The comparison of characteristics of smooth pursuit in left-handed and right-handed persons

The estimation of the smooth pursuit efficiency in healthy young adults by method based on stroboscopic stimulation is given. The influence of manual function asymmetry on smooth pursuit was tested. Subjects were classified as left-handed or right-handed under a well known handedness questionnaire of Annett supplemented by Luria's tests. It was shown that the strong right-handed persons have a high quality of smooth pursuit of stimuli moving horizontally in rightward and leftward directions with the velocities 20 degrees/s and 25 degrees/s. Left-handed persons track similar stimuli, on the average, worse than the strong right-handed ones. It haven't been observed the influence of manual function asymmetry on the dependence of the smooth pursuit efficiency from the moving stimuli direction (left to right or right to left).     

Characteristics of smooth pursuit in children and adults in apparent motion tests

The efficiency of smooth pursuit was estimated in healthy young subjects (college and school students) by a contactless method based on stroboscopic stimulation causing an illusion of smooth motion of an object. Stable individual differences in the smooth pursuit efficiency were found in both children and adults. Eleven-to 12-year-old children exhibited, on average, a less smooth pursuit of stimuli moving horizontally at velocities of 6–17 deg/s than young adults did.     

Characterization of the thermal tolerances of forest ants of New England

Characterization of thermal tolerances of ants, which are both abundant and important in most terrestrial ecosystems, is needed since thermal constraints can inform how a species may respond to local climatic change. Here we identified the thermal tolerances of 16 common ant species of the Northeastern United States and determined relationships between body size, desiccation, and thermal tolerance among species. We hypothesized that maximum heat tolerances of these species would differ and be related to body size and capacity to resist desiccation. We identified four distinct groups of species belonging to one of three subfamilies, Dolichoderinae, Formicinae, or Myrmicinae, with different maximum thermal tolerances. Group “a” had a mean thermal tolerance of approximately 43°C (±1°C), group “b” had a mean thermal tolerance of 40°C (±1°C), group “c” had a mean thermal tolerance of 38°C (±0°C), and group “d” had a mean thermal tolerance of 36°C (±0°C). Groups “a” and “d” consisted of a single species (in the subfamilies Myrmicinae and Formicinae, respectively), while groups “b” and “c” were a mix of species in the subfamilies Myrmicinae, Formicinae, and Dolichoderinae. In the subfamily Formicinae, thermal tolerance increased with body size and critical water content, a metric of desiccation tolerance. In contrast, in the subfamily Myrmicinae, higher thermal tolerance was correlated with intermediate body size and lower critical water content. These findings suggest that the two dominant subfamilies in Northeastern deciduous forests have different relationships between body size, capacity to tolerate desiccation, and thermal tolerances across species. This variation in thermal tolerance suggests that climatic change may impact species differently.     

Interhemispheric asymmetry of neocortex and hippocampus in orienting exploratory behavior of rabbits

Correlation of discharges of cortical neurons in symmetrical points of the visual and parietal cortices and left and right hippocampal CA1 neurons was studied in freely moving rabbits during exposure to emotional stimuli. Crosscorrelation histograms were plotted. As compared to the initial state, during an active orienting exploratory reaction to stimuli, the left-side influence on right-hemispheric cortical neurons with a delay about 100 ms increased, which led to asymmetry in interhemispheric interaction with the left-side dominance. During freezing, the left-side influence became weaker, and the effects of the right hemisphere prevailed. Hippocampal asymmetry in neuronal activity was in reciprocal relationship with neocortical asymmetry. In the hippocampus, the right-side influence with a delay about 200 ms increased during the active exploratory reactions resulting in the right-side dominance. Freezing was accompanied by strengthening of the left-side influence (the left-side dominance). During the active locomotion, neuronal interaction in the hippocampus was predominantly realized in the theta-range frequency, whereas freezing was characterized by the delta-range correlation. It was concluded that the active or passive nature of a behavioral reaction to emotional stimuli was correlated with changes in asymmetry in the interhemispheric neuronal interactions at the cortical and hippocampal levels.     

