Correlations between the psychological peculiarities of an individual and the efficacy of a single neurofeedback session (by the EEG characteristics)

Modifications of different EEG rhythms induced by a single neurofeedback session (by the EEG characteristics) directed toward an increase in the ratio of the spectral powers (SPs) of the α vs θ oscillations were compared with the psychological characteristics of the tested subjects (the group included 30 persons). A generally accepted neurofeedback technique was used; the intensity of acoustic white noise served as the feedback signal. EEG potentials were recorded from the C3 and C4 leads. Psychological testing was carried out using Eysenck’s (EPQ), Rusalov’s (OST), and (16 PF) questionnaires. The directions of changes in the SPs of EEG frequency components were found to significantly correlate with some individuality-related peculiarities of the tested subjects. The SP of the δ rhythm correlated with the EPQ scale “neuroticism,” OST scale “social plasticity,” and 16 PF factors H (“parmia”), I (“premsia”), and Q₃ (“self-control of behavior”). The SP of the θ component demonstrated correlations with the OST scales “ergisity,” “plasticity,” and “social temp” and with 16 PF factors M (“autia”), Q₄ (“frustration”), and Q1 (“exvia”). The SP of the α rhythm correlated with 16 PF factors Q₃ (“self-control of behavior”), G (“strength of superEgo”), O (“hypothymia”), L (“protension”), and N (“shrewdness”). The SP of the β rhythm correlated with the OST scale “emotionality,” while that of the γ rhythm showed correlations with the 16 PF indices L (“protension”) and M (“autia”). Changes in the ratio of the α vs θ SPs correlated with the EPQ scale “neuroticism.” Thus, our data confirm the statement that a high individual variability of the results of a single (first in the series) neurofeedback session is to a great extent related to peculiarities of the individual psychological pattern of the subject. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 239–247, May–June, 2006.     

Feedbacks between nutrient cycling and vegetation predict plant species coexistence and invasion

To investigate the role of species‐specific litter decomposability in determining plant community structure, we constructed a theoretical model of the codevelopmental dynamics of soil and vegetation. This model incorporates feedback between vegetation and soil. Vegetation changes the nutrient conditions of soil by affecting mineralization processes; soil, in turn, has an impact on plant community structure. The model shows that species‐level traits (decomposability, reproductive and competitive abilities) determine whether litter feedback effects are positive or negative. The feedback determines community‐level properties, such as species composition and community stability against invasion. The model predicts that positive feedback may generate multiple alternative steady states of the plant community, which differ in species richness or community composition. In such cases, the realized state is determined by initial abundance of co‐occurring species. Further, the model shows that the importance of species‐level traits depends on environmental conditions such as system fertility.     

Fast axon activity and the motor pattern in cockroach legs during swimming

Abstract Electromyographic recordings were made from muscles that extend the trochanter/femur of each of the six legs of American cockroaches, Periplaneta americana (L.), while the insects swam in water. The recordings showed two novel features. (1) During swimming, muscle activity in different legs was coordinated in the alternating tripod pattern commonly seen during free walking on land, not in the pattern of synchronous leg pairs common to other large terrestrial insects in water. (2) Fast axons were usually recruited along with slow axons, even when the insect swam at a moderate pace. Fast axon activity always started after the middle of the slow axon burst in intact insects, but vanished from most bursts in the stump of the leg after amputation of the femur. The alternating tripod pattern was maintained even after amputation. Possible causes of fast axon recruitment are discussed.     

Effect of calcium on synthesis of dipicolinic acid inPenicillium citreoviride and its feedback resistant mutant

Dipicolinic acid synthesis inPenicillium citreoviride strain 3114 was inhibited by Ca²⁺ ions, but not by Ba²⁺, Cu²⁺or Fe²⁺. Among the metals tested, only Zn²⁺ inhibited the synthesis of dipicolinic acid and promoted sporulation. None of these metals reversed the inhibition by Ca²⁺ or Zn²⁺. A mutant 27133-dpa-ca selected for resistance to feedback inhibition by dipicolinic acid: Ca²⁺ complex showed cross-resistance to inhibition by dipicolinic acid: Zn²⁺. Both 3114 and271 33-dpa-ca excreted a number of aliphatic and amino acids during secondary metabolism of dipicolinic acid. In the presence of 1000 ppm of Ca²⁺, accumulation of citric acid and α-aminoadipic acid was completely inhibited under conditions of inhibition of dipicolinic acid in parent strain 3114 but not in the mutant. Citric acid with or without Ca²⁺ did not inhibit thede novo synthesis of dipicolinic acid in the strain 3114. In fact, citric acid in the presence of Ca²⁺ improved significantly rate of dipicolinic acid synthesis. Apart from resistance to feed back inhibition by dipicolinic acid: Ca²⁺ complex, mutant differed from the parent in three other aspectsviz. (i) dipicolinic acid synthesis was not subject to catabolite repression by glucose, (ii) sporulation as well as dipicolinic acid synthesis was dependent on the presence of Ca²⁺ ions in the medium and (iii) Mg²⁺ requirement for the mutant increased three fold. Higher requirement of the Mg²⁺ could be partially relieved by Ca²⁺ during secondary metabolism. The results support the inference thatde novo synthesis of dipicolinic acid is regulated through feedback inhibition by dipicolinic acid: Ca²⁺complex.     

