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  • 1
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The present report considers goal directed human saccadic eye movements. It addresses the question how a given perceived target excentricity is transformed into the innervation pattern that creates the saccade to the target. More specifically, it investigates whether this pattern is an appropriately selected preprogram or whether it is continuously controlled by a local feedback loop that compares a non-visual eye position signal to the perceived target excentricity (a visual signal would be too slow). To this end, the relation between the accuracy of saccades aimed at a given target and their velocity and duration was examined. Duration and velocity were found to vary by as much as 60% while the amplitude showed no related variation and had an almost constant accuracy of about 90%. By administrating diazepam, the variability of saccade duration and velocity could be further increased, but still the amplitude remained almost constant. These results favour the hypothesis that saccadic innervation is controlled by a local feedback loop.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 2 (1966), S. 318-327 
    ISSN: 1432-1106
    Keywords: Vestibular projection area ; Cortex cerebri ; Rhesus monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Corticale Reizantworten nach elektrischer Reizung des Nervus vestibularis bei Rhesus-Affen ergaben mit 5 msec Latenzzeit als prim***äre corticale Vestibularis-Projektion den unteren hinteren Teil der Postzentralwindung am Ende der Fissura intraparietalis. Das vestibuläre Rindenfeld liegt zwischen dem ersten und zweiten somatischen Feld und entspricht der unteren Area 2 nach Vogt. 2. Ein Irrtum durch Mitreizung benachbarter Hirnnerven wurde durch Exstirpation von Cochlearis, Facialis und Intermedius sowie durch Vestibularisreizung vor und nach Wurzeldurchschneidungen von Trigeminus, Glossopharyngeus, Vagus, Accessorius und Vestibularis ausgeschlossen. 3. Das vestibuläre Rindenfeld ist partiell überlagert vom somatosensiblen Projektionsfeld S I, das auf contralateralen Medianus-Reiz antwortet. Es besteht Interaktion der evoked potentials zwischen Vestibularisund Medianus-Reizung in dieser Übergangszone. 4. Die Möglichkeit, daß die corticale Vestibularis-Projektion zu höheren motorischen Regelungen und zur bewußten räumlichen Orientierung beiträgt, wird diskutiert.
    Notes: Summary 1. Cortical potentials evoked by electrical stimulation of the vestibular nerve in the Rhesus monkey indicate that the primary receiving area for the vestibular nerve is located in the posterior part of the postcentral gyrus at the base of the intraparietal sulcus between the first and second somatosensory fields, probably in Brodmann's area 2. 2. An origin of the evoked cortical potential from other cranial nerves was excluded by extirpation of the cochlear, facial and intermedius nerves and by vestibular stimulation before and after section of the V, IX, X and XI nerve roots at the brainstem. Only sectioning the vestibular nerve abolished the response. 3. This field partially overlaps the SI cortical region responsive to electrical stimulation of the contralateral median nerve. There is interaction between vestibular and median nerve afferents within the overlap zone. 4. It is postulated that the primary cortical vestibular field contributes information for higher motor regulation and conscious spatial orientation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 70 (1988), S. 99-108 
    ISSN: 1432-1106
    Keywords: Event-related potentials ; Slow negative potential shifts ; Bereitschaftspotential ; Learning ; Language
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the present experiment pairs of words had to be memorized. The words were either meaningful or meaningless. The experimental design compares conditions of preestablished learning (L-) with active learning (L+). The effects of these two factors, “semantic content (S)” and “learning (L)”, on the slow potential shifts accompanying presentation and processing of the verbal material were tested. In the memorizing tasks, the two words were given in a fixed temporal sequence. A slow negative potential shift having a maximum in parietal leads emerged within the inter-stimulus-interval. Its amplitudes were larger in the learning tasks (L+) than in conditions of pre-established learning (L-). This difference of amplitudes may reflect different levels of attention: In L-, the second word could be anticipated, but not in the L+ tasks. After the presentation of the second item, learning tasks (L+) were characterized by a slow negative potential shift in the recordings of the left dorso-lateral frontal lobe. It is assumed that this potential shift may indicate an importance of the left frontal lobe in the elaborative encoding of verbal material.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 65 (1986), S. 219-223 
    ISSN: 1432-1106
