Peculiarities of interrelations of activation levels of frontal,temporal, and parietal cortex by parameters of ultraslow biopotentials in the 4–5-year-old children with the age norm and delayed speech development

Possibilities were considered of the integrative approach with use of parameters of the ultraslow informational-control brain and organism system in studying physiological grounds of the rest state, which determine structure and quality of the adaptive behavior. By using the proposal approach there were analyzed results of comparative studies of peculiarities of the wakefulness level, of its autonomous, hemodynamic, and oxygen-depended energy maintenance, and of activation levels and their interrelations in neocortical outputs of the brain systems of the frontal, temporal-parietal, and parietal cortex participating in organization of the higher integrative functions and speech in the 4–7-year-old children with the age norm of the general psychic and verbal development and with delay of the neuropsychic development, including development of speech.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 455–468.Original Russian Text Copyright © 2004 by Ilyukhina, Krivoshchapova, Matveev, Ponomareva, Shaptilei.To the 100-Anniversary of N. N. Traugott     

Peculiarities of individually oriented hearing prosthetics in rehabilitation at limited auditory possibilities

A new method is proposed for evaluation of correction of impairments of hearing with the help of hearing aids allowing detection of the dependence of speech formation on limitations of auditory possibilities, particularly of the labyrinth origin. The method permits revealing inadequacy of hearing prosthetics, considering its possible causes, and proposing ways of elimination.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 476–480.Original Russian Text Copyright © 2004 by Tsirulnikov, Vartanyan, Boitsova.To the 100-Anniversary of N. N. Traugott     

Significance of functional interactions for understanding of cerebral mechanisms of speech disturbances in children

The problems are considered of cerebral mechanisms of the main types of speech pathology developed in children in disturbances of interzonal interactions.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 407–410.Original Russian Text Copyright © 2004 by Vizel.To the 100-Anniversary of N. N. Traugott     

<Emphasis Type="Italic">Homo loquens</Emphasis>: Evolution of cerebral functions and language

The paper reviews the state of the problem of evolution of language and brain. Various points of view are considered: nativism and connectionism, principle of modular organization of the higher psychic functions including language, and that of organization of all functions on the basis of the network and associative principle. There is also considered the justifiability of the idea of macromutation that has resulted in the appearance of language and a series of micromutations that have led to the same. Also considered are specific verbal disturbances including genetic ones.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 400–406.Original Russian Text Copyright © 2004 by Chernigovskaya.To the 100-Anniversary of N. N. Traugott     

Formation of interzonal interaction of cortical fields during verbal-mental activity

Verbal activity as the higher psychic brain function is performed as a result of systemic interactions of many cerebral structures and processes at various levels of organization. It is shown in this work that based on analysis of spatial-temporal relations of EEG waves during performance by adult examinees of such verbal-mnestic tasks as mental count, listening of a rhyme and its recalling, tests for verbal fluency, and search for homonyms there is revealed an enhancement of diagonal connections between activities of posterior parts of the left hemisphere cortex and anterior parts of the right hemisphere cortex. During performance by the examinees of recognition of grammatical or semantic errors in sentences the interhemispheric interactions on the whole are also enhanced statistically significantly, but without domination of diagonal interactions. These data show that during performance by examinees of verbal tasks of analytical character there also are simultaneously actualized intercentral interactions related to the functional system responsible for recognition not only of verbal, but also of any other stimuli. In children with motor alalia and dysarthria, disturbances of distant EEG connections were revealed either in the left or in the right hemisphere with a simultaneous enhancement of ipsilateral interactions in symmetrical parts of the contralateral hemisphere. A special attention is paid to significance of the degree of formation of neurophysiological systems of the general cerebral integration for realization of the verbal function.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 411–422.Original Russian Text Copyright © 2004 by Shepovalnikov, Tsitseroshin.To the 100-Anniversary of N. N. Traugott     

Ivan Mikhailovich Sechenov—the outstanding russian neurophysiologist and psychophysiologist

