Brain mechanisms of mental processing: from evoked and spontaneous brain activities to enactive brain activity.

Within the context of the computer metaphor, evoked brain activity acts as a primary carrier for the brain mechanisms of mental processing. However, many studies have found that evoked brain activity is not the major part of brain activity. Instead, spontaneous brain activity exhibits greater intensity and coevolves with evoked brain activity through continuous interaction. Spontaneous and evoked brain activities are similar but not identical. They are not separate parts, but always dynamically interact with each other. Therefore, the enactive cognition theory further states that the brain is characterized by unified and active patterns of activity. The brain adjusts its activity pattern by minimizing the error between expectation and stimulation, adapting to the ever-changing environment. Therefore, the dynamic regulation of brain activity in response to task situations is the core brain mechanism of mental processing. Beyond the evoked brain activity and spontaneous brain activity, the enactive brain activity provides a novel framework to completely describe brain activities during mental processing. It is necessary for upcoming researchers to introduce innovative indicators and paradigms for investigating enactive brain activity during mental processing.

The effectiveness of physical activity interventions on communication and social functioning in autistic children and adolescents: A meta-analysis of controlled trials.

LAY ABSTRACT: Difficulty with communication and social functioning are two outstanding core symptoms of autism spectrum disorder, while there is no efficacious pharmacologic treatment available to deal with them. Traditional behavioral therapies usually require specialist therapist and be conducted in specific settings, increasing burdens on families and individuals with autism. Physical activity has long been found to promote physical and mental well-beings, and it is more affordable and versatile than traditional therapies. There is preliminary support for the use of physical activity interventions to improve communication and social functioning in individuals with autism. In this study, we quantitatively aggregate data from existing controlled trials to provide an up-to-date inquiry into the effectiveness of physical activity interventions on communication and social functioning in autistic children and adolescents. We included 12 trials involving 350 participants (8 trials reported communication outcomes and 11 trials reported social functioning outcomes) and found small to moderate benefits on communication and social functioning. Further analyses showed that the benefit of physical activity interventions is greater in younger participants. Results of this study suggest that physical activity interventions are effective to improve communication and social functioning in autistic children and adolescents, and early participation in the interventions can be more beneficial. Given their affordability, versatility, and efficacy, physical activity interventions could be considered a cost-effective option for autism spectrum disorder management in the future.

The effectiveness of dance interventions on cognition in patients with mild cognitive impairment: A meta-analysis of randomized controlled trials.

This meta-analysis of randomized controlled trials (published or unpublished RCTs in English) examined the effectiveness of dance interventions compared to waitlist/active controls on cognitive functions in patients with mild cognitive impairment (MCI). Literature search was conducted on MEDLINE, EMBASE, CINAHL and related databases through 3 August 2019. Risk of bias was assessed with the PEDro scale regarding randomization, allocation concealment, group comparability, blinding, attrition and selective reporting. Five included RCTs (N = 358) used Latin, ballroom and aerobic dances (frequency: 1-3 session/week; intensity: light to moderate; time: 25-60 min/session; type: aerobic). Results show that dance interventions improve global cognition (SMD [95 % CI] = 0.48 [0.21, 0.74]), attention (SMD [95 % CI] = 0.33 [0.12, 0.54]), immediate (SMD [95 % CI] = 0.54 [0.38, 0.71]) and delayed recall (SMD [95 % CI] = 0.33 [0.01, 0.64]), and visuospatial ability (SMD [95 % CI] = 0.16 [0.01, 0.32]). Study limitations include a small number of RCTs and high heterogeneity in some cognitive domains. In summary, dance interventions improve some cognitive domains in MCI. (PROSPERO registration: CRD42019145418).

Explicit Aiming Strategy Decreases the Differences in Visuomotor Adaptation between Children and Young Adults.

We examined the visuomotor adaptation of children and adults with and without explicit aiming strategies. Younger children were slower and less smooth in visuomotor adaption than adults. Specifically, in the course of adaptation and re-adaptation, older children had better movement accuracy than adults, while their movement speed and smoothness were similar to those of the adults. Explicit aiming improved movement accuracy for all participants, but also facilitated movement smoothness for younger children. The contribution of explicit adjustment was greater for older children than for younger children. These results show the ongoing development of cognitive functions and movement experiences in children.

Effects of Meditation and Mind-Body Exercises on Older Adults' Cognitive Performance: A Meta-analysis.

