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F Walberg

Publications and source records attributed to F Walberg.

At least 73 records · Page 4Linked to original sources
PubMed1978

The cerebellar projection from locus coeruleus as studied with retrograde transport of horseradish peroxidase in the cat.

The cerebellar afferent projection from locus coeruleus has been studied in the cat by means of retrograde axonal transport of horseradish peroxidase. Labelled cells are present bilaterally in locus coeruleus only following injections in the cerebellar vermis (especially its anterior and posterior parts), the ventral paraflocculus and the flocculus. The labelled cells are restricted to the caudal half of the nucleus. A few labelled cells are also present in locus coeruleus following injections in the fastigial nucleus, and in nucleus interpositus anterior. The findings are discussed in relation to other studies on the efferent and afferent connections of the locus coeruleus.

Animals↗
PubMed1978

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. VII. The projection to lobulus simplex, crus I and II.

The olivocerebellar projection to lobulus simplex, crus I and II in the cat was investigated by means of retrograde axonal transport of horseradish peroxidase (HRP). The distribution of labeled cells in the inferior olive following HRP injections in lobulus simplex, crus I and II confirmed the findings by Brodal ('40b) that the rostral half of the principal olive projects to these areas of the cerebellar hemisphere. However, concerning details there are some differences in so far as the heaviest contribution to crus I comes from the medial parts of the ventral and dorsal lamella, that to crus II from its lateral part, especially the ventral bend. The present findings show that in addition the rostral part of the medial and the rostromedial part of the dorsal accessory olive project to these areas of the cerebellar cortex. Further details in the projection are shown in figure 8B. The findings agree fairly well with the electrophysiological results of Armstrong et al. ('74) and the experimental anatomical data of Groenewegen and Voogd ('77a,b). An attempt is made to correlate the findings with the pattern of longitudinal zonal subdivision of the cerebellum. There is evidence for a topical organization within the projection to crus I and II and parts of their projection areas in the principal olive. The distribution of the labeled cells which project to lobulus simplex, crus I and II is discussed in relation to afferent pathways to the inferior olive.

Animals↗
PubMed1978

Cerebellar afferents from the paramedian reticular nucleus studied with retrograde transport of horseradish peroxidase.

Details in the cerebellar projections from the paramedian reticular nucleus (PRN) were studied in cats and monkeys by means of retrograde axonal transport of horseradish peroxidase (HRP). In the cat the majority of the fibres projects to the anterior lobe and to the vermis of the posterior lobe (with the exception of lobules VIIB and VIIIA). A less conspicuous projection was found to the lobulus simplex, the crura and the flocculus. The cerebellar nuclei, the paramedian lobule and the paraflocculus appear to be weakly connected with the PRN. A similar distribution of the cerebellar afferent fibres was found in the monkey material. The three subgroups of the PRN in the cat are not equal in their projection. The dorsal group appears to be connected with the greater part of the cerebellar cortex and with all nuclei. The ventral group lacks a connection with lobulus IX, the flocculus and the paraflocculus, and the accessory group appears to have its strongest connection with lobulus I (lingula), the flocculus and the vermal lobules VII-X. The findings are discussed in relation to other studies on the efferent and afferent connections of the nucleus.

Animals↗
PubMed1978

Cerebellar afferent projections from the vestibular nuclei in the cat: an experimental study with the method of retrograde axonal transport of horseradish peroxidase.

Details of cerebellar afferent projections from the vestibular nuclei were investigated by the method of retrograde axonal transport of horseradish peroxidase (HRP) in the cat. The distribution of labeled cells in the vestibular nuclei following HRP injections in various parts of the cerebellum indicates that vestibular neurons in the medial and descending nuclei and cell groups f and x project bilaterally to the entire cerebellar vermis, the flocculus, the fastigal nucleus and the anterior and posterior interpositus nuclei. In addition, labeled cells (giant, medium and small) were consistently found bilaterally in the superior and lateral vestibular nuclei following HRP injections in the nodulus, flocculus, fastigal nucleus, and following large injections in the vermis. No labeled cells were observed in cases of HRP injections in crus I and II, the paramedian lobule, paraflocculus and lateral cerebellar nuclei. The present findings indicate that secondary vestibulocerebellar fibers project to larger areas in the cerebellum and originate from more subdivisions and cell groups of the vestibular nuclear complex than previously known.

Animals↗
PubMed1978

Cerebellar afferent projections from the perihypoglossal nuclei: an experimental study with the method of retrograde axonal transport of horseradish peroxidase.

