Identification of sensorimotor components accounting for individual variability in Zahlen–Verbindungs-Test (ZVT) performance

The Zahlen–Verbindungs-Test (ZVT) represents a highly feasible measure of information-processing speed that correlates quite highly with standard psychometric tests of intelligence. The present study was designed to identify specific stages of the sensorimotor processing system that may account for individual differences in overall variability of ZVT performance. For this purpose, ZVT, reaction time (RT), lateralized readiness potential (LRP), and electromyogram (EMG) measures were obtained in 48 female participants. While faster RT, smaller intraindividual variability in RT, shorter response-locked LRP and EMG latencies were associated with superior ZVT performance, speed of stimulus analysis, as reflected by stimulus-locked LRP latency, was unrelated to ZVT performance. Additional commonality analyses suggested a functional relationship between ZVT performance and the time course of central aspects of response organization rather than the time required for execution of the overt motor response. These findings provide converging evidence for the general notion of an association between speed of motor processing and intelligence.     

Validity of Treatment Target Progress Ratings as Indicators of Youth Improvement

We examined whether clinical progress ratings on the Monthly Treatment and Progress Summary form (MTPS), an idiographic treatment progress measure, were meaningfully related to changes measured by two separate standardized instruments; the Child and Adolescent Functional Assessment Scale (CAFAS) and the Child and Adolescent Level of Care Utilization System (CALOCUS). Validity coefficients were examined at intake and three-, six-, and nine-month follow-up periods. Samples were selected for each measure and follow-up period from the population of youth receiving services through the Hawaii Child and Adolescent Mental Health Division’s (CAMHD) system of care. Significant youth improvement was evident on all three measures across all follow-up intervals. The type of changes measured by the MTPS and CAFAS were more alike over longer follow-up intervals than changes measured by the CALOCUS. The MTPS captures distinct aspects of client change that overlaps somewhat with CAFAS and CALOCUS measures. The MTPS is a brief client-tailored measure that seems to provide valid, sensitive, and nonredundant client specific treatment outcome information that can be collected on a frequent basis within a complex system of care.     

Movement adaptations in 7- to 10-year-old typically developing children: evidence for a transition in feedback-based motor control

We used a modified double-step pointing task to study movement adaptations in 7- to 10-year-old typically developing children. We found that the majority (63%) were able to optimally adapt fast, goal-directed visually-guided movements to a late change in target location meeting the requirements of speed and accuracy. A minority (35%) failed to meet the requirement of accuracy resulting in a less optimal adaptation. The results showed that the ability to adapt movements optimally develops before the age of 7 years in typically developing children. Literature proposes a transition in development of motor control around the age of 8 years. The present results replicate and extend this by suggesting that this transition affects the later phases of fast, goal-directed visually-guided movements rather than the early phases, such as movement programming and acceleration. Finally, the results indicate that the optimally adapted movements were the result of a specific strategy in which a specific component of movement execution was slowed on all trials. This suggests that 7- to 10-year-old typically developing children have developed implicit knowledge about which movement components are the most efficient to adapt.     

Visuomotor contribution to force variability in the plantarflexor and dorsiflexor muscles

The visual correction employed during isometric contractions of large proximal muscles contributes variability to the descending command and alters fluctuations in muscle force. This study explored the contribution of visuomotor correction to isometric force fluctuations for the more distal dorsiflexor (DF) and plantarflexor (PF) muscles of the ankle. Twenty-one healthy adults performed steady isometric contractions with the DF and PF muscles both with (VIS) and without (NOVIS) visual feedback of the force. The target forces exerted ranged from 2.5% to 80% MVC. The standard deviation (SD) and coefficient of variation (CV) of force was measured from the detrended (drift removed) VIS and NOVIS steadiness trials. Removal of VIS reduced the CV of force by 19% overall. The reduction in fluctuations without VIS was significant across a large range of target forces and was more consistent for the PF than the DF muscles. Thus, visuomotor correction contributes to the variability of force during isometric contractions of the ankle dorsiflexors and plantarflexors.     

Speech Planning at Turn Transitions in Dialog Is Associated With Increased Processing Load

Speech planning is a sophisticated process. In dialog, it regularly starts in overlap with an incoming turn by a conversation partner. We show that planning spoken responses in overlap with incoming turns is associated with higher processing load than planning in silence. In a dialogic experiment, participants took turns with a confederate describing lists of objects. The confederate’s utterances (to which participants responded) were pre‐recorded and varied in whether they ended in a verb or an object noun and whether this ending was predictable or not. We found that response planning in overlap with sentence‐final verbs evokes larger task‐evoked pupillary responses, while end predictability had no effect. This finding indicates that planning in overlap leads to higher processing load for next speakers in dialog and that next speakers do not proactively modulate the time course of their response planning based on their predictions of turn endings. The turn‐taking system exerts pressure on the language processing system by pushing speakers to plan in overlap despite the ensuing increase in processing load.     