The effect of feedback-assisted reduction in heart rate reactivity on videogame performance

In 67 male volunteers, we examined the reduction of cardiovascular responsivity to a psychomotor challenge (videogame) achieved by use of heart rate (HR) feedback and effects of these procedures on concomitant behavioral performance. Each subject participated in a pretraining assessment of his cardiovascular responses to the videogame, a training condition, and a posttraining assessment identical to the initial evaluation. During training, subjects were assigned to one of four conditions: (a) a habituation control group receiving no instructions to alter HR (HC); (b) an instructions-only control group receiving instructions to maintain a low or unchanged HR during videogame presentations (IC); (c) a feedback group receiving instructions to reduce HR using ongoing HR feedback (FB–); or (d) a feedback group receiving instructions to lower HR and given HR feedback plus a score contingency in which total game score was jointly determined by subjects' game performance and success at HR control (FB+). Subjects receiving feedback (FB+, FB–) exhibited greater reductions in HR response to the videogame in the posttraining assessment than control (HC, IC) subjects; FB+ subjects showed greater HR reductions than subjects in any other group. FB+ and FB– subjects showed a lower SBP at posttraining relative to the two control groups, but no reduction in task-induced blood pressure reactivity. There were no group differences in videogame performance, either before or following training.The authors wish to thank Fred Claus, who served as a research assistant for this study.     

紫外激光消融过程的等效模型研究

本文引用等效模型,对激光消融过程进行了推导与计算,和实验结果比较表明,所得公式与实验结果能较好相符,可用于描述紫外激光消融过程。     

Gain control in a proprioceptive feedback loop as a prerequisite for working close to instability

In the artificially closed femur-tibia control system of stick insects oscillations were induced in 3 different ways: Increasing the phase-shift by introducing an electronic delay, afference sign reversal and coupling the tibia to an inert mass. In all 3 cases the oscillations stopped after some time. The gain of the open-loop system was significantly smaller after the oscillations. Afference sign reversal by surgically crossing of the receptor apodeme of the femoral chordotonal organ for 25–85 days does not lead to altered characteristics of the control loop. When sinusoidal passive movements are forced upon the intact femur-tibia joint the forces resisting these movements do not decrease with time. In contrast to direct stimulation of the femoral chordotonal organ, these passive movements also influence the contralateral leg. The experiments show that the gain-control system of the femur-tibia control loop of stick insects consists of at least two components: A sensitization system (with inputs from many kinds of stimuli indicating some kind of disturbance) increases the gain of all reflex loops. A specific habituation-like system decreases the gain with repetitive stimulation only of one control system.Abbreviations fCO femoral chordotonal organ - SETi slow extensor tibiae motor neuron     

Visual feedback in the control of pheromone-mediated flight ofHeliothis virescens males (Lepidoptera: Noctuidae)

MaleHeliothis virescens (F.) (Lepidoptera: Noctuidae) were made to fly into a uniformly white and translucent tube within a large wind tunnel while responding to sex pheromone. Different visual patterns placed within the tube greatly affected the ability of the male moths to maintain upwind progress or remain oriented to the wind while in contact with the plume. Over 89% of males attempting to fly through a blank tube, lacking visual patterns, became disoriented, the males gaining or losing altitude and repeatedly hitting the sides of the tube. Patterns of 20–40 dots placed on the sides of the tube at or slightly above plume level resulted in high levels of sustained upwind flight (47–74%) relative to patterns placed directly below (30–40%), directly above (35%), or slightly below the level of the flight path (26–44%). Optimal upwind progression in pheromone-responding males occurred when image motion could be resolved both transversely (T), orthogonally to the longitudinal axis of the body relative to the horizontal plane of the environment, and longitudinally (L), along the body axis. Even very sparse patterns (single rows of dots) could elicit high levels of sustained upwind flight (53–63%) when positioned within the tube such that the males' movements would create both L and T image motion. However, successful negotiation of the tube was also unexpectedly facilitated by patterns apparently providing no horizontal transverse component for flying males but providing longitudinal flow while centering the moth in the plume through a symmetrical left-right input (4–40%).     

Soil legacy effects of plants and drought on aboveground insects in native and range-expanding plant communities

Soils contain biotic and abiotic legacies of previous conditions that may influence plant community biomass and associated aboveground biodiversity. However, little is known about the relative strengths and interactions of the various belowground legacies on aboveground plant–insect interactions. We used an outdoor mesocosm experiment to investigate the belowground legacy effects of range-expanding versus native plants, extreme drought and their interactions on plants, aphids and pollinators. We show that plant biomass was influenced more strongly by the previous plant community than by the previous summer drought. Plant communities consisted of four congeneric pairs of natives and range expanders, and their responses were not unanimous. Legacy effects affected the abundance of aphids more strongly than pollinators. We conclude that legacies can be contained as soil ‘memories’ that influence aboveground plant community interactions in the next growing season. These soil-borne ‘memories’ can be altered by climate warming-induced plant range shifts and extreme drought.