Biomedical subjects

Oliver Tucha

Publications and source records attributed to Oliver Tucha.

18 recordsLinked to original sources

PubMed2006

Attention and movement execution during handwriting.

Two studies were performed in order to test the hypothesis that movement execution during handwriting in skilled writers is independent of attention. Study I examined the relationship between attentional functioning and kinematic aspects of handwriting movements in 24 adult participants. A digitizing tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task and various components of their attention were assessed. Correlation analysis indicated no significant relationship between attention functions and both kinematic aspects of handwriting movements and quality of handwriting. In Study II, 20 participants underwent total sleep deprivation (TSD) for 24h. While attention, as assessed with alertness and vigilance tasks, deteriorated during TSD, the execution of handwriting movements, as assessed with a digitizing tablet, improved markedly. The quality of handwriting was not affected by TSD. These findings may suggest an independence between attention and movement generation during handwriting.

Adult↗

PubMed2006

The effect of caffeine on handwriting movements in skilled writers.

In laboratory tasks, caffeine has been shown to improve psychomotor performance. The aim of the present experiment was to assess the effects of caffeine on a skilled everyday life task in habitual caffeine consumers. The assessment of handwriting movements of 20 adults was performed following the administration of 0mg/kg (placebo), 1.5mg/kg, 3.0mg/kg or 4.5mg/kg of caffeine. A digitising tablet was used for the assessment of fine motor movements. Participants were asked to perform a simple writing task. Kinematic analysis of handwriting movements showed that, in comparison to placebo administration, high doses of caffeine (i.e., 4.5mg/kg) can produce improvements in handwriting as indicated by more fluent handwriting movements as well as an increase in maximum velocity and maximum positive and negative accelerations. The results suggest that higher doses of caffeine can enhance psychomotor performance.

Adult↗

PubMed2006

Brain dopamine and kinematics of graphomotor functions.

Three experiments were performed in an attempt to achieve a better understanding of the effect of dopamine on handwriting. In the first experiment, kinematic aspects of handwriting movements were compared between healthy participants and patients with Parkinson's disease (PD) on their usual dopaminergic treatment and following withdrawal of dopaminergic medication. In the second experiment, the writing performance of healthy participants with a hyperechogenicity of the substantia nigra as detected by transcranial sonography (TCS) was compared with the performance of healthy participants with low echogenicity of the substantia nigra. The third experiment examined the effect of central dopamine reduction on kinematic aspects of handwriting movements in healthy adults using acute phenylalanine and tyrosine depletion (APTD). A digitising tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task. Movement time, distance, velocity, acceleration and measures of fluency of handwriting movements were measured. The kinematic analysis of handwriting movements revealed that alterations of central dopaminergic neurotransmission adversely affect movement execution during handwriting. In comparison to the automatic processing of handwriting movements displayed by control participants, participants with an altered dopaminergic neurotransmission shifted from an automatic to a controlled processing of movement execution. Central dopamine appears to be of particular importance with regard to the automatic execution of well-learned movements.

Adult↗

PubMed2006

Neural networks of response shifting: influence of task speed and stimulus material.

Functional magnetic resonance imaging (fMRI) was used in 14 healthy subjects to measure brain activation, while response shifting was performed. In the activation phase, subjects were asked to shift their attention between two different types of visually presented stimuli. In the baseline phase, subjects were required to attend to one stimulus type only. Subjects responded by pressing a left or right key according to the side of presentation of the target stimuli. In a verbal task, subjects were required to switch between letters and numbers. In a figural task, subjects reacted to round and square shapes. Stimuli were presented for 750 or 1500 ms. Response shifting revealed significantly increased activation compared to non-switching in the bilateral superior parietal cortex, right occipital cortex, left inferior frontal cortex, left and right striatum, and bilateral dorsolateral prefrontal cortex (DLPFC). Superior parietal and occipital cortex activation may be due to spatial analysis during response shifting. Subvocal rehearsal of the task instructions may have led to activation in the left inferior frontal cortex. Activation in the striatum was related to prefrontal activation and may represent the association between basal ganglia and prefrontal activation during executive control. However, the most important brain region involved in the execution of response shifting was the bilateral DLPFC. Higher task speed increased executive top-down attentional control and, therefore, significantly increased activity in the bilateral DLPFC. Brain activation did not differ significantly between verbal and figural stimulus material. This result suggests that brain activation in the present study illustrates the brain regions involved in the basic cognitive mechanisms of response shifting.

