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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 27 (1977), S. 131-141 
    ISSN: 1432-1106
    Keywords: Colliculus superior ; Single neurons ; Eye movements ; Head movements ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 452 single neurons from the superior colliculus were recorded in awake and non-paralysed cats. 75 neurons were obtained from cats with unrestrained horizontal head movements. 228 neurons remained unaffected by saccadic eye movements. Eye movement related discharge followed the onset of saccades in 156 neurons either only in the presence of a visual pattern (92 neurons) or in darkness, too (64 neurons). The latter reaction type probably depends on eye muscle afferents. In 48 neurons eye movement related activity preceded the onset of eye movements. 12 neurons fired in synchrony with eye movements of any direction (type I). 30 neurons were excited during contralaterally directed eye versions within or into the contralateral head related hemifield. They were inhibited when the eyes moved within or into the ipsilateral head related hemifield (type II). 6 neurons with constant maintained activity during fixation were inhibited by ipsilaterally directed saccades, but remained unaffected by contralateral eye movements. Head movement related discharge followed the onset of head movements in 20 neurons only in presence of a visual pattern and also in darkness in 6 neurons. Ipsilateral head movements or postures strongly suppressed maintained activity and visual responsiveness of some neurons. 15 neurons discharged in synchrony with and prior to contralateral head movements. Ipsilateral head movements inhibited these neurons. Activation or inhibition were usually related to movement and to posture, exceptionally to movement or to posture. Electrical stimulation of recording sites of these neurons through the recording microelectrode elicits contralateral head movements.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 11 (1970), S. 318-326 
    ISSN: 1432-1106
    Keywords: Movement detectors ; Tectum opticum ; Eye movements ; Retinal image shifts ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Activity of tectal movement specific neurons was recorded during spontaneous eye movements in total darkness and in presence of stationary visual stimuli. According to their reactions in presence or absence of stationary visual stimuli tectal units can be divided into four categories: 1. Neurons which are silent or discharge independently of eye movements, when the animal stays in total darkness, but which fire in synchrony with eye movements when stationary stimuli are presented. 2. Neurons which remain unaffected when the animal makes eye movements in total darkness or in presence of a stationary pattern. 3. Neurons which fire in synchrony with eye movements in absence and in presence of stationary patterns. In a few of these neurons tested curarization of the animal led to a marked increase of spontaneous activity. 4. Neurons whose spontaneous and stimulus driven discharge is suppressed in synchrony with eye movements when the animal is exposed to total darkness or when it faces stationary patterns
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 353-367 
    ISSN: 1432-1106
    Keywords: Tectum opticum ; Movement detecting neurons ; Directional sensitive neurons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden 80 Einheiten des Tectum opticum der Katze abgeleitet und ihre Reaktionen auf stationäre und bewegte optische Reize geprüft. Neben den Neuronen, die in ihrer Reaktionsweise retinalen Einheiten vergleichbar waren, fanden sich überwiegend (89%) Neurone, die auf bewegte optische Reize reagierten. Unter den letzteren zeigte die Mehrheit (70%) richtungsspezifisches Verhalten. Bei einigen Neuronen war in einem beschränkten Bereich von 1–7.5∘/sec die Reaktion gesetzmäßig abhängig von der Winkelgeschwindigkeit des Bewegungsreizes (Potenzfunktion mit dem Exponenten 0.67). Die rezeptiven Felder waren meist rund mit einem durchschnittlichen Durchmesser von 8.1∘ (3–22∘). 68% der Einheiten reagierten nicht auf diffusen Lichtreiz. Die Reaktionen auf nicht bewegte Punktlichtreize waren rasch adaptierend und inkonstant in ihrer Art und Stärke. In kurzen Abständen mehrfach wiederholte Bewegungsreize bewirkten bei einem Teil der Bewegungsneurone rasche Adaptation. Zwei kurz aufeinander folgende Punktlichtreize ergaben eine Reaktion, die niedriger als die Summe der Erregungen der jeweils einzeln gegebenen Lichtreize war, wenn die zeitliche Folge der beiden Reize der Vorzugsrichtung des Neurons entgegengesetzt war. Bei Reizfolgen entsprechend der Vorzugsrichtung entsprach die Gesamtreaktion der Summe der Einzelreizantworten. Dies läßt vermuten, daß die Richtungsspezifität durch unilaterale Hemmung bedingt ist.
