Effect Of Prestimulation Research Articles

Transcranial Direct Current Stimulation-based Neuromodulation Improves the Performance of Brain-Computer Interfaces Based on Steady-State Visual Evoked Potential.

The study of brain state estimation and intervention methods is of great significance for the utility of brain-computer interfaces (BCIs). In this paper, a neuromodulation technology using transcranial direct current stimulation (tDCS) is explored to improve the performance of steady-state visual evoked potential (SSVEP)-based BCIs. The effects of pre-stimulation, sham-tDCS and anodal-tDCS are analyzed through a comparison of the EEG oscillations and fractal component characteristics. In addition, in this study, a novel brain state estimation method is introduced to assess neuromodulation-induced changes in brain arousal for SSVEP-BCIs. The results suggest that tDCS, and anodal-tDCS in particular, can be used to increase SSVEP amplitude and further improve the performance of SSVEP-BCIs. Furthermore, evidence from fractal features further validates that tDCS-based neuromodulation induces an increased level of brain state arousal. The findings of this study provide insights into the improvement of BCI performance based on personal state interventions and provide an objective method for quantitative brain state monitoring that may be used for EEG modeling of SSVEP-BCIs.

Effects of Auditory Pre-Stimulation on Cognitive Task Performance in a Noisy Environment

The accident rate due to human errors in industrial fields has been consistently high over the past few decades, and noise has been emerging as one of the main causes of human errors. In recent years, auditory pre-stimulation has been considered as a means of preventing human errors by improving workers’ cognitive task performance. However, most previous studies demonstrated the effectiveness of the auditory pre-stimulation in a quiet environment. Accordingly, studies on the effects of pre-stimulation in a noisy environment are still lacking. Therefore, this study aimed to empirically investigate: (1) the effects of noisy environments on the performances of cognitive tasks related to different functions of working memory and (2) the effects of auditory pre-stimulation on the performances of cognitive tasks in a field-noise environment. To accomplish these research objectives, two major experiments were conducted. In the first experiment, a total of 24 participants performed each of three basic short-term/working memory (STM/WM) tasks under two different experimental conditions (quiet-noise environment and field-noise environment) depending on the presence or absence of field noise. In the second experiment, the participants performed each of the three basic STM/WM tasks in a field-noise environment after they were provided with one of four different auditory pre-stimulations (quiet noise, white noise, field noise, and mixed (white and field) noise). The three STM/WM tasks were the Corsi block-tapping, Digit span, and 3-back tasks, corresponding to the visuospatial sketchpad, the phonological loop, and the central executive of WM, respectively. The major findings were that: (1) the field-noise environment did not affect the scores of the Corsi block-tapping and 3-back tasks, significantly affecting only the Digit span task score (decreased by 15.2%, p < 0.01); and (2) the Digit span task performance in the field-noise environment was improved by 17.9% (p < 0.05) when mixed noise was provided as a type of auditory pre-stimulation. These findings may be useful for the work-space designs that prevent/minimize human errors and industrial accidents by improving the cognitive task performance of workers in field-noise environments.

Steel Factor Enhances Supraoptimal Antigen-Induced IL-6 Production from Mast Cells via Activation of Protein Kinase C-β

Ag-triggered mast cell (MC) activation follows a bell-shaped dose-response curve. Reduced activation in response to supraoptimal Ag concentrations is thought to be due to preferential engagement of inhibitory-acting proteins like SHIP1, Lyn, and protein kinase C (PKC)-delta. We show in this study that short-term prestimulation with Steel factor (SF) prevents supraoptimal Ag inhibition, resulting in synergistic MC degranulation and IL-6 secretion. These events are preceded by synergistic phosphorylation/activation of numerous signaling proteins, e.g., Erk, p38, and LAT. However, these effects of prestimulation with SF appear not to be due to reduced engagement of the attenuator SHIP1. Pharmacological analyses suggest that the activation of conventional PKCs is important for this synergy. Specifically, although we found that the conventional PKC inhibitor, Gö6976, likely has some PKC-independent targets in MCs, it led us to further studies that established SF plus Ag-induced IL-6 secretion was severely impaired in PKC-beta(-/-) MCs, but not PKC-alpha(-/-) MCs. Thus, PKC-beta joins PI3K and Btk as important players in this synergistic MC activation.

