Handedness as a major determinant of lateral bias in human functional cradling.

Studies examining infant cradling have almost uniformly concluded with a general human left-side bias for cradling, indicating that people prefer to hold an infant to the left of their body. Explanations for the notion of the left-side cradling bias have traditionally been searched for in a variety of factors, for example, in terms of maternal heartbeat, genetic factors, in the form of an ear asymmetry where auditory information is perceived faster through the left ear, as a result of a right hemispheric functional specialization for perception of emotions and faces, and in identifying a motor bias of the infant, such as the tendency of newborn infants to lie with the face to the right when placed supine. Interestingly, handedness is generally considered an inadequate explanation for the lateralized cradling bias, despite it being an intuitively plausible one. In this brief review, I put forward the cradler's handedness as the most convincing and elegant determinant of the cradling bias. This explanation is consistent with a developmental cascades' framework where the cradling bias can be understood as the result of a multitude of factors across a range of levels and systems.

Handwriting but not typewriting leads to widespread brain connectivity: a high-density EEG study with implications for the classroom.

As traditional handwriting is progressively being replaced by digital devices, it is essential to investigate the implications for the human brain. Brain electrical activity was recorded in 36 university students as they were handwriting visually presented words using a digital pen and typewriting the words on a keyboard. Connectivity analyses were performed on EEG data recorded with a 256-channel sensor array. When writing by hand, brain connectivity patterns were far more elaborate than when typewriting on a keyboard, as shown by widespread theta/alpha connectivity coherence patterns between network hubs and nodes in parietal and central brain regions. Existing literature indicates that connectivity patterns in these brain areas and at such frequencies are crucial for memory formation and for encoding new information and, therefore, are beneficial for learning. Our findings suggest that the spatiotemporal pattern from visual and proprioceptive information obtained through the precisely controlled hand movements when using a pen, contribute extensively to the brain's connectivity patterns that promote learning. We urge that children, from an early age, must be exposed to handwriting activities in school to establish the neuronal connectivity patterns that provide the brain with optimal conditions for learning. Although it is vital to maintain handwriting practice at school, it is also important to keep up with continuously developing technological advances. Therefore, both teachers and students should be aware of which practice has the best learning effect in what context, for example when taking lecture notes or when writing an essay.

Neural Aspects of Prospective Control through Resonating Taus in an Interceptive Timing Task.

High-density electroencephalography from visual and motor cortices in addition to kinematic hand and target movement recordings were used to investigate τ-coupling between brain activity patterns and physical movements in an interceptive timing task. Twelve adult participants were presented with a target car moving towards a destination at three constant accelerations, and an effector dot was available to intercept the car at the destination with a swift movement of the finger. A τ-coupling analysis was used to investigate involvement of perception and action variables at both the ecological scale of behavior and neural scale. By introducing the concept of resonance, the underlying dynamics of interceptive actions were investigated. A variety of one- and two-scale τ-coupling analyses showed significant differences in distinguishing between slow, medium, and fast target speed when car motion and finger movement, VEP and MRP brain activity, VEP and car motion, and MRP and finger movement were involved. These results suggested that the temporal structure present at the ecological scale is reflected at the neural scale. The results further showed a strong effect of target speed, indicating that τ-coupling constants k and kres increased with higher speeds of the moving target. It was concluded that τ-coupling can be considered a valuable tool when combining different types of variables at both the ecological and neural levels of analysis.

Longitudinal study of infants receiving extra motor stimulation, full-term control infants, and infants born preterm: High-density EEG analyses of cortical activity in response to visual motion.

Electroencephalography was used to investigate the effects of extrastimulation and preterm birth on the development of visual motion perception during early infancy. Infants receiving extra motor stimulation in the form of baby swimming, a traditionally raised control group, and preterm born infants were presented with an optic flow pattern simulating forward and reversed self-motion and unstructured random visual motion before and after they achieved self-produced locomotion. Extrastimulated infants started crawling earlier and displayed significantly shorter N2 latencies in response to visual motion than their full-term and preterm peers. Preterm infants could not differentiate between visual motion conditions, nor did they significantly decrease their latencies with age and locomotor experience. Differences in induced activities were also observed with desynchronized theta-band activity in all infants, but with more mature synchronized alpha-beta band activity only in extrastimulated infants after they had become mobile. Compared with the other infants, preterm infants showed more widespread desynchronized oscillatory activities at lower frequencies at the age of 1 year (corrected for prematurity). The overall advanced performance of extrastimulated infants was attributed to their enriched motor stimulation. The poorer responses in the preterm infants could be related to impairment of the dorsal visual stream that is specialized in the processing of visual motion.