Contribution of the outstanding russian physiologist Ivan Mikhailovich Sechenov to establishment and development of neurophysiology and psychophysiology is considered. Analysis is presented of I.M. Sechenovs fundamental discoveries that laid foundation of the modern neurophysiology. Logic of formation of his objective physiological approach to analysis of psychic phenomena is followed. It is shown that I.M. Sechenov was the first psychophysiologist to approach analysis of human from systemic positions by considering reflex as a morpho-functional system that operates with signals from environment for the purpose of achievement of an expedient result.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 481–485.Original Russian Text Copyright © 2004 by Kanunikov.To the 175-Anniversary of I.M. Sechenov     

Peculiarities of formation of the cognitive functions in junior school children with different maturity of regulatory brain systems

To reveal the specific role of maturation of modulating, regulatory brain systems in formation of cognitive processes at the junior school age, was performed a complex electroencephalographic and neuropsychological examination of the 7–8-year-old children with different degrees of functional maturity of the regulatory systems. It has been shown that an essential factor determining formation of the higher psychic functions (HPF) at the junior school age is maturation of the fronto-thalamic system. Immaturity of this system in the 7–8-year-old children leads to a deficiency of functions of programming, regulation, and control of the activity. The most substantial changes were revealed for the components of the voluntary organization of the activity, which are connected with its selectivity both in realization of current tasks and in creation of the activity strategy. The deficiency of processes of voluntary regulation in the 7–8-year-old children with immaturity of the fronto-thalamic system is combined with a delay of development of the meaning-forming speech function. Comparison of data of the neuropsychological and electroencephalographic examination has permitted suggesting that the basis of the revealed changes in the HPF formation in the 7–8-year-old children is immaturity of the main neurophysiological mechanisms that provide a selective involvement of different cortical regions in providing their activity both in the course of its realization and during preparation to it as well as an under-development of differentiated intracortical connections in the left hemisphere.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 427–435.Original Russian Text Copyright © 2004 by Machinskaya, Semenova.To the 100-Anniversary of N. N. Traugott     

Contribution of L. Ya. Balonov and V. L. Deglin to Study of Verbal-Thinking Activity from the Viewpoint of Functional Brain Asymmetry

This paper summarized experimental data on the role of the right and left brain hemispheres in performance of the verbal and thinking activity, which were obtained by Lev Yakovlevich Balonov and Vadim L'vovich Deglin and published in numerous articles and monographs. The interpretation of these results, the concepts of Balonov and Deglin on regularities underlying division of functions between two hemispheres and on mechanisms of the hemispheric interaction are presented. The original concept is exposed, which consists in that the functional brain asymmetry is based on different relation of the right and left hemispheres to the language sign, its different vision and perception by each hemisphere. The data of study on the functional brain asymmetry also helped the authors to find answers to the questions concerning general scientific and general human problems dealing with the conscious and the unconscious, speech development in child, evolution of psychic activity. The authors understood clearly that the answers to these questions ...by no means will be exhaustive... and that ...this is merely one of possible points of view.     

Human perception of acoustic models of spatial sound translocation on the background of hearing and production of verbal signals (ontogenetic aspect)

Studied in the work was human perception of acoustic signals changing in amplitude on the background of production and hearing of syllables composed, from the ontogenetic viewpoint, of the earliest and the latest consonants and vowels —[pa] and [ly], as well as on the background of noise. It was shown that on the background of the syllable pronunciation their recognition occurred at the same rate; however, the number of mistakes with the syllable [ly] was statistically significantly greater than with the syllable [pa]. According to the data of paired comparison and dispersion analysis the differences at recognition of external stimuli on the background of: hearing [pa] — pronunciation [ly]; hearing [ly] — pronunciation [pa]; hearing [ly] — pronunciation [ly] are statistically significant. The most difficult task turned out to be the task of signal recognition on the background of isolated articulation, i.e., reproduction without voice. When evaluating sound stimuli on the background of noise, the correctness of signal recognition was more affected by masking as compared to the time of reaction. The results of signal perception on the background of the wideband noise differ qualitatively and quantitatively from the data of recognition both at intensive verbal activity and at passive hearing of speech.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 423–426.Original Russian Text Copyright © 2004 by Vartanyan, Tokareva, Lange.To the 100-Anniversary of N. N. Traugott     

Neurophysiological Characteristics of Compensatory Brain Processes in Rehabilitation of Impairments of the Visual and Acoustic Systems

