Recent research provides evidence that galvanic vestibular stimulation (GVS) has a modulating eff... more Recent research provides evidence that galvanic vestibular stimulation (GVS) has a modulating effect on somatosensory perception and spatial cognition. However, other vestibular stimulation techniques have induced changes in affective control and decision making. The aim of this study was to investigate the effect of GVS on framing susceptibility in a risky-choice game. The participants were to decide between a safe and a risky option. The safe option was framed either positively or negatively. During the task, the participants were exposed to either left anodal/right cathodal GVS, right anodal/left cathodal GVS, or sham stimulation (control condition). While left anodal/right cathodal GVS activated more right-hemispheric vestibular brain areas, right anodal/left cathodal GVS resulted in more bilateral activation. We observed increased framing susceptibility during left anodal/right cathodal GVS, but no change in framing susceptibility during right anodal/left cathodal GVS. We propo...
Lesions of the brain stem can either affect the nuclei or the fascicles of the third, fourth or s... more Lesions of the brain stem can either affect the nuclei or the fascicles of the third, fourth or sixth cranial nerves and thus produce ocular motor disorders. Lesions of the oculomotor nuclear complex differ from lesions of the third nerve, since the motoneurones in the nucleus are specifically grouped. Similarly, a lesion of the sixth nerve nucleus results in a conjugate gaze palsy and not in an abducens palsy, because of 'interneurones' being intermingled with the abducens motoneurons. Isolated lesions of a nerve fascicle, which is the part of the cranial nerve running through the brain stem, usually cannot be distinguished clinically from lesions of the nerve outside the brain stem unless other brain stem signs are present. In the case of an isolated ocular motor nerve palsy, modern imaging techniques, particularly magnetic resonance imaging, may help to localize the lesion to the brain stem. Most often, however, brain stem lesions also involve structures surrounding the o...
In general, intermittent diplopia evokes suspicion of ocular myasthenia gravis. However, other et... more In general, intermittent diplopia evokes suspicion of ocular myasthenia gravis. However, other etiologies such as Brown syndrome or myokymia of the superior oblique may provoke intermittent diplopia. We present a case of intermittent diplopia due to a tumor in the cavernous sinus. A 59-year-old patient reported intermittent diplopia after prolonged downward gaze to the right. All other gaze directions failed to provoke symptoms. In 1992, the diagnosis of inactive macroadenoma of the pituitary gland was established and the patient underwent surgery and radiation therapy. At physical examination, prolonged downward gaze to the right of about 2 minutes provoked paresis of abduction, slight ptosis, and restriction of elevation on the left side, corresponding to sixth nerve palsy and palsy of the superior branch of the third nerve on the left side. MRI showed a relapse of the macroadenoma with infiltration of the cavernous sinus on the left side. The patient underwent surgery then focal ...
Hemispatial neglect - defined as the failure to attend, explore, and act upon the contralesional ... more Hemispatial neglect - defined as the failure to attend, explore, and act upon the contralesional side of space - is a frequent and disabling neurological syndrome. Interhemispheric rivalry is considered as a major pathophysiological mechanism underlying hemispatial neglect. According to this account, the contralesional, intact hemisphere undergoes a pathological hyperactivity due to a deficient transcallosal inhibition from the damaged hemisphere. This model offers a framework for possible therapeutic interventions with repetitive transcranial magnetic stimulation (rTMS), i.e. a reduction of the pathological hyperactivity with a rTMS protocol that has lasting inhibitory effects. In the present work, we will first review evidence for the interhemispheric rivalry account coming from animals and humans. We will then describe studies showing the possibility to perturb and to restore interhemispheric balance in healthy subjects as a proof of concept for therapeutic rTMS application. Finally, we will consider studies applying rTMS as a therapeutic approach in hemispatial neglect. We conclude that rTMS is a promising approach to reduce the interhemispheric imbalance in neglect patients and to ameliorate symptoms. Newly developed protocols such as Theta Burst Stimulation (TBS) - with short stimulation times and long offline effects - seem to be particularly convenient. However, future studies should assess stimulation effects not only in clinical testing, but also on disability, considering combination with traditional therapies as well.