Adult↗

PubMed2006

Effects of methylphenidate on multiple components of attention in children with attention deficit hyperactivity disorder.

RATIONALE: Methylphenidate (MPH) has been shown to be effective in the treatment of attention deficits in children with attention deficit hyperactivity disorder (ADHD). Although a variety of studies have been performed, there is little available information as to which components of attentional functioning are disturbed in ADHD. OBJECTIVES: The aim of the present study was to monitor the effect of MPH on various measures of attention in children with ADHD. METHODS: In a double-blind, placebo-controlled, crossover study, the attentional functioning of 58 children diagnosed with ADHD without psychiatric comorbidity was examined. Assessment of attention was performed on their usual MPH treatment and following withdrawal of the drug. Furthermore, the attentional performance of 58 healthy children was assessed. The test battery consisted of reaction time tasks, including measures of alertness, vigilance, divided attention, flexibility, and aspects of selective attention such as focused attention, inhibition, and integration of sensory information. RESULTS: In comparison to the test performance of healthy children, children with ADHD displayed impairments of vigilance, divided attention, flexibility, and aspects of selective attention including focused attention, inhibition, and integration of sensory information. Statistical comparison of attentional functioning of children with ADHD on and off MPH treatment revealed that the medication resulted in an improved task accuracy regarding vigilance, divided attention, inhibition, focused attention, integration of sensory information, and flexibility. CONCLUSION: The present findings indicate that various aspects of attention are markedly impaired in children with ADHD. Treatment with MPH was accompanied by improvements in attention functions of small to moderate sizes. Although MPH-induced improvements were observed in a broad range of attention measures, children with ADHD who were on MPH treatment nevertheless displayed serious deficits in a number of components of attention.

Attention↗

PubMed2005

Executive functions in children with dyslexia.

There is little data available concerning the executive functions of children with dyslexia. The small number of existing studies in this field focus on single aspects of these functions such as working memory. The aim of the present study was therefore to assess a variety of aspects of executive functioning in children with dyslexia. Forty-two children with dyslexia and 42 non-dyslexic children were examined using a neuropsychological test battery. The test battery consisted of standardised tests examining the assessment of working memory, concept formation, inhibition, flexibility, problem solving and fluency functions. Comparison between the test performance of non-dyslexic children and children with dyslexia revealed obvious difficulties of children with dyslexia in tests measuring working memory. Inhibition of inappropriate reactions was impaired in children with dyslexia in more demanding tests, but not in simple ones. Furthermore, children with dyslexia displayed impairments of both verbal and figural fluency functions. While in comparison to non-dyslexic children no disturbances of concept formation were observed, problem solving seemed to be partially impaired. The present findings suggest that children with dyslexia demonstrate impairments in a variety of executive functions. This should be considered in the development of new concepts in the treatment of dyslexia.

Attention↗

PubMed2005

Clustering and switching on verbal and figural fluency functions in adults with attention deficit hyperactivity disorder.

INTRODUCTION: Neuropsychological studies of adult patients with ADHD have revealed marked disturbances of executive functions including impairments of attention, working memory, impulsivity, shifting, and divergent thinking. Phonemic fluency tasks, in particular, have been shown to be sensitive measures for the assessment of executive functions of adults with ADHD. METHODS: The present study has examined figural fluency and both phonemic and semantic verbal fluency in 34 adult patients with ADHD and 34 healthy participants. For evaluation of fluency performance the number of words or designs, the number of repetitions and the number of deviations from test rules were calculated. Furthermore, clustering strategies and switching responses were analysed. In comparison with healthy participants, patients with ADHD produced significantly fewer words or designs, but they did not differ from healthy participants in the number of repetitions or rule violations. RESULTS: Analysis of switching and clustering showed that patients produced significantly fewer switching responses on both verbal fluency tasks, although patients tended to generate smaller clusters. Switching on the figural fluency task was unimpaired. CONCLUSIONS: The results of the present study suggest that adult patients with ADHD may suffer from a dysfunction that may affect retrieval processes and the categorisation of knowledge.

