Heiko K. Strüder

Impact of Singular Excessive Computer Game and Television Exposure on Sleep Patterns and Memory Performance of School-aged Children

OBJECTIVE. Television and computer game consumption are a powerful influence in the lives of most children. Previous evidence has supported the notion that media exposure could impair a variety of behavioral characteristics. Excessive television viewing and computer game playing have been associated with many psychiatric symptoms, especially emotional and behavioral symptoms, somatic complaints, attention problems such as hyperactivity, and family interaction problems. Nevertheless, there is insufficient knowledge about the relationship between singular excessive media consumption on sleep patterns and linked implications on children. The aim of this study was to investigate the effects of singular excessive television and computer game consumption on sleep patterns and memory performance of children. METHODS. Eleven school-aged children were recruited for this polysomnographic study. Children were exposed to voluntary excessive television and computer game consumption. In the subsequent night, polysomnographic measurements were conducted to measure sleep-architecture and sleep-continuity parameters. In addition, a visual and verbal memory test was conducted before media stimulation and after the subsequent sleeping period to determine visuospatial and verbal memory performance. RESULTS. Only computer game playing resulted in significant reduced amounts of slow-wave sleep as well as significant declines in verbal memory performance. Prolonged sleep-onset latency and more stage 2 sleep were also detected after previous computer game consumption. No effects on rapid eye movement sleep were observed. Television viewing reduced sleep efficiency significantly but did not affect sleep patterns. CONCLUSIONS. The results suggest that television and computer game exposure affect childrens sleep and deteriorate verbal cognitive performance, which supports the hypothesis of the negative influence of media consumption on childrens sleep, learning, and memory.

Acute BDNF and cortisol response to low intensity exercise and following ramp incremental exercise to exhaustion in humans

The effect of short-term aerobic exercise and a following ramp incremental cycle ergometry to exhaustion on the acute response of the serum concentrations of brain derived neurotrophic factor (BDNF) and cortisol (COR) was examined in 8 healthy male athletes. Venous and capillary blood samples were drawn at rest, immediately after a 10 min warm-up period with aerobic exercise and after a ramp test to exhaustion, as well as 3, 6, 10 and 15 min post exercise. Capillary blood lactate (LA) concentration and blood gases as well as serum BDNF and COR concentrations did not change during the warm-up period. LA was increased (p<0.05) at the end of the ramp test and during recovery period while bicarbonate concentration, carbon dioxide pressure, pH and base excess were decreased (p<0.05) during this period. Serum BDNF was increased at the point of exhaustion (p<0.05) while no significant differences were found between values at rest and those during recovery period. At 10 and 15 min post incremental exercise, COR concentrations were increased (p<0.05) compared to rest. The present study is the first to demonstrate in humans that in contrast to short duration aerobic exercise immediately after a following short duration high-intensity exercise to exhaustion, there is a transient augmentation of serum BDNF concentration. Short-term response of serum BDNF and COR concentrations differs as BDNF returns to baseline level faster than COR.

EEG activity and mood in health orientated runners after different exercise intensities.

An increasing number of studies within the recent years connected physical exercise with changes in brain cortical activity. Most of this data (1) refers to aerobic exercise and (2) does not correlate to psychological parameters although it is well known that exercise has a positive effect on mood. In times where health activities play a major role it is increasingly necessary to connect somato-physiological and somatopsychological components of physical activity. This study aimed to find changes in EEG activity and mood after low, preferred and high intensity running. EEG and actual state of mood were recorded before and after exercise. Results showed an effect for the preferred and high intensity velocity in both, EEG and mood. As only the higher frequency areas N18 Hz showed persisting decreases post-exercise we concluded that this might be a sign of outlasting effects of exercise on brain cortical activity which may have influences on general well-being. We could also show that there is a clear relationship between EEG activity and mood reflecting a basic principle of cortical excitation.

Effects of Strength and Endurance Training on Brain-derived Neurotrophic Factor and Insulin-like Growth Factor 1 in Humans

Blood neurotrophins like insulin-like growth factor (IGF-1) and brain-derived neurotrophic factor (BDNF) are discussed to mediate health benefits of physical activity in humans. The aim of the study was to analyze the training effects of moderate endurance training (Em) and strength training with high loads (Sh) on blood plasma concentrations of IGF-1 and BDNF in humans. Venous blood samples were obtained from 27 healthy students, randomly assigned to an Em, Sh, and a control group, before and after a 12-week training intervention. Sh resulted in an increase in isometric (14.5%) and dynamic (8.3%) strength of the knee extensor muscles in the Sh group and Em led to a significant increase in the endurance performance in the Em group (p<0.05). IGF-1 basal plasma concentrations decreased (p<0.05) after the intervention in all groups. There were no significant changes for BDNF. Despite specific functional adaptations induced by Em and Sh there are no correspondingly different adaptations in the basal blood concentrations of the neurotrophins IGF-1 and BDNF. Additionally, exercise per se does not result in changes in basal plasma concentrations of BDNF, suggesting that the mode of the exercise programme is a decisive factor.