BACKGROUND AND OBJECTIVES: Meditation and mind-body exercises are suggested to delay decline or enhance cognitive capabilities in older adults. However, their effectiveness remains uncertain. This study assessed the effectiveness of meditation and mind-body exercises to improve cognition in elderly people aged 60 years or above. Moderator variables were also explored. RESEARCH DESIGN AND METHODS: A databases search (MEDLINE, EMBASE, CINAHL, PsycINFO, Cochrane Library, Web of Science, CNKI, and Wangfang) was conducted from the first available date to January 10, 2018. Inclusion criteria include (a) human older adults aged 60 years or above, (b) meditation, Tai Chi, Qigong, or yoga intervention, (c) intervention should be structured, (d) inclusion of a control group, (e) at least one outcome measure of cognition was measured at baseline and post-training, and (f) peer-reviewed journal articles in English or Chinese. RESULTS: Forty-one studies (N = 3,551) were included in the meta-analysis. In general, meditation and mind-body exercises improve cognition in the elderly people (SMD = 0.34, 95% CI: 0.19 to 0.48), but the cognition-enhancing effects depend on the type of exercise. In addition, cognitive performance is only improved when the length of intervention is longer than 12 weeks, exercise frequency is 3-7 times/week, or duration of an exercise session is 45-60 min/session. DISCUSSION AND IMPLICATIONS: This study suggests that meditation and mind-body exercises are effective to improve cognition of older adults aged 60 years or above, and exercise parameters should be considered for intervention planning.

Movement segmentation and visual perturbation increase developmental differences in motor control and learning.

We examined the developmental differences in motor control and learning of a two-segment movement. One hundred and five participants (53 female) were divided into three age groups (7-8 years, 9-10 years and 19-27 years). They performed a two-segment movement task in four conditions (full vision, fully disturbed vision, disturbed vision in the first movement segment and disturbed vision in the second movement segment). The results for movement accuracy and overall movement time show that children, especially younger children, are more susceptible to visual perturbations than adults. The adults' movement time in one of the movement segments could be increased by disturbing the vision of the other movement segment. The children's movement time for the second movement segment increased when their vision of the first movement segment was disturbed. Disturbing the vision of the first movement segment decreased the percentage of central control of the second movement in younger children, but not in the other two age groups. The children's normalized jerk was more easily increased by visual perturbations. The children showed greater improvement after practice in the conditions of partial vision disturbance. As the participants' age increased, practice tended to improve their feedforward motor control rather than their feedback motor control. These results suggest that children's central movement control improves with age and practice. We discuss the theoretical implications and practical significance of the differential effects of visual perturbation and movement segmentation upon motor control and learning from a developmental viewpoint.

Special Issue - Therapeutic Benefits of Physical Activity for Mood: A Systematic Review on the Effects of Exercise Intensity, Duration, and Modality.

In contemporary society, people experience considerable stress in their daily lives. Therefore, developing effective approaches and convenient means to cope with their mood problems is important nowadays. Physical activity has been consistently reported as a cost-effective way to improve physical fitness, prevent mental illnesses, and alleviate mood problems. In this systematic review, the effects of exercise intensity, duration, and modality on mood change are discussed. Results show that moderate-intensity anaerobic exercise is associated with greater mood improvements. The relationship between exercise duration and mood change is non-linear; A regime of 10- to 30-minute exercise is sufficient for mood improvements. For exercise modality, anaerobic exercise improves mood, but the efficacy of aerobic and mindfulness-related exercises remains to be further examined. In addition to the systematic review of potential moderators, a narrative review of psychological and neurophysiological theories of exercise effects on mood is provided; we have highlighted the central role of neuroplasticity in integrating the two classes of theories. An adoption of neuroimaging techniques in future research is critical to reveal the mechanisms underpinning the therapeutic influence of physical activity on affective responses. Some future research directions are also raised.

Dysfunctional preparatory processes in hazardous drinkers: An ERP study.

Alcohol drinking is associated with impaired cognitive and motor performance. This electrophysiological study examined the differences in the preparatory processes preceding motor imagery (visual and kinesthetic) and execution between hazardous drinkers and non-hazardous drinking controls. Twenty-two hazardous drinkers and 22 non-hazardous drinking controls were recruited to participate in the study. They were required to produce a 3-key response sequence physically or mentally 3 s after the appearance of a corresponding cue. Here we showed significantly smaller amplitudes of both early and late negative contingent variation in hazardous drinkers compared to controls. In addition, the early negative contingent variation preceding motor execution was greater than those in the motor imagery conditions in both groups. Results of this study suggest impairments of attentional control and motor preparation in hazardous drinkers. Preparatory processes of motor execution and motor imagery mainly differ from each other in voluntary attention orientation, but not in motor preparation.

