Left hemispheric deficit in the sustained neuromagnetic response to periodic click trains in children with ASD.

BACKGROUND: Deficits in perception and production of vocal pitch are often observed in people with autism spectrum disorder (ASD), but the neural basis of these deficits is unknown. In magnetoencephalogram (MEG), spectrally complex periodic sounds trigger two continuous neural responses-the auditory steady state response (ASSR) and the sustained field (SF). It has been shown that the SF in neurotypical individuals is associated with low-level analysis of pitch in the 'pitch processing center' of the Heschl's gyrus. Therefore, alternations in this auditory response may reflect atypical processing of vocal pitch. The SF, however, has never been studied in people with ASD. METHODS: We used MEG and individual brain models to investigate the ASSR and SF evoked by monaural 40 Hz click trains in boys with ASD (N = 35) and neurotypical (NT) boys (N = 35) aged 7-12-years. RESULTS: In agreement with the previous research in adults, the cortical sources of the SF in children were located in the left and right Heschl's gyri, anterolateral to those of the ASSR. In both groups, the SF and ASSR dominated in the right hemisphere and were higher in the hemisphere contralateral to the stimulated ear. The ASSR increased with age in both NT and ASD children and did not differ between the groups. The SF amplitude did not significantly change between the ages of 7 and 12 years. It was moderately attenuated in both hemispheres and was markedly delayed and displaced in the left hemisphere in boys with ASD. The SF delay in participants with ASD was present irrespective of their intelligence level and severity of autism symptoms. LIMITATIONS: We did not test the language abilities of our participants. Therefore, the link between SF and processing of vocal pitch in children with ASD remains speculative. CONCLUSION: Children with ASD demonstrate atypical processing of spectrally complex periodic sound at the level of the core auditory cortex of the left-hemisphere. The observed neural deficit may contribute to speech perception difficulties experienced by children with ASD, including their poor perception and production of linguistic prosody.

Association of SLC6A4 gene 5-HTTLPR polymorphism with parameters of simple and complex reaction times and critical flicker frequency threshold in athletes during exhaustive exercise.

The incidence of SLC6A4 gene 5HTTLPR polymorphism alleles was evaluated in 223 male athletes engaged in endurance sports, the results were compared with those in 177 male nonathletes. Association between 5-HTTLPR genotypes and the effect of exhaustive treadmill running on simple and complex visual reactions and critical flicker frequency threshold was studied. We found that the incidence of LL genotype was significantly higher in athletes in comparison to nonathletes; after exercise, the velocity of visual reactions and critical flicker frequency increased; exercise did not change the velocity of complex visual reaction in LL-carriers, and increased it in SS-carriers. We conclude that exhausting treadmill running leads to facilitation sensory information processing in athletes and that SS-carriers are more susceptible to the effect of exhaustive treadmill running than LL-carriers.

Effects of genetic variations in the dopaminergic system on fatigue in humans: gender aspects.

Changes in the functional status under the effect of intense mental exercise were studied in carriers of different variants of DAT1, DRD2, and COMT genes. The volunteers (n=140) performed 3-h monotonous mental work (information processing and logical problem solving). The degree of fatigue was evaluated before and after exercise by the HAM (Health status-Activity-Moods) and AMF (Acute Mental Fatigue) questionnaires. A significant relationship between the DAT1, DRD2, and COMT gene polymorphism and changes in the mental sphere status were revealed. The effects of these polymorphisms were the most pronounced in girls. The results are discussed within the framework of hypothesis on the effects of changes in the phasic/tonic dopamine proportion on the studied functions.

[The influence of auditory rhythmic stimulation on the subjective time flow and the reaction time in cognitive tasks].

The influence of rhythmic stimulation on subjective time flow and cognitive processes was studied. Forty four subjects had to categorize abstract, concrete and pseudo words, or duration of stimuli in series with different parallel auditory stimulation (simulated clock ticks with increased (1.25 Hz), normal (1.00 Hz) and decreased (0.75 Hz) rates), or without stimulation (control block). The reaction time was shown to be smaller under conditions of the decreased clock rate as compared to the increased rate or the absence of stimulation. The subjective duration of the series was also shorter in the first case. EEG data revealed the higher amplitude of the P300 component of the event-related potential and the lower alpha-rhythm power under conditions of stimulation with the decreased clock rate as compared to the increased rate.

[Genetic and social factors in developing of aggression].

The association of 5-HTTLPR gene polymorthism and aggression was studied in control group of males and females and in the athletes. The sport activities were found to decrease the aggression: the effect persist for the synchronized swimmers and for the wrestlers. Control group of males were characterized by higher aggression scores (Assault, Negativism, Suspicion and Verbal aggression scales of Buss-Durkee Hostility Inventory) compared to females. For all female-subjects irrespective of sport activities and age, the association between the variants of 5-HTTLPR gene and the Indirect Aggression and Negativism scores were found: carries of SS genotype has higher scores on Indirect Aggression and lower scores on Negativism. For the males the association was different: The averaged Hostility scores were higher for the carriers of LL-genotype. The brain processes, presumably underlying the association between aggression and 5-HTLPR gene, were studied in male control group. The increased MMN component of ERP, which responsible for the automatic change detection, and decreased P3a component, related to involuntary attention and cognitive control were found in LL-carries. It might be considered as a sign that SS-carries process the information with more cognitive resources. Probably they perceive the stimulus as more complicated, which lead to activation the additional resources of frontal cortex. It might be also suggested that the carries of SS-genotype tend to deeper processing of the incoming information. Probably, it is this more "serious" analysis of external information, which underlies the rejection of impulsive aggressive actions.

Gender effects on association of serotonin transporter gene polymorphism with symptoms of central fatigue.

