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Notes: Abstract From three intact and awake monkeys, 149 Purkinje cells and 44 presumed mossy fibres were recorded in the intermediate part of the cerebellar anterior lobe, and this activity was analyzed with regard to different parameters of a passive hand movement. The tonic discharge rate of the simple spikes (SS) varied according to different joint positions only in a single Purkinje cell, whereas such a position relation was found in nine out of 44 presumed mossy fibres. A phasic increase of the complex spike (CS) discharge rate of Purkinje cells in response to passive wrist movements usually occurred within 100 ms after movement onset. However, in some units a phase of increased CS rate was observed which lasted for the whole movement duration. The amount of this phasic increase in the CS rate depended on the acceleration of movement, but the SS response to movements of different velocity remained unchanged.

Notes: Summary 1) The present experiments were undertaken to study how information about the parameters of a passive movement is processed at different neuronal levels of the cat cerebellar cortex. The analysis has been performed by recording extracellularly in the intermediate part of the cerebellar anterior lobe from presumed mossy fibres, presumed granule cells, and Purkinje cells with simple spikes and complex spikes. 2) The discharge patterns obtained during passive movements of the cat's forepaw were characterized by components which could be related to dynamic or static parameters of the movement. With respect to the occurrence of dynamic responses, patterns were classified according to a statistically derived measure in three different types. By using the same statistical measure, discharge patterns were additionally classified into two subgroups according to their response components reflecting static parameters. Within the patterns a clearcut relationship between dynamic and static components was observed. The corresponding distributions are shown and discussed. 3) A very interesting result of the classification of cerebellar discharge patterns is that the distribution of the different types depended on the level of integration within the cerebellar cortex. Patterns of the low scale integrated cerebellar input (mossy fibre-system), as well as those of granule cells (the first cerebellar computational niveau), reflected both static and dynamic movement parameters. At the Purkinje cell level (a level with a high degree of convergence) the discharge patterns are characterized predominantly by dynamic responses. 4) The interrelationship between complex- and simple spikes of Purkinje cells was tested by different methods: a) By analyzing the paired values of the mean complex-(CS) and simple spike (SS) discharge probabilities of 110 Purkinje cells a scatter was obtained, indicating an underlying hyperbolic relation (prob(CS) = a/(prob(SS))b). Thus, a high CS discharge probability is accompanied by a low SS probability and vice versa, b) The timelocked complex- and simple spike responses were studied by comparing the similarity of their responses. All combinations of complex- and simple spike patterns were observed, ranging from a sign correct similarity to a mirror image similarity. The distribution of the measure for similarity shows that the mirror image predominated, c) The individual simple spike discharge probability is characterized by a pause evoked by the occurrence of a complex spike event. The simple spike discharge probabilities during an interval preceeding and following a complex spike event were compared. A post climbing pause coefficient was defined as a measure for the effectiveness of the complex spike event. No relationship between these coefficients and the above mentioned measure for similarity was found. Hence, for the Purkinje cell discharging with the simple spikes independent spike generating processes have to be assumed. 5) From these results it can be derived that cerebellar discharge patterns can be classified with respect to responses to static and dynamic parameters of passive limb movements. Based on this classification it appears that the distribution of responses to static and dynamic parameters depends on the computational level within the cerebellar cortex. If both static and dynamic parameters are conveyed by a single unit, a clear relationship between the response components could be observed. However, this effect was independently found at all cerebellar cortical computational levels indicating a functional principle of processing a pair of movement parameters. The interrelation of complex- and simple spike responses to passive movement was further studied. Since transients of complex- and simple spike patterns were observed ranging from two almost identical patterns to mirror image like patterns, it is assumed that under physiological conditions one of the tasks of the climbing fibre system consists of tuning the simple spike discharge according to the peripheral requirements.