Development of motion speed perception from infancy to early adulthood: a high-density EEG study of simulated forward motion through optic flow.

This study investigated evoked and oscillatory brain activity in response to forward visual motion at three different ecologically valid speeds, simulated through an optic flow pattern consisting of a virtual road with moving poles at either side of it. Participants were prelocomotor infants at 4-5 months, crawling infants at 9-11 months, primary school children at 6 years, adolescents at 12 years, and young adults. N2 latencies for motion decreased significantly with age from around 400 ms in prelocomotor infants to 325 ms in crawling infants, and from 300 and 275 ms in 6- and 12-year-olds, respectively, to 250 ms in adults. Infants at 4-5 months displayed the longest latencies and appeared unable to differentiate between motion speeds. In contrast, crawling infants at 9-11 months and 6-year-old children differentiated between low, medium and high speeds, with shortest latency for low speed. Adolescents and adults displayed similar short latencies for the three motion speeds, indicating that they perceived them as equally easy to detect. Time-frequency analyses indicated that with increasing age, participants showed a progression from low- to high-frequency desynchronized oscillatory brain activity in response to visual motion. The developmental differences in motion speed perception are interpreted in terms of a combination of neurobiological development and increased experience with self-produced locomotion. Our findings suggest that motion speed perception is not fully developed until adolescence, which has implications for children's road traffic safety.

The Importance of Cursive Handwriting Over Typewriting for Learning in the Classroom: A High-Density EEG Study of 12-Year-Old Children and Young Adults.

To write by hand, to type, or to draw - which of these strategies is the most efficient for optimal learning in the classroom? As digital devices are increasingly replacing traditional writing by hand, it is crucial to examine the long-term implications of this practice. High-density electroencephalogram (HD EEG) was used in 12 young adults and 12, 12-year-old children to study brain electrical activity as they were writing in cursive by hand, typewriting, or drawing visually presented words that were varying in difficulty. Analyses of temporal spectral evolution (TSE, i.e., time-dependent amplitude changes) were performed on EEG data recorded with a 256-channel sensor array. For young adults, we found that when writing by hand using a digital pen on a touchscreen, brain areas in the parietal and central regions showed event-related synchronized activity in the theta range. Existing literature suggests that such oscillatory neuronal activity in these particular brain areas is important for memory and for the encoding of new information and, therefore, provides the brain with optimal conditions for learning. When drawing, we found similar activation patterns in the parietal areas, in addition to event-related desynchronization in the alpha/beta range, suggesting both similarities but also slight differences in activation patterns when drawing and writing by hand. When typewriting on a keyboard, we found event-related desynchronized activity in the theta range and, to a lesser extent, in the alpha range in parietal and central brain regions. However, as this activity was desynchronized and differed from when writing by hand and drawing, its relation to learning remains unclear. For 12-year-old children, the same activation patterns were found, but to a lesser extent. We suggest that children, from an early age, must be exposed to handwriting and drawing activities in school to establish the neuronal oscillation patterns that are beneficial for learning. We conclude that because of the benefits of sensory-motor integration due to the larger involvement of the senses as well as fine and precisely controlled hand movements when writing by hand and when drawing, it is vital to maintain both activities in a learning environment to facilitate and optimize learning.

A high-density EEG study of differentiation between two speeds and directions of simulated optic flow in adults and infants.