Asymmetry of Tactile Perception and Interhemispheric Interactions in Stutterers

The effect of inverse masking on the skin of the left and right hands and of bimanual reverse masking during coordinated work of both hands in stutterers was studied to detect the changes in cerebral asymmetry related to stuttering. The study showed that (1) asymmetry of tactile perception is absent in stutterers in the conditions of masking; it is supposed that when stuttering begins in early childhood, the formation of the hemispheric specialization in performing both sensory (all modalities) and speech functions is interrupted; (2) stuttering right-handers demonstrate a strongly levotropic nature of the interhemispheric interactions under conditions of bimanual masking, which testifies to a more considerable retardation of the perception of a test stimulus in the stutterers' left hemisphere under the influence of the masking stimulus in the right hemisphere than in right-handers with normal speech. It is assumed on this basis that stuttering begins because of the combination of symmetry and asymmetry in the interhemispheric relations. There is a hypothetical model that supposes that the phenomenon of stuttering is caused by two fundamental factors, namely, bilateral symmetry (existence of two identical speech centers in the right and left hemispheres) and a specific levotropic asymmetry of the interhemispheric relations, i.e., a more manifest influence of the right hemisphere on the left hemisphere in stutterers. This conditions the emergence of two identical speech impulses that appear with long intervals between them, which cause a dissonance in the functioning of the speech-forming apparatus.     

A study of the macro-environment at BenCat in southern Vietnam

Based on the meteorological data over a period of 4 years (1980–3), the macro-environment of BenCat Farm situated in the southern part of Vietnam (27 m above mean sea-level, 11° N and 106° E) was categorized as a “monsoon tropical climate”, due to heavy rainfall (annual mean 2028.96 mm) and about 32% wet days (annual mean 116.52 days) together with high air temperature (annual mean daily temperature 28.58, max. 32.33 and min 24.85° C). April was the hottest (monthly mean >35°C) and January the coldest month (monthly mean <22° C) of the year. The maximum number of wet days were during September and October (mean 18 days.month), whereas the minimum number of wet days were during January and February (mean <1 day/month). The months of December and January at Ben-Cat buffalo farm were categorized as the “comfortable (moderate-Dry) period” as the mean daily temperature was <27° C, while the remaining 10 months of the Calender year (February–November) were categorized as the “hot period” (mean daily temperature >27° C). On the basis of rainfall and the number of wet days, the hot period was further subdivided into a “hot-dry period” (February–April, mean of 1.67 wet days/month and mean rainfall 19.43 mm/month) and a “hot-humid period” (May–November, mean of 15.57 wet days/month and mean rainfall 276.28 mm/month).     

Eye-specific learning of routes and “signposts” by walking honeybees

This study investigates the honeybee's ability to learn routes based on visual stimuli presented to a single eye, and to then navigate these routes using the other (naive) eye. Bees were trained to walk through a narrow tunnel carrying visual stimuli on the two walls. At the end of the tunnel the bees had to choose between two arms, one of which led to a feeder. In a first experiment, bees had to learn to choose the left arm to get a reward when the right wall carried a yellow grating, but the right arm when the left wall carried a blue grating. The bees learned this task well, indicating that stimuli encountered by different eyes could be associated with different routes. In a second experiment, bees had to turn left when the right eye saw a blue grating, but to the right when the same eye saw a yellow grating. They also learned this task well. In subsequent tests, they chose the correct arm even when these gratings were presented to the untrained eye. These results suggest that there is interocular transfer of route-specific learning with respect to visual stimuli that function as navigational “signposts”. Accepted: 18 December 1997     

A study of dilute aqueous solutions of humic acids by scanning microcalorimetry

It has been found by reversed-phase chromatography that humic acids obtained from vermicomposts of different duration of vermicomposting consist of a hydrophilic and a hydrophobic fractions, the hydrophobic fraction having a substantially lower content of charged, probably carboxylic, groups. A change in the sign of the temperature dependence of the heat capacity of dilute aqueous solutions of humic acids at ∼58°C has been found by differential scanning microcalorimetry, which indicates an increase in the hydration of hydrophobic groups. A jump-wise increase in heat capacity in the temperature range from 86 to 90°C was also found, which is perhaps due to hydration of hydrophobic groups in the interior of “micelles“, because of “devitrification” of the hydrophobic nucleus of micelle-like structures. It was shown that increasing the duration of vermicomposting leads to an increase in the relative content of the hydrophobic fraction of humic acids and in the cooperativity of the thermodynamic transition, which manifests itself as the jump of heat capacity, which probably results from the increase in the “micelle” size.     