Age-Related Changes in Field Dependence-Independence and Implications for Geriatric Rehabilitation: A Review.

Human aging is a dynamic life-long process and an inevitable experience. As the average age of the world's population rises, demands for effective geriatric rehabilitation dramatically increase. An important consideration for enhancing geriatric behavioral interventions is to better understand aging characteristics in perceptual, cognitive, and motor performances. A general shift in cognitive style from field independence to field dependence has been consistently observed during human aging, as older adults show a greater tendency to rely on environmental information, presumably reflecting a neuro-compensatory mechanism of reducing top-down control and relying instead on bottom-up processing. These changes in cognitive style can impact motor skill learning and relearning and, consequently, affect geriatric rehabilitation and behavioral treatments. In this article, we review research related to the cognitive style of field dependence and independence, and its dynamic associations with aging. We also identify implications of cognitive style for geriatric rehabilitation and explore future research.

Children benefit differently from night- and day-time sleep in motor learning.

Motor skill acquisition occurs while practicing (on-line) and when asleep or awake (off-line). However, developmental questions still remain about whether children of various ages benefit similarly or differentially from night- and day-time sleeping. The likely circadian effects (time-of-day) and the possible between-test-interference (order effects) associated with children's off-line motor learning are currently unknown. Therefore, this study examines the contributions of over-night sleeping and mid-day napping to procedural skill learning. One hundred and eight children were instructed to practice a finger sequence task using computer keyboards. After an equivalent 11-h interval in one of the three states (sleep, nap, wakefulness), children performed the same sequence in retention tests and a novel sequence in transfer tests. Changes in the movement time and sequence accuracy were evaluated between ages (6-7, 8-9, 10-11years) during practice, and from skill training to retrievals across three states. Results suggest that night-time sleeping and day-time napping improved the tapping speed, especially for the 6-year-olds. The circadian factor did not affect off-line motor learning in children. The interference between the two counter-balanced retrieval tests was not found for the off-line motor learning. This research offers possible evidence about the age-related motor learning characteristics in children and a potential means for enhancing developmental motor skills. The dynamics between age, experience, memory formation, and the theoretical implications of motor skill acquisition are discussed.

Developmental implications of children's brain networks and learning.

The human brain works as a synergistic system where information exchanges between functional neuronal networks. Rudimentary networks are observed in the brain during infancy. In recent years, the question of how functional networks develop and mature in children has been a hotly discussed topic. In this review, we examined the developmental characteristics of functional networks and the impacts of skill training on children's brains. We first focused on the general rules of brain network development and on the typical and atypical development of children's brain networks. After that, we highlighted the essentials of neural plasticity and the effects of learning on brain network development. We also discussed two important theoretical and practical concerns in brain network training. Finally, we concluded by presenting the significance of network training in typically and atypically developed brains.

Obesity Reduces Cognitive and Motor Functions across the Lifespan.

Due to a sedentary lifestyle, more and more people are becoming obese nowadays. In addition to health-related problems, obesity can also impair cognition and motor performance. Previous results have shown that obesity mainly affects cognition and motor behaviors through altering brain functions and musculoskeletal system, respectively. Many factors, such as insulin/leptin dysregulation and inflammation, mediate the effect of obesity and cognition and motor behaviors. Substantial evidence has suggested exercise to be an effective way to improve obesity and related cognitive and motor dysfunctions. This paper aims to discuss the association of obesity with cognition and motor behaviors and its underlying mechanisms. Following this, mechanisms of exercise to improve obesity-related dysfunctions are described. Finally, implications and future research direction are raised.

Mild cognitive impairment affects motor control and skill learning.

Mild cognitive impairment (MCI) is a transitional phase between normal cognitive aging and dementia. As the world population is aging rapidly, more MCI patients will be identified, posing significant problems to society. Normal aging is associated with cognitive and motor decline, and MCI brings additional impairments. Compared to healthy older adults, MCI patients show poorer motor control in a variety of tasks. Efficient motor control and skill learning are essential for occupational and leisure purposes; degradation of motor behaviors in MCI patients often adversely affects their health and quality of life. In this article, we first define MCI and describe its pathology and neural correlates. After this, we review cognitive changes and motor control and skill learning in normal aging. This section is followed by a discussion of MCI-related degradation of motor behaviors. Finally, we propose that multicomponent interventions targeting both cognitive and motor domains can improve MCI patients' motor functions. Future research directions are also raised.