Compensatory rehabilitative reorganization of brain functions upon medical modulating electric treatment directed at afferent inputs of the impaired visual or acoustic systems is considered. General and specific characteristics of the reorganization of brain functioning aimed at compensating visual or hearing defects were revealed by estimating the electroencephalogram (EEG) dynamics and evoked potentials (EP). Electrographic correlates of the transitory and compensated states of the brain in rehabilitation of the disturbed sensory functions were established. Short-term functional structures sharing , , and synchronization patterns were revealed. These structures reflect sequential participation of specific and nonspecific brain systems in the reorganization of brain functioning. Specific interactions between the damaged and the intact sensory systems were found, which indicated common nonspecific mechanisms for processing acoustic and visual afference. The existence of a programmed central mechanism that compensates the disturbed functions of the sensory systems is suggested.     

Perceptual Learning of Interrupted Speech

The intelligibility of periodically interrupted speech improves once the silent gaps are filled with noise bursts. This improvement has been attributed to phonemic restoration, a top-down repair mechanism that helps intelligibility of degraded speech in daily life. Two hypotheses were investigated using perceptual learning of interrupted speech. If different cognitive processes played a role in restoring interrupted speech with and without filler noise, the two forms of speech would be learned at different rates and with different perceived mental effort. If the restoration benefit were an artificial outcome of using the ecologically invalid stimulus of speech with silent gaps, this benefit would diminish with training. Two groups of normal-hearing listeners were trained, one with interrupted sentences with the filler noise, and the other without. Feedback was provided with the auditory playback of the unprocessed and processed sentences, as well as the visual display of the sentence text. Training increased the overall performance significantly, however restoration benefit did not diminish. The increase in intelligibility and the decrease in perceived mental effort were relatively similar between the groups, implying similar cognitive mechanisms for the restoration of the two types of interruptions. Training effects were generalizable, as both groups improved their performance also with the other form of speech than that they were trained with, and retainable. Due to null results and relatively small number of participants (10 per group), further research is needed to more confidently draw conclusions. Nevertheless, training with interrupted speech seems to be effective, stimulating participants to more actively and efficiently use the top-down restoration. This finding further implies the potential of this training approach as a rehabilitative tool for hearing-impaired/elderly populations.     

Chronic nitrate additions dramatically increase the export of carbon and nitrogen from northern hardwood ecosystems

A long-term field experiment was initiated to simulate chronic atmospheric N deposition, a widespread phenomenon in industrial regions of the world. Eight years of experimental nitrate ( ) additions (3 g -N m^–2 per year) to four different northern hardwood forests located along a 500 km geographic gradient dramatically increased leaching losses of -N, dissolved organic carbon (DOC), and dissolved organic nitrogen (DON). During the last two water years, the average increase in solution -N and DON leaching from the -amended plots was 2.2 g N m^–2, equivalent to 72% of the annual experimental N addition. Results indicate that atmospheric N deposition may rapidly saturate some northern hardwood ecosystems across an entire biome in the upper Great Lakes Region of the USA. Changes in soil C and N cycling induced by chronic N deposition have the potential in this landscape to significantly alter the flux of DOC and DON from upland to aquatic ecosystems. Michigan Gradient study site characteristics are similar to those of European forests most susceptible to N saturation.     

Cognitive-motor brain–machine interfaces

Brain–machine interfaces (BMIs) open new horizons for the treatment of paralyzed persons, giving hope for the artificial restoration of lost physiological functions. Whereas BMI development has mainly focused on motor rehabilitation, recent studies have suggested that higher cognitive functions can also be deciphered from brain activity, bypassing low level planning and execution functions, and replacing them by computer-controlled effectors. This review describes the new generation of cognitive-motor BMIs, focusing on three BMI types:

• 1.Speech BMI – reconstructing a person’s speech based on the neuronal activity.
• 2.Direct object control – controlling object movement without mimicking the limb movement that would yield the desired object movement.
• 3.Decoding internal processes, such as neuronal representations of sensory information and decision making.

By outlining recent progress in developing these BMI types, we aim to provide a unified view of contemporary research towards the replacement of behavioral outputs of cognitive processes by direct interaction with the brain.     