Lesions of the ventromedial prefrontal cortex can result in a deficient decision-making behavior.... more Lesions of the ventromedial prefrontal cortex can result in a deficient decision-making behavior. So far, most experimental results in the neuropsychological decision-making research have been obtained with gambling tasks. Due to their high complexity, it is difficult to evaluate the underlying processes of the decision-making deficits. The aim of this study was to assess if patients with ventromedial prefrontal damage compared to patients with dorsolateral prefrontal damage and controls show a deficit in an early stage of the decision-making process. Nine patients with ventromedial prefrontal damage, three with dorsolateral prefrontal damage, and eleven healthy controls were tested with a newly developed decision task in which they had to search actively for the information they needed for their decisions. Our results show that patients with ventromedial prefrontal damage compared to the brain-lesioned dorsolateral prefrontal control group and healthy controls searched less for information with regard to risk defusing operators or consequences of their decisions indicating impairment already in the early stage of the decision-making process.
Multiple sclerosis (Houndmills, Basingstoke, England), Jan 26, 2015
Impaired manual dexterity is frequent and disabling in patients with multiple sclerosis (MS), aff... more Impaired manual dexterity is frequent and disabling in patients with multiple sclerosis (MS), affecting activities of daily living (ADL) and quality of life. We aimed to evaluate the effectiveness of a standardized, home-based training program to improve manual dexterity and dexterity-related ADL in MS patients. This was a randomized, rater-blinded controlled trial. Thirty-nine MS patients acknowledging impaired manual dexterity and having a pathological Coin Rotation Task (CRT), Nine Hole Peg Test (9HPT) or both were randomized 1:1 into two standardized training programs, the dexterity training program and the theraband training program. Patients trained five days per week in both programs over a period of 4 weeks. Primary outcome measures performed at baseline and after 4 weeks were the CRT, 9HPT and a dexterous-related ADL questionnaire. Secondary outcome measures were the Chedoke Arm and Hand Activity Inventory (CAHAI-8) and the JAMAR test. The dexterity training program resulte...
Eye movement disturbances resulting from cerebral lesions are reviewed and the specific roles of ... more Eye movement disturbances resulting from cerebral lesions are reviewed and the specific roles of the different ocular motor areas are summarized. Three cortical areas may trigger saccades: the frontal eye field (FEF), the supplementary eye field (SEF) and the parietal eye field (PEF). The FEF could be involved mainly in intentional visual exploration (intentional saccades), the PEF mainly in reflexive visual exploration (reflexive saccades) and the SEF in the preparation of motor programs (sequences of saccades). Only bilateral lesions affecting these areas result in visible saccade disturbances (at bedside examination), as manifested in Balint's syndrome after parietal lesions, and ocular motor apraxia after fronto-parietal lesions. Other cortical areas prepare saccades: the posterior parietal cortex (near the PEF) controls visuomotor integration; the prefrontal cortex (i.e. area 46 of Brodmann) is involved in inhibition of unwanted reflexive saccades, prediction (predictive saccades) and spatial memory. Smooth pursuit is controlled by the FEF and the medial superior temporal area, located in the posterior part of the cerebral hemisphere. Eye movement disorders resulting from basal ganglia lesions are also reviewed. Lastly, the contribution of eye movement recordings in early diagnosis of some cerebral degenerative diseases (such as progressive supranuclear palsy or corticobasal degeneration) is emphasized.
Driving a car is a complex instrumental activity of daily living and driving performance is very ... more Driving a car is a complex instrumental activity of daily living and driving performance is very sensitive to cognitive impairment. The assessment of driving-relevant cognition in older drivers is challenging and requires reliable and valid tests with good sensitivity and specificity to predict safe driving. Driving simulators can be used to test fitness to drive. Several studies have found strong correlation between driving simulator performance and on-the-road driving. However, access to driving simulators is restricted to specialists and simulators are too expensive, large, and complex to allow easy access to older drivers or physicians advising them. An easily accessible, Web-based, cognitive screening test could offer a solution to this problem. The World Wide Web allows easy dissemination of the test software and implementation of the scoring algorithm on a central server, allowing generation of a dynamically growing database with normative values and ensures that all users have access to the same up-to-date normative values. In this pilot study, we present the novel Web-based Bern Cognitive Screening Test (wBCST) and investigate whether it can predict poor simulated driving performance in healthy and cognitive-impaired participants. The wBCST performance and simulated driving performance have been analyzed in 26 healthy younger and 44 healthy older participants as well as in 10 older participants with cognitive impairment. Correlations between the two tests were calculated. Also, simulated driving performance was used to group the participants into good performers (n=70) and poor performers (n=10). A receiver-operating characteristic analysis was calculated to determine sensitivity and specificity of the wBCST in predicting simulated driving performance. The mean wBCST score of the participants with poor simulated driving performance was reduced by 52%, compared to participants with good simulated driving performance (P<.001). The area under the receiver-operating characteristic curve was 0.80 with a 95% confidence interval 0.68-0.92. When selecting a 75% test score as the cutoff, the novel test has 83% sensitivity, 70% specificity, and 81% efficiency, which are good values for a screening test. Overall, in this pilot study, the novel Web-based computer test appears to be a promising tool for supporting clinicians in fitness-to-drive assessments of older drivers. The Web-based distribution and scoring on a central computer will facilitate further evaluation of the novel test setup. We expect that in the near future, Web-based computer tests will become a valid and reliable tool for clinicians, for example, when assessing fitness to drive in older drivers.
