Arend W A Van Gemmert

Louisiana State University | LSU · School of Kinesiology

Joint decomposition of functional magnetic resonance imaging (fMRI) time series into time courses of neural activity events and hemodynamic response functions (HRF) can enable new insights into functional connectivity, task activation, and neurovascular coupling in health and disease. Current methods for this problem handle time series of either te...

Age-related effects on motor asymmetry provide insight into changes in cortical activation during aging. To investigate potential changes in manual performance associated with aging, we conducted the Jamar hand function test and the Purdue Pegboard test on young and older adults. All tests indicated reduced motor asymmetry in the older group. Furth...

Adopting an external focus of attention (EF) has been found beneficial over internal focus (IF) for performing motor skills. Previous studies primarily examined focus of attention (FOA) effects on performance outcomes (such as error and accuracy), with relatively less emphasis on movement coordination. Given that human movements are kinematically a...

The purpose of the present study was to compare motor asymmetry between older and younger adults performing a graphic task. Thirty-four right-handed older and 38 younger adults drew continuous cursive “l” loops on a digitizer tablet using their right and left hand, respectively, aimed to assess age-related hand asymmetry differences in the performa...

The label ‘Stop’ potentially generates conflict—signifying important corrective action, or a warning not to touch. To examine potential conflict between an incongruent label (i.e. STOP) and an imperative command (i.e. MOVE!), 18 participants used a computer mouse to move a crosshair cursor to targets with superimposed labels. Trials systematically...

Objective As images are used within graphical user interfaces to signify menu selection, it is important to understand how image properties can influence cursor placement online. Background Objects have multiple dimensions that create potential ambiguity and Stroop-like confusions for the operator if a previously habitual response conflicts with t...

Introduction: Visual feedback of hand and target location can influence strategies for visuomotor adaptation. Contributions of the hand and eyes during visuomotor adaptation are unknown yet would provide insights into adaptive control strategies used. Purpose: In this study we aimed to assess the effects of a visual feedback manipulation on movem...

Prior research has suggested that measurements of brain functioning and performance on dual tasks (tasks which require simultaneous performance) are promising candidate predictors of fall risk among older adults. However, no prior study has investigated whether brain function measurements during dual task performance could improve prediction of fal...

Background: Visuomotor adaptation tasks provide insights into how humans integrate sensory information to interact with our environment. Successful updates of motor plans ensues in visuomotor adaptation. Effective visuomotor adaptation might be workspace specific and associated neural activity, in particular the central and parietal areas, may diff...

Previous nonstandard visuomotor transformation studies using variations of eye-hand coupling and decoupling tasks focused on dominant hand use. The present study expanded this work by including the non-dominant hand. Twenty-four right-hand dominant adults (M = 21 yrs.; 12 females) slid their index finger along a vertical or horizontal touchscreen t...

Introduction: Bilateral transfer occurs when a learned behavior transfers from one group of effectors(s) to another. The strength of transfer of movement parameters differs from one hand to the other i.e. asymmetry of transfer. Based on the dynamic dominance model, the asymmetry depends on the information each arm controller can access. For instanc...

The present study expands previous work on eye-hand decoupling deficits in youth with concussion history. It examines whether deficits can be linked to difficulties adapting to new task constraints or meeting ongoing task demands. Data from 59 youth with concussion history (M=11 months post-concussion) and 55 no history controls were analyzed. All...

Age-related changes have been identified in neural and motor level. A prominent change is reduced asymmetry in cortical activation as well as motor performance. Cortical activation models have been established based on cognitive research utilizing neuroimaging techniques to explain age-related effects on neural recruitment and reduced brain asymmet...

Although learning and adapting to visuo-motor tasks is critical to child development and health conditions requiring rehabilitation, the neural processes involved in learning a new visuo-motor task and adapting it to novel conditions such as execution with an untrained limb are not fully understood. Therefore, we trained 27 healthy, right-hand-domi...

Introduction: Logic suggests that spatial location constraints affect motor skill learning. Studies have addressed spatial location constraints and others, bilateral transfer of learning (a learned skill with one limb transfers to the untrained contralateral limb; usually benefits of the transfer are unequal between limbs), but none have tried to a...

Introduction: Bilateral transfer can be described as a situation in which a learned skill, practiced on one side of the body is performed on the opposite side of the body following training. The strength of the transfer of information from one part to the other varies, and this is known as the asymmetry of inter-limb transfer. Studies have shown ho...

Cognitive-motor integration (CMI) tasks require the implementation of a cognitive rule to perform the necessary motor action, e.g., when we look to the right but have to move to the left (i.e., decoupling of vision and action). We use this ability often during our daily life and in sport activities. A previous study showed CMI deficits in children...