Peculiarities of brain mechanisms of regulation of level of wakefulness and of cognitive activity in children with retardation of psychic development and in healthy children of the same age

The work opens possibilities of the of modifications of the developed at the Laboratory systemic-integrative psychophysiological approach to study of the age-related organization or of deviation from norm in formation of superslow informational-controlling brain systems participating in mechanisms of regulation of the wakefulness level and of cognitive activity in the 5–7-year old healthy children and in children of the same age group with retardation of psychic and speech development of the cerebral-organic genesis. There are disclosed peculiarities of organization of: (a) cortical-brainstem and limbic-reticular mechanisms of regulation of the level of wakefulness; (b) suprasegmentary mechanisms of autonomic, hemodynamic, and oxygen-dependent energy supply of the wakefulness level in the examined children’s contingent. There are substantiated concepts about interrelations of peculiarities of the level of actual development of emotional and cognitive spheres with age-related peculiarities or disturbances of formation of mechanisms of regulation of the wakefulness level, its autonomic and hemodynamic provision as well as of the oxygen-dependent energetic potential.     

Multiform wave organization of neurophysiological processes-universal “language” of human brain in realization of informational-controlling functions

The paper summarizes literature data and results of many-year Laboratory studies disclosing principles of the multiform spatial-time organization of differing by rates of neurophysiologic brain processes as the universal “language” of its informational-controlling functions. There are considered current concepts of electrogenesis and physiological significance of ratios of gradual changes of biopotentials and impulse activity of neurons considered in studies of cerebral mechanisms of regulation of normal and pathological states, and organization of human psychic activity. Put forward and argumented are concepts of the probability principle of hierarchical organization of differing by rates of neurophysiologic processes brain zones, structures, and areas in formation of the brain systems participating in provision of the higher psychic functions and states. It is proposed to discuss the concept of the brain as the “swimming,” many-contour, neurodynamic informational-controlling suprasystem with universal, hierarchically organized neurodynamic structures—”functional organs” by A.A. Ukhtomskii (1978), of which formation provides large informational brain capacity and a wide specter of adaptive possibilities of the human organism.     

Brain Training Game Boosts Executive Functions,Working Memory and Processing Speed in the Young Adults: A Randomized Controlled Trial

Background

Do brain training games work? The beneficial effects of brain training games are expected to transfer to other cognitive functions. Yet in all honesty, beneficial transfer effects of the commercial brain training games in young adults have little scientific basis. Here we investigated the impact of the brain training game (Brain Age) on a wide range of cognitive functions in young adults.

Methods

We conducted a double-blind (de facto masking) randomized controlled trial using a popular brain training game (Brain Age) and a popular puzzle game (Tetris). Thirty-two volunteers were recruited through an advertisement in the local newspaper and randomly assigned to either of two game groups (Brain Age, Tetris). Participants in both the Brain Age and the Tetris groups played their game for about 15 minutes per day, at least 5 days per week, for 4 weeks. Measures of the cognitive functions were conducted before and after training. Measures of the cognitive functions fell into eight categories (fluid intelligence, executive function, working memory, short-term memory, attention, processing speed, visual ability, and reading ability).

Results and Discussion

Our results showed that commercial brain training game improves executive functions, working memory, and processing speed in young adults. Moreover, the popular puzzle game can engender improvement attention and visuo-spatial ability compared to playing the brain training game. The present study showed the scientific evidence which the brain training game had the beneficial effects on cognitive functions (executive functions, working memory and processing speed) in the healthy young adults.

Conclusions

Our results do not indicate that everyone should play brain training games. However, the commercial brain training game might be a simple and convenient means to improve some cognitive functions. We believe that our findings are highly relevant to applications in educational and clinical fields.

Trial Registration

UMIN Clinical Trial Registry 000005618.     