A high-density EEG study was carried out to investigate cortical activity in response to forward and backward visual motion at two different driving speeds, simulated through optic flow. Participants were prelocomotor infants at the age of 4-5 months and infants with at least 3 weeks of crawling experience at the age of 8-11 months, and adults. Adults displayed shorter N2 latencies in response to forward as opposed to backward visual motion and differentiated significantly between low and high speeds, with shorter latencies for low speeds. Only infants at 8-11 months displayed similar latency differences between motion directions, and exclusively in response to low speed. The developmental differences in latency between infant groups are interpreted in terms of a combination of increased experience with self-produced locomotion and neurobiological development. Analyses of temporal spectral evolution (TSE, time-dependent amplitude changes) were also performed to investigate nonphase-locked changes at lower frequencies in underlying neuronal networks. TSE showed event-related desynchronization activity in response to visual motion for infants compared to adults. The poorer responses in infants are probably related to immaturity of the dorsal visual stream specialized in the processing of visual motion and could explain the observed problems in infants with differentiating high speeds of up to 50 km/h.

Only Three Fingers Write, but the Whole Brain Works: A High-Density EEG Study Showing Advantages of Drawing Over Typing for Learning.

Are different parts of the brain active when we type on a keyboard as opposed to when we draw visual images on a tablet? Electroencephalogram (EEG) was used in young adults to study brain electrical activity as they were typing or describing in words visually presented PictionaryTM words using a keyboard, or as they were drawing pictures of the same words on a tablet using a stylus. Analyses of temporal spectral evolution (time-dependent amplitude changes) were performed on EEG data recorded with a 256-channel sensor array. We found that when drawing, brain areas in the parietal and occipital regions showed event related desynchronization activity in the theta/alpha range. Existing literature suggests that such oscillatory neuronal activity provides the brain with optimal conditions for learning. When describing the words using the keyboard, upper alpha/beta/gamma range activity in the central and frontal brain regions were observed, especially during the ideation phase. However, since this activity was highly synchronized, its relation to learning remains unclear. We concluded that because of the benefits for sensory-motor integration and learning, traditional handwritten notes are preferably combined with visualizations (e.g., small drawings, shapes, arrows, symbols) to facilitate and optimize learning.

TauG-guidance of dynamic balance control during gait initiation in patients with chronic fatigue syndrome and fibromyalgia.

BACKGROUND: Impaired postural control has been reported in static conditions in chronic fatigue syndrome and fibromyalgia, but postural control in dynamic tasks have not yet been investigated. Thus, we investigated measurements from a force plate to evaluate dynamic balance control during gait initiation in patients with chronic fatigue syndrome and fibromyalgia compared to matched healthy controls. METHODS: Thirty female participants (10 per group) performed five trials of gait initiation. Center of pressure (CoP) trajectory of the initial weight shift onto the supporting foot in the mediolateral direction (CoPX) was analyzed using General Tau Theory. We investigated the hypothesis that tau of the CoPX motion-gap (τCoPx) is coupled onto an intrinsic tauG-guide (τG) by keeping the relation τCoPx=KτG, where K is a scaling factor that determines the relevant kinematics of a movement. FINDINGS: Mean K values were 0.57, 0.55, and 0.50 in fibromyalgia, chronic fatigue syndrome, and healthy controls, respectively. Both patient groups showed K values significantly higher than 0.50 (P<0.05), indicating that patients showed poorer dynamic balance control, CoPX colliding with the boundaries of the base of support (K>0.5). INTERPRETATION: The findings revealed a lower level of dynamic postural control in both fibromyalgia and chronic fatigue syndrome compared to controls.

Longitudinal study of preterm and full-term infants: High-density EEG analyses of cortical activity in response to visual motion.

Electroencephalogram (EEG) was used to investigate brain electrical activity of full-term and preterm infants at 4 and 12 months of age as a functional response mechanism to structured optic flow and random visual motion. EEG data were recorded with an array of 128-channel sensors. Visual evoked potentials (VEPs) and temporal spectral evolution (TSE, time-dependent amplitude changes) were analysed. VEP results showed a significant improvement in full-term infants' latencies with age for forwards and reversed optic flow but not random visual motion. Full-term infants at 12 months significantly differentiated between the motion conditions, with the shortest latency observed for forwards optic flow and the longest latency for random visual motion, while preterm infants did not improve their latencies with age, nor were they able to differentiate between the motion conditions at 12 months. Differences in induced activities were also observed where comparisons between TSEs of the motion conditions and a static non-flow pattern showed desynchronised theta-band activity in both full-term and preterm infants, with synchronised alpha-beta band activity observed only in the full-term infants at 12 months. Full-term infants at 12 months with a substantial amount of self-produced locomotor experience and neural maturation coupled with faster oscillating cell assemblies, rely on the perception of structured optic flow to move around efficiently in the environment. The poorer responses in the preterm infants could be related to impairment of the dorsal visual stream specialized in the processing of visual motion.