Cognitive-motor integration (CMI) tasks require the implementation of a cognitive rule to perform the necessary motor action, e.g., when we look to the right but have to move to the left (i.e., decoupling of vision and action). We use this ability often during our daily life and in sport activities. A previous study showed CMI deficits in children...

Parkinson’s disease is manifested as well in handwriting as in voice. Previous researches have carried out different procedures to estimate the dysfunctions of the illness in voice and handwriting separately. This paper proposes one parameter to evaluate the influence of the illness on both voice and handwriting as the symptoms affecting both has a...

The use of large digitizers, allowing users to interact using both hands simultaneously, are getting more and more popular in applications requiring human computer interaction. In most of these applications, gesture commands are used and these commands to activate specific actions can provide also information about the neuromuscular system of the u...

Bimanual coordination requires task-specific control of the spatial and temporal characteristics of the movements of both hands. The present study focused on the spatial relationship between hand movements when their amplitude and direction were manipulated. In the experiment in question, participants were instructed to draw two lines simultaneousl...

The literature has shown robust effects of transfer-of-learning to the contralateral side and more recently transfer-of-learning effects to a new effector type on the ipsilateral side. Few studies have investigated the effects of transfer-of-learning when skills transfer to both a new effector type and the contralateral side (two-step transfer). Th...

In this study, we explored the relationship between the clinical features and motor impairments related to the graphomotor function of individuals with Parkinson’s disease (PD) and essential tremor (ET). We recruited 46 participants: 12 with PD, 13 with ET, and 21 controls. All participants were asked to perform six graphomotor tasks on a digitizer...

In this study, we explored the relationship between the clinical features and motor impairments related to the graphomotor function of individuals with Parkinson’s disease (PD) and essential tremor (ET). We recruited 46 participants: 12 with PD, 13 with ET, and 21 controls. All participants were asked to perform six graphomotor tasks on a digitizer...

Asymmetry of inter-limb transfer has been associated with the specialization of the dominant and non-dominant motor system. Reductions of asymmetry have been interpreted as behavioural evidence showing a decline of hemispheric lateralization. A previous study showed that ageing did not qualitatively change the inter-limb transfer asymmetry of a vis...

The term graphonomics was conceived in the early 1980s; it defined a multidisciplinary emerging field focused on handwriting and drawing movements. Researchers in the field of graphonomics have made important contribution to the field of motor behavior by developing models aimed to conceptualize the production of fine motor movements using graphica...

Research on the effects of stress on motor performance has produced inconsistent findings. The neuromotor noise perspective attempts to explain these divergent results by suggesting that stress has activating properties on the motor-system that may result in decreased reaction times; however, the increased activation due to higher amounts of stress...

Research has attempted to address what characteristics benefit from transfer of learning; however, it is still unclear which characteristics are effector dependent or independent. Furthermore, it is not clear if intralimb transfer shows, similarly to interlimb transfer, an asymmetry of benefits between the upper limbs. The purpose of the current st...

The present study investigated how Parkinson's disease (PD) affects temporal coordination among the trunk, arm, and fingers during trunk-assisted reach-to-grasp movements. Seated participants with PD and healthy controls made prehensile movements. During the reach to the object, the involvement of the trunk was altered based on the instruction; the...

The direction of the asymmetry of inter-limb transfer has been suggested to identify the specialization of each hemisphere when performing a motor task. In an earlier study, we showed that trajectory information is only transferred from the right to the left hand, while final movement outcome-associated parameters transferred in both directions whe...

Research has attempted to address what characteristics benefit from transfer of learning; however, it is still unclear which characteristics are effector dependent or independent. Furthermore , it is not clear if intralimb transfer shows, similarly to interlimb transfer, an asymmetry of benefits between the upper limbs. The purpose of the current s...

Objective: To investigate whether the timing of presentation of tones while practicing a serial reaction time task affects retention. Design: Thirty-eight young adults practiced 4 different 12-sequence aiming tasks. There was one control condition without a tone and three experimental conditions in which a tone was presented; i.e., a tone could app...

The present study investigated how the involvement and direction of trunk movement during reach-to-grasp movements affect the coordination between the transport and grasping components. Seated young adults made prehensile movements in which the involvement of the trunk was varied; the trunk was not involved, moved forward (flexion), or moved backwa...

Recordings of the dominant finger during the reading of braille sentences by experienced readers reveal that the velocity of the finger changes frequently during the traverse of a line of text. These changes, not previously reported, involve a multitude of accelerations and decelerations, as well as reversals of direction. We investigated the origi...