Receptive Fields of Visually Sensitive Neurons of the Extrastriate Associative Area 21b of the Cat Cerebral Cortex

Organization of the receptive fields (RFs) of neurons of the extrastriate associative region 21b of the cerebral cortex was studied in cats. Most neurons under study (63%) were “monocular,” while 37% of the cells were “binocular” units. Among 178 neurons examined in detail, heterogeneous RF functional organization was typical of about 76% of the units; point-to-point testing of the entire RF area by stationary stimuli resulted in the generation of various types of responses (on, off, or on-off). The rest of the neurons (24%) generated homogeneous responses. The dimension, form, and functional organization of RFs of the neurons under study depended to a certain extent on the parameters of visual stimuli used for the measurements. Examination of the influence of the visual space, which surrounded the RF, on responses of the neurons evoked by stimulation of the RF per se showed that darkening of the visual space adjacent to the RF inhibited neuronal responses to moving stimuli; in some cases the responses were totally suppressed. Analysis of spatial overlapping of the RF sequentially recorded in the course of each insertion of the electrode showed that the density of distribution of the overlapping RF areas of neighboring neurons with the RF of the examined neuron is irregular, and that the RF is of a mosaic nature. We hypothesize that the visual space surrounding the RF plays a significant role in the formation of responses of visually sensitive neurons to presentation of moving stimuli. Neirofiziologiya/Neurophysiology, Vol. 37, No. 3, pp. 223–234, May–June, 2005.     

Functional asymmetry of the brain and effectiveness of sensorimotor function of oral cavity organs]

It has been established that in healthy persons functional brain asymmetry positively influences the effective performance of sensomotor function of oral cavity organs. Individual brain asymmetry is of considerable importance, the higher it is, the quicker the final results of sensomotor function are achieved. The character of brain asymmetry (right hand or left hand) does not practically influence the performance of sensomotor functions.     

Final thermal preference in parthenogenetic females of Daphnia magna straus (Crustacea: Cladocera) acclimated to various temperatures

The final thermal preference FTP) range in parthenogenetic females of cladoceran Daphnia magna was assessed by “acute” and “chronic” methods. The first method included 4-month acclimation to different temperatures in the range of 14.2 ± 0.7 to 27.1 ± 0.3°C; the “chronic” method was characterized by long-term acclimation to +20°C. Two ranges of FTP were found for D. magna, 13.3–15.4°C and 20.2–26.2°C. The thermal preference of daphnids and the temperature of acclimation were correspondingly linearly. The range of FTP was independent of the season. The searching activity of D. magna rose in April, when the FTP range increased, and the FTP was less pronounced.     

Using sensory weighting to model the influence of canal,otolith and visual cues on spatial orientation and eye movements

 The sensory weighting model is a general model of sensory integration that consists of three processing layers. First, each sensor provides the central nervous system (CNS) with information regarding a specific physical variable. Due to sensor dynamics, this measure is only reliable for the frequency range over which the sensor is accurate. Therefore, we hypothesize that the CNS improves on the reliability of the individual sensor outside this frequency range by using information from other sensors, a process referred to as “frequency completion.” Frequency completion uses internal models of sensory dynamics. This “improved” sensory signal is designated as the “sensory estimate” of the physical variable. Second, before being combined, information with different physical meanings is first transformed into a common representation; sensory estimates are converted to intermediate estimates. This conversion uses internal models of body dynamics and physical relationships. Third, several sensory systems may provide information about the same physical variable (e.g., semicircular canals and vision both measure self-rotation). Therefore, we hypothesize that the “central estimate” of a physical variable is computed as a weighted sum of all available intermediate estimates of this physical variable, a process referred to as “multicue weighted averaging.” The resulting central estimate is fed back to the first two layers. The sensory weighting model is applied to three-dimensional (3D) visual–vestibular interactions and their associated eye movements and perceptual responses. The model inputs are 3D angular and translational stimuli. The sensory inputs are the 3D sensory signals coming from the semicircular canals, otolith organs, and the visual system. The angular and translational components of visual movement are assumed to be available as separate stimuli measured by the visual system using retinal slip and image deformation. In addition, both tonic (“regular”) and phasic (“irregular”) otolithic afferents are implemented. Whereas neither tonic nor phasic otolithic afferents distinguish gravity from linear acceleration, the model uses tonic afferents to estimate gravity and phasic afferents to estimate linear acceleration. The model outputs are the internal estimates of physical motion variables and 3D slow-phase eye movements. The model also includes a smooth pursuit module. The model matches eye responses and perceptual effects measured during various motion paradigms in darkness (e.g., centered and eccentric yaw rotation about an earth-vertical axis, yaw rotation about an earth-horizontal axis) and with visual cues (e.g., stabilized visual stimulation or optokinetic stimulation). Received: 20 September 2000 / Accepted in revised form: 28 September 2001     