In order to test the "serotonin" hypothesis of the genesis of central fatigue, we studied association between genotype and fatigue (3-hour mental workload consisting of information processing and logical task solution) using analysis of variance for different indices (well-being, activity, mood, mental fatigue index). It was concluded that young men with serotonin deficit (LL genotype) and girls with serotonin excess (S genotype) were less tolerant to long-lasting mental workload. Thus, we confirmed that the degree of central fatigue depends on the function of the serotonin system and revealed gender differences in adaptive capacities of carriers of different variants of serotonin transporter.

Peculiarities of brain information processing in persons with different serotonin transporter gene variants.

Association of brain processes presumably underlying aggression with serotonin transporter gene polymorphism in men was studied. Carriers of more active gene variant are characterized by higher aggression index, increased component of brain potential mismatch negativity responsible for automatic difference detection, and decreased P300 component characterizing involuntary attention and cognitive control.

Role of renin-angiotensin system in the formation of emotional state in humans.

We studied the effect of angiotensin-converting enzyme gene polymorphism on human emotional state in humans (189 athletes and 212 volunteers not engaged in sport activity). The distribution of angiotensin-converting enzyme genotypes was estimated. The dependence of aggression on age, sex, and professional activity was evaluated. This polymorphism was associated with physical aggression in female synchronized swimmers. Physical aggression in II genotype carriers was lower than in D allele carriers. Our results indicate that individual differences in aggression depend on professional activity and are genetically determined.

Effect of functional catechol-O-methyltransferase Val158Met polymorphism on physical aggression.

Genetic and psychological analysis of the relationships between catechol-O-methyltransferase Val158Met polymorphism and various types of aggressiveness was performed in 114 women. Dispersion analysis revealed significant association of ValVal genotype with elevated physical aggression.

Two semantic systems in the brain for rapid and slow differentiation of abstract and concrete words.

Most studies of semantic processing address changes in the late (300-800 msec) components of evoked potentials. However, recent years have seen the appearance of data showing that humans can perceive the sense of stimuli presented to them in significantly shorter periods of time. We report here studies of the mechanism of semantic analysis of written abstract and concrete words in four series of experiments: 1) reading of words on a monitor screen; 2) simple classification of all presented words into the categories "abstract" and "concrete;" 3) complex, i.e., selective classification of words written only in a specified color with a prompt as to which color would be used for the word; 4) complex classification of words of only a specified color without a prior prompt. Early (40-100 msec) differences in evoked brain potentials were seen on comparison of responses to abstract and concrete words, predominantly in the frontal areas in the case of simple reading of words and in the more dorsal areas in the case of tasks with simple classification. All cases of explicit classification of words were characterized by differences in late (450-700 msec) components in the left frontal zone. The results indicate the existence of two semantic systems: a rapid, implicit system associated with activation of the right frontal area, and a slow, explicit system of word classification which is predominantly associated with activity in the left frontal area. The relationship between the two systems is to a certain extent reciprocal: the rapid system can by inhibited by introduction of a word classification task.

[Two semantic brain systems for rapid and slow differentiation of the abstract and concrete words].

In the previous studies, semantic processing was repeatedly found to be reflected in the late (300-800 ms) components of event-related potentials (ERP). However, a human may catch the meaning of the words much earlier. In this work we investigated brain mechanisms of semantic analysis of abstract and concrete written words in four experimental conditions: (1) simple reading (a subjects had to read words to him/herself); (2) simple classification (a subjects had to classify presented words into abstract and concrete categories); (3) cued and (4) uncued selective classification conditions (a subject had to classify only the words typed in a particular color). In the simple reading condition, early (40-100 ms) differences between the ERPs to concrete and abstract words were found mostly in the right frontal areas. During simple classification, the early differences between the ERPs were observed in more dorsal areas. Differences in the late ERP components (450-700 ms) in the left frontal area were characteristic of all cases of explicitly classified words. The findings suggest the existence of two semantic systems: a rapid implicit system which involves the right frontal cortex and can be suppressed by task demands, and a slow explicit system of word classification involving, predominantly, the left frontal area.

[Genetic basis of time perception in athletes].

The association between the subjective time perception and polymorphism of some genes, regulating activity of serotonin and dopamine, was studied in 89 synchronized swimmers. COMT gene, responsible for dopamine destruction, influences on reproduction of short time intervals (1-2 s). 5-HT2A and MAOA genes, regulating activity of serotonin, influence on subjective time flow. 5-HTT and COMT genes, regulating activity of serotonin and dopamine respectively, are related with accuracy of orientation in time. Association of time perception with different genes and mediators suggests different perception mechanisms, in different time ranges, in concordance with the previous physiological studies. The current study reveals that these physiological mechanisms have different molecular-neurochemical basis that helps to overcome the gap between the investigation on systemic and molecular levels.

[Effect of 5HTT genetic polymorphism on aggression in athletes].

Genetic variations of serotonin transporter gene (5HTT) are closely related with human adaptive ability to control emotions and are very attractive in investigation of athletes whose life is accompanied by high emotional pressure. This study was concerned with the effect of genetic polymorphism of 5HTT on aggression of athletes. In total, the study enrolled 86 synchronized swimmers. Analysis of genotype was carried out in 73 young females (aged 8-18) actively engaged in competitions. Psychological testing of aggression (Buss-Durkee Hostility Inventory) was performed in 64 sportswomen. Analysis of correlation between scores on the primary scales of this test and genotypic features showed that scores of Indirect Hostility were higher but scores of Irritability and Negativism were lower in sportswomen with genotype of the SS type as compared to other groups (LS and LL types). The correlation of 5HTT genotype, aggressiveness and success in competitions is discussed.