The present study investigated performance of unimanual and bimanual anti-phase and in-phase upper limb line drawing using three different types of cues. Fifteen Parkinson's disease (PD) patients, 15 elderly, and 15 young adults drew lines away from and towards their body on a tabletop every 1000 ms for 30 s under three different cueing conditions:...

To address the hypothesis that Parkinson’s disease (PD) patients have deficits in controlling acceleration, a drawing task was used in which target size, frequency, and weight of pen were manipulated. In accordance with previous results, it was found that, relative to controls, PD patients produced movements at the required frequency, but moved sig...

Handwriting impairments in Parkinson's disease (PD) have been associated with micrographia, i.e. diminished letter size. However, dyscoordination of the wrist and fingers may also contribute to handwriting deterioration in PD. To investigate this hypothesis, right-handed PD patients and controls were tested in performance of three types of cyclic w...

Elderly adults often exhibit performance deficits during goal-directed movements of the dominant arm compared with young adults. Recent studies involving hemispheric lateralization have provided evidence that the dominant and non-dominant hemisphere-arm systems are specialized for controlling different movement parameters and that hemispheric speci...

During the past 20 years graphonomic research has become a major contributor to the understanding of human movement science. Graphonomic research investigates the relationship between the planning and generation of fine motor tasks, in particular, handwriting and drawing. Scientists in this field are at the forefront of using new paradigms to inves...

Two experiments tested how changing a planned movement affects movement initiation and execution in idiopathic Parkinson's disease (PD) patients. In Experiment 1, PD patients, elderly controls, and young adults performed discrete aiming movements to one of two targets on a digitizer. A precue (80% valid cue and 20% invalid cue of all trials) reflec...

Much sensory-motor behavior develops through imitation, as during the learning of handwriting by children. Such complex sequential acts are broken down into distinct motor control synergies, or muscle groups, whose activities overlap in time to generate continuous, curved movements that obey an inverse relation between curvature and speed. The Adap...

The term graphonomics refers to the scientific and technological effort involved in identifying relationships between the planning and generation of handwriting and drawing movements, the resulting spatial traces of writing and drawing instruments (either conventional or electronic), and the dynamic features of these traces (International Graphonom...

This is a special issue of the Journal of Forensic Document Examination, devoted entirely to contributions originally presented at the 11 th International Graphonomics Society (IGS) conference, held in November, 2003 in Scottsdale, Arizona. This issue contains articles on cutting-edge computer applications that pave the way to-wards future forensic...

Previous research suggested that people with Parkinson's disease are able to increase handwriting stroke size up to 1.5 cm without an increase of stroke duration; whereas age matched individuals in normal health are able to modulate stroke size without changes in stroke duration for sizes up to 2 cm. This study was designed to test this finding by...

This study examined the impact of target geometry on the trajectories of rapid pointing movements. Participants performed a graphic point-to-point task using a pen on a digitizer tablet with targets and real time trajectories displayed on a computer screen. Circular- and elliptical-shaped targets were used in order to systematically vary the accura...

This study investigated the effect of lengthening the time the hand remains immobilized on an aiming movement performed by Parkinson's disease (PD) patients and elderly adults, and whether visual information could compensate for the effects of delay. In Experiment One, PD patients and elderly adults kept the limb in a static position for 1, 6, or 1...

This study examined the impact of target geometry on the trajectories of rapid pointing movements. Participants performed a graphic point-to-point task using a pen on a digitizer tablet with targets and real time trajectories displayed on a computer screen. Circular- and elliptical-shaped targets were used in order to systematically vary the accura...

Since the early 1980s the study of drawing and handwriting movements has come to be known as the field of graphonomics". The term graphonomics intends to capture the multi-disciplinary scientific effort involved in identifying lawful relationships between the planning and generation of drawing and handwriting movements, and defining the nature and...

Position sense has been found to decay as a function of the time delay the limb remains in a static position prior to movement onset. Position sense has also been found to deteriorate as a function of aging, with increased reliance on vision by the elderly. This study investigated whether the pointing kinematics of elderly adults were differentiall...

Objectives: To systematically investigate the ability of Parkinson's disease patients to discretely and dynamically scale the size of continuous movements and to assess the impact of movement size on outcome variability. Methods: Ten patients with Parkinson's disease (mean age 72 years) were compared with 12 healthy elderly controls (mean age 70...

A simple timing movement was used to investigate augmented feedback on motor learning in Parkinson's disease (PD) patients and controls. During acquisition, participants received knowledge of results (KR) about their errors after every trial (100%) or every fifth trial (20%). Participants then performed a retention test without KR. Controls perform...