Development of Visual Motion Perception for Prospective Control: Brain and Behavioral Studies in Infants.

During infancy, smart perceptual mechanisms develop allowing infants to judge time-space motion dynamics more efficiently with age and locomotor experience. This emerging capacity may be vital to enable preparedness for upcoming events and to be able to navigate in a changing environment. Little is known about brain changes that support the development of prospective control and about processes, such as preterm birth, that may compromise it. As a function of perception of visual motion, this paper will describe behavioral and brain studies with young infants investigating the development of visual perception for prospective control. By means of the three visual motion paradigms of occlusion, looming, and optic flow, our research shows the importance of including behavioral data when studying the neural correlates of prospective control.

A high-density EEG study of differences between three high speeds of simulated forward motion from optic flow in adult participants.

A high-density EEG study was conducted to investigate evoked and oscillatory brain activity in response to high speeds of simulated forward motion. Participants were shown an optic flow pattern consisting of a virtual road with moving poles at either side of it, simulating structured forward motion at different driving speeds (25, 50, and 75 km/h) with a static control condition between each motion condition. Significant differences in N2 latencies and peak amplitudes between the three speeds of visual motion were found in parietal channels of interest P3 and P4. As motion speed increased, peak latency increased while peak amplitude decreased which might indicate that higher driving speeds are perceived as more demanding resulting in longer latencies, and as fewer neurons in the motion sensitive areas of the adult brain appear to be attuned to such high visual speeds this could explain the observed inverse relationship between speed and amplitude. In addition, significant differences between alpha de-synchronizations for forward motion and alpha synchronizations in the static condition were found in the parietal midline (PM) source. It was suggested that the alpha de-synchronizations reflect an activated state related to the visual processing of simulated forward motion, whereas the alpha synchronizations in response to the static condition reflect a deactivated resting period.

Longitudinal study of perception of structured optic flow and random visual motion in infants using high-density EEG.

Electroencephalogram (EEG) was used in infants at 3-4 months and 11-12 months to longitudinally study brain electrical activity as the infants were exposed to structured forwards and reversed optic flow, and non-structured random visual motion. Analyses of visual evoked potential (VEP) and temporal spectral evolution (TSE, time-dependent amplitude changes) were performed on EEG data recorded with a 128-channel sensor array. VEP results showed infants to significantly differentiate between the radial motion conditions, but only at 11-12 months where they showed shortest latency for forwards optic flow and longest latency for random visual motion. When the TSE results of the motion conditions were compared with those of a static non-flow dot pattern, infants at 3-4 and 11-12 months both showed significant differences in induced activity. A decrease in amplitudes at 5-7 Hz was observed as desynchronized theta-band activity at both 3-4 and 11-12 months, while an increase in amplitudes at 9-13 Hz was observed as synchronized alpha-band activity only at 11-12 months. It was concluded that brain electrical activities related to visual motion perception change during the first year of life, and these changes can be observed both in the VEP and induced activities of EEG. With adequate neurobiological development and locomotor experience infants around 1 year of age rely, more so than when they were younger, on structured optic flow and show a more adult-like specialization for motion where faster oscillating cell assemblies have fewer but more specialized neurons, resulting in improved visual motion perception.

Combining findings from gaze and electroencephalography recordings to study timing in a visual tracking task.

