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Electroencephalography.
No full textRecent advances in electroencephalography (EEG) research are presented. Particular emphasis is placed on sleep and epilepsy research in humans. In this context, among others, studies on the modifications of EEG epileptic activity during sleep are discussed in more detail. A large number of reports come from EEG monitoring during presurgical evaluation and surgical treatment of drug-resistant epilepsy; information provided by these studies is therefore considered with special attention
Neurophysiological evaluation of dopaminergic transmission in the visual system of normal humans
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Topographical analysis of the onset VEP in the detection of paracentral visual field defects
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Multichannel visual evoked potentials in migraine.
No full textMultichannel recordings of visual evoked potentials (VEPs) have proved to be
useful in the evaluation of visual field defects. We studied the topographic
distribution of transient VEPs in 15 migraine patients (8 with visual aura and 7
without) and 15 age-matched controls during the migraine-free interval. All the
subjects included in the study had normal visual fields. VEPs were recorded from
9 electrodes placed on the posterior scalp. Stimuli were full-field and hemifield
reversing square wave grating patterns of medium spatial frequency (4 c/deg). The
groups did not show significant differences in latencies and amplitudes of the
major components (N70, P100) recorded from the midline. However, migraine
patients with visual hemianopic aura showed definite asymmetries in the VEP
amplitude distribution. Significantly reduced, absent or polarity-invered VEP
responses were recorded ipsilateral to the side of the prodromic visual symptoms.
Direct comparison of affected and unaffected hemispheres by partial field
stimulation confirmed these findings. According to the VEP cortical generator
theory, these abnormalities suggest a functional anomaly consistent with the
clinical syndrome and detectable also in the migraine-free interval. None of the
migraine patients without aura or the controls showed VEP amplitude asymmetries.
We conclude that multichannel VEP recordings may discriminate between different
subtypes of migraine and contribute important physiopathological information to
the study of this disease
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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