Since the early 1980s the study of drawing and handwriting movements has come to be known as the field of graphonomics". The term graphonomics intends to capture the multi-disciplinary scientific effort involved in identifying lawful relationships between the planning and generation of drawing and handwriting movements, and defining the nature and...

Much recent research using discrete unimanual tasks has indicated that individuals with Down syndrome (DS) have more difficulty performing verbal-motor tasks as compared to visual-motor tasks (see Perceptual-Motor Behavior in Down Syndrome, Human Kinetics, Champaign, IL, 2000, p. 305 for a review). In continuous tasks, however, individuals with DS...

Work-related Upper Extremity Disorders (WRUEDs) are conceived of as a multifactorial syndrome caused by the effects of excessive repetitive motions, sustained static postures, and muscular stiffness. Our aim is to test an etiological model derived from a theory by Van Galen and Van Huygevoort [2000] Biol Psychol 51:151-171. The theory holds that ph...

In the horizontal plane on a digitizer tablet, subjects made an elbow-extension, two-stroke movement away from the trunk to a first target and then on to a second target. If the two segments of the movement were executed in an integrative manner, the accuracy constraint on the first segment should have produced changes in kinematic features not onl...

Fifteen older adults (M = 68 years old) and 15 young adults (M = 23 years old) participated in a speed–accuracy task in which aiming movements were performed on a digitizing tablet to assess movement slowing and variability in older adults. Target-size and movement amplitude influences were analyzed separately to determine if they affected the perf...

Parkinson's disease (PD) patients often show reductions in writing size (micrographia) as the length of the text they produce increases. The cause for these reductions in stroke size are not well understood. Reductions in stroke size could be associated with either concurrent processing demands that result from the coordination and control of finge...

Research suggests that Parkinson's Disease (PD) patients have difficulty scaling the magnitude of their movements. Longstaff et al (2001) showed that patients could continuously scale a drawing movement (spiral) up to a diameter of 5cm like elderly controls, but their trajectories were more variable and there was a smaller distance between each rev...

The present study investigates intrinsic preferences and tendencies in coordination of the wrist and finger movements during handwriting-like tasks. Movement of the inkless pen tip in nine right-handed subjects was registered with a digitizer. One circle-drawing task and four line-drawing tasks were included in the experiment. The line-drawing task...

This experiment investigated whether Parkinson's disease (PD) patients experience problems in producing stroke size, stroke duration or both, in a handwriting task. Thirteen PD patients and 15 elderly controls wrote four patterns of varying complexity on a digitizer tablet. The participants were instructed to execute the writing movements: at a nor...

This experiment investigated whether Parkinsons disease (PD) patients experience problems in producing stroke size, stroke duration or both, in a handwriting task. Thirteen PD patients and 15 elderly controls wrote four patterns of varying complexity on a digitizer .tablet. The participants were instructed to execute the writing movements: at a nor...

In two experiments, during handwriting movements, the on-line visual feedback of either slant (Experiment 1) or size (Experiment 2) was transformed to study the time course and biomechanics of the participants' compensations for these distortions. Fluency, movement time, and axial pen force were measured. According to our theory, changing the scali...

This experiment tested the hypothesis that Parkinson's disease (PD) patients are more vulnerable to a moderate level of secondary task load than elderly or young controls due to heightened variability in the motor system. PD patients, elderly, and young adults performed a handwriting task with different secondary tasks. The secondary task imposed m...

Effects of physical and mental stress, on the preparation and execution of a psychomotor task were studied to test the applicability of the neuromotor noise concept (Van Gemmert and Van Galen, 1997) as an explanation of stress effects. Central to this notion is that both physical stress and mental load raise neuromotor noise levels in the human inf...

A new theory on stress and human performance is proposed in which physical and cognitive stressors enhance the level of neuromotor noise in the information-processing system. The neuromotor noise propagates in time and space. A 2nd assumption states that such noise facilitates easy tasks but disrupts complex tasks. In 4 experiments, 2 graphic tasks...

A new theory on stress and human performance is proposed in which physical and cognitive stressors enhance the level of neuromotor noise in the information-processing system. The neuromotor noise propagates in time and space. A 2nd assumption states that such noise facilitates easy tasks but disrupts complex tasks. In 4 experiments, 2 graphic tasks...

In this study the simulation of another person's handwriting is approached from the psy-chomotor point of view. It is theorized that imitating another person's handwriting places specific de-mands on the motor system of the forger which might be invisible in the global and spatial features of the handwriting product, but which would be expressed in...

The restructuring of planning processes during movement initiation and execution in 7 persons with Parkinson's disease (PD) off medication was compared to that of 7 older controls. Participants performed a two-stroke aiming movement on a digitizer. From a start position, they passed through a center box to one of two targets located to the left and...