Introduction Clinico-anatomical studies have shown that, after brain damage, the ability to imita... more Introduction Clinico-anatomical studies have shown that, after brain damage, the ability to imitate meaningless and meaningful gestures may be selectively affected suggesting that different posterior parietal structures may be involved (dual route model). The aim of the present study was therefore to investigate the effect of imaging-guided neuro-navigated continuous theta burst stimulation (cTBS) on the imitation domain over inferior (IPL) and superior parietal cortex (SPL). We hypothesized that SPL stimulation mainly affects meaningless and IPL stimulation predominantly meaningful gestures. Subjects and methods Twelve healthy subjects participated in this study. All subjects underwent structural MRI acquisition to be used for imaging guided neuro-navigation cTBS. Participants were targeted with one train of cTBS in three experimental sessions: sham stimulation over vertex and real cTBS over left SPL and IPL, respectively. The imitation task was performed ‘offline’ including 24 meaningless and 24 meaningful (communicative and tool-related). Results cTBS over left posterior parietal cortex, irrespective of whether IPL or SPL was stimulated, significantly affected gestural imitation. By contrast, differential effects on gesture subtypes (meaningless versus meaningful) could not be detected. Discussion The present study shows that a single train of cTBS over left posterior parietal regions significantly interferes with gestural imitation confirming the domain-specific role this region has. However, the findings do not support the predictions based on the dual route model.
Recent research provides evidence that galvanic vestibular stimulation (GVS) has a modulating eff... more Recent research provides evidence that galvanic vestibular stimulation (GVS) has a modulating effect on somatosensory perception and spatial cognition. However, other vestibular stimulation techniques have induced changes in affective control and decision making. The aim of this study was to investigate the effect of GVS on framing susceptibility in a risky-choice game. The participants were to decide between a safe and a risky option. The safe option was framed either positively or negatively. During the task, the participants were exposed to either left anodal/right cathodal GVS, right anodal/left cathodal GVS, or sham stimulation (control condition). While left anodal/right cathodal GVS activated more right-hemispheric vestibular brain areas, right anodal/left cathodal GVS resulted in more bilateral activation. We observed increased framing susceptibility during left anodal/right cathodal GVS, but no change in framing susceptibility during right anodal/left cathodal GVS. We propo...
Lesions of the brain stem can either affect the nuclei or the fascicles of the third, fourth or s... more Lesions of the brain stem can either affect the nuclei or the fascicles of the third, fourth or sixth cranial nerves and thus produce ocular motor disorders. Lesions of the oculomotor nuclear complex differ from lesions of the third nerve, since the motoneurones in the nucleus are specifically grouped. Similarly, a lesion of the sixth nerve nucleus results in a conjugate gaze palsy and not in an abducens palsy, because of 'interneurones' being intermingled with the abducens motoneurons. Isolated lesions of a nerve fascicle, which is the part of the cranial nerve running through the brain stem, usually cannot be distinguished clinically from lesions of the nerve outside the brain stem unless other brain stem signs are present. In the case of an isolated ocular motor nerve palsy, modern imaging techniques, particularly magnetic resonance imaging, may help to localize the lesion to the brain stem. Most often, however, brain stem lesions also involve structures surrounding the o...
