•Physical activity has beneficial effects on executive functions and memory in humans.•Neural systems that are known to have a high capacity for change appear to be the first that are enhanced by ...exercise.•Maintenance of cardiovascular fitness is necessary for long-term effects on cognition.
The human brain adapts to changing demands by altering its functional and structural properties (“neuroplasticity”) which results in learning and acquiring skills. Convergent evidence from both human and animal studies suggests that physical activity facilitates neuroplasticity of certain brain structures and as a result cognitive functions. Animal studies have identified an enhancement of neurogenesis, synaptogenesis, angiogenesis and the release of neurotrophins as neural mechanisms mediating beneficial cognitive effects of physical exercise.
This review summarizes behavioral consequences and neural correlates at the system level following physical exercise interventions in humans of different ages. The results suggest that physical exercise may trigger processes facilitating neuroplasticity and, thereby, enhances an individual's capacity to respond to new demands with behavioral adaptations. Indeed, some recent studies have suggested that combining physical and cognitive training might result in a mutual enhancement of both interventions. Moreover, new data suggest that to maintain the neuro-cognitive benefits induced by physical exercise, an increase in the cardiovascular fitness level must be maintained.
The impact of congenital deafness on the development of vision has been investigated to a considerable degree. However, whether multisensory processing is affected by auditory deprivation has often ...remained largely overlooked. To fill this gap, we investigated the consequences of a profound auditory deprivation from birth on visuo-tactile processing. While the electroencephalogram (EEG) was recorded, dynamic visuo-tactile stimuli with a congruent or an incongruent motion direction were presented to a group of congenitally deaf native signers (N = 21) and matched hearing controls (N = 21). Standard stimuli were moving continuously for 200 ms either upwards or downwards, whereas the motion of deviant stimuli was interrupted in one of the two modalities. Participants were asked to detect deviant stimuli, moving in a predefined direction while ignoring deviants moving in the non-target direction. Behaviorally, deaf individuals committed more false alarms than hearing controls in the incongruent condition, that is, they responded more often when deviants moved in the non-target motion direction. ERPs (140–164 ms) of the deaf group were more anteriorly distributed for the visuo-tactile stimulation in comparison to hearing controls. Moreover, visuo-tactile motion congruency effects emerged with a later latency in the deaf group (350–450 ms) than in the hearing control group (200–280 ms). These findings suggest altered selection strategies and neural correlates for visuo-tactile motion processing as a result of congenital deafness.
The ability to detect the absolute location of sensory stimuli can be quantified with either error-based metrics derived from single-trial localization errors or regression-based metrics derived from ...a linear regression of localization responses on the true stimulus locations. Here we tested the agreement between these two approaches in estimating accuracy and precision in a large sample of 188 subjects who localized auditory stimuli from different azimuthal locations. A subsample of 57 subjects was subsequently exposed to audiovisual stimuli with a consistent spatial disparity before performing the sound localization test again, allowing us to additionally test which of the different metrics best assessed correlations between the amount of crossmodal spatial recalibration and baseline localization performance. First, our findings support a distinction between accuracy and precision. Localization accuracy was mainly reflected in the overall spatial bias and was moderately correlated with precision metrics. However, in our data, the variability of single-trial localization errors (variable error in error-based metrics) and the amount by which the eccentricity of target locations was overestimated (slope in regression-based metrics) were highly correlated, suggesting that intercorrelations between individual metrics need to be carefully considered in spatial perception studies. Secondly, exposure to spatially discrepant audiovisual stimuli resulted in a shift in bias toward the side of the visual stimuli (ventriloquism aftereffect) but did not affect localization precision. The size of the aftereffect shift in bias was at least partly explainable by unspecific test repetition effects, highlighting the need to account for inter-individual baseline differences in studies of spatial learning.
