Single Dose of an Energy Dietary Supplement with a Small Amount of Caffeine Prevents an Increase of a Low Frequency Resting State EEG in Possible Mental Fatigue.

Due to the increasing needs to enhance our cognitive performance, and decrease fatigue with increasing number of tasks in our everyday life, it's interesting to study whether a small amount of active substance present in dietary supplements, is enough to impact cognition. We investigated an acute effect of an energy dietary supplement containing low amount of caffeine (55 mg) and other stimulatory ingredients by means of a resting state EEG in a double blind, placebo controlled study (N = 47, 27 women). The use of a nonparametric cluster-based permutation analysis allowed us to observed a significant group × block interaction effect after 90 minutes post-ingestion (P = 0.022 cluster corrected) in the 'eyes closed' condition, i.e. an increase in normalized rsEEG power in the placebo group, which was abolished in the study group. This difference corresponded to a broad spatio-spectral cluster between around 6.5 Hz and 10.5 Hz (i.e. high theta and low alpha band) maximal over centro-temporo-parieto-occipital scalp areas. Similar trend but without significant effect was found in the 'eyes open' condition. Our results suggest that low caffeine content dietary supplementation acts as a reversal of the fatigue-related brain activity in the neural networks active in the resting state. These findings not only may help to clarify previous nonconclusive findings, but more importantly, show that an ingestion of caffeinated stimulants before neurocognitive examinations, both in research and diagnostics, should be taken into account, as they may influence cognition, even in small doses and when the effects are absent in the behavioral measures.

Individual differences in behavioral and electrophysiological signatures of familiarity- and recollection-based recognition memory.

Our everyday memories can vary in terms of accuracy and phenomenology. According to one theoretical account, these differences hinge on whether the memories contain information about both an item itself as well as associated details (remember) versus those that are devoid of these associated contextual details (familiar). This distinction has been supported by computational modeling of behavior, studies in patients, and neuroimaging work including differences both in electrophysiological and functional magnetic resonance imaging. At present, however, little evidence has emerged to suggest that neurophysiological measures track individual differences in estimates of recollection and familiarity. Here, we conducted electrophysiological recordings of brain activity during a recognition memory task designed to differentiate between behavioral indices of recollection and familiarity. Non-parametric cluster-based permutation analyses revealed associations between electrophysiological signatures of familiarity and recollection with their respective behavioral estimates. These results support the idea that recollection and familiarity are distinct phenomena and is the first, to our knowledge, to identify distinct electrophysiological signatures that track individual differences in these processes.

Hierarchical Classification of Event-Related Potentials for the Recognition of Gender Differences in the Attention Task.

Research on the functioning of human cognition has been a crucial problem studied for years. Electroencephalography (EEG) classification methods may serve as a precious tool for understanding the temporal dynamics of human brain activity, and the purpose of such an approach is to increase the statistical power of the differences between conditions that are too weak to be detected using standard EEG methods. Following that line of research, in this paper, we focus on recognizing gender differences in the functioning of the human brain in the attention task. For that purpose, we gathered, analyzed, and finally classified event-related potentials (ERPs). We propose a hierarchical approach, in which the electrophysiological signal preprocessing is combined with the classification method, enriched with a segmentation step, which creates a full line of electrophysiological signal classification during an attention task. This approach allowed us to detect differences between men and women in the P3 waveform, an ERP component related to attention, which were not observed using standard ERP analysis. The results provide evidence for the high effectiveness of the proposed method, which outperformed a traditional statistical analysis approach. This is a step towards understanding neuronal differences between men's and women's brains during cognition, aiming to reduce the misdiagnosis and adverse side effects in underrepresented women groups in health and biomedical research.

Acute effect of energy boost dietary supplement on P3 waveform: double blind, placebo controlled study.