Contribution to the probabilistic theory of neural nets: II. Facilitation and threshold phenomena

The output curve of a single neuron with a threshold of response with respect to the frequency of the stimuli is derived. If the stimuli are regularly spaced in time, the output curve has discontinuities. If the threshold and/or refractory period are sufficiently large, the output curve approaches the “all-or-none” curve. In the case of completely randomized stimuli, the output curve is sigmoid. The equation of this curve is derived and some properties are studied. Threshold and “all-or-none” effects can be achieved by “pyramiding” neurons of this type to converge on neurons of higher order.     

Isolation and characterization of OmpF-like porin from <Emphasis Type="Italic">Yersinia ruckeri</Emphasis>

The polypeptide profile of the porin protein fraction of Yersinia ruckeri, a Gram-negative bacterium causing yersiniosis in fish, has been shown to depend on cultivation temperature. OmpF-like porins are expressed mainly in the outer membrane (OM) of the “cold” variant (4°C) of the microorganism and OmpC-like proteins are expressed in the OM of the “warm” variant (37°C). Both types of porins are present in the OM of Y. ruckeri at room temperature. The OmpF-like porin of the “cold” variant was isolated and characterized. The molecular weight and primary structure of the protein were determined. The methods of optical spectroscopy (circular dichroism and intrinsic protein fluorescence) have shown that the protein has a spatial structure typical of β-structured porins from the OM of Gram-negative bacteria. The functional activity of isolated protein was characterized by the bilayer lipid membrane (BLM) technique. The most probable level of channel conductivity was 320 ± 60 pS, corresponding to the channel conductivity of OmpF porins of the genus Yersinia. The distinctive feature of OmpF porin from Y. ruckeri is high thermostability of its functionally active conformation: the protein forms stable pores in the BLM even after heating to 85°C.     

Lesions in thighs from hunted Brown Hares (<Emphasis Type="Italic">Lepus europaeus</Emphasis>) and microflora under vacuum-packaging storage

In two surveys, thighs of a total of 137 hunted hares were tested for the presence of intramuscular shots and femur fractures, which were detected in 42.7% and 29.2% of 274 thighs, respectively. Femur fractures were significantly associated with the presence of intramuscular shots. In the second survey (46 hares), 92 thighs were grouped into three categories, “A” (no fractures, no intramuscular shot), “B” (one intramuscular shot), and “C” (multiple shots and hematoma), with 49.0%, 33.6%, and 17.4%, respectively. Category “C” was found unfit for human consumption. During 7-day storage of vacuum-packed “A” and “B” thighs, total aerobic counts increased from initially 3.3 ± 0.3 (mean ± SD) and 4.1 ± 0.6 log cfu/g by ca. 2 log units when stored at 3–4°C, whereas the increase was clearly <1 log unit at 0°C. In comparison to temperature, differences between “A” and “B” category were less pronounced. Similar dynamics were observed for Enterobacteriaceae. In all categories, muscle pH values (mean = 5.83) were similar. It is concluded that storage at temperatures of ca. 4°C, although in compliance with EU legislation, does not afford keeping microbial contaminants in check, and thus will not preserve microbiological quality of vacuum-packed hare meat.     

Eye movements and target fixation during dragonfly prey-interception flights

The capture of flying insects by foraging dragonflies is a highly accurate, visually guided behavior. Rather than simply aiming at the prey’s position, the dragonfly aims at a point in front of the prey, so that the prey is intercepted with a relatively straight flight trajectory. To better understand the neural mechanisms underlying this behavior, we used high-speed video to quantify the head and body orientation of dragonflies (female Erythemis simplicicollis flying in an outdoor flight cage) relative to an artificial prey object before and during pursuit. The results of our frame-by-frame analysis showed that during prey pursuit, the dragonfly adjusts its head orientation to maintain the image of the prey centered on the “crosshairs” formed by the visual midline and the dorsal fovea, a high acuity streak that crosses midline at right angles about 60° above the horizon. The visual response latencies to drifting of the prey image are remarkably short, ca. 25 ms for the head and 30 ms for the wing responses. Our results imply that the control of the prey-interception flight must include a neural pathway that takes head position into account.     

