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Ivan Bodis-Wollner

Publications and source records attributed to Ivan Bodis-Wollner.

6 recordsLinked to original sources
PubMed2006

Conjugate eye movements and gamma power modulation of the EEG in persistent vegetative state.

BACKGROUND: Power in the gamma band EEG increases during saccades in normal subjects. OBJECTIVE: To develop a potential method to quantify signs of cortical responsiveness in persistent vegetative state (PVS) we quantified gamma range EEG in association with conjugate slow ballistic eye movements (SBEM). METHODS: The EEG and the simultaneous electro-oculogram were recorded in 14 (8F/6M) PVS patients. Clinical scoring was based on the Glasgow Coma Scale (GCS) and Coma Rating Scale (CRS). The Wavelet Transform, followed by Hilbert transform was applied to the EEG and gamma power distribution was quantified relative to the timing of an eye movement. We correlated the clinical and the neurophysiological measures. RESULTS: Gamma activity was present in all PVS patients. Its power was modulated in association with eye movements only in less severely affected patients, with minimum power prior to, and maximum power during the eye movement. In severely affected patients there was no evidence of a temporal relationship between gamma power and the phase of the eye movement. CONCLUSIONS: Detecting changes in the time course of gamma power in relation to conjugate ballistic eye movements provides a quantitative neurophysiological method for prospective longitudinal studies to explore if the preservation of this CNS function relates to the potential for recovery in PVS patients.

Adult↗
PubMed2003

Neuropsychological and perceptual defects in Parkinson's disease.

Neuropsychiatric, perceptual and cognitive deficits are increasingly recognized as non-motor manifestations of Parkinson's Disease (PD).The premorbid personality profile of PD patients is characterized by a number of traits which figure prominently after the disease becomes manifest. In particular, less novelty seeking is one premorbid trait providing an understanding of later cognitive deficits. Anxiety and depression have been shown to precede in some patients motor manifestations and cannot be attributed to anti-parkinsonian therapy. Some neuropsychiatric manifestations and in particular hallucinosis are linked to select perceptual and cognitive changes. Cognitive deficits are common in PD, in particular in younger onset patients. Current animal studies link genetic differences in the dopamine transporter and dopamine catabolic enzyme system to select cognitive impairments attributed to frontal lobe dysfunction.Visuo-cognitive impairment is prevalent in PD. Retinal dopaminergic deficiency has been shown in patients and in the animal model of PD. Visuo-spatial deficits, however, are not simply passive reflections of retinal deficiency. In addition to vision, saccadic eye movements are affected in PD whether they contribute to visuo-spatial dysfunction is unknown. However, recent functional Magnetic Resonance Imaging (fMRI) and electroencephalogram (EEG) studies show an essential role of the occipital cortex in saccadic eye movements and positron emission tomography (PET) studies show occipital hypometabolism in PD. Visual and eye movement studies suggest that certain neuropsychiatric and cognitive deficits in PD are linked to the visual system. Synchrony of signals are essential for the co-operation of distributed neuronal network engaged in sensory-motor coordination. Local, dopaminergic neuronal groups in the retina, basal ganglia and frontal cortical memory system are affected in PD. These connections may not primarily rely on dopamine as a neurotransmitter. It is suggested that to understand visuocognitive changes we should consider pathology affecting neuronal connections, necessary for binding parallel distributed networks.

Hallucinations↗
PubMed2002

Electrophysiological correlates of visual categorization: evidence for cognitive dysfunctions in early Parkinson's disease.

Our aim was to examine the electrophysiological correlates of perceptual categorization in Parkinson's disease (PD). We recorded visual event-related potentials (ERPs) in a natural scene categorization task in drug naive idiopathic PD patients and healthy control subjects. In the control group, there was a significant early difference (150-250 ms poststimulus) between ERPs elicited by pictures containing animals and scenes without animals. In spite of relatively preserved basic-level visual functions, this was not observable in the PD group. These results raise the possibility for striatal contributions to visual categorization and may provide a novel protocol for further clinical studies.

Aged↗
PubMed2002

Topographical analysis of the onset VEP in the detection of paracentral visual field defects.

Transient visual evoked potentials (VEP) were recorded simultaneously from 16 electrodes evenly placed over posterior scalp locations covering the occipital, posterior parietal and temporal areas. Interhemispheric amplitude difference of the N70 deflection was established across 6 homologous lateral electrode pairs in 15 normal controls and 32 patients with chiasmatic or retrochiasmatic cerebral lesions. Twenty-three of these had known homonymous or bitemporal field defects while 9 had normal fields on routine perimetry. Significant interhemispheric asymmetry of any single electrode pair occurred in 55% of the 32 patients with known pathology, while the cumulative yield of all electrode pairs was over 80 percent. The diagnostic yield of individual electrode pairs was significantly different: the electrode pair placed over the temporo-parietal junction detected the highest number of abnormalities. The cumulative abnormality taken over all lateral electrode pairs could be described with a curve well fitted with a probability summation function. It is inferred that the contribution of several independent generator sources is reflected in the N70 of the pattern onset VEP. The results suggest that multichannel recording of the interhemispheric amplitude distribution of the N70 of the onset VEP is useful for the evaluation of paracentral visual field defects.

Adult↗