Stefan Schneider

Conditions for Interference Versus Facilitation During Sequential Sensorimotor Adaptation

Abstract. We investigated how sensorimotor adaptation acquired during one experimental session influenced the adaptation in a subsequent session. The subjects task was to track a visual target using a joystick-controlled cursor, while the relationship between joystick and cursor position was manipulated to introduce a sensorimotor discordance. Each subject participated in two sessions, separated by a pause of 2xa0min to 1xa0month duration. We found that adaptation was achieved within minutes, and persisted in the memory for at least a month, with only a small decay (experiment A). When the discordances administered in the two sessions were in mutual conflict, we found evidence for task interference (experiment B). However, when the discordances were independent, we found facilitation rather than interference (experiment C); the latter finding could not be explained by the use of an easier discordance in the second session (experiment D). We conclude that interference is due to an incompatibility between task requirements, and not to a competition of tasks for short-term memory. We further conclude that the ability to adapt to a sensorimotor discordance can be improved by practicing with an unrelated discordance.

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.

Sensorimotor adaptation in young and elderly humans.

Our brains capacity for adaptation allows us to interact meaningfully with an ever-changing environment. Experimental evidence suggests that the time course of sensorimotor adaptation is preserved or only moderately degraded in old age, and that seniors benefit from a previous adaptive experience even more than younger subjects. However, experimental evidence suggests that sensorimotor adaptation seems to be associated with a higher computational load in the elderly. We discuss two possible explanations for this pattern of findings: Older adults may take longer to consolidate newly gained information into long-term motor memory, or they may have problems to utilize supplementary (e.g. cognitive) strategies. In any case, the age-related deficits were relatively mild. If these deficits are related to an increased computational load, it should be possible to reduce them by extended practice on adaptation tasks.

Brain cortical activity is influenced by exercise mode and intensity.

INTRODUCTIONnPrevious research suggests that different exercise modes and intensities lead to variations in brain cortical activity. However, because of variability and limitations in previous study designs, the mechanisms behind this link remain unclear. The aim of this study was to evaluate the effects on brain cortical activity that are dependent on exercise mode, intensity, and individual preferences and to localize these changes within the frontal, temporal, parietal, and occipital cortexes of the brain.nnnMETHODSnTwelve runners were asked to perform four modes of exercise (treadmill, bicycle, arm crank, and isokinetic wrist flexions), each at 50% and 80% of their individual maximum capacity. In a second experiment, five hand cycling athletes completed an arm crank exercise protocol. Electrocortical activity was recorded for 5 min under rest conditions, before and after exercise. Standardized low-resolution brain electromagnetic tomography was used to localize changes in electroencephalographic α and β frequency ranges within the brain.nnnRESULTSnWe found effects of exercise mode and intensity. Moderate-intensity exercise (50% maximum) was followed by an increase in α activity in either somatosensory brain areas after familiar exercise or in emotional areas after unfamiliar exercise modes. After high-intensity exercise, changes in α and β frequencies were observed, which also seem to be specific to individual exercise familiarization/preference. When runners completed intense running and hand cyclists completed the intense arm crank exercise, we observed reductions of frontal β activity indicating a deactivation of emotional brain regions.nnnCONCLUSIONSnIn conclusion, these findings demonstrate that cortical activation patterns depend on exercise mode and intensity and that individual exercise preferences may contribute to the positive psychophysiological response.

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.

Changes in brain cortical activity measured by EEG are related to individual exercise preferences

Exercise is well known to result in changes of brain cortical activity measured by EEG. The aim of this study was (1) to localise exercise induced changes in brain cortical activity using a distributed source localisation algorithm and (2) to show that the effects of exercise are linked to participants physical exercise preferences. Electrocortical activity (5 min) and metabolical parameters (heart rate, lactate, peak oxygen uptake) of eleven recreational runners were recorded before and after incremental treadmill, arm crank and bicycle ergometry. Electroencephalographic activity was localised using standardised low resolution brain electromagnetic tomography (sLORETA). Results revealed an increase in frontal alpha activity immediately post exercise whereas increases after bike exercise were found to be localised in parietal regions. All three kinds of exercise resulted in an increase of beta activity in Brodmann area 7. Fifteen and thirty minutes post exercise a specific activation pattern (decrease in frontal brain activity-increase in occipital regions) was noticeable for treadmill and bike but not arm crank exercise. We conclude that specific brain activation patterns are linked to different kinds of exercise and participants physical exercise preferences.

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.

Parabolic flight experience is related to increased release of stress hormones

Numerous studies have shown significant effects of weightlessness on adaptational processes of the CNS, cardiovascular and/or muscular system. Most of these studies have been carried out during parabolic flights, using the recurring 20xa0s of weightlessness at each parabola. Although some of these studies reported on potential influences not only of weightlessness but also of the stressful situation within a parabolic flight, especially provoked by the ongoing changes between 1.8, 1 and 0xa0G, so far there seems to be only marginal information about objective parameters of stress evoked by parabolic flights. By collecting blood samples from a permanent venous catheter several times during parabolic flights, we were able to show an increase of prolactin, cortisol and ACTH in the course of a 120xa0min flight. We conclude, therefore, that previous reported effects of weightlessness on adaptational processes may be affected not only by weightlessness but also by the exposure to other stressors experienced within the environment of a Zero-G airbus.

Brain and exercise : a first approach using electrotomography

PURPOSEnThe impact of exercise on brain function has gained broad interest. Because hemodynamic and imaging studies are difficult to perform during and after exercise, electroencephalography (EEG) is often the method of choice. Within this study, we aimed 1) to extend prior work examining changes in scalp-recorded brain electrical activity associated with exercise and 2) to use a distributed source localization algorithm (standardized low-resolution brain electromagnetic tomography [sLORETA]) to model the probable neural sources of changes in EEG activity after exercise.nnnMETHODSnElectrocortical activity of 22 recreational runners (21-45 yr) was recorded before and after exhaustive treadmill ergometry. Data were analyzed using sLORETA.nnnRESULTSnThere was an increase in alpha-1 activity (7.5-10 Hz) immediately after exercise, which was localized to the left frontal gyrus (Brodmann area 8). This finding is consistent with alterations in emotional processing. Fifteen minutes after exercise, a decrease in alpha-2 (10-12.5 Hz), beta-1 (12.5-18 Hz), and gamma activities (35-48 Hz) was observed in Brodmann areas 18 and 20-22, which are well known to be involved in language processing.nnnCONCLUSIONnThis study demonstrates that sLORETA is a robust method that allows brain activity maps to be generated from standardized EEG recordings following exercise.

School sport—A neurophysiological approach

The aim of this study was to identify neurophysiological correlates for previously reported positive effects of exercise on academic achievement in school children using a distributed source localization algorithm. Electro-cortical activity of 11 school children (9-10y) was recorded before and after a moderate 15-min bike exercise. Data were analyzed using standardized low resolution brain electromagnetic tomography (sLORETA) in the alpha (7.5-12.5Hz) and beta (12.5-35Hz) frequency range. We were able to show a significant increase in alpha activity post-exercise, which could be localized in the precuneus. Moreover a distinct decrease in beta activity could be noticed post-exercise in left temporal areas including Wernickes area. We propose that apart from health-promoting aspects school sport serves a second even more important challenge. On a central level a well observed overall state of physical relaxation after exercise is reflected by a more synchronized state in the precuneus. We speculate this to be responsible for an increase in concentrativeness and cognitive function post-exercise. Moreover a previously reported increase in academic achievement post-exercise could be directly linked to exercise induced neuroplasticity in regions that are relevant for language processing.