Rapid shifting of foraging pattern by Yakushima macaques ( Macaca fuscata yakui ) in response to heavy fruiting of Myrica rubra

We describe short-term changes in foraging behavior by wild Yakushima macaques (Macaca fuscata yakui),which inhabit a warm-temperate broad—leaved forest on Yakushima Island (30°N, 131°E), Japan. Rapid changes of dietary composition, activity budget, and range use by the monkeys occurred from May to June, apparently associated with changes in the availability of the fruit of Myrica rubraBefore the fruit ripened, monkeys spent less time moving and more time feeding on many species of leaves, which accounted for 40% of feeding time. However, when M. rubrabegan to ripen, they fed intensively on the fruit, which accounted for three-fourths of feeding time,though the activity budget remained unaffected As fiuit of M. rubradecreased,the monkeys fed more on the fruit of other species and on insects, and spent more time moving at higher speeds. There marked shifts in foraging pattern occurred within only two months. In terms of moving cost and dietary quality,Yakushima macaques shifted their foraging pattern according to the availability of M. rubrafrom a “low-cost, low-yield” strategy to a “low-cost, high-yield” strategy, and then to a more costly strategy. The ability to make such rapid shifts in foraging pattern may allow the macaques to effectively use the highly variable food supply within their small range.     

A “micromere model” of cell-cell interactions in sea urchin early embryos

It has been shown that isolation of sea urchin blastomeres before the post-division adhesion leads mainly to the formation of equal blastomeres at the stage of 4th cleavage division, whereas isolation after adhesion results in the formation of micromeres simultaneous with that in intact embryos. Similar results were obtained in five sea urchin species. It has been concluded that there exists a critical point in the cleavage process, when blastomeres exchange information that determines the further cleavage pattern. It has been shown with this “micromere model” that serotonin and its analogs influence the cleavage pattern of half-embryos. These data have served as a basis for the hypothesis of “protosynapse,” a bilaterally symmetric structure in which the blastomeres are not only source and target of the signal but also a passive obstacle to leakage of the signal substance from the interblastomere cleft to the milieu. Such a structure may also specify the primary asymmetry of the blastomeres. The micromere model may be useful in specific pharmacological screening.     

Functional Brain Asymmetry and Individual Differences in Hand Preference in Early Ontogeny

This work was aimed at studying the brain mechanisms of hand preference in 10- to 11-month-old infants. According to the results of neuropsychological investigations, the preference for the right hand in children of this age (at the populational level) primarily arises in actions that demand involvement of the functions of planning and motor control of reaching (functions of the motor control of reaching: FMCR) for an object. The stage of development of the FMCR in each child was scored on the Diamond scale. Total numbers of movements performed by the right and left hands and a coefficient of the manual asymmetry (AC) were calculated. On the basis of quartile analysis of the AC distribution, groups of right-handers, left-handers, and ambidextrals were formed. The EEG was recorded in the state of visual focused attention, and the spectral absolute amplitude density (AAD) of the sensorimotor rhythm and other infant EEG rhythms in the frequency band was analyzed. In order to estimate the statistical correlation of manual asymmetry, gender, and stage of development of the FMCR with functional asymmetry of the AAD of the -band rhythms in different cortical derivations, analysis of variance with factors of repeated measurements and analysis of multiple regression were used. The main results showed that 10- to 11-month-old children with different types of manual asymmetry differed in interhemispheric asymmetry of the visual attention-related EEG -band rhythms (including asymmetry of the sensorimotor rhythm). The maximum differences were observed in the lateral frontal and posterotemporal areas of the brain cortex. The leftward amplitude asymmetry was characteristic of right-handers; in left-handers and ambidextrals, the EEG amplitude was distributed over the brain hemispheres in a more symmetric way. The correlation between the brain and manual asymmetries was stronger in boys than in girls. There was a strict linear correlation between the degree of manual asymmetry and interhemispheric asymmetry of the EEG sensorimotor rhythm in the precentral and lateral frontal brain areas. On the whole, the close correlation of the manual asymmetry with functional asymmetry of the EEG sensorimotor rhythm suggests that it is determined by the formation of the brain FMCR lateralization.