Practice and nap schedules modulate children's motor learning.

Night- or day-time sleep enhances motor skill acquisition. However, prominent issues remained about the circadian (time-of-day) and homeostatic (time since last sleep) effects of sleep on developmental motor learning. Therefore, we examined the effects of nap schedules and nap-test-intervals (NTIs) on the learning of finger tapping sequences on computer keyboards. Children aged 6-7, 8-9, and 10-11 years explicitly acquired the short and long tapping orders that share the same movement strings (4-2-3-1-4, 4-2-3-1-4-2-3-1-4). Following a constant 8- or 10-hr post-learning period in one of the four NTIs (2, 4, 5, 7 hr), children in the morning napping groups, the afternoon napping groups, or the waking group performed the original long sequence in retention test (4-2-3-1-4-2-3-1-4) and the mirrored-order sequence in transfer test (1-3-2-4-1-3-2-4-1). Age and treatment differences in the movement time (MT, ms) and sequence accuracy (SA, %) were compared during skill learning and in retrieval tests. Results suggest that practice or nap affects MT and SA in a greater extent for the younger learners than for the older learners. The circadian effects might not change nap-based skill learning. Importantly, the longer NTIs resulted in superior retention performance than the shorter ones, suggesting that children require a relatively longer post-nap period to form motor memory. Finally, nap-based motor learning was more marked in skill retention than in skill transfer. Brain development may play an important role in motor learning. Our discussion centers on memory consolidation and its relevance for skill acquisition from early to late childhood.

Low frequency steady-state brain responses modulate large scale functional networks in a frequency-specific means.

Neural oscillations are essential for brain functions. Research has suggested that the frequency of neural oscillations is lower for more integrative and remote communications. In this vein, some resting-state studies have suggested that large scale networks function in the very low frequency range (<1 Hz). However, it is difficult to determine the frequency characteristics of brain networks because both resting-state studies and conventional frequency tagging approaches cannot simultaneously capture multiple large scale networks in controllable cognitive activities. In this preliminary study, we aimed to examine whether large scale networks can be modulated by task-induced low frequency steady-state brain responses (lfSSBRs) in a frequency-specific pattern. In a revised attention network test, the lfSSBRs were evoked in the triple network system and sensory-motor system, indicating that large scale networks can be modulated in a frequency tagging way. Furthermore, the inter- and intranetwork synchronizations as well as coherence were increased at the fundamental frequency and the first harmonic rather than at other frequency bands, indicating a frequency-specific modulation of information communication. However, there was no difference among attention conditions, indicating that lfSSBRs modulate the general attention state much stronger than distinguishing attention conditions. This study provides insights into the advantage and mechanism of lfSSBRs. More importantly, it paves a new way to investigate frequency-specific large scale brain activities.

Visuospatial working memory training facilitates visually-aided explicit sequence learning.

Finger sequence learning requires visuospatial working memory (WM). However, the dynamics between age, WM training, and motor skill acquisition are unclear. Therefore, we examined how visuospatial WM training improves finger movement sequential accuracy in younger (n=26, 21.1±1.37years) and older adults (n=22, 70.6±4.01years). After performing a finger sequence learning exercise and numerical and spatial WM tasks, participants in each age group were randomly assigned to either the experimental (EX) or control (CO) groups. For one hour daily over a 10-day period, the EX group practiced an adaptive n-back spatial task while those in the CO group practiced a non-adaptive version. As a result of WM practice, the EX participants increased their accuracy in the spatial n-back tasks, while accuracy remained unimproved in the numerical n-back tasks. In all groups, reaction times (RT) became shorter in most numerical and spatial n-back tasks. The learners in the EX group - but not in the CO group - showed improvements in their retention of finger sequences. The findings support our hypothesis that computerized visuospatial WM training improves finger sequence learning both in younger and in older adults. We discuss the theoretical implications and clinical relevance of this research for motor learning and functional rehabilitation.

Steady-state BOLD Response to Higher-order Cognition Modulates Low-Frequency Neural Oscillations.