Molecular Mechanisms of Actions of Interleukin-6 on the Brain,with Special Reference to Serotonin and the Hypothalamo-Pituitary-Adrenocortical Axis

Biological activities of the multifunctional cytokine, interleukin-6 (IL-6) include stimulation of B cell proliferation, immunoglobulin production, and initiation of the acute-phase response. IL-6 affects the CNS in that it activates the hypothalamo-pituitary-adrenocortical (HPA) axis and increases brain tryptophan and serotonin metabolism. IL-6 has been proposed as an important mediator of interaction between the neuroendocrine and immune systems. The peripheral and central effects of IL-6 are presumably mediated through its membrane receptor (IL-6R). IL-6, IL-6R and their respective mRNAs have been detected in several brain regions. Although the functions of cytokines overlap considerably, each displays its own characteristic properties. Expression of IL-6 in the brain has been observed in several CNS disorders, some of which have been associated with disorders of serotonin metabolism. It is proposed that interactions between IL-6 and brain serotonin is a complex process which involves corticotropin-releasing factor (CRF) and opioid peptides. It is likely that the molecular mechanisms underlying the actions of IL-6 on the HPA axis and its other brain functions involve the integrated effects of glutamate, Ca²⁺, 3,5-cyclic AMP, protein kinase C, and other metabolic pathways.     

Image-driven modeling of the proliferation and necrosis of glioblastoma multiforme

Background

The heterogeneity of response to treatment in patients with glioblastoma multiforme suggests that the optimal therapeutic approach incorporates an individualized assessment of expected lesion progression. In this work, we develop a novel computational model for the proliferation and necrosis of glioblastoma multiforme.

Methods

The model parameters are selected based on the magnetic resonance imaging features of each tumor, and the proposed technique accounts for intrinsic cell division, tumor cell migration along white matter tracts, as well as central tumor necrosis. As a validation of this approach, tumor growth is simulated in the brain of a healthy adult volunteer using parameters derived from the imaging of a patient with glioblastoma multiforme. A mutual information metric is calculated between the simulated tumor profile and observed tumor.

Results

The tumor progression profile generated by the proposed model is compared with those produced by existing models and with the actual observed tumor progression. Both qualitative and quantitative analyses show that the model introduced in this work replicates the observed progression of glioblastoma more accurately relative to prior techniques.

Conclusions

This image-driven model generates improved tumor progression profiles and may contribute to the development of more reliable prognostic estimates in patients with glioblastoma multiforme.

     

Regulation of mineral nitrogen uptake in plants

In the biosphere plants are exposed to different forms of N, which comprise mineral and organic N forms in soils as well as gaseous NH3, NOx, and molecular N2 in the atmosphere. The form of N uptake is mainly determined by its abundance and accessibility, which make and the most important N forms for plant nutrition under agricultural conditions. With minor importance, the form of N uptake is also subject to plant preferences, by which plants maintain their cation/anion balance during uptake. However, some species seem to have an obligatory preference which even prevents their growth on certain other N sources. In general, uptake of a certain N form closely matches the growth-related demand of the plant, at least when N transport to the root surface is not limiting. In addition, many plants accumulate large pools of N during vegetative growth which are remobilized in the generative stage. As a consequence, systems responsible for N transport need to be tightly regulated in their expression and activity upon sensing N availability and plant demand. Employing the tools of molecular genetics, the first plant genes encoding transporters for inorganic N have recently been isolated and characterized. These data can now complete the wealth of physiological and nutritional studies on N uptake. The present article will focus on the uptake of and into root cells and tries to link data derived from physiological, genetic and molecular studies.     

Continued Evolution of H5N1 Influenza Viruses in Wild Birds,Domestic Poultry,and Humans in China from 2004 to 2009