Human cognition may be enhanced by energy drinks containing caffeine and/or other stimulants, which are thought to improve attentional as well as motor performance, and reduce reaction times. Due to the fact that literature shows that even low doses of caffeine may improve cognitive performance, we investigated an acute effect of a single dose of a caffeinated energy dietary supplement, on attention and motor responses by means of event related potentials. Healthy volunteers were examined in double blind, placebo controlled study. EEG recordings from 32 channels were performed in three sessions: before the supplementation (session 1), 30 min after the supplementation (session 2) and 90 min after the supplementation (session 3) in three tasks: visual P3, auditory P3, and motor task. Repeated measures ANOVA analysis showed reduced P3 amplitude increase after energy dietary supplementation (compared to placebo group) throughout all sessions (up to 90 min after consumption) in the visual task, and speeding the classification process observed as a decrease of P3 midpoint latency, but only 30 min after supplementation. The latter effect was present in both, but more pronounced in the visual task. Nonparametric cluster based permutation analysis showed one significant cluster in the placebo group from visual P3 task (approximately between 400 and 520 ms) over the centro­parietal area, which was absent in the study group. Our results suggest that caffeinated energy dietary supplement containing only 55 mg of caffeine may enhance some attentional processes observed by changes in P3 features, but not in motor performance.

The effect of acute, moderate intensity indoor cycling on the temporal resolution of human vision system, measured by critical fusion frequency.

Critical fusion frequency (CFF) reflects the basic temporal function of the visual system and therefore is a good measure of its performance. CFF has been implemented in psychological and pharmacological studies to evaluate cognitive functions. The influence of abnormal environmental conditions, such as physical exercise, has been recently explored. Previous studies have presented alterations of cognitive processes due to acute exercise. However, the duration of the effect after the end of exercise has not been investigated. This evaluation is important especially in reference to long-term conclusions on the effect of training on CFF as an improvement of cognition. The main goal of this study was to check whether a stimulatory effect of acute submaximal physical exercise on CFF among non-experienced cyclists persists over time. Moreover, we asked whether this effect differs between areas of visual field. CFF thresholds from 15 volunteers were measured by means of an automated medical perimeter PTS 910 (Bogdani) before, immediately after the end, and 30 min after the end of two sessions (training and rest). During rest, CFF did not change significantly, but we observed an increased CFF immediately after training. Interestingly, this increase was maintained 30 min after the end of exercise in fovea. A greater decrease of CFF during rest was observed for lower than for upper hemifield. Our results suggest that an acute, moderate-intensity cycling improved CFF in non-experienced cyclists, with the duration of the effect depending on eccentricity. The possible visual hemifield asymmetries of CFF changes over time will be further investigated.

Differences in spatio­temporal distribution of the visual P3b event-related potential between young men and women.

Here, we evaluated the P3b potential evoked in a visual two-stimulus oddball paradigm. The experiment was conducted in 20 healthy students (23.1±1.1 years, 10 women), using a 32 channel electroencephalography (EEG) montage system. The paradigm included geometric figures; a black square on a white background as a target and a white circle on a black background as a standard stimulus. We examined the maximal amplitude and latency of the P3b component at 18 electrode sites, as well as, temporal changes of scalp voltage distribution. We observed a non-equal spatial distribution of the visual ERP (event related potentials) waveforms on the scalp surface, with the highest P3b waveform observed over midline parietal areas and the lowest over frontal regions. Moreover, the spatial distribution of ERP signal on the scalp surface was more lateralized towards the right side in men and more centralized in women. Gender-related differences in P3b amplitude and latency were observed only in left hemisphere. Differences in P3b between men and women observed in our study arose not only from different P3b amplitudes and latencies, but also from the speed and character of P3b waveform fall, resulting in spatio-temporal amplitude changes. Moreover, the spatial distribution of the P200 potential also changed on the scalp differently in men and women. These results suggest that gender-related differences evoked in visual two-stimulus oddball paradigm, which engage attention processes, are complex and include spatio-temporal changes in P3b waveform generation, distribution, and suppression across the scalp.

The changes in bone organic and inorganic matrix in newborn rats after maternal application of antiretroviral agents: Indinavir and zidovudine.

