Biomedical subjects

Eric A Roy

Publications and source records attributed to Eric A Roy.

16 recordsLinked to original sources

PubMed2006

Neuropsychological profile of acute alcohol intoxication during ascending and descending blood alcohol concentrations.

Numerous studies have investigated the effects of alcohol on motor processes during rising and declining blood alcohol concentrations (BAC), however, relatively little research has examined the alcohol-induced impairment of cognitive performance on the two limbs of the BAC curve. This experiment administered a neuropsychological test battery to assess the degree to which rising and declining BACs during an acute dose of alcohol impair nine cognitive processes within an individual. In all, 20 healthy male social drinkers (university students) were assigned to one of two groups (n = 10) who received a beverage containing either 0.0 g/kg (placebo) or 0.65 g/kg alcohol and performed the test battery when BAC was increasing and was decreasing. Comparisons of alcohol and placebo groups revealed impairment (slower response and/or increased errors) in seven of the cognitive processes: long-term verbal memory; information processing; declarative memory; inhibitory control; short-term visual memory; long-term visual memory, and visual-spatial working memory. However, some processes were impaired only during rising BACs whereas the impairment of others during declining BACs was evident only by an increase in errors. These results show cognitive tasks performed by an individual are not similarly affected by rising and declining BACs, and call attention to the importance of assessing both speed and accuracy on both limbs of the BAC curve. The particular cognitive processes differentially affected by rising vs declining BACs raised the possibility that acute alcohol intoxication may impair one cerebral hemisphere to a greater degree than the other, and this could be explored by neuroimaging techniques.

Adult↗

PubMed2006

Using hand performance measures to predict handedness.

Handedness is defined by the individual's preference to use one hand predominately for unimanual tasks and the ability to perform these tasks more efficiently with one hand (Corey, Hurley, & Foundas, 2001). It is important to use performance variables to measure handedness because they are more objective than traditional hand preference questionnaires (Bryden, Pryde, & Roy, 2000a). The current study develops a predictive model of handedness as measured by the Waterloo Handedness Questionnaire (WHQ) using several performance indicators of handedness. A total of 120 individuals (60 right-handers and 60 left-handers) were asked to complete four performance-based tasks: the Grooved Pegboard (GP), the Annett pegboard (AP), finger tapping (FT), and grip strength (GS) as well as an observational measure of preference, the Wathand Box Test (WBT). Backward linear regression analysis showed that the Wathand Box measure and the laterality quotients for several performance measures (GP place, AP, and FT) combined to act as the most accurate predictors of hand preference. The predictive model of handedness developed is as follows: WHQ = -2.760- - 0.667(GP place) + 0.809(FT) + 0.234(WBT) - 0.748(AP) with an explained variance of 0.836. These results illustrate, as Corey et al. (2001) suggested, that the best predictive model of handedness combines preference measures and several performance measures that tap into different elements of motor performance. By developing this model, it is possible to get an accurate measure of handedness using objective measures.

Adolescent↗

PubMed2006

Reaching patterns across working space: the effects of handedness, task demands, and comfort levels.

Two experiments are reported which examine skill demands, location, and perceived comfort levels for a preferential reaching test with left- and right-handed participants. In Experiment 1, the effect of task demands was examined by having participants perform tasks of varying difficulty with tools (Lift, Pantomime, and Use) that were placed in an array in working space. Preferred hand reaches predominated at the midline and ipsilateral positions, and decreased significantly for contralateral positions, where the frequency of preferred hand reaches increased with task difficulty. In Experiment 2 we developed a new measure (the Comfort Rating Scale) to rate the subjective feeling of comfort for reaching movements. Using the same array of tools and tasks, participants were instructed which hand to use to perform reaching movements, and then rated how the movement felt. The preferred hand was always rated as being comfortable, whereas the non-preferred hand was sensitive to the effects of task demands and tool position. The ratings showed that it was the level of comfort with the non-preferred hand, rather than with the preferred hand, that contributed to the patterns seen on the first study. The Comfort Rating Scale provides new insight into the distribution of reaching movements within working space.

Adolescent↗

PubMed2005

The performance of left-handed participants on a preferential reaching test.

