropsychological functions are suitable for everyday clinical examination by neurologists. A relatively short form of the cognitive status examination was devised, which covers general attention, language, calculation, praxis, visuospatial ability, directional attention and memory. Not only quantitative but also qualitative assessment of patients' performance would give clinicians valuable clues for the neuronal bases of cognitive functions.