The development of simple acoustic reaction time in normal children

Motor Unit Firing Properties During Force Control Task and Associations With Neurological Tests in Children

The present study aimed to clarify the development of motor unit (MU) firing properties and the association between those neural properties and force steadiness (FS)/neurological tests in 6- to 12-year-old children. Fifty-eight school-aged children performed maximal voluntary knee extension contraction, a submaximal FS test at 10% of maximal voluntary knee extension contraction, knee extension reaction time to light stimulus test, and single-leg standing test, and data from 38 children who passed the criteria were subject to analysis. During the FS test, high-density surface electromyography was recorded from the vastus lateralis muscle to identify individual MU firing activity. FS was improved with an increase in age (r = -.540, P < .001). The MU firing rate (MUFR) was significantly decreased with an increase in age (r = -.343, P = .035). MUFR variability was not associated with age. Although there was no significant correlation between FS and MUFR, FS was significantly correlated with MUFR variability even after adjustment for the effect of age (r = .551, P = .002). Neither the reaction time nor the single-leg standing test was correlated with any MU firing properties. These findings suggest that MUFR variability makes an important contribution to precise force control in children but does not naturally develop with age.

Can a Multidisciplinary Weight Loss Treatment Improve Motor Performance in Children with Obesity? Results from an Observational Study

In the last two decades, the relationship between weight status and children's motor skill competence has been receiving increasing attention, given its possible role in the prevention and treatment of obesity. This study aimed to evaluate the effect of a multidisciplinary obesity treatment on motor performance in a sample of Italian children and adolescents. Visual and auditory reaction time (VRT and ART), vertical jump elevation (VJE) and power (VJP), body mass index (BMI) and BMI-standard deviation score (BMI-SDS), waist circumference (WC), body composition, dietary habits and physical activity (PA) levels were assessed at baseline and at 6- and 12-month follow-up. Significant improvements were observed in BMI-SDS and FFM, diet and PA levels. Adolescents showed significant improvements in VRT and ART. Jump elevation and power increased in both children and adolescent subgroups. Girls exhibited greater changes than boys in both VRT and ART and VJP but lower changes in VJE. VRT improvement was related to age (OR = 0.285, 95%CI 0.098-0.830, p = 0.021) and FFM (OR = 0.255, 95%CI 0.070-0.933, p = 0.039). An increase in VJE was associated with BMI-SDS (OR = 0.158, 95%CI 0.036-0.695, p = 0.015) and with PA level (OR = 19.102, 95%CI 4.442-82.142, p < 0.001); the increase in VJP was related with the increase in PA (OR = 5.564, 95%CI 1.812-17.081, p = 0.003). These findings suggest the possible effects of a multidisciplinary obesity treatment on children's motor competence. Since the improvement in motor skills can increase children's motivation and adherence to weight loss treatment in the long term, these aspects should be further investigated.

Influence of Sex, Age, and Trial Blocks on Simple Reaction Times of Elementary School Children

The present study was conducted to examine the influence of sex, age, and trial blocks on the simple reaction times of elementary school children. Each of 78 right-handed 6-, 8-, and 10-yr.-old boys and girls depressed a key in response to the onset of a blue light imperative stimulus for 4 familiarization- and 20 test-trials. Changes across the test-trials were assessed by grouping simple RTs into five blocks of four reactions each. A three-way factorial analysis of variance (sex × age × trial blocks) with repeated measures on the last factor indicated that all three main effects were significant and that none of the interactions was significant. Boys reacted faster than girls, simple RT decreased with each successive age and was faster during trial Blocks 1 and 2 than at Block 5.

The development of organized visual search

Visual search plays an important role in guiding behavior. Children have more difficulty performing conjunction search tasks than adults. The present research evaluates whether developmental differences in children's ability to organize serial visual search (i.e., search organization skills) contribute to performance limitations in a typical conjunction search task. We evaluated 134 children between the ages of 2 and 17 on separate tasks measuring search for targets defined by a conjunction of features or by distinct features. Our results demonstrated that children organize their visual search better as they get older. As children's skills at organizing visual search improve they become more accurate at locating targets with conjunction of features amongst distractors, but not for targets with distinct features. Developmental limitations in children's abilities to organize their visual search of the environment are an important component of poor conjunction search in young children. In addition, our findings provide preliminary evidence that, like other visuospatial tasks, exposure to reading may influence children's spatial orientation to the visual environment when performing a visual search.