Previous research in our laboratory has examined the distribution of preferred hand (PH) reaches in working space with right-handed participants. In one study, we examined the effects of tool position and task demands on the frequency of PH reaches with right-handers (Mamolo, Roy, Bryden, & Rohr, 2004). We found that PH reaches were at a maximum within ipsilateral space, and predominated within contralateral space. This was mediated by the task demands, as shown by an increased frequency of PH reaches for the more skill demanding tasks. In the current study, we tested left-handed participants on the same procedure. Five different tools were placed in an array in front of the participant, who was required to reach for, and perform one of three tasks with the tool: Lift the tool; lift and Pantomime its use; or lift and Use the tool on its corresponding object. The results showed that PH reaches were at a maximum within ipsilateral space for all three tasks. Significantly fewer PH reaches were made for tools in contralateral space. In particular, almost no PH reaches were made for the Lift task at the most extreme contralateral position. This indicates the willingness of left-handers to use their non-preferred (i.e., right) hand. One possible explanation supported by these results is that left-handers have adapted to an environment designed for right-handers.

Adult↗

PubMed2005

Unilateral basal ganglia damage causes contralesional force control deficits: a case study.

When grasping to lift an object, the grip force is usually scaled to the mass of the object. However, it has been shown that lifting objects of different sizes but equal masses results in the generation of higher forces for larger compared to smaller objects. The objective of this study was to investigate whether a similar effect is present in an individual (RI) with a unilateral lesion to the basal ganglia (BG). It was hypothesized that if the BG have an influence on the use of visual information in updating of the internal model used to anticipate the forces required for grasping, damage to these structures should result in the inability of RI's contralesional hand to anticipate object mass based on size cues. To test this hypothesis three objects of equal mass but different sizes were grasped and lifted by RI and six control individuals. The forces that were generated during these lifts were quantified. The controls showed the expected increases in peak grip force as object size increased. RI showed no effect of object size for his contralesional hand, but did show force scaling with his ipsilesional hand. In conclusion, RI's BG damage affected the on-line control of grip forces and the inability to integrate visual and tactile information in the programming of finger forces.

Adult↗

PubMed2005

Relative processing demands influence cerebral laterality for verbal-motor integration in persons with Down syndrome.

The study of cerebral specialization in the Down syndrome (DS) population has revealed an anomalous pattern of organization. In particular, dichotic-listening studies have suggested a left-ear/right hemisphere dominance for speech perception, whereas motor control research has revealed a left hemisphere dominance for executive-motor control. In the present investigation, we employed a recent adaptation of the dichotic listening procedure to examine interhemispheric integration during the performance of a lateralized verbal-motor task. Specifically, using the selective dichotic-listening procedure, participants were required to complete a rapid left or right hand pointing movement to one of two pictorial icons corresponding to the word presented to their precued ear. We observed that persons with DS (N = 17) and age-matched controls (N = 35) exhibited a right-ear advantage (REA) for our dichotic-aiming task. While these results appear to contradict previous dichotic listening studies, we propose that the manifestation of a lateral ear advantage in the DS population may have more to do with the response requirements of the task than with the characteristics or complexity of the stimulus material.

Acoustic Stimulation↗

PubMed2004

Preference and performance measures of handedness.

Handedness cannot be predicted using a single performance measure, and preference measures of handedness are unreliable because of their subjectivity. This report was designed to examine the relationship between hand performance and hand preference using six different measures: the Waterloo Handedness Questionnaire (a measure of hand preference), the Wathand Box (a performance-based indicator of hand preference), two pegboard tasks, finger tapping, and grip strength and to determine the most accurate performance-based predictor of hand preference as measured by the Waterloo Handedness Questionnaire. Multiple linear regression analysis showed that together, the Wathand Box score and the lateralized place phase of the grooved pegboard task were the most accurate predictors of hand preference.

Adolescent↗

PubMed2004

The effects of skill demands and object position on the distribution of preferred hand reaches.