Previous studies have indicated that crossmodal visual predictions are instrumental in controlling early visual cortex activity. The exact time course and spatial precision of such crossmodal ...top-down influences on the visual cortex have been unknown. In the present study, participants were exposed to audiovisual combinations comprising one of two sounds and a Gabor patch either in the top left or in the bottom right visual field. Event-related potentials (ERPs) were recorded to these frequent crossmodal combinations (standards) as well as to trials in which the visual stimulus was omitted (omissions) or the visual and auditory stimuli were recombined (deviants). Standards and deviants elicited an ERP between 50 and 100 ms of opposite polarity known as the C1 effect commonly associated with retinotopic processing in early visual cortex. By contrast, a C1 effect was not observed in omission trials. Spatially specific omission and mismatch effects (deviants minus standards) started only later with a latency of 230 ms and 170 ms, respectively. These results suggest that crossmodal visual predictions control visual cortex activity in a spatially specific manner. However, visual predictions do not modulate visual cortex activity with the same timing as visual stimulation activates these areas but rather seem to involve distinct neural mechanisms. This article is part of the theme issue 'Decision and control processes in multisensory perception'.
Humans preferentially match arbitrary words containing higher- and lower-frequency phonemes to angular and smooth shapes, respectively. Here, we investigated the role of visual experience in the ...development of audiovisual and audiohaptic sound–shape associations (SSAs) using a unique set of five groups: individuals who had suffered a transient period of congenital blindness through congenital bilateral dense cataracts before undergoing cataract-reversal surgeries (CC group), individuals with a history of developmental cataracts (DC group), individuals with congenital permanent blindness (CB group), individuals with late permanent blindness (LB group), and controls with typical sight (TS group). Whereas the TS and LB groups showed highly robust SSAs, the CB, CC, and DC groups did not—in any of the modality combinations tested. These results provide evidence for a protracted sensitive period during which aberrant vision prevents SSA acquisition. Moreover, the finding of a systematic SSA in the LB group demonstrates that representations acquired during the sensitive period are resilient to loss despite dramatically changed experience.
In animals, physical activity has been shown to induce functional and structural changes especially in the hippocampus and to improve memory, probably by upregulating the release of neurotrophic ...factors. In humans, results on the effect of acute exercise on memory are inconsistent so far. Therefore, the aim of the present study was to assess the effects of a single bout of physical exercise on memory consolidation and the underlying neuroendocrinological mechanisms in young adults. Participants encoded a list of German-Polish vocabulary before exercising for 30 minutes with either high intensity or low intensity or before a relaxing phase. Retention of the vocabulary was assessed 20 minutes after the intervention as well as 24 hours later. Serum BDNF and salivary cortisol were measured at baseline, after learning, and after the intervention. The high-intensity exercise group showed an increase in BDNF and cortisol after exercising compared to baseline. Exercise after learning did not enhance the absolute number of recalled words. Participants of the high-intensity exercise group, however, forgot less vocabulary than the relaxing group 24 hours after learning. There was no robust relationship between memory scores and the increase in BDNF and cortisol, respectively, suggesting that further parameters have to be taken into account to explain the effects of exercise on memory in humans.
Recent studies have suggested that the location of tactile stimuli is automatically recoded from anatomical into external coordinates, independent of the task requirements. However, research has ...mainly involved the two hands, which may not be representative for the whole body because they are excessively used for the visually guided manipulation of objects and tools. We recorded event-related potentials (ERPs) while participants received tactile stimuli to the hands and feet, but attended only one limb. The hands were placed near the feet either in an uncrossed or a crossed posture, thus varying the spatial distance of each hand from each foot. Centro-parietal ERPs 100–140 msec poststimulus were more positive when stimulating the anatomically same-side hand while attending a foot. They were also more positive when the Euclidean distance between the stimulated hand and the attended foot was small rather than large. When a foot was stimulated and a hand attended, a similar modulation of foot ERPs was observed for the right foot. To assess the spatial distance between two limbs in space, the external location of both must be known. The present ERP results therefore suggest that not only the hands but also other body parts are remapped into external coordinates. The use of both anatomical and external coordinates may facilitate the control of actions toward tactile events and the choice of the most suitable effector.