Steady-state responses (SSRs) reflect the synchronous neural oscillations evoked by noninvasive and consistently repeated stimuli at the fundamental or harmonic frequencies. The steady-state evoked potentials (SSEPs; the representative form of the SSRs) have been widely used in the cognitive and clinical neurosciences and brain-computer interface research. However, the steady-state evoked potentials have limitations in examining high-frequency neural oscillations and basic cognition. In addition, synchronous neural oscillations in the low frequency range (<1 Hz) and in higher-order cognition have received a little attention. Therefore, we examined the SSRs in the low frequency range using a new index, the steady-state BOLD responses (SSBRs) evoked by semantic stimuli. Our results revealed that the significant SSBRs were induced at the fundamental frequency of stimuli and the first harmonic in task-related regions, suggesting the enhanced variability of neural oscillations entrained by exogenous stimuli. The SSBRs were independent of neurovascular coupling and characterized by sensorimotor bias, an indication of regional-dependent neuroplasticity. Furthermore, the amplitude of SSBRs may predict behavioral performance and show the psychophysiological relevance. Our findings provide valuable insights into the understanding of the SSRs evoked by higher-order cognition and how the SSRs modulate low-frequency neural oscillations.

Children's age modulates the effect of part and whole practice in motor learning.

Motor skills can be learned by practicing the whole or part of a movement. In whole practice (WP), a skill is acquired by practicing the movement in its entirety, whereas in part practice (PP), a task is learned by practicing its components before combining them. However, the effectiveness of WP and PP in children is unclear. We, therefore, examined the effects of WP and PP on the learning of juggling among first-, third-, and fifth-graders. Children of each grade were pseudo-randomly assigned to the WP or PP group to learn cascade juggling in 6 days. After baseline assessments, the WP learners practiced three-beanbag juggling. The PP learners practiced one-beanbag juggling on the first 2 days, two-beanbag juggling on the following 2 days, and three-beanbag juggling on the last 2 days. Practice consisted of 40 trials each day. Skill retention and transfer trials (juggling in the opposite direction) were measured 24h after training (number of catches). There was no significant difference between WP and PP in skill retention (WP: 1.28 ± 0.73; PP: 1.42 ± 046, p = .40) and transfer (WP: 1.31 ± 0.78; PP: 1.37 ± 0.55, p = .49). However, a time × grade × group interaction (p < .001) was observed in retention. Children of different grades received differential benefits from the WP and PP regimens. The fifth-graders learned better using WP, whereas the first- and third-graders showed better learning with PP. We discuss the three possible explanations for the results (neural maturity, explicit learning, and coordination capabilities).

Reliable Attention Network Scores and Mutually Inhibited Inter-network Relationships Revealed by Mixed Design and Non-orthogonal Method.

The attention system can be divided into alerting, orienting, and executive control networks. The efficiency and independence of attention networks have been widely tested with the attention network test (ANT) and its revised versions. However, many studies have failed to find effects of attention network scores (ANSs) and inter-network relationships (INRs). Moreover, the low reliability of ANSs can not meet the demands of theoretical and empirical investigations. Two methodological factors (the inter-trial influence in the event-related design and the inter-network interference in orthogonal contrast) may be responsible for the unreliability of ANT. In this study, we combined the mixed design and non-orthogonal method to explore ANSs and directional INRs. With a small number of trials, we obtained reliable and independent ANSs (split-half reliability of alerting: 0.684; orienting: 0.588; and executive control: 0.616), suggesting an individual and specific attention system. Furthermore, mutual inhibition was observed when two networks were operated simultaneously, indicating a differentiated but integrated attention system. Overall, the reliable and individual specific ANSs and mutually inhibited INRs provide novel insight into the understanding of the developmental, physiological and pathological mechanisms of attention networks, and can benefit future experimental and clinical investigations of attention using ANT.

Steady-state BOLD response modulates low frequency neural oscillations.

Neural oscillations are the intrinsic characteristics of brain activities. Traditional electrophysiological techniques (e.g., the steady-state evoked potential, SSEP) have provided important insights into the mechanisms of neural oscillations in the high frequency ranges (>1 Hz). However, the neural oscillations within the low frequency ranges (<1 Hz) and deep brain areas are rarely examined. Based on the advantages of the low frequency blood oxygen level dependent (BOLD) fluctuations, we expected that the steady-state BOLD responses (SSBRs) would be elicited and modulate low frequency neural oscillations. Twenty six participants completed a simple reaction time task with the constant stimuli frequencies of 0.0625 Hz and 0.125 Hz. Power analysis and hemodynamic response function deconvolution method were used to extract SSBRs and recover neural level signals. The SSEP-like waveforms were observed at the whole brain level and at several task-related brain regions. Specifically, the harmonic phenomenon of SSBR was task-related and independent of the neurovascular coupling. These findings suggested that the SSBRs represent non-linear neural oscillations but not brain activations. In comparison with the conventional general linear model, the SSBRs provide us novel insights into the non-linear brain activities, low frequency neural oscillations, and neuroplasticity of brain training and cognitive activities.