Notes: Summary 1) Experiments were designed to detect how static parameters of natural, passive hand movements are encoded and integrated within the cerebellar cortex. For this purpose unit activity was recorded extracellularly from presumed mossy fibres (MF), presumed granule cells (GrC) and from Purkinje cells (PC) discharging with simple spikes (SS) and complex spikes (CS). With respect to the PC, our interest was focussed primarily on the SS activity. The recordings were performed in the intermediate part of the cerebellar anterior lobe of decerebrate cats. The animal's forepaw was passively moved around the wrist joint by an electronically controlled device. The movements were exactly reproducible so that peristimulus time histograms of the unit activity could be constructed. 2) At the input level (MF) and at the first level of integration within the cerebellar cortex (GrC), patterns with similar discharge characteristics were found. Such patterns could, to a limited extent, also be detected at the cerebellar output (SS of PC). However, in most cases of SS discharge, patterns were found with weak correlation between the tonic activity and static parameters of the movements. 3) Absolute paw position, amplitude, and duration of movements were found to be related over wide ranges to the activities of MF and GrC. Absolute position is directly encoded by tonic discharge during the low or high holding phases. Beside this, units were found without a correlation between the tonic discharge and the position of the nonmoving paw. However, in these units it was sometimes observed that the information about the momentary position or the information about the mean position was sometimes conveyed exclusively during the proceeding upward or downward movement. Thus, information about static parameters was transmitted only at times when a dynamic parameter (such as velocity) occurred. This type of position information encoding is termed “indirect mode of transmission”. 4) A specific relationship between SS unit activity of PC and the absolute position of the forepaw or amplitude of the movement could be found primarily by using multiple ramps instead of single ramp movements. This was observed even if both types of ramp movements had the same velocity, individual amplitude, and tested range. However, on multiple ramp movements the paw generally remained for a shorter period at a specific position level as compared to the single ramp movements. 5) Apart from this timing phenomenon, a late movement response was observed, which results in a specific type of position information encoding on multiple ramp functions. 6) These results indicate that static parameters of a passive limb movement are conveyed via the MF input to the cerebellar cortex. Patterns related to these parameters undergo a change within the MF-, GrC-, Parallel fibre-, PC-system. Different modes of encoding these parameters were observed depending primarily on the neuronal niveau within the cerebellar cortex. Tonic discharge related e.g. to limb position was found at MF and GrC level. Such patterns resemble, at least to a certain extent, those obtained from different peripheral receptors. The high tonic SS activity never showed such a strong relationship to static parameters as observed at the input level; static parameters could be resolved only within relatively short periods of time, especially during the dynamic phases of the movement or during short periods immediately following these phases. This implies that the function of this part of the cerebellum, which is to provide correction signals, should be considered as a more dynamic process characterized by evaluating predominantly information about the momentary ongoing movement.

Notes: Summary Discharges of Purkinje cells (PCs) with simple (SS) and complex spikes (CS) in the c1zone of lobule Vc of the anterior lobe of the cerebellar cortex were analyzed in the decerebrate cat during a passive movement of the cat forepaw. The CS of the PC responded differentially and/or proportionally to the position of the extremity, amplitude of the movement, velocity and acceleration. Inphase and outphase responses of the climbing fiber (CF) system to sinusoidal movements could depend on the position of the extremity within the operational range. From these results we deduce that peripheral events can be signalled by the CF system. The possible function of the interaction between the two inputs at the PC level is discussed.

Notes: Summary In precollicular decerebrate cats, limb nerves have been stimulated and field potentials and unitary activity recorded from the cerebellar cortex. Doses of pentothal up to 8 mg/kg affect neither the activity evoked in the fast mossy fibre pathways, nor the size of the postsynaptic potentials in granule cells, but the axon discharge in these latter cells is clearly affected. With 4–8 mg/kg the axon discharge of granule cells is abolished and as a consequence Purkinje cells do not respond to the peripheral stimulation via the mossy fibres. In contrast the activity evoked through the climbing fibres is enhanced. This effect takes place at precerebellar level. Both the effects on the mossy fibre and climbing fibre pathways show a recovery in 15–60 min depending on the dose.