Journal Article↗

PubMed2005

The effect of conscious control on handwriting in children with attention deficit hyperactivity disorder.

Two experiments were performed regarding the effect of conscious control on handwriting fluency in healthy adults and ADHD children. First, 26 healthy students were asked to write a sentence under different conditions. The results indicate that automated handwriting movements are independent from visual feedback. Second, the writing performance of 12 children with ADHD was examined on their usual medication with methylphenidate and under placebo. In comparison to placebo, medication with methylphenidate resulted in a reduced fluency of handwriting. Automated handwriting movements could be elicited in children with ADHD on medication. The results suggest that both visual and mental control of handwriting movements affect the automation of handwriting movements. Furthermore, a simple training procedure was designed and performed in a case study of a boy with ADHD.

Adult↗

PubMed2004

Chewing gum differentially affects aspects of attention in healthy subjects.

In a study published previously in this journal (Wilkinson et al., 2002), the effect of chewing gum on cognitive functioning was examined. The results of this study indicated that chewing a piece of gum results in an improvement of working memory and of both immediate and delayed recall of words but not of attention. In the present study, memory and a variety of attentional functions of healthy adult participants were examined under four different conditions: no chewing, mimicking chewing movements, chewing a piece of tasteless chewing gum and chewing a piece of spearmint flavoured chewing gum. The sequence of conditions was randomised across participants. The results showed that the chewing of gum did not improve participants' memory functions. Furthermore, chewing may differentially affect specific aspects of attention. While sustained attention was improved by the chewing of gum, alertness and flexibility were adversely affected by chewing. In conclusion, claims that the chewing a gum improves cognition should be viewed with caution.

Adult↗

PubMed2004

Effects of gum chewing on memory and attention: reply to Scholey (2004).

Recent studies have reported varying results regarding cognitive performance while chewing gum. The differences between the results of these studies may be explained by methodological and statistical factors. Future studies are needed to assess various aspects of cognitive functioning using extensive standardised neuropsychological test batteries, adequate experimental designs and appropriate statistical methods.

Attention↗

PubMed2004

Limitations of the dual-process-theory regarding the writing of words and non-words to dictation.

It is generally assumed that the lexical and phonological systems are involved in writing to dictation. In an experiment concerned with the writing of words and non-words to dictation, the handwriting of female students was registered using a digitising tablet. The data contradict the assumption that the phonological system represents an alexical process. Both words and non-words which were acoustically presented to the subjects were lexically parsed. The analysis of kinematic data revealed significant differences between the subjects' writing of words and non-words. The findings reveal gross disturbances of handwriting fluency during the writing of non-words. The findings of the experiment cannot be explained by the dual-process-theory.

Adult↗

PubMed2004

Handwriting and attention in children and adults with attention deficit hyperactivity disorder.

Adverse effects of drug therapy on handwriting fluency attributed to increased attentional control have been observed in children with attention deficit hyperactivity disorder (ADHD). The writing performance of 8 children with ADHD was assessed using a digitizing tablet in a double-blind, placebo-controlled test. Participants wrote a phrase in cursive script both on and off stimulant medication writing normally, writing with eyes closed, and writing faster than normal. Medication reduced fluency of normal handwriting movements. When children with ADHD were instructed to write faster than normal or with eyes closed, however, more fluent and even automated movements resulted, even on medication. We also assessed 10 children with ADHD, 10 children without ADHD, 10 adults with ADHD, and 10 adults without ADHD. Participants with ADHD were assessed both on and off medication. Children with ADHD on medication were less fluent than children without ADHD. Without medication, Children with ADHD did not differ from children without ADHD; those on medication showed increased handwriting dysfluency. There was no significant difference between the adults. Both children and adults with ADHD could perform age-appropriate and automated handwriting movements. Children with ADHD on medication, however, gave more attention to the writing process, possibly hampering fluent handwriting movements.

Adult↗

PubMed2003

Effects of nicotine chewing gum on a real-life motor task: a kinematic analysis of handwriting movements in smokers and non-smokers.