Motor coordination uses external spatial coordinates independent of developmental vision

The constraints that guide bimanual movement coordination are informative about the processing principles underlying movement planning in humans. For example, symmetry relative to the body midline benefits finger and hand movements independent of hand posture. This symmetry constraint has been interpreted to indicate that movement coordination is guided by a perceptual code. Although it has been assumed implicitly that the perceptual system at the heart of this constraint is vision, this relationship has not been tested. Here, congenitally blind and sighted participants made symmetrical and non-symmetrical (that is, parallel) bimanual tapping and finger oscillation movements. For both groups, symmetrical movements were executed more correctly than parallel movements, independent of anatomical constraints like finger homology and hand posture. For the blind, the reliance on external spatial factors in movement coordination stands in stark contrast to their use of an anatomical reference frame in perceptual processing. Thus, the externally coded symmetry constraint evident in bimanual coordination can develop in the absence of the visual system, suggesting that the visual system is not critical for the establishment of an external-spatial reference frame in movement coordination.     

Knowledge of response location alone is not sufficient to generate social inhibition of return

Previous research has revealed that the inhibition of return (IOR) effect emerges when individuals respond to a target at the same location as their own previous response or the previous response of a co-actor. The latter social IOR effect is thought to occur because the observation of co-actor's response evokes a representation of that action in the observer and that the observation-evoked response code subsequently activates the inhibitory mechanisms underlying IOR. The present study was conducted to determine if knowledge of the co-actor's response alone is sufficient to evoke social IOR. Pairs of participants completed responses to targets that appeared at different button locations. Button contact generated location-contingent auditory stimuli (high and low tones in Experiment 1 and colour words in Experiment 2). In the Full condition, the observer saw the response and heard the auditory stimuli. In the Auditory Only condition, the observer did not see the co-actor's response, but heard the auditory stimuli generated via button contact to indicate response endpoint. It was found that, although significant individual and social IOR effects emerged in the Full conditions, there were no social IOR effects in the Auditory Only conditions. These findings suggest that knowledge of the co-actor's response alone via auditory information is not sufficient to activate the inhibitory processes leading to IOR. The activation of the mechanisms that lead to social IOR seems to be dependent on processing channels that code the spatial characteristics of action.     

Differences in practices of body stimulation during the first 3 months: Ethnotheories and behaviors of Italian mothers and West African immigrant mothers

This study investigated cultural differences, continuity and change of practices concerning body stimulation in a context of immigration. Parenting behaviors during the interaction with infants at 4, 8 and 12 weeks, and parenting ethnotheories at 12 weeks of first-generation West African immigrant mothers in Italy and autochthonous Italian mothers were compared. A qualitative inspection of ethnotheories using a thematic approach was included. As expected, results showed that immigrant mothers placed more emphasis on motor stimulation and showed longer durations of rhythmic motor and rhythmic tactile behaviors than Italian mothers; the latter placed more emphasis on tactile stimulation than immigrant mothers. The practice of motor stimulation in immigrant mothers was also adapted to values of the new context of life, becoming a positive interaction game with a mutual exchange of positive emotions. Findings express the complexity of a multidimensional process of acculturation.     

Motor planning in Parkinson’s disease patients experiencing freezing of gait: The influence of cognitive load when approaching obstacles

Freezing of gait (FOG) in Parkinson’s disease (PD) is typically assumed to be a pure motor deficit, although it is important to consider how an abrupt loss of gait automaticity might be associated with an overloaded central resource capacity. If resource capacity limits are a factor underlying FOG, then obstacle crossing may be particularly sensitive to dual task effects in eliciting FOG. Participants performed a dual task (auditory digit monitoring) in order to increase cognitive load during obstacle crossing. Forty-two non-demented participants (14 PD patients with FOG, 13 PD who do not freeze, and 14 age-matched healthy control participants) were required to walk and step over a horizontal obstacle set at 15% of the participants’ height. Kinematic data were split into two phases of their approach: early (farthest away from the obstacle), and late (just prior to the obstacle). Interestingly, step length variability and step time variability increased when PD patients with FOG performed the dual task, but only in the late phase prior to the obstacle (i.e. when closest to the obstacle). Additionally, immediately after crossing, freezers landed the lead foot abnormally close to the obstacle regardless of dual task condition, and also contacted the obstacle more frequently (planning errors). Strength of the dual task effect was associated with low general cognitive status, declined executive function, and inappropriate spatial planning, but only in the PD-FOG group. This study is the first to demonstrate that cognitive load differentially impacts planning of the final steps needed to avoid an obstacle in PD patients with freezing, but not non-freezers or healthy controls, suggesting specific neural networks associated with FOG behaviours.     

The influence of attentional focus on the development of skill representation in a complex action

ObjectivesRecent research has indicated that performers' mental representation of a motor skill changes over the course of learning. In the present study, we sought to ascertain whether the type of instructions (instructions that emphasize either an internal or external focus of attention) influences the development of skill representation during motor learning.DesignParticipants without golf experience were recruited to practice a golf putting task over the course of three training days. Participants were randomly assigned to either an internal focus (focus on the swing of the arms; n = 10) or external focus (focus on the speed of the ball roll; n = 10) learning group. Changes in putting performance and mental representation structure were assessed over the course of learning, as well as during a follow-up retention test two days after practice.MethodsMental representation structure was measured employing the structural dimensional analysis of mental representations (SDA-M), which provided psychometric data on the structure of the mental representation in long-term memory. Additionally, the change in putting accuracy and consistency was recorded over the course of learning.ResultsFindings indicated that the external focus group performed with greater accuracy and consistency during training, and revealed a larger degree of development in their mental representation of the putting task.ConclusionsOverall, our findings suggest that facilitating the link between an action and its effect by means of an external focus is crucial for motor performance as well as the development of skill representation.