Notes: Zusammenfassung Der Zweck der vorliegenden Arbeit war die Beschreibung der Beziehung zwischen den Oberflächen-Evoked Potentials, ausgelöst durch Reizung des N. radialis superficialis und des N. splanchnicus und den evozierten Faserentladungen am Kleinhirn der Katze. Die Entladungen der Moosfasern, Kletterfasern und Axone der Purkinje-Zelle wurden identifiziert und ihre Beziehung zu den Oberflächenpotentialen festgestellt. Die Moosfasern feuern mit Spikesalven und in verschiedenen Gruppen. Diese entsprechen wahrscheinlich Impulsen, die von Fasern mit verschiedener Leitungsgeschwindigkeit fortgeleitet werden und die synchron mit der ersten Positivität der Evoked Potentials sind. Die Kletterfasern stehen in zeitlicher Beziehung zu der Entwicklung der scharfen negativen Ablenkung des EPs und werden zum ersten Male identifiziert. Schließlich weisen die Axone der Purkinje-Zelle dieselben Entladungsmuster auf wie die Purkinje-Zelle selbst. Cutane und viscerale Afferenzen benutzen nicht nur gemeinsame Elemente des cerebellären Cortex, sondern wahrscheinlich auch gemeinsame Leitungswege, obwohl es quantitative Differenzen zwischen beiden Afferenzen gibt.

Notes: Zusammenfassung Zehn Katzen wurden als Versuchstiere in einem Experiment benutzt, welches die Einflüsse der Entfernung der corticalen cerebellären Hemisphären auf das Erlernen und Behalten einer Licht-Dunkelheit Diskrimination untersuchte. Die Diskriminationsaufgabe wurde bei hungrigen Katzen nach der Skinner Methode durchgeführt. Die Ergebnisse dieser Studie zeigten, daß unilaterale oder bilaterale Entfernungen der cerebellären corticalen Hemisphären keinen Einfluß auf das Behalten der erlernten Diskriminationsaufgabe hatten. Dagegen schien die bilaterale Entfernung der cerebellären corticalen Hemisphären das Erlernen der Diskriminationsaufgabe zu verzögern, besonders während der ersten 5 Tage der Lernperiode. Es wurde angenommen, daß dieser einfluß auf einer dynamischen Kompensationsperiode beruht, während der, wieCarrea undMettler [3] vermuteten, der cerebrale Kortex die Funktion der entfernten Teile des Kleinhirns übernimmt.

Notes: Zusammenfassung 1. In folgenden corticalen Arealen wurde die Repräsentation des N. splanchnicus unterscuht: Area somatica II, ipsi-und kontralateral und Area somatica I, kontralateral. Die von uns ermittelten Repräsentationsgebiete sind flächenmäßig größer als sie in früheren Arbeiten angegeben sind. 2. Die Aβ-und Aγδ-Fasern des N. splanchnicus sind in diesen Arealen unterschiedlich repräsentiert. Die schnellsten Fasern der Aβ-Gruppe sind vornehmlich in der Area somatica II, kontralateral repräsentiert. Die Area somatica II, ipsilateral empfängt Impulse aus der ganzen Streubreite der Aβ-Fasern und wahrscheinlich auch von den Aγδ-Fasern. In der Area somatica I, kontralateral sind die schnellsten Fasern der Aβ-Gruppe wahrscheinlich nicht repräsentiert, ansonsten alle anderen Fasergrößen der Aβ-Gruppe und mit Sicherheit auch die Aγδ-Fasern. 3. Von den Leitungswegen, die zu den verschiedenen Arealen führen, hat der nach der Area somatica II, kontralateral die größte Übertragungsstärke. 4. Die Aβ-Afferenzen eines N. splanchnicus interferieren auf supraspinaler Ebene mit Afferenzen des ipsilateralen N. radialis superficialis und mit Afferenzen des kontralateralen N. splanchnicus. Dabei zeigt sich eine Dominanz der somatischen über die visceralen Afferenzen und eine Dominanz der kontralateralen über die ipsilateralen Afferenzen der N. splanchnici.

Notes: Summary After stimulation of the superficial radial nerve and the splanchnic nerve, evoked potentials were recorded on the surface of the cerebellum and their distribution mapped. It was shown, that the potentials of both afferents were quite different from each other. The differences in shape indicate that both afferents are differentially organized by the cerebellar cortex. This conclusion was reached through interaction experiments, frequency studies, and input-output-relation.