Reactivity of Airway Phagocytes during the Development of Acute Pneumonia under Conditions of Stimulation of Mononuclear Phagocyte System with Zymosan

Pneumonia was induced in (CBA x C57Bl)F1 mice under conditions of stimulation of the mononuclear phagocyte system with zymosan. The number of neutrophils in airways increased after 3 days; by day 14, the number of cells in the bronchoalveolar lavage fluid further increased due to migration of macrophages. After zymosan prestimulation, the number and functional activity of neutrophils during the early period of inflammation (3 days) did not change, but the increase in phagocytic activity of macrophages was inhibited by 20%. By day 14, the effect of prestimulation manifested in 4.5-fold decreased capacity of neutrophils and macrophages to reduce NBT.

Effect of pre-stimulation on milk flow pattern and distribution of milk constituents at a quarter level

The aim of this study was to investigate milk flow patterns and milk composition in relation to pre-milking udder stimulation. The milk of one quarter of each of the sixteen cows was removed separately and in the course of milking it was divided into six fractions (P – cisternal milk during milking without stimulation and the first 300 ml during milking with pre-stimulation, 0−25%, 25−50%, 50−75%, 75−100%, 75−100%, MS-machine stripping) and into five portions (25%, 50%, 75%, 100%, 100% + MS). Two milkings were performed during two consecutive evening milkings with or without manual stimulation. Pre-stimulation resulted in a reduction of milking time, duration of the increase and decline phase of milk flow, stripping yield, but it increased the peak flow rate as compared to milking without pre-stimulation (<i>P</i> < 0.05). In both fractions and portions the content of fat increased steadily during milking and reached a maximum at MS. Lactose increased from P to 50−75% and then it decreased to MS. Significantly higher fat contents at 25% and 50% portions and in both protein and dry matter at 25% portions were found during milking with pre-stimulation as compared to no stimulation (<i>P</i> < 0.05). The content of fat, protein and dry matter were also higher in both P and 0−25% fractions for milking with pre-stimulation (<i>P</i> < 0.05). Pre-stimulation positively influenced the parameters of milk flow and therefore the efficiency of milk removal and contributed to better distribution of components in milk fractions during milking.

Olfactory coding in a simple system: adaptation in Drosophila larvae.

Drosophila melanogaster larvae were pre-stimulated with high concentrations of six homologous alcohols (C4-C9) and then tested for adaptation and cross-adaptation using these same alcohols, four aliphatic n-acetates and three acids. Pre-stimulation with hexanol effectively reduced to zero (abolished) test responses to all six alcohols, whereas test responses to hexanol were only affected by pre-stimulation with hexanol. This substance appears to play a fundamental role in the organization of the larval olfactory system. Test responses to butanol and pentanol, and the effect of pre-stimulation with butanol and pentanol, were not significantly different, indicating that they are sensory equivalents. Heptanol, octanol and nonanol induce a complex set of responses among one another. Cross-adaptation between functional groups was observed, in particular following pre-stimulation with hexanol, but there was also evidence that functional groups are coded separately. A model of olfactory processing in the fruitfly maggot is presented that explains the data and provides predictions for future anatomical, genetic and electrophysiological studies.

Effect of repeated sampling and prestimulation on saliva buffer capacity and flow rate values in children

Great variations reported in the frequency distribution of buffer capacity values may partly be due to methodological differences in saliva sampling. In this study we wanted to see to what extent these variations are due to repetition and prestimulation. 9-yr-old schoolchildren (n: 41, 23 girls and 18 boys), who had never had saliva samples taken before, participated in the present study. The repetition tests were carried out between 9 and 11 a.m. on three subsequent days. The effect of prestimulation was tested 4 days later with the same subjects. The buffer capacity of the samples was determined electrometrically immediately after sampling using the commercial Dentobuff-test. The intraindividual analysis revealed a significant increase in flow rate but not in buffer capacity along with repetition of the sampling. The analysis further showed that the buffer capacity of children accustomed to saliva sampling increased significantly through prestimulation of 1 min. The use of prestimulation resulted in substantial changes also in the frequency distribution of the buffer capacity values. Our results emphasize the importance of proper sampling conditions in saliva collection when screening children for high caries risk.