In general, intermittent diplopia evokes suspicion of ocular myasthenia gravis. However, other et... more In general, intermittent diplopia evokes suspicion of ocular myasthenia gravis. However, other etiologies such as Brown syndrome or myokymia of the superior oblique may provoke intermittent diplopia. We present a case of intermittent diplopia due to a tumor in the cavernous sinus. A 59-year-old patient reported intermittent diplopia after prolonged downward gaze to the right. All other gaze directions failed to provoke symptoms. In 1992, the diagnosis of inactive macroadenoma of the pituitary gland was established and the patient underwent surgery and radiation therapy. At physical examination, prolonged downward gaze to the right of about 2 minutes provoked paresis of abduction, slight ptosis, and restriction of elevation on the left side, corresponding to sixth nerve palsy and palsy of the superior branch of the third nerve on the left side. MRI showed a relapse of the macroadenoma with infiltration of the cavernous sinus on the left side. The patient underwent surgery then focal ...
Hemispatial neglect - defined as the failure to attend, explore, and act upon the contralesional ... more Hemispatial neglect - defined as the failure to attend, explore, and act upon the contralesional side of space - is a frequent and disabling neurological syndrome. Interhemispheric rivalry is considered as a major pathophysiological mechanism underlying hemispatial neglect. According to this account, the contralesional, intact hemisphere undergoes a pathological hyperactivity due to a deficient transcallosal inhibition from the damaged hemisphere. This model offers a framework for possible therapeutic interventions with repetitive transcranial magnetic stimulation (rTMS), i.e. a reduction of the pathological hyperactivity with a rTMS protocol that has lasting inhibitory effects. In the present work, we will first review evidence for the interhemispheric rivalry account coming from animals and humans. We will then describe studies showing the possibility to perturb and to restore interhemispheric balance in healthy subjects as a proof of concept for therapeutic rTMS application. Finally, we will consider studies applying rTMS as a therapeutic approach in hemispatial neglect. We conclude that rTMS is a promising approach to reduce the interhemispheric imbalance in neglect patients and to ameliorate symptoms. Newly developed protocols such as Theta Burst Stimulation (TBS) - with short stimulation times and long offline effects - seem to be particularly convenient. However, future studies should assess stimulation effects not only in clinical testing, but also on disability, considering combination with traditional therapies as well.
Lesions of the ventromedial prefrontal cortex can result in a deficient decision-making behavior.... more Lesions of the ventromedial prefrontal cortex can result in a deficient decision-making behavior. So far, most experimental results in the neuropsychological decision-making research have been obtained with gambling tasks. Due to their high complexity, it is difficult to evaluate the underlying processes of the decision-making deficits. The aim of this study was to assess if patients with ventromedial prefrontal damage compared to patients with dorsolateral prefrontal damage and controls show a deficit in an early stage of the decision-making process. Nine patients with ventromedial prefrontal damage, three with dorsolateral prefrontal damage, and eleven healthy controls were tested with a newly developed decision task in which they had to search actively for the information they needed for their decisions. Our results show that patients with ventromedial prefrontal damage compared to the brain-lesioned dorsolateral prefrontal control group and healthy controls searched less for information with regard to risk defusing operators or consequences of their decisions indicating impairment already in the early stage of the decision-making process.
Multiple sclerosis (Houndmills, Basingstoke, England), Jan 26, 2015
Impaired manual dexterity is frequent and disabling in patients with multiple sclerosis (MS), aff... more Impaired manual dexterity is frequent and disabling in patients with multiple sclerosis (MS), affecting activities of daily living (ADL) and quality of life. We aimed to evaluate the effectiveness of a standardized, home-based training program to improve manual dexterity and dexterity-related ADL in MS patients. This was a randomized, rater-blinded controlled trial. Thirty-nine MS patients acknowledging impaired manual dexterity and having a pathological Coin Rotation Task (CRT), Nine Hole Peg Test (9HPT) or both were randomized 1:1 into two standardized training programs, the dexterity training program and the theraband training program. Patients trained five days per week in both programs over a period of 4 weeks. Primary outcome measures performed at baseline and after 4 weeks were the CRT, 9HPT and a dexterous-related ADL questionnaire. Secondary outcome measures were the Chedoke Arm and Hand Activity Inventory (CAHAI-8) and the JAMAR test. The dexterity training program resulte...