Details of cerebellar afferent projections from the perihypoglossal nuclei were studied in the cat by means of retrograde axonal transport of horseradish peroxidase (HRP). Labeled cells were observed bilaterally (with a preponderance ipsilaterally) in nuclei intercalatus and praepositus hypoglossi following injections in various folia of the entire vermis, paraflocculus, flocculus, fastigial nucleus, and the nucleus interpositus anterior and posterior. Relatively high densities of labeled cells were found in nucleus intercalatus following injections in the anterior part of the vermis, whereas labeled cells in nucleus praepositus hypoglossi were found more frequently following injections in the posterior part of the vermis. Labeled cells in the nucleus of Roller were found only following injections in the anterior lobe vermis, posterior vermal lobules VI and VII, in the flocculus and in the nucleus interpositus anterior. No labeled cells could be detected in the three subdivisions of the perihypoglossal nuclei following HRP injections in crus I, crus II, paramedian lobule, and lateral cerebellar nucleus. The distribution of the HRP positive cells indicated the presence of a topographically organized projection from certain regions of the perihypoglossal nuclei to different parts of the cerebellum. The afferent and efferent connections of the perihypoglossal nuclei in relation to a functional role in eye and head movements are discussed.

Afferent Pathways↗
PubMed1977

The cerebellar projection from the raphe nuclei in the cat as studied with the method of retrograde transport of horseradish peroxidase.

Following injections of horseradish peroxidase (HRP) in the cerebellar cortex and nuclei of the cat, the distribution of labeled cells in the raphe nuclei was mapped. The findings confirm those made previously in studies of retrograde cell degeneration following cerebellar ablations (Brodal et al., 1960a), and in addition reveal new details in the projection of the raphe nuclei onto the cerebellar cortex and nuclei. All the raphe nuclei except nucleus linearis intermedius and nucleus linearis rostralis project onto the cerebellar cortex. The nuclei raphe obscurus and pontis contribute the greatest number of afferents to the cerebellum. With the exception of lobule VI which probably is the recipient of a weak projection, all parts of the cerebellar cortex receive afferents from the raphe nuclei. The heaviest projection is to the vermis of lobules VIIA and X, and to crus II. The afferents to the cerebellar nuclei are few in number (Tables 2-6). The observations indicate that each raphe neuron probably projects to more than one terminal site in the cerebellum. The findings are discussed with reference to other efferent and afferent studies of the raphe nuclei. All these studies indicate that the raphe nuclei have widespread efferent and afferent connections, making them capable to participate in a variety of regulatory functions.

Animals↗
PubMed1977

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. VI. The projection onto longitudinal zones of the paramedian lobule.

Microinjections (30-50 nl) of a horseradish peroxidase (HRP) suspension of 25% (wt./vol.) were made in different folia of the paramedian lobule of cats, and the sites of occurrence of labeled cells in the inferior olive were precisely determined. In each case only a small number of cells are labeled, aggregated in a minute area. The labeled cells are found within three only of the four olivary areas previously determined (Brodal et al., '75) to project onto the paramedian lobule (fig. 1): one area in the rostral half of the medial accessory olive, another in the dorsal accessory olive (except its caudalmost part), and a third in part of the caudal half of the dorsal lamella of the principal olive. Labeled cells were never found in the fourth area, the ventral lamella. A distinct zonal pattern in the projection is demonstrated (figs. 3, 5B): a middle longitudinal zone of the paramedian lobule receives olivary afferents from the area in the medial accessory olive, a medial zone from part of the projection area in the dorsal accessory olive, a lateral zone from part of the projection area in the dorsal lamella. This zonal projection appears to extend throughout the length of the paramedian lobule (the two caudalmost folia could not be studied). tthe somatotopical pattern in the projections from the accessory olives described previously (Brodal et al., '75) is confirmed. The pattern of a zonal projection obtained with the HRP-method (fig 5B) is simpler than that deduced by Armstrong et al ('74) from recordings of antidromic potentials in the olive (fig 5A). Concerning main points there is satisfactory agreement. The phenomenon that following microinjections of HRP in superficial parts of the folia labeled cells occur within parts only of the regions of the olive which contain labeled cells following large HRP-injections in the paramedian lobule is discussed.

Afferent Pathways↗
PubMed1977

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. IV. The projection to the anterior lobe.