This work presents results concerning influence of indinavir (protease inhibitor, PI(1)) and zidovudine (nucleoside and nucleotide inhibitor of reverse transcriptase, NRTI) administered to pregnant Wistar rat females on organic and mineral constituents of bones and teeth (mandibles, skulls, tibiae, femurs, and incisors) of their offspring at the age of: 7, 14, and 28 days studied by means of induced laser and X-ray fluorescence spectroscopy supported by digital radiography. Influence of indinavir administered to pregnant female rats on bone of their offspring revealed mainly in changes of mineral concentration: lowered Ca concentration and disturbances of trace elements. Zidovudine influenced organic matter more than inorganic matrix which was seen in enhancement of LIF fluorescence. However, there was also an unexpected increase of bone density for rats from zidovudine group, unlike indinavir group, observed. Our studies suggest that studied antiretroviral agents given to pregnant women, may have different destructive impact on bone state of their offspring in the first period of life. Maternal administration of zidovudine may delay development of organic matrix, while indinavir may have adverse effects on inorganic structure.

Role of trace elements (Zn, Sr, Fe) in bone development: energy dispersive X-ray fluorescence study of rat bone and tooth tissue.

Osteoporosis is one of the most common debilitating disease around the world and it is more and more established among young people. There are well known recommendations for nutrition of newborns and children concerning adequate calcium and vitamin D intake in order to maintain proper bone density. Nevertheless, important role in structure and function of a healthy bone tissue is played by an integration between all constituents including elements other than Ca, like trace elements, which control vital processes in bone tissue. It is important from scientific point of view as well as prevention of bone diseases, to monitor the mineralization process considering changes of the concentration of minerals during first stage of bone formation. This work presents studies of trace element (zinc, strontium, and iron) concentration in bones and teeth of Wistar rats at the age of 7, 14, and 28 days. Energy dispersive X-ray fluorescence (EDXRF) was used to examine mandibles, skulls, femurs, tibiae, and incisors. The quantitative analysis was performed using fundamental parameters method (FP). Zn and Sr concentrations were highest for the youngest individuals and decreased with age of rats, while Fe content was stable in bone matrix for most studied bones. Our results reveal the necessity of monitoring concentration of not only major, but also minor elements, because the trace elements play special role in the first period of bone development.

Does maternal treatment with zidovudine affect changes in mandibles of newborns? Laser induced fluorescence study.

The influence of antiretroviral drug zidovudine treatment during pregnancy on mandible development in newborn rats was studied. The fluorescence of mandibles from 7-, 14- and 28-days old individuals was measured by means of fiber-optical fluorescence analyzer with 407 nm laser excitation. Obtained results revealed disturbing effect of maternal zidovudine administration on mandible fluorescence intensity which should decrease with bone development. Small changes in fluorescence of porphyrin forms are maintaining in the first month of newborns life while the changes observed in 440-585 nm range disappear.

Optical and X-ray fluorescence spectroscopy studies of bone and teeth in newborn rats after maternal treatment with indinavir.

An experiment estimating influence of antiviral drug indinavir treatment during pregnancy on bones and teeth development in newborn rats was performed. Two different fluorescence noninvasive spectroscopy techniques, i.e. laser (407 nm)-induced fluorescence method to characterize the organic fluorescent molecules and X-ray fluorescence analysis to determine mineral components were used to study the surface response of femur, mandible and incisor during their formation in the first month of a rat's life. Differences in autofluorescence depending on the form of the bone were observed on the basis of the emission from enamel in 7-, 14- and 28-day-old newborn rats. The dependence between decrease in intensity of fluorescence and increase in mineralization with age in newborn rats was observed. An enhancement of the autofluorescence and a decrease in the concentration of Ca as a main element, as well as disturbances in the concentration of Zn as trace element were observed for bone as well as teeth in newborns during the first month of their life after maternal administration of indinavir (500 mg kg(-1) p.o.) in comparison with the control group. The results indicate that indinavir causes a delay in development of the skeleton and teeth in newborn rats.