Eye movement disturbances resulting from cerebral lesions are reviewed and the specific roles of ... more Eye movement disturbances resulting from cerebral lesions are reviewed and the specific roles of the different ocular motor areas are summarized. Three cortical areas may trigger saccades: the frontal eye field (FEF), the supplementary eye field (SEF) and the parietal eye field (PEF). The FEF could be involved mainly in intentional visual exploration (intentional saccades), the PEF mainly in reflexive visual exploration (reflexive saccades) and the SEF in the preparation of motor programs (sequences of saccades). Only bilateral lesions affecting these areas result in visible saccade disturbances (at bedside examination), as manifested in Balint's syndrome after parietal lesions, and ocular motor apraxia after fronto-parietal lesions. Other cortical areas prepare saccades: the posterior parietal cortex (near the PEF) controls visuomotor integration; the prefrontal cortex (i.e. area 46 of Brodmann) is involved in inhibition of unwanted reflexive saccades, prediction (predictive saccades) and spatial memory. Smooth pursuit is controlled by the FEF and the medial superior temporal area, located in the posterior part of the cerebral hemisphere. Eye movement disorders resulting from basal ganglia lesions are also reviewed. Lastly, the contribution of eye movement recordings in early diagnosis of some cerebral degenerative diseases (such as progressive supranuclear palsy or corticobasal degeneration) is emphasized.
Driving a car is a complex instrumental activity of daily living and driving performance is very ... more Driving a car is a complex instrumental activity of daily living and driving performance is very sensitive to cognitive impairment. The assessment of driving-relevant cognition in older drivers is challenging and requires reliable and valid tests with good sensitivity and specificity to predict safe driving. Driving simulators can be used to test fitness to drive. Several studies have found strong correlation between driving simulator performance and on-the-road driving. However, access to driving simulators is restricted to specialists and simulators are too expensive, large, and complex to allow easy access to older drivers or physicians advising them. An easily accessible, Web-based, cognitive screening test could offer a solution to this problem. The World Wide Web allows easy dissemination of the test software and implementation of the scoring algorithm on a central server, allowing generation of a dynamically growing database with normative values and ensures that all users have access to the same up-to-date normative values. In this pilot study, we present the novel Web-based Bern Cognitive Screening Test (wBCST) and investigate whether it can predict poor simulated driving performance in healthy and cognitive-impaired participants. The wBCST performance and simulated driving performance have been analyzed in 26 healthy younger and 44 healthy older participants as well as in 10 older participants with cognitive impairment. Correlations between the two tests were calculated. Also, simulated driving performance was used to group the participants into good performers (n=70) and poor performers (n=10). A receiver-operating characteristic analysis was calculated to determine sensitivity and specificity of the wBCST in predicting simulated driving performance. The mean wBCST score of the participants with poor simulated driving performance was reduced by 52%, compared to participants with good simulated driving performance (P<.001). The area under the receiver-operating characteristic curve was 0.80 with a 95% confidence interval 0.68-0.92. When selecting a 75% test score as the cutoff, the novel test has 83% sensitivity, 70% specificity, and 81% efficiency, which are good values for a screening test. Overall, in this pilot study, the novel Web-based computer test appears to be a promising tool for supporting clinicians in fitness-to-drive assessments of older drivers. The Web-based distribution and scoring on a central computer will facilitate further evaluation of the novel test setup. We expect that in the near future, Web-based computer tests will become a valid and reliable tool for clinicians, for example, when assessing fitness to drive in older drivers.
Introduction Clinico-anatomical studies have shown that, after brain damage, the ability to imita... more Introduction Clinico-anatomical studies have shown that, after brain damage, the ability to imitate meaningless and meaningful gestures may be selectively affected suggesting that different posterior parietal structures may be involved (dual route model). The aim of the present study was therefore to investigate the effect of imaging-guided neuro-navigated continuous theta burst stimulation (cTBS) on the imitation domain over inferior (IPL) and superior parietal cortex (SPL). We hypothesized that SPL stimulation mainly affects meaningless and IPL stimulation predominantly meaningful gestures. Subjects and methods Twelve healthy subjects participated in this study. All subjects underwent structural MRI acquisition to be used for imaging guided neuro-navigation cTBS. Participants were targeted with one train of cTBS in three experimental sessions: sham stimulation over vertex and real cTBS over left SPL and IPL, respectively. The imitation task was performed ‘offline’ including 24 meaningless and 24 meaningful (communicative and tool-related). Results cTBS over left posterior parietal cortex, irrespective of whether IPL or SPL was stimulated, significantly affected gestural imitation. By contrast, differential effects on gesture subtypes (meaningless versus meaningful) could not be detected. Discussion The present study shows that a single train of cTBS over left posterior parietal regions significantly interferes with gestural imitation confirming the domain-specific role this region has. However, the findings do not support the predictions based on the dual route model.
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