INTENSE EXERCISE INCREASES ADENOSINE CONCENTRATIONS IN RAT BRAIN: IMPLICATIONS FOR A HOMEOSTATIC SLEEP DRIVE

Intense exercise and sleep deprivation affect the amount of homeostatically regulated slow wave sleep in the subsequent sleep period. Since brain energy metabolism plays a decisive role in the regulation of behavioral states, we determined the concentrations of nucleotides and nucleosides: phosphocreatine, creatine, ATP, ADP, AMP, adenosine, and inosine after moderate and exhaustive treadmill exercise as well as 3 and 5 h of sleep deprivation and sleep in the rat brain using the freeze-clamp technique. High intensity exercise resulted in a significant increase of the sleep-promoting substance adenosine. In contrast, following sleep, inosine and adenosine levels declined considerably, with an accompanied increase of ADP after 3 h and ATP after 5 h. Following 3 h and 5 h sleep deprivation, ADP and ATP did not differ significantly, whereas inosine increased during the 3 and 5-h period. The concentrations of AMP, creatine and phosphocreatine remained unchanged between experimental conditions. The present results are in agreement with findings from other authors and suggest that depletion of cerebral energy stores and accumulation of the sleep promoting substance adenosine after high intensity exercise may play a key role in homeostatic sleep regulation, and that sleep may play an essential role in replenishment of high-energy compounds.

Primary Motor Cortex Activity is Elevated with Incremental Exercise Intensity

While the effects of exercise on brain cortical activity from pre-to post-exercise have been thoroughly evaluated, few studies have investigated the change in activity during exercise. As such, it is not clear to what extent changes in exercise intensity influence brain cortical activity. Furthermore, due to the difficulty in using brain-imaging methods during complex whole-body movements like cycling, it is unclear to what extent the activity in specific brain areas is altered with incremental exercise intensity over time. Latterly, active electroencephalography (EEG) electrodes combined with source localization methods allow for the assessment of brain activity, measured as EEG current density, within specific cortical regions. The present study aimed to investigate the application of this method during exercise on a cycle ergometer, and to investigate the effect of increasing exercise intensity on the magnitude and location of any changes in electrocortical current density. Subjects performed an incremental cycle ergometer test until subjective exhaustion. Current density of the EEG recordings during each test stage, as well as before and after exercise, was determined. Spatial changes in current density were localized using low-resolution brain electromagnetic tomography (LORETA) to three regions of interest; the primary motor cortex, primary sensory cortex and prefrontal cortex, and were expressed relative to current density within the local lobe. It was demonstrated that the relative current density of the primary motor cortex was intensified with increasing exercise intensity, whereas activity of the primary sensory cortex and that of the prefrontal cortex were not altered with exercise. The results indicate that the combined active EEG/LORETA method allows for the recording of brain cortical activity during complex movements and incremental exercise. These findings indicate that primary motor cortex activity is elevated with incremental exercise intensity during a whole-body movement, like cycling.

Energy expenditure in ball games for wheelchair users.

Purpose:Wheelchair sports have become popular in Germany. This is important because of the difficulty experienced by wheelchair-dependent people in maintaining cardiovascular health and fitness by daily activities. Increasing energy expenditure (EE; kcal h−1) is one of the most effective ways of decreasing risk of cardiovascular disease. The purpose of this study was to evaluate the EE of individuals with spinal cord injury in ball games for wheelchair-dependent persons.Methods:Fourteen tennis players (WT), 10 basketball players (WB) and 12 rugby players (WR) completed a basal metabolism evaluation and a training test to measure respiratory parameters.Results:In the basal metabolism test EE in WT was 66.8±12.8 kcal h−1, in WB 62.7±15.0 kcal h−1 and in WR 63.5±12.9 kcal h−1. During training EE in WT was 325.8±73.0 kcal h−1, in WB 374.8±127.1 kcal h−1 and in WR 248.5±69.4 kcal h−1. The average EE of the whole group was: 316.4±89.6 kcal h−1 with a corresponding heart rate of 118.5±23.1 b.p.m. and a lactate concentration of 2.09±0.7 mmol l−1. Statistical analysis showed significantly lower values of EE, heart rate and oxygen uptake for the WR group in comparison to the other groups.Conclusion:The results indicate that the additional leisure time EE of persons participating in WB and WT is sufficient to maintain fitness. This level of EE is comparable to the recommendations of the ACSM for able-bodied persons, and therefore might be sufficient to prevent the development of cardiovascular diseases.