Developmental differences in auditory detection and localization of approaching vehicles

Pedestrian safety is a significant problem in the United States, with thousands being injured each year. Multiple risk factors exist, but one poorly understood factor is pedestrians' ability to attend to vehicles using auditory cues. Auditory information in the pedestrian setting is increasing in importance with the growing number of quieter hybrid and all-electric vehicles on America's roadways that do not emit sound cues pedestrians expect from an approaching vehicle. Our study explored developmental differences in pedestrians' detection and localization of approaching vehicles. Fifty children ages 6-9 years, and 35 adults participated. Participants' performance varied significantly by age, and with increasing speed and direction of the vehicle's approach. Results underscore the importance of understanding children's and adults' use of auditory cues for pedestrian safety and highlight the need for further research.

Intensive baseball practice improves the Go/Nogo reaction time, but not the simple reaction time

Baseball hitters are required to make decisions whether to swing or not as quickly as possible. Therefore, we can assume that skilled baseball players have a quicker response. To verify this hypothesis, we assessed the effect of baseball experience or skill levels on simple reaction times and Go/Nogo reaction times in 82 university students (22 baseball players, 22 tennis players, and 38 nonathletes) and 17 professional baseball players. Also, to clarify whether this ability was innate or acquired, we examined the effects of long-term practice for baseball hitting in 94 senior high school students (26 baseball players and 68 non-baseball players). There were no differences in simple reaction time either for sports experience or for skill levels. On the contrary, the Go/Nogo reaction time for baseball players was significantly shorter than that of the tennis players and nonathletes. The Go/Nogo reaction time of higher-skill baseball players was significantly shorter than that of lower-skill players, while that of the professional baseball players was the shortest. The professional players showed the highest (almost linear) correlation between the Go/Nogo reaction time and simple reaction time. A longitudinal study showed that 2 years of hitting practice improved the Go/Nogo reaction time, while the simple reaction time remained constant. A cross-sectional study of high school non-baseball players showed no differences either in the simple or Go/Nogo reaction times in relation to school year. In conclusion, intensive practice, including Go or Nogo decision making, improved the Go/Nogo reaction time, but not the simple reaction time.

Developmental course of auditory processing interactions: Garner interference and Simon interference

Previous research suggests that with increasing age children become more efficient in inhibiting conflicting responses and in resisting interference from irrelevant information. We assessed the abilities of 100 children (ages 3-16 years) and 20 adults to resist interference during the processing of 2 auditory dimensions of speech, namely the speaker's gender and spatial location. The degree of interference from irrelevant variability in either dimension did not vary with age. Apparently, young children do not have more difficulty in resisting interference when the nontarget and the target are both perceptual attributes. We also assessed the participants' abilities to inhibit conflicting task-irrelevant information from spatial location and to resist interference from spatial variability in the context of conflict. In the presence of conflicting task-irrelevant information, both interference effects declined significantly with age. Developmental change in auditory processing seems to vary as a function of (1) the nature of the target-nontarget combination and (2) the presence/absence of conflicting task-irrelevant information.

Fast corticospinal system and motor performance in children: conduction proceeds skill

Transcranial magnetic stimulation and motor performance tests were used to study the correlation between corticospinal maturation and actual motor performance in a group of young school children (n = 10, mean age = 7 years, age range = 6-9 years). The results were compared with normal adults (n = 10, mean age = 24 years, age range = 22-26 years). In children the central conduction time under the preinnervation condition of facilitation and the postexcitatory silent period was similar to that in adults. However, the central conduction time under relaxation, the latency jump (defined as the difference between the two preinnervation conditions), and the stimulus intensity were statistically different between children and adults (P < 0.01-0.001). Children did not reach the same level of performance as adults in any of the motor performance tasks (simple acoustic reaction time, tapping, ballistic movement, tracking, and diadochokinesis) (P < 0.05-0.01). The results indicate that at an early school age, children already possess mature fast corticospinal pathways able to access spinal motoneurons through the pyramidal tract. However, despite the partially adult-like level of neuronal maturation, young school children were not able to perform deliberate motor actions with the same proficiency as adults.