RATIONALE: In laboratory tasks nicotine has consistently been shown to improve psychomotor performance. OBJECTIVES: The aim of the present experiment was to assess the effects of nicotine on a skilled task of everyday life in smoking and non-smoking healthy adults. METHODS: Assessment of handwriting movements of 38 non-deprived smokers and 38 non-smokers was performed following the chewing of gum containing 0 mg, 2 mg or 4 mg of nicotine. A digitising tablet was used for the assessment of fine motor movements. Subjects were asked to perform a simple writing task. Movement time, velocity and acceleration of the handwriting movements were measured. Furthermore, every writing specimen was independently rated by two examiners regarding the quality of handwriting. RESULTS: Kinematic analysis of writing movements revealed that nicotine could produce absolute improvements in handwriting. Following nicotine administration, reduced movement times, increased velocities and more fluent handwriting movements were observed. These improvements were more striking in smokers than in non-smokers. No effects of nicotine were found with regard to the quality of handwriting. CONCLUSION: The results suggest that nicotine can enhance psychomotor performance to a significant degree in a real-life motor task.

Adult↗

PubMed2003

Echogenicity of the substantia nigra in relatives of patients with sporadic Parkinson's disease.

Increased echogenicity of the substantia nigra (SN) on ultrasound is a typical sonographic finding in Parkinson's disease (PD). Sonographic signal intensity of the SN is related to tissue iron content with higher iron level being associated with increased echogenicity. Recent findings indicate that hyperechogenicity of the SN represents an important susceptibility factor for nigrostriatal degeneration. In this study we determined the prevalence of a characteristic ultrasound sign of Parkinson's disease in first-degree relatives of PD patients. Fourteen patients with sporadic PD and 58 of their relatives underwent neurological, neuropsychological, and ultrasound examination. In addition, four pairs of relatives (one member of each pair exhibiting increased echogenicity of the SN and the other with regular SN echogenicity) underwent (18)F-Dopa PET examination. On transcranial sonography, 26 of the 58 relatives exhibited SN hyperechogenicity. Twenty-four relatives showed minor signs of motor slowing. Relatives with SN hyperechogenicity more often showed signs of hypokinesia (16 v 8 relatives; U test, P = 0.01) and impaired executive functions (Tower of London task, problems solved with the minimum number of moves; U test, P = 0.012) than relatives without this echo pattern. In addition, (18)F-Dopa uptake (influx constants) at the putamen was reduced in subjects with SN hyperechogenicity compared to their relatives without this ultrasound sign (Wilcoxon, P = 0.03). In conclusion, approximately 45% of relatives of PD patients exhibited an increased echogenicity of the SN. This sign is associated with clinical findings and objective measurements, indicating some degree of impaired nigrostriatal function.

Adult↗

PubMed2003

Preoperative and postoperative cognitive functioning in patients with frontal meningiomas.

OBJECT: There is presently no specific information available concerning the nature and course of cognitive deficits caused by intracranial meningiomas. In this prospective study the authors examined the cognitive functioning of patients with frontal meningiomas. METHODS: Fifty-four patients with frontal meningiomas were examined neuropsychologically before and after neurosurgery. The test battery consisted of standardized instruments including those assessing memory, attention, visuoconstructive abilities, and executive functions. The time period between pre-and postoperative assessment ranged from 4 to 9 months. The patients' performance was compared with the results in 54 healthy adults who were also assessed twice by using the same test battery in a period ranging from 4 to 9 months. In addition, the effect on cognition of meningioma lateralization, localization, lesion size, edema, brain compression, time course, and the occurrence of preoperative seizures was analyzed. CONCLUSIONS: Except in the case of working memory, comparisons of pre- and postoperative assessments of cognition revealed no differences in memory, visuoconstructive abilities, or executive functions, although a postoperative improvement in attentional functions was observed. The results of this study indicate that the surgical removal of frontal meningiomas does not impair patients' cognitive functioning. Furthermore, improvements in attentional functions may occur in these patients.

Brain Neoplasms↗

PubMed2002

Vestibular evoked potentials from the vertical semicircular canals in humans evoked by roll-axis rotation in microgravity and under 1-G.