    Keywords: Bereitschaftspotential ; Voluntary movement ; Speech ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cerebral potentials prior to speaking were recorded in 36 healthy righthanded subjects. Subjects began holding breath at irregular intervals prior to the voluntary onset of speech. This was done in order to avoid respiration-related potential shifts. The Bereitschaftspotential (BP) or readiness potential started already 2 s prior to the onset of speaking and was present over either hemisphere. During the last 100 to 200 ms of preparation period, the BP became significantly lateralized towards the left hemisphere. The close temporal relation to speech onset characterized this hemispheric lateralization to be an indicator of the final motor mechanisms for speech. Still, the BP was a bilateral phenomenon, i.e. it was also present over the right hemisphere, indicating involvement of the non-dominant hemisphere as well. The data are compatible with the view of an early bihemispheric motor preparation for speech followed by a late left hemisphere preponderance as the final common pathway.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 22 (1975), S. 331-334 
    ISSN: 1432-1106
    Keywords: Somatosensory ; Evoked potentials ; Psychophysics ; Merkel discs ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With step indentations of the index finger tip in randomized order, via a mechanostimulator, the tactile receptors of human skin were adequately stimulated. Recording the EEG over the contralateral and ipsilateral cortex, the evoked potentials and their 95% confidence limits were analysed. Simultaneously the psychophysical magnitude estimations were analysed. 1. The perceptual estimations were linearly related to step amplitude. 2. The early components of the E.P. show no obvious correlation to stimulus amplitude. 3. The later components (with peak latencies of 120 msec or more) show a monotone, non-linear rising function with respect to stimulus amplitude. 4. The early waves of the evoked potentials up to about 120 msec are well localized over the contralateral postcentral hand area while the late components resemble the alpha rhythm in wave length and distribution over both hemispheres. The possible role of alpha-synchronisation in the later components is discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 33 (1996), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Event-related potentials (ERPs) were recorded in 19 healthy subjects as they completed two Sternberg (1969, American Scientist, 57, 421–457) memory tests. In separate sessions, either single digits (i.e., 0–9) or 10 abstract figures were used as stimuli. In both sessions, memory set sizes were 1 (M1), 2 (M2), or 4 (M4). The amplitude and latency of the parietal P400 and the frontocentral negativity preceding P400 varied significantly with set size, but only between M1 and M2, whereas reaction time increased dramatically from M1 to M2 and from M2 to M4. These findings challenge previous assertions that the ERPs reflect aspects of the exhaustive serial search proposed by Sternberg. A late parietal positivity (P620), which failed to vary with set size, was larger in response to figures than to digits and may represent the search for, or utilization of, semantic traces of the stimuli.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0093-934X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Linguistics and Literary Studies , Medicine , Psychology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 70 (1987), S. 175-179 
    ISSN: 1435-1463
    Keywords: Dopamine ; autoantibodies ; schizophrenia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Autoantibodies against dopamine receptors in schizophrenic patients have been postulated. IgG was fractionated from sera of 15 schizophrenic patients (DSM III) in an acute episode. However, 3H-spiperone binding to dopamine receptors was not inhibited by this fraction.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1435-1463
    Keywords: Voluntary movement ; EEG ; frequency analysis ; uncertainty analysis ; haloperidol ; biperidene ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 15 normal volunteers were treated over three weeks with haloperidol (HAL) and in the third week additionally with biperidene (BIP). The order of the EEG spectra at different topographical locations and in different frequency bands during a movement task was analyzed using uncertainty analysis (UA), a multivariate analysis technique based on informationtheoretical methods. Different patterns of drug-induced changes were found. HAL decreases the theta and alpha band order at the fronto-central lateral areas but increases it at the fronto-central midline in the theta band and at the parietal areas in the alpha band. With the exception of the fronto-central midline locations, BIP more or less counterbalances the effect of HAL. Volunteers felt unwell and had motor disturbances during HAL and felt well again during HAL + BIP. Reaction time values were increased during HAL and normalized during HAL + BIP.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 194 (1969), S. 111-148 
    ISSN: 1434-4726
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The review summarizes the vestibular contributions to posture, eye movement and spatial orientation and the vestibular and oculomotor symptoms accompanying lesions at different levels of the nervous system.
    Type of Medium: Electronic Resource
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