What happens to the brain in weightlessness? A first approach by EEG tomography.

Basic changes in environmental conditions are fundamental to understanding brain cortical mechanisms. Several studies have reported impairment of central nervous processes during weightlessness. There is ongoing debate as to whether these impairments are attributable to primary physiological effects or secondary psychological effects of the weightlessness environment. This study evaluates the physiological effects of changed gravity conditions on brain cortical activity. In a first experiment, EEG activity of seven participants was recorded at normal, increased and zero gravity during a parabolic flight. Additionally an EEG under normal gravity conditions preflight was recorded. In a second experiment, 24 participants were exposed to a supine, seated and 9 degree head-down tilt position while EEG was recorded. Data were analysed using low resolution brain electromagnetic tomography (LORETA). Beta-2 EEG activity (18-35 Hz) was found to be increased in the right superior frontal gyrus under normal gravity conditions inflight. By exposure to weightlessness a distinct inhibition of this activity within the same areas could be noticed. As the tilt experiment showed changes in the left inferior temporal gyrus in supine and tilted positions we conclude that the observed changes under weightlessness are not explainable by hemodynamic changes but rather reflect emotional processes related to the experience of weightlessness. These findings suggest that weightlessness has a major impact on electro cortical activity and may affect central nervous and adaptation processes.

IMPACT OF EXERCISE ON NEUROPLASTICITY-RELATED PROTEINS IN SPINAL CORD INJURED HUMANS

The present study investigated the effects of exercise on the serum concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), prolactin (PRL) and cortisol (COR) in 11 chronically spinal cord-injured athletes. In these subjects BDNF concentration at rest was sixfold higher compared with the concentrations reported earlier in able-bodied persons, while IGF-1, PRL and COR were within normal range. Ten minutes of moderate intensity handbiking (54% of the maximal heart rate) during a warm-up period (W) induced an increase (P<0.05) of BDNF of approximately 1.5-fold from basal level at rest, while a decrease to basal level was found after an immediately succeeding handbiking time trial (89% of the maximal heart rate) over the marathon distance of 42 km (M). An increase (P<0.01) of serum IGF-1 was found after W and this levels remained elevated (P<0.01) until the end of M. W had no significant effects on the serum PRL and COR, however, M induced an increase (P<0.01) of both hormones. This is the first study showing elevated BDNF concentrations at rest in spinal cord-injured athletes. Furthermore, short moderate intensity handbiking but not immediately following long lasting high intensity handbiking further increases serum BDNF concentrations. IGF-1 response to exercise differs to BDNF response as this neuroplasticity-related protein remains elevated during the long lasting physical demand with high intensity. The augmented PRL concentration suggests that a possible mechanism by which exercise promotes neuroplasticity might be the activation of neural serotonergic pathways as 5-HT is the main PRL releasing factor. Elevated COR concentrations after M are unlikely to be deleterious to neuroplasticity as COR concentrations remain within the physiological range. The present study suggests that exercise might be beneficial to enhance neuroprotection and neuroplasticity, thereby improving recovery after spinal cord injury.

Exercise as a countermeasure to psycho-physiological deconditioning during long-term confinement

Confinement studies are performed to simulate the psychological effects that may be experienced on a long-term space flight. A general psycho-physiological model assumes that mood and cognitive functioning are impaired during confinement as a result of an absence of physical activity. The aim of the MARS500 study initiated by the Institute of Biomedical Problems (IBMP) and the European Space Agency (ESA) is to gather data, knowledge and experience to help prepare for a real mission to Mars. A test run with 105 days of isolation was performed prior to 520 days of isolation. Psycho-physiological data of this study are presented here. We hypothesized that exercise, as it has been shown in laboratory settings, would be able to prevent and counteract mood changes during isolation. Electrocortical data (EEG) and a self report on current psychological and physical state were recorded several times prior to and after exercise during the isolation period. Data revealed a clear effect of exercise on mood and electrocortical activity. Moreover, it was shown that mood and brain cortical activity decreased during the first 11 weeks of isolation and reached baseline again in the last week of isolation. A correlation analysis revealed a significant relation between mood data and electrocortical activity. We conclude (1) that confinement is accompanied by psycho-physiological changes and (2) that exercise is a suitable method to counteract psycho-physiological deconditioning during confinement.