Despite substantial efforts to control H5N1 avian influenza viruses (AIVs), the viruses have continued to evolve and cause disease outbreaks in poultry and infections in humans. In this report, we analyzed 51 representative H5N1 AIVs isolated from domestic poultry, wild birds, and humans in China during 2004 to 2009, and 21 genotypes were detected based on whole-genome sequences. Twelve genotypes of AIVs in southern China bear similar H5 hemagglutinin (HA) genes (clade 2.3). These AIVs did not display antigenic drift and could be completely protected against by the A/goose/Guangdong/1/96 (GS/GD/1/96)-based oil-adjuvanted killed vaccine and recombinant Newcastle disease virus vaccine, which have been used in China. In addition, antigenically drifted H5N1 viruses, represented by A/chicken/Shanxi/2/06 (CK/SX/2/06), were detected in chickens from several provinces in northern China. The CK/SX/2/06-like viruses are reassortants with newly emerged HA, NA, and PB1 genes that could not be protected against by the GS/GD/1/96-based vaccines. These viruses also reacted poorly with antisera generated from clade 2.2 and 2.3 viruses. The majority of the viruses isolated from southern China were lethal in mice and ducks, while the CK/SX/2/06-like viruses caused mild disease in mice and could not replicate in ducks. Our results demonstrate that the H5N1 AIVs circulating in nature have complex biological characteristics and pose a continued challenge for disease control and pandemic preparedness.The highly pathogenic H5N1 influenza viruses that emerged over a decade ago in southern China have evolved into over 10 distinct phylogenetic clades based on their hemagglutinin (HA) genes. The viruses have spread to over 63 countries and to multiple mammalian species, including humans, resulting in 498 cases of infection and 294 deaths by 6 May 2010 according to the World Health Organization (WHO) (http://www.who.int). To date, none of the different H5N1 clades has acquired the ability to consistently transmit among mammalian species. The currently circulating H5N1 viruses are unique in that they continue to circulate in avian species. All previous highly pathogenic H5 and H7 viruses have naturally “burned out” or were stamped out because of their high pathogenicity in domestic poultry. While there is growing complacency about the potential of H5N1 “bird flu” to attain consistent transmissibility in humans and develop pandemicity, it is worth remembering that we have no knowledge of the time that it took the 1918 Spanish, the 1957 Asian, the 1968 Hong Kong, and the 2009 North American pandemics to develop their pandemic potentials. We may therefore currently be witnessing in real time the evolution of an H5N1 pandemic influenza virus.H5N1 avian influenza viruses (AIVs) were first detected in sick geese in Guangdong province in 1996, and both nonpathogenic and highly pathogenic (HP) H5N1 viruses were described (18). In 1997, H5N1 reassortant viruses that derived the HA gene from A/goose/Guangdong/1/96 (GS/GD/1/96)-like viruses and the other genes from H6N1 and/or H9N2 viruses caused lethal outbreaks in poultry and humans in Hong Kong (6, 7). Since then, long-term active surveillance of influenza viruses in domestic poultry has been performed, and multiple subtypes of influenza viruses have been detected in chickens and ducks in China (16, 19, 37). H5N1 influenza viruses have been repeatedly detected in apparently healthy ducks in southern China since 1999 (4, 13) and were also detected in pigs in Fujian province in 2001 and 2003 (39).Since the beginning of 2004, there have been significant outbreaks of H5N1 avian influenza virus infection involving multiple poultry farm flocks in more than 20 provinces in China (2). H5N1 viruses resulted in the deaths of millions of domestic poultry, including chickens, ducks, and geese, as the result of infection or of culling and the deaths of thousands of wild birds (5, 20). Thirty-eight human cases of HP H5N1 infection with 25 fatalities have been associated with direct exposure to infected poultry (WHO; http://www.who.int). Since 2004, the vaccination of domestic poultry has been used for the control of HP H5N1 influenza virus in China. While this strategy has been effective at reducing the incidence of HP H5N1 in poultry and at markedly reducing the number of human cases, it is impossible to vaccinate every single bird due to the enormous poultry population. Outbreaks of H5N1 influenza virus still continue to occur in poultry although at a reduced frequency.A previous study by Smith et al. reported that a “Fujian-like” H5N1 influenza virus emerged in late 2005 and predominated in poultry in southern China (26). Those authors suggested that vaccination may have facilitated the selection of the “Fujian-like” sublineage. Here, we analyzed 51 representative H5N1 viruses that were isolated from wild birds, domestic poultry, and humans from 2004 to 2009 in China and described their genetic evolution and antigenicity profiles. Our results indicate that H5N1 influenza viruses in southern China, including the “Fujian-like” viruses, are complicated reassortants, which could be well protected against by GS/GD/1/96 virus-based vaccines. We documented the emergence of the latest variant of H5N1 (A/chicken/Shanxi/2/06 [CK/SX/2/06]) that broke through existing poultry vaccines. We show that this variant is less pathogenic in mice and ducks than the earlier strains and propose that the variant was not selected by the use of vaccines.