Electroencephalography (EEG) and gaze data have traditionally been separated in neurocognitive studies because of the artefacts that even small controlled eye movements produce. Study of gaze control in a visual tracking task provides information about an individual's prospective control. By including gaze events in the EEG analysis, we studied prospective control and its neural correlates during deceleration in a visual tracking task. Adult participants followed with their gaze a small car moving horizontally on a large screen, where the final approach of the car was temporarily occluded, and pushed a button to stop the car at the reappearance point. Two gaze events, the behavioural push button response and the nonbehavioural stimulus onset, were used to time-lock the averaged event-related potential (ERP) waveform. A significant effect of deceleration on peak amplitude in parietal channel Pz (P<0.05) was found when ERP waveforms were time-locked to the prospective gaze shift over the occluder. The peak decreased in amplitude as car deceleration increased when participants successfully stopped the car, indicating successful deceleration discrimination. No such effect was found when ERP waveforms were time-locked to any of the other events. Thus, a traditional stimulus onset time-locking procedure is likely to distort the averaged signal and consequently hide important Pz-peak amplitude differences on the prospective timing of decelerating object motion during occlusion. This study shows the importance of including behavioural data when studying neural correlates of prospective control and proposes active incorporation of behavioural data into the EEG analysis.

Longitudinal study of looming in infants with high-density EEG.

A rapidly approaching object provides information about the object's approach and how imminent a collision is. Prospective control when responding to a looming virtual object approaching on a direct collision course was studied longitudinally in 10 infants aged 5/6 and 12/13 months. Different characteristics of the looming-related visual evoked potential (VEP) responses from infants' brain electrical recordings (EEG) were explored and compared between the infants at these different ages. The aim of this study was to find evidence for infant brain electrical responses coherent with a looming stimulus approaching the infant under three different accelerations. It was also investigated whether the use of different timing strategies to estimate the loom's time-to-collision would produce differences in the EEG recordings. The results showed that the timing and the duration of the VEP responses differed with age. At the age of 5/6 months, infants showed VEP peaks earlier in the looming sequence and VEP responses with longer duration than when they were 12/13 months old. Results from the timing-strategy analysis showed that with age, 4 infants shifted from a less efficient timing strategy involving the loom's velocity to the more efficient strategy involving the loom's time-to-collision. Further, it was found that peak VEP activation in the investigated areas propagated across the cortex, showing the highest observed activation in the occipital area at the age of 5/6 months, whereas the parietal area showed the highest activation when the infants were 12/13 months. The decrease in processing time together with a peak VEP response closer to the loom's time-to-collision indicate a developmental trend in infants' prediction of an object's time-to-collision. This developmental trend is further substantiated by the shift from a less efficient to a more efficient timing strategy and by evidence of propagated peak VEP activation towards higher information processing areas in the visual pathway with age. As infants grow older and become more mobile, one of the underlying causes of the developmental trend found in our study could be due to an increase in locomotor experience. More follow-up research is needed to investigate the relation between behavioural development and changes in brain activity associated with infants' perception of looming motion.

TauG-guidance of dynamic balance control during gait initiation across adulthood.

Measurements from force plates were investigated to identify the life-span developmental course of dynamic balance control during gait initiation across adulthood. Center of pressure (CoP) data of the initial weight shift onto the supporting foot in the mediolateral (CoP(x)) direction were tauG analyzed, investigating the hypothesis that tau of the CoP(x) motion gap (τ(CoPx)) is tau-coupled onto an intrinsic tauG-guide (τ(G)), by maintaining the relation τ(CoPx)=Kτ(G), for a constant K. Participants were in their twenties, forties, sixties, and eighties. As regression analysis suggested a strong linear relationship between τ(CoPx) and τ(G), an investigation of the regression slope as an estimate of the coupling constant K in the tau-coupling equation was justified. Mean K values increased significantly with age from 0.40, 0.47, 0.67, to 0.79, suggesting that control of dynamic balance deteriorates from participants in their twenties making touch contact (K≤0.5) to participants in their sixties and eighties colliding with the boundaries of the base of support (K>0.5). The findings may prove useful as a measure for testing prospective balance control, a helpful tool for early detection of elderly people at increased risk of falling.

Seeing it coming: infants' brain responses to looming danger.