Childhood hearing impairment: processing dependencies in multidimensional speech perception for an auditory level of analysis

OBJECTIVE

Our purpose was to determine whether the influence of childhood hearing impairment (HI) on multidimensional speech processing is a purely linguistic effect or whether childhood HI also affects the processing of speech dimensions representing an auditory level of analysis.

DESIGN

The processing dependencies characterizing the two dimensions of talker-gender and spatial location were studied in 40 children with HI and in two normal-hearing (NH) comparison groups representing similar chronological ages (N = 30) or similar vocabulary skills (N = 70). The processing interactions were assessed with a speeded selective-attention task requiring listeners to attend selectively to the gender of the talker and to ignore the spatial location and vice versa. The logic is that performance for the target dimension will not be affected by what is happening on the nontarget dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, listeners will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the irrelevant dimension. In the latter case, results may be analyzed in terms of Garner interference (the effect on performance of irrelevant variability in the to-be-ignored dimension) (Garner, 1974a) and Simon interference (the effect on performance of an irrelevant spatial source) (Simon, 1990).

RESULTS

Overall results in all listeners, those with NH or HI, showed significant interference when the participants were attending to the gender of the talker and ignoring spatial location and vice versa. The talker-gender and spatial-location dimensions of speech were not processed independently by these children. When the processing interactions were compared between the NH and HI groups, the presence of childhood HI as a general rule significantly diminished the degree of interference from spatial location. The degree of interference from the gender of the talker, on the other hand, remained normal in the presence of childhood HI. All listeners seemed stimulus bound by the gender of the talker. The degree of Garner interference did not show age-related or degree of loss-related change. The degree of Simon interference showed significant change as a function of age in the children with mild-moderate HI, but not in the children with severe HI. The developmental function for Simon interference in the children with mild-moderate HI was delayed to a degree that corresponded to the duration of the auditory deprivation.

CONCLUSIONS

The overall pattern of results indicates that the influence of childhood HI on multidimensional speech processing is not a purely linguistic effect.

Childhood hearing impairment: auditory and linguistic interactions during multidimensional speech processing

Children with mild-severe sensorineural hearing losses often use hearing aids and aural/oral language as their primary mode of communication, yet we know little about how speech is processed by these children. The purpose of this research was to investigate how the multidimensional information underlying accurate speech perception is processed by children with mild-severe hearing impairments. The processing of the auditory and linguistic dimensions of speech was assessed with a speeded selective-attention task (Garner, 1974a). Listeners were required to attend selectively to an auditory dimension (gender of the talker) and ignore a linguistic dimension (word) and vice versa. The hypothesis underlying the task is that performance for the target dimension will be unaffected by what is happening on the nontarget dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, listeners will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the irrelevant dimension (termed "Garner" interference). Both children with normal hearing (N = 90) and children with hearing impairment (N = 40) showed some degree of Garner interference, implying that the dimensions of speech are not processed independently by these children. However, relative to the children with normal hearing, the children with hearing impairment showed normal Garner interference when attending selectively to the word dimension (normally effective at ignoring talker-gender input) and reduced Garner interference when attending selectively to the talker-gender dimension (more effective at ignoring word input). This pattern of results implies that the auditory dimension has a normal strength-of-processing level that makes it normally distracting and that the linguistic dimension has an underdeveloped strength-of-processing level that makes it easier to ignore in children with hearing impairment.