Performance-based measures of hand preference have been developed as an objective method of examining handedness. Previous research using this method showed that both skill demands and the position of the object in working space affect preferential hand reaching. Specifically, preferred hand reaches predominated in left hemispace, in spite of the biomechanical inefficiency involved in reaching across the body midline. This was mediated by the skill demands, with a higher frequency of preferred hand reaches for tasks requiring more skill. To further examine this issue, we increased the task skill demands. Twenty-two right-handed adults reached for five tools located in an array of five positions in front of them. Participants were required to pick up the tool, pick up and demonstrate how to use it, or pick up and actually use the tool on the materials provided. The results showed that the frequency of right hand reaches was greatest for the tool use condition. This effect was mediated by the position of the object in hemispace, with more right hand reaches occurring for the Use task in left hemispace than the other tasks, in support of our previous work.

Adult↗

PubMed2004

Gestural imitation and limb apraxia in corticobasal degeneration.

Limb apraxia is a common symptom of corticobasal degeneration (CBD). While previous research has shown that individuals with CBD have difficulty imitating transitive (tool-use actions) and intransitive non-representational gestures (nonsense actions), intransitive representational gestures (actions without a tool) have not been examined. In the current study, eight individuals with CBD and eight age-matched healthy adults performed transitive, intransitive representational and intransitive non-representational gestures to imitation. The results indicated that compared to controls, individuals with CBD were significantly less accurate in the imitation of transitive and intransitive non-representational gestures but showed no deficits for the imitation of intransitive representational gestures. This advantage for intransitive representational gestures was thought to be due to fewer demands being placed on the analysis of visual-gestural information or the translation of this information into movement when imitating these gestures. These findings speak to the importance of context and the representation of gestures in memory in gesture performance.

Aged↗

PubMed2004

Effect of movement termination in single- and dual-phase pointing tasks.

Two experiments are reported that focus on manipulating both the context and the spatial precision of a computer-pointing task. Single goal-directed actions are compared to dual-phase tasks, where participants are required to sequentially attain two goal locations. Results support the idea that for movements in series, movement planning, and online feedback, control can occur simultaneously. Additionally, for single-phase tasks and the final phase of dual-phase tasks, the termination requirement influences the temporal components of the movement. The effects of termination and movement context appear to hold regardless of the spatial precision of the task. This suggests that the effects of spatial precision and movement termination are independent, although both have an impact on the deceleration time for goal-directed movements.

Biomechanical Phenomena↗

PubMed2003

Patterns of limb apraxia in primary progressive aphasia.

Primary progressive aphasia (PPA) is a syndrome characterized by a progressive language deficit without other dementia features for at least two years (). Other deficits that are likely to co-exist with aphasia, such as apraxia, have only been investigated in a few case studies and only at a rudimentary level for the most part. In this study we investigate the frequency and severity of apraxic deficits in PPA patients. Ten PPA patients and twelve aged-matched healthy adults performed eight transitive gestures to pantomime and to imitation. Gesture performance was measured along five movement dimensions and a composite score based on the arithmetic mean of the five dimensions was calculated. Overall, PPA patients performed worse than controls with both pantomime and imitation. Furthermore, individual comparisons revealed that out of the three apraxia patterns described by (pantomime alone, imitation alone, or apraxia in both conditions), the most frequent pattern in PPA patients was apraxia in both conditions. This result corresponds with previous findings in populations of stroke and Alzheimer's patients. Considering the occurrence of apraxia in this population, this study supports the idea that a comprehensive apraxia assessment should be administered in cases of PPA.

Aphasia↗

PubMed2003

Hand differences in pegboard performance through development.

Handedness is often measured by comparing the relative performance of the two hands on a given task, such as peg moving. Studies of the development of manual skill have typically found that the difference between the hands for a peg-moving task does not fluctuate with age. The current study was conducted to examine age-related changes in manual performance, on the standard Annett pegboard. Ninety-eight right-handed individuals ranging in age from 5 to 24 performed three trials on the pegboard with each hand. Performance with each hand was reflected in movement time and as a laterality quotient. Analyses revealed a right-hand advantage in performance which was larger in the younger than the older participants. The smaller hand difference in the older participants appeared due to greater changes in performance with the non-preferred hand as a function of age.

Adult↗

PubMed2003

Selective dysfunction of tool-use: a failure to integrate somatosensation and action.