    Notes: Summary Recordings were made from 80 single units in cat's Tectum opticum during visual stimulation with moving and stationary optic stimuli. The majority of units (89%) showed movement specific reactions, the rest behaved functionally similar to retinal or geniculate neurons. 70% of the movement specific units showed directional selective reactions. The receptive fields, as determined with stationary and moving stimuli were mostly circular with an average diameter of 8.1° (range 3–22°). Stimuli passing through the periphery of the field led to less pronounced reactions than those going through the center. In 10 out of 30 units, the relation between discharge rate and angular velocity in a restricted range from 1°–7.5°/sec could be approximated by a power function with an exponent of 0.67. Above 10°/sec irregular and unsystematic alterations of reactivity were observed. 68% of the tectal units recorded did not respond to diffuse light stimuli. The reactions to localized intermittent stationary light stimuli were mostly off (42%) or on-off-responses (19%) and were characterized by fast adaptation, change of reaction type during successive intermittent stimulation and by the absence of an antagonistic field-structure. Stimulation of adjacent points in a temporal sequence corresponding to movement opposite to the most sensitive direction of a directional specific neuron led to a reaction which was below the sum of the reaction of the two stimuli given alone. At a temporal sequence of the two stimuli such as to simulate the most sensitive direction, the resulting reaction corresponded to the sum of the reactions of both stimuli given alone. This suggests a mechanism of unilateral inhibition to be responsible for directional selectivity.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European archives of psychiatry and clinical neuroscience 231 (1981), S. 81-91 
    ISSN: 1433-8491
    Keywords: Focal epilepsy ; Penicillin focus ; Somatosensory evoked potential ; Rat ; Focale Epilepsie ; Sensorische evozierte Potentiale ; Penicillinepilepsy ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Corticale, durch elektrische Vorderpfotenreizung evozierte somatosensorische Potentiale (SEP) der Ratte bestehen aus früzhen (P 1 und N 1) und späteren (P 2 und N 2) Komponenten. Mikroelektrodenableitungen ergeben unter denselben Reizbedingungen Einzelneuronenantworten kurzer und längerer Latenzen synchron mit den frühen (P 1, N 1) bzw. späten Komponenten (P 2). Im Verlauf einer durch topische Penicillin-Applikation erzeugten Focalepilepsie vergrößern sich nur die Amplituden der späten SEP-Komponenten. Mit der Größenzunahme der späten Komponenten verlängert sich die Entladungsdauer der Einzelneuronenantworten entsprechender längerer Latenzen. Die frühen SEP-Komponenten und die entsprechenden Einzelneuronenantworten kurzer Latenz bleiben unverändert. Im Cortex und in den sensorichen Relaisstationen (N. cuneatus, spezif. Kern des Thalamus) werden von 100 (N. cuneatus) bis zu 300 ms (Thalamus und Cortex) nach einem epileptischen Spike die somatosensorischen Potentiale partiell oder komplett unterdrückt. Der zeitliche Verlauf der Normalisierung der Amplituden ist für die frühen Komponenten thalamischer und corticaler SEP gleich, jedoch gegenüber den späteren corticalen Komponenten initial rascher. Unsere Befunde berechtigen zur Annahme zweier Gruppen somatosensorischer corticaler Neuronaktivität, deren Erregung frühe bzw. spätere Komponenten des SEP erzeugt und die unterschiedlich vom epileptogenen Agens beeinflußt werden.
    Notes: Summary The cortical somatosensory evoked potential (SEP) of the rat, evoked by contralateral forepaw stimulation, consisted of early (P 1 and N 1) and late components (P 2 and N 2). Microelectrode recording yielded evoked unitary responses of short latencies in the range of the early components and responses of longer latencies in the range of P 2. During the development of focal epilepsy after topical application of penicillin, the late components of SEP were enhanced and the enhanced late negativity corresponded to a surface negative cortical spike. The prominent enlargement of later components was associated with prolonged, often recurrent discharges of longer latency unitary responses and with enlarged local field potentials. Early components of SEP remained relatively unaffected and so did unitary responses with short latencies. Epileptic spike-conditioned SEPs in the cuneate nucleus, thalamic sensory relay nucleus and sensory cortex were depressed from 100 ms (cuneate nucleus) to about 300 ms (thalamus and cortex) subsequent to spike discharge. Transmission in the cuneate nucleus was least affected. Thalamic and cortical early components of SEP had similar time courses of recovery, which differed markedly from that of cortical late components. Our findings suggest that two different neuronal activities generate different components of SEP and are differentially involved in the epileptic activities, which results in the different amplitude recovery following spontaneous epileptic spike discharges.
    Type of Medium: Electronic Resource
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