A fundamental property of most animals is the ability to see whether an object is approaching on a direct collision course and, if so, when it will collide. Using high-density electroencephalography in 5- to 11-month-old infants and a looming stimulus approaching under three different accelerations, we investigated how the young human nervous system extracts and processes information for impending collision. Here, we show that infants' looming related brain activity is characterised by theta oscillations. Source analyses reveal clear localised activity in the visual cortex. Analysing the temporal dynamics of the source waveform, we provide evidence that the temporal structure of different looming stimuli is sustained during processing in the more mature infant brain, providing infants with increasingly veridical time-to-collision information about looming danger as they grow older and become more mobile.

A longitudinal study of prospective control in catching by full-term and preterm infants.

Prospective control when catching moving toys was studied longitudinally in full-term and preterm infants between the ages of 22 and 48 weeks. The toy's distance and time to the catching place and its velocity were explored as possible timing strategies used by infants to start their hand movement. The aim of the study was to find evidence for a shift in timing strategy and whether there were differences between full-term and preterm infants. In addition, it was investigated how infants continuously guided their hands to the toy and whether this guidance was influenced by their use of timing strategy. The toy approached the infants from the side with different constant velocities and constant accelerations. Results showed that there was little difference between full-term and preterm infants' use of timing strategies. Initially, infants used a distance- or velocity-strategy, possibly causing them to have many unsuccessful catches. After a shift to a time-strategy, infants appeared to increase the number of successful catches and performed longer and more functional tau-couplings between the hand and the toy. One preterm infant did not switch to a time-strategy, and frequently missed the moving toy. The same infant also showed less functional tau-coupling with non-controlled collisions between the hand and the toy. More follow-up research is needed to investigate whether problems with extracting the relevant perceptual information for action could be an early indication of later perceptuo-motor difficulties.

Perception of structured optic flow and random visual motion in infants and adults: a high-density EEG study.

Electroencephalogram (EEG) was used in 8-month-old infants and adults to study brain electrical activity as a function of perception of structured optic flow and random visual motion. A combination of visual evoked potential (VEP) analyses and analyses of temporal spectral evolution (TSE, time-dependent spectral power) was carried out. Significant differences were found for the N2 component of VEP for optic flow versus random visual motion within and between groups. Both adults and infants showed shorter latencies for structured optic flow than random visual motion, and infants showed longer latencies, particularly for random visual motion, and larger amplitudes than adults. Both groups also showed significant differences in induced activity when TSE of the two motion stimuli (optic flow and random visual motion) was compared with TSE of a static dot pattern. Infants showed an induced decrease in the amplitudes in theta-band frequency, while adults showed an induced increase in beta-band frequency. Differences in induced activity for the two motion stimuli could, however, not be observed. Brain activity related to motion stimuli is different for infants and adults and the differences are observed both in VEPs and in induced activity of the EEG. To investigate how changes in locomotor development are related to accompanying changes in brain activity associated with visual motion perception, more data of infants with different experiences in self-produced locomotion are required.

Preterm infants' timing strategies to optical collisions.

BACKGROUND: A virtual object approaching on a collision course will elicit defensive blinking in infants. Previous research has shown that when precisely timing their blinks, full-term infants shift from using a strategy based on visual angle/angular velocity to a strategy based on time between 22 and 30 weeks of age. AIM: To investigate which timing strategy preterm infants use to determine when to make the defensive blink. METHODS: Eight preterm infants were tested at 26 weeks, corrected for prematurity. For three of these infants, longitudinal data at 22, 26, and 30 weeks were available. The virtual object approached the infants with different constant velocities and constant accelerations. RESULTS: At 26 weeks, three infants blinked when the virtual object's visual angle reached a threshold value causing them to have problems with fast, accelerating approaches. Four infants blinked when the virtual object was a certain time away, allowing them to blink in time on all approach conditions. One infant stood out because he relied on a timing strategy based on angular velocity on all three test sessions, causing him to blink late on a large number of trials even at 30 weeks. CONCLUSION: As good timing is essential for successful interaction with the environment, the inability to switch from a timing strategy that is prone to errors to a strategy that enables successful defensive blinking reflects lack of flexibility to adjust appropriately to local circumstances. This might be an early indication of perceptuo-motor problems that warrants further investigation.