Developmental trends in the interaction between auditory and linguistic processing

The developmental course of multidimensional speech processing was examined in 80 children between 3 and 6 years of age and in 60 adults between 20 and 86 years of age. Processing interactions were assessed with a speeded classification task (Garner, 1974a), which required the subjects to attend selectively to the voice dimension while ignoring the linguistic dimension, and vice versa. The children and adults exhibited both similarities and differences in the patterns of processing dependencies. For all ages, performance for each dimension was slower in the presence of variation in the irrelevant dimension; irrelevant variation in the voice dimension disrupted performance more than irrelevant variation in the linguistic dimension. Trends in the degree of interference, on the other hand, showed significant differences between dimensions as a function of age. Whereas the degree of interference for the voice-dimension-relevant did not show significant age-related change, the degree of interference for the word-dimension-relevant declined significantly with age in a linear as well as a quadratic manner. A major age-related change in the relation between dimensions was that word processing, relative to voice-gender processing, required significantly more time in the children than in the adults. Overall, the developmental course characterizing multidimensional speech processing evidenced more pronounced change when the linguistic dimension, rather than the voice dimension, was relevant.

Sleep and wakefulness in preadolescent children with deficits in attention, motor control and perception

In 10 children with deficits in attention, motor control and perception (DAMP), the relation between daytime vigilance and night-time sleep quality was examined with polygraphic sleep recordings, multiple sleep latency tests and measurements of reaction times. Two girls and eight boys, 6-12 years of age were studied. Eighteen normal children served as controls. Normal sleep regulation and sleep quality was found, but the children with DAMP tolerated the recording procedure less well than the controls. Most patients did not suffer from increased daytime sleepiness, but at MSLT 3, patients had short sleep latencies as in daytime hypersomnolence. Reaction times were significantly longer among the patients than among the controls. It is proposed that the findings may be related to functional changes in the forebrain.

The influence of attention on visual evoked potentials in normal adults and dementias

In normal subjects (n = 58, 22-71 y) the influence of the attention level on the VEP latency is studied, as is done in an additional small group of dementias (n = 14). The motor reaction time test (MRT) was selected to measure the attention level. The MRT was administered simultaneously with the VEP (checkerboard pattern reversal). By comparing VEP in test and non-test situations it proved that administration of MRT during VEP examination does not influence the VEP latencies. In dementias the motor reaction time is delayed but the degree of MRT delay did not correlate with the VEP latencies. This holds true for healthy volunteers as well as for demented patients. It is thus concluded that the latency increase of the late peaks of the VEP in dementias cannot be attributed to attentional deficits.

Continuous reaction times in cerebral dysfunction

The Continuous Reaction Times (CRT) method was used to examine pharmacological, psychiatric, medical and neurological problems in clinical practice where a detailed neuropsychological examination with a test battery was not possible. Either 100 visual or 150 auditory stimuli were given within a period of 6 1/2 or 10 min respectively, and the patients were instructed to react as quickly as possible to every stimulus. The same CRT method was applied to heterogeneous groups of patients with cerebral dysfunction and control subjects. The results demonstrated that it was useful as a screening test for the presence of cerebral dysfunction and was especially sensitive to progressive diseases. Its discriminative power was equivalent to more sophisticated and complex psychological tests. Even if CRT is a valid and reliable method of testing cerebral affection, the neural background for the reaction time process is still unknown and the test did not distinguish between patients with right- or left-hemisphere lesions and was not influenced by the etiology of the disease. CRT is therefore considered a provisional method, suggestive only for the actual diagnostic procedures. Only when the patients have a well-defined diagnosis e.g. a diffuse cerebral affection caused by a drug or a metabolic disorder can CRT be recommended as a measure of the degree of lowered consciousness.

Thermal sensitivity in healthy subjects is decreased by a central mechanism after TNS

Using the thermal sense as a model for nociception, the effects of conventional and acupuncture-like transcutaneous nerve stimulation (TNS) were tested on thresholds for warm and cold sensation in 8 healthy subjects. Photic stimulation did not change the thermically neutral zone (the warm-cold difference limen) from that seen under baseline conditions. However, the thermal difference limen usually increased with both types of TNS. The effect was ipsi- as well as contralateral, implying that a central inhibitory mechanism is activated by conventional and acupuncture-like TNS.