Apraxia is thought to reflect a disruption to high-level perceptual, cognitive and motor systems that form a distributed praxis network. Some authors suggest that apraxic deficits are unique to the neurology clinic; however, mounting evidence suggests that apraxic deficits are observable in natural contexts (e.g. Foundas et al., 1995). Naturalistic gesture production involves the integration of conceptual knowledge, gesture ideation, visual and somatosensory cues, and executive processes. Impairments in this context are therefore of interest from a clinical and theoretical standpoint. We present the case of a young female stroke patient (CK) demonstrating a novel limb praxis profile. CK's conceptual, evocation and praxis executive stages were evaluated: performance was contrasted to 30 healthy controls. CK was able to pantomime and imitate transitive gestures, suggesting that her ideational, executive and visual analytic systems were intact. Moreover, CK showed a good conceptual understanding of tools, objects and actions. However, CK demonstrated poor gesture production when actually using the tool associated with the action--a chronic and bilateral deficit that persisted at a 5-year follow-up assessment. Thus, CK's deficit appears to represent a specific and chronic disruption to high-level praxis systems that incorporates tactile inputs into the unfolding gesture production sequence.

Adult↗

PubMed2003

No evidence for accurate visuomotor memory: systematic and variable error in memory-guided reaching.

The authors explored whether the motor system has access to highly accurate information about the aiming environment after visual occlusion. Participants (N = 14) reached to 1 of 3 midsagittal targets in 4 visual conditions (open-loop, brief-delay, 500-ms delay, and 2,000-ms delay). In all conditions, the aiming environment was first viewed for 2,000 ms. Movements were cued immediately after the initial viewing period in the open-loop and brief-delay conditions. Vision was not occluded until movement onset in the open-loop condition, whereas vision was occluded coincidentally with the movement cue in the brief-delay condition. In the 2 longer delay conditions, the movement was cued following a 500- or a 2,000-ms no-vision delay period. Participants overshot the target in the open-loop condition, but that tendency was significantly reduced in the 3 delay conditions. Moreover, endpoint variability was greater in the 3 delay conditions than in the open-loop condition. A speed-accuracy tradeoff account could not explain the differences between open-loop and delayed reaching. Those findings suggest that the motor system does not have access to highly accurate information about the aiming environment for any appreciable period of time following visual occlusion, consistent with the view that the visuomotor system operates in real time.

Acoustic Stimulation↗

PubMed2002

Manual asymmetries in tool-use: implications for apraxia.

Previous examinations of manual performance asymmetries have utilised relatively simple movements such as goal-directed aiming and rapid finger-tapping. In the present research, three-dimensional kinematic analyses were employed to examine manual asymmetries in the production of transitive limb gestures. Transitive limb gestures involve the use of tools and/or objects and are complex movements used in the evaluation of limb apraxia. Ten healthy right hand dominant participants produced two transitive limb gestures in response to verbal command both with (tool-use) and without (pantomime) the appropriate tool. Analyses revealed a dominant (right) hand advantage, although the magnitude of this advantage was influenced by movement context (pantomime vs tool-use). This study provides the first evidence that manual asymmetries are elicited during the production of transitive limb gestures, and mandates that future kinematic analyses of limb apraxia consider the impact of pre-morbid manual asymmetries when contrasting the performance of left and right hemisphere damaged patients.

Journal Article↗

PubMedDate not supplied

Screening for apraxia: a short assessment for stroke patients.

Apraxia is a disorder that involves impaired ability to execute previously learned movements that cannot be attributed to basic sensory or motor disturbances. A thorough assessment of apraxia typically entails both pantomiming and imitation of transitive (tool-related), intransitive (communication-related), and meaningless gestures, presented in an array of different, process-dependent sensory conditions. Precise and detailed assessment tools are often time-consuming and a shorter screening tool may be desirable for efficient surveillance of this disorder in stroke patients. In the present study, stroke patients (N = 37) were compared to healthy controls (N = 30) in their production of commonly used transitive and intransitive gestures. Five gestures (knife, flipper, tweezers, okay sign, cab hailing) were consistently performed with poorer accuracy in stroke patients when compared to healthy controls. The combination of gestures that best captured apraxic performance was statistically determined based on Z-score data. Results provide a shortened and sensitive method of detecting apraxia in stroke patients.

Apraxias↗