Effect of prestimulation on sentence comprehension by aphasic subjects

Aphasic subjects and controls were tested to determine whether comprehension of spoken sentences was enhanced by prestimulation concerning their contents. For each of the 20 test points, the subject listened to the test sentence and selected the corresponding picture from among four pictures presented simultaneously. The preparatory suggestions were given in one test condition and withheld in the other. Each prestimulation consisted of one or two sentences that indicated the persons, objects, or general situation to be presented in the test sentence. Analysis of variance indicated that the effect of the prestimulation was not significant.

Sensitized effect of prestimulation on insulin release from the perifused rat islets with a slow-rise glucose stimulation.

The sensitized effect of prestimulation with 16.7 mM glucose on insulin release with a slow-rise glucose stimulation from the perifused rat islets of Langerhans was studied, together with the kinetic analysis of insulin release, and the interrelationship between the prestimulation time and the maximal rate of insulin release. All dose-response relationships which were derived from the dynamics of insulin release from islets prestimulated over various time periods within 60 min, showed sigmoidal profiles. Kinetic analyses were performed with Lineweaver-Burk's and Hill's equations. The 30-min prestimulation significantly reduced Hill's constant (n) from 6.2 +/- 0.7 of the control to 3.7 +/- 0.6 (p less than 0.05) and also enhanced the logarithmic equilibrium constant (log K) from -5.4 +/- 0.6 mM-n to -3.7 +/- 0.6 mM-n (p less than 0.05). However, the Km value was almost the same as that of the control (7.3 +/- 0.5 mM). On the other hand, the 60-min prestimulation remarkably diminished the Km value and the maximal rate of insulin release to 5.3 +/- 0.4 mM (p less than 0.05) and 0.6 +/- 0.08 muU/ml/islet/min (p less than 0.005), respectively. The maximal rate of insulin release linearly increased in proportion to the prestimulation time within 30 min. In conclusion, these results suggested that there would be some regularity depending on the prestimulation time in the process of transmission of the insulin-releasing signal in the pancreatic B cell and the accumulation of insulin into the provisional pool such as the labile insulin.

Effect of prestimulation on avoidance responding in rats, and hormonal dependence of the effect.

Rats were tested daily in a free-operant avoidance task and were found to make more avoidance responses in sessions preceded by a brief period of prestimulation than in control sessions. Footshock, air blast, and handling were effective sources of prestimulation for this effect. Further experiments showed that the effect of prestimulation depended on the presence of circulating mineralocorticoid and not on any other adrenal or pituitary hormone. Adrenalectomy, but not hypophysectomy, abolished the effect. The effect was also abolished in intact rats by maintaining them on saline drinking fluid, a procedure that inhibits mineralocorticoid production. In either adrenalectomized rats or intact, saline-maintained rats, injection of mineralocorticoid permitted the effect of prestimulation to reappear while leaving the nonprestimulated response rate unaffected.

Effects of prestimulation on the electromyographic response associated with the acoustic startle reaction in rats

Rats (n = 5) received high intensity acoustic stimuli, presented alone (control trials) or 60 msec after a low intensity random noise burst or a light flash (prepulse trials). Stabilimetric measures of the startle reflex as well as the amplitudes and latencies of EMG activity to the stimuli were recorded. Both sorts of prestimulation depressed the amplitude of subsequent effector activity to the startle stimulus as well as the stabilimetric measure, indicating that demonstrations of stabilimetric depression caused by prepulses do result from direct effector inhibition. The auditory prepulse but not the visual prepulse increased the latency of the subsequent startle reaction. The inhibitory effects were not determined by effector activity initiated by the prepulse, supporting, thereby, central rather than peripheral mechanisms of reflex inhibition.