Vision usually provides the most accurate and reliable information about the location of objects in our environment, and thus serves as a reference for recalibrating auditory spatial maps. Recent ...studies have shown that recalibration does not require accumulated evidence of cross-modal mismatch to be triggered, but occurs as soon as after one single exposure. Here we tested whether instantaneous recalibration and recalibration based on accumulated evidence represent the same underlying learning mechanism or involve distinct neural systems. Participants had to localize two sounds, a low- and a high-frequency tone, which were paired with opposite directions of audiovisual spatial mismatch (leftward vs. rightward). In accordance with the cumulative stimulus history, localization in unimodal auditory trials was shifted in opposite directions for the two sound frequencies. On a trial-by-trial basis, however, frequency-specific recalibration was reduced when preceded by an audiovisual stimulus with a different sound frequency and direction of spatial mismatch. Thus, the immediate past invoked an instantaneous frequency-invariant recalibration, while the cumulative past invoked changes in frequency-specific spatial maps. These findings suggest that distinct recalibration mechanisms operating at different timescales jointly determine sound localization behavior.
Self-motion perception used for locomotion and navigation requires the integration of visual, vestibular, and proprioceptive input. In the absence of vision, postural stability and locomotor tasks ...become more difficult. Previous research has suggested that in visually deprived children, postural stability and levels of physical activity are overall lower than in sighted controls. Here we hypothesized that visually impaired and blind children and adolescents differ from sighted controls in postural stability and gait parameters, and that physically active individuals outperform sedentary peers in postural stability and gait parameters as well as in navigation performance. Fourteen blind and visually impaired children and adolescents (8–18 years of age) and 14 matched sighted individuals took part. Assessments included postural sway, single-leg stance time, parameters of gait variability and stability, self-reported physical activity, and navigation performance. Postural sway was larger and single-leg stance time was lower in blind and visually impaired participants than in blindfolded sighted individuals. Physical activity was higher in the sighted group. No differences between the group of blind and visually impaired and blindfolded sighted participants were observed for gait parameters and navigation performance. Higher levels of physical activity were related to lower postural sway, longer single-leg stance time, higher gait stability, and superior navigation performance in blind and visually impaired participants. The present data suggest that physical activity may enhance postural stability and gait parameters, and thereby promote navigation performance in blind and visually impaired children and adolescents.
Physical exercise has been shown to induce structural plasticity in the human brain and to enhance cognitive functions. While previous studies focused on aerobic exercise, suggesting a link between ...increased cardiorespiratory fitness and exercise-induced neuroplasticity, recent findings have suggested that whole-body exercise with minor metabolic demands elicits beneficial effects on brain structure as well. In the present study, we tested if balance training, challenging the sensory-motor system and vestibular self-motion perception, induces structural plasticity. Thirty-seven healthy adults aged 19–65 years were randomly assigned to either a balance training or a relaxation training group. All participants exercised twice a week for 12 weeks. Assessments before and after the training included a balance test and the acquisition of high-resolution T1-weighted images to analyze morphological brain changes. Only the balance group significantly improved balance performance after training. Cortical thickness was increased in the superior temporal cortex, in visual association cortices, in the posterior cingulate cortex, in the superior frontal sulcus, and in the precentral gyri in the balance group, compared to the relaxation group. Moreover, there was evidence that the balance training resulted in decreased putamen volume. Improved balance performance correlated with the increase of precentral cortical thickness and the decrease in putamen volume. The results suggest that balance training elicits neuroplasticity in brain regions associated with visual and vestibular self-motion perception. As these regions are known for their role in spatial orienting and memory, stimulating visual-vestibular pathways during self-motion might mediate beneficial effects of physical exercise on cognition.
•Structural plasticity after 12 weeks of balance training was studied.•Balance training elicited changes in visual-vestibular motion processing areas.•Gray matter changes correlated with balance improvements.•Vestibular networks may contribute to cognitive benefits after physical exercise.
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