Vestibular evoked potentials during rotation of human subjects around their naso-occipital roll-axis were recorded. The effect of stimulating the vertical semicircular canals and otolithic stimulation was investigated by comparing the evoked potentials obtained under the 1-G condition with those recorded in microgravity conditions. Subjects lay on their side with the head in the center of rotation and were tilted feet upward (roll up) and back into the lying position (roll down). The microgravity environment was created by parabolic flight maneuvers. In microgravity, transient bell-shaped negativity was recorded for roll up and down motion. In the 1-G condition the potentials were superimposed on sustained components, probably due to additional otolithic stimulation. It seems to be possible to separate the evoked responses in a transient canal response and a sustained otolithic response. The results are encouraging with respect to the goal of developing a tool for the selective assessment of canal and otolithic responses of the vestibular system.

Adult↗

PubMed2002

Echogenicity of the substantia nigra: association with increased iron content and marker for susceptibility to nigrostriatal injury.

BACKGROUND: Patients with Parkinson disease characteristically exhibit an increased echogenicity of the substantia nigra (SN) on transcranial sonography, a new neuroimaging technique. The same echo feature of the SN can be identified in 9% of healthy adults. OBJECTIVE: To evaluate the relevance of the echogenic SN in healthy adults. DESIGN: In the first part of the study, 10 healthy subjects younger than 40 years with a distinct SN hyperechogenicity underwent extensive neurological, motor, neuropsychological, and fluorine 18-dopa positron emission tomographic ([18F]-dopa PET) examinations. Results were compared with those of 10 subjects with a low echogenic SN. In the second part of the study, the postmortem brains of 20 patients without extrapyramidal disorders during their lifetime were sonographically examined with a particular focus on SN echogenicity. Subsequently, one half of the brain was prepared for heavy metal analysis, the other for a histological examination. RESULTS: Healthy subjects with SN hyperechogenicity exhibited a significant reduction of the [18F]-dopa uptake, especially in the putamen (Wilcoxon matched pair test: left side, P =.006; right side, P =.009), whereas their neuropsychological and motor performance were normal. Postmortem studies showed that the echogenicity of the SN correlated with its iron content. CONCLUSIONS: Increased echogenicity of the SN, characteristically seen in Parkinson disease, is related to a functional impairment of the nigrostriatal system (even in young healthy adults) that can be revealed by [18F]-dopa PET studies. Substantia nigra hyperechogenicity is related to a higher tissue iron level, which is known to enhance the cells' generation of reactive oxygen specimens. Therefore, we hypothesize that transcranial sonography may identify a susceptibility marker for the development of nigral injury that can be detected early in life, prior to the onset of Parkinson disease.

Adolescent↗

PubMed2001

The impact of tricyclic antidepressants and selective serotonin re-uptake inhibitors on handwriting movements of patients with depression.

RATIONALE: Psychomotor retardation is a common symptom of patients with major depressive disorder. While a variety of clinical examinations using different techniques have been undertaken to assess the motor component of psychomotor retardation in depression, the effects of antidepressants on psychomotor functions have been examined less extensively. OBJECTIVE: The aim of the present study was to examine the effect of various pharmacological treatments on handwriting movements of patients with depression. METHODS: Kinematic data of automated handwriting movements of 18 depressed patients receiving tricyclic antidepressants (TCAs), 18 patients on selective serotonin re-uptake inhibitors (SSRIs) and 18 healthy subjects was recorded and analysed. Groups were matched according to age, sex, handedness and education level. For the assessment of fine motor movements, a digitising tablet was used. Subjects were asked to perform a simple writing task. Movement time, velocity and acceleration of the handwriting movements were measured. RESULTS: Statistical analysis of writing movements revealed motor slowing in patients receiving TCAs. In comparison with both healthy subjects and patients receiving SSRIs, the TCA group displayed an increased movement time, reduced automation of handwriting, lower maximum velocities and reduced acceleration of descending strokes. CONCLUSIONS: The results suggest either that TCAs have adverse effects on motor functioning or that they are less effective in the treatment of motor retardation than SSRIs.

Adult↗