Following injections of horseradish peroxidase (HRP) in the cerebellar cortex of the anterior lobe of the cat, the distribution of labeled cells in the inferior olive was mapped. The findings largely confirm those made previously in studies of olivary retrograde cell loss following cerebellar ablations (Brodal, '40b). In addition, they reveal further olivary areas projecting onto the anterior lobe, and permit a more detailed analysis of the pattern in this projection. Concerning major points the results are in agreement with physiological studies by Armstrong et al. ('74). They bring supporting evidence for a longitudinal zonal pattern in the anterior lobe (fig. 6C). The middle zone of the vermis receives its fibers from a large central area in the caudal half of the medial accessory olive, a lateral zone of the vermis from the lateral half of the dorsal accessory olive. Both olivary areas project to the corresponding cerebellar zone throughout lobules V-I. The lateralmost part of the anterior lobe (lobules IV-V) receives afferents from an area in the dorsal lamella of the principal olive. The intermediate part of lobules IV-V receives afferents from the medial half of the dorsal accessory olive and from an area in the rostral half of the medial accessory olive. There is suggestive evidence that the latter projects to a middle zone, the former to a medial and a lateral zone within the intermediate part as found physiologically. Conclusions concerning projections to the intermediate part of lobules III-II could not be made. The findings in this and preceding studies with the HRP-method show that the concept of a longitudinal pattern in the cerebellum is scarcely generally valid of the entire olivocerebellar projection. Within the projections of the lateral half of the dorsal accessory olive and the area in the rostral part of the medial accessory olive there appears to be a topical relation with the folial pattern in the anterior lobe. An analysis of the findings with reference to the afferents traced anatomically to the various olivary areas permits some conclusions as to the functional role of the olivary areas. Comparison with Oscarsson's ('73) diagram of the sites of termination of two of the spinal-olivary pathways (his DF-SOCP) and VF-SOCP) permits an anatomical explanation as concerns the projections to the vermis, while correlations as concerns the intermediate part are less satisfactory.

Animals↗
PubMed1976

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. III. The projection to the vermal visual area.

Horseradish peroxidase (HRP) was injected separately in one of the cerebellar lobules VI, VIIA, VIIB, VIIIA or VIIIB (together corresponding to the vermal visual area) in 17 cats. After 1-3 days the distribution of labeled cells in the inferior olive was mapped. In spite of some overlapping it is clear that the various lobules of the vermal visual area receive fibers from separate parts of a horseshoeshaped region in the caudal half of the contralateral medial accessory olive (fig. 5C). The projection area of lobule VIIA is found caudomedially and overlapping with the area supplying lobule VIIB. This in addition receives a few fibers from the nucleus beta. Fibers terminating in lobule VIIIA arise caudolaterally as do fibers destined for lobule VIIIB. A central part of the total projection area projects to lobule VI. Following injections leading to a similar extent of cortical staining in lobules VI, VII or VIII the projection of labeled cells in the corresponding projection areas differ markedly. In the area of lobule VII apparently all cells are labeled, in the area of lobule VI the density of labeled cells is considerably less, and in that of lobule VIII there are rather few labeled cells. In a few cases with widespread staining of the cerebellar visual area there was spreading of HRP to the nucleus fastigii. The projection to this form the olive was therefore investigated to avoid erroneous conclusions. In the discussion it is pointed out that on most points our findings agree fairly well with the results of studies of the olivocerebellar projection undertaken with other methods (studies of retrograde cellular changes, electrophysiological methods). No support for a longitudinal subdivision of lobules VI-VIII was found. Studies of the available literature indicate that the areas in the medial accessory olive projecting onto lobules VI-VIII probably do not receive direct afferents from regions which are known to be concerned in the transmission of visually evoked impulses. Fibers to the olive from the superior colliculus appear to pass to the nucleus beta only. This projects mainly to the uvula, to a little extent only to lobule VII. However, it may be imagined that visual impulses may reach the vermal visual area via the inferior olive by way of intercalated neurons, for example in the mesencephalic RF. Major contingents of afferents to the olivary regions projecting onto the vermal area come from the spinal cord, the motor cortex and the periaqueductal gray.

Animals↗
PubMed1976

A note on the method of retrograde transport of horseradish peroxidase as a tool in studies of afferent cerebellar connections, particularly those from the inferior olive; with comments on the orthograde transport in Purkinje cell axons.

1. Injections of horseradish peroxidase (HRP) suspension were made in the cerebellar cortex of cats (most often the paramedian lobule). The staining of the cerebellar cortex and the ensuing labeling of neurons in the inferior olive were studied in experiments with variations of concentration of HRP, amounts of fluid injected, survival time and age of the animals. Light microscopical studies were supplemented with electron microscopical observations. The folded cerebellar cortex offers particular difficulties with regard to obtaining a predictable extent of stained tissue, and the spreading of the fluid within the cortex shows great variations even with the same amounts and concentrations of HRP suspension. Diffusion of fluid appears to occur most easily within the molecular layer. Often there are unstained parts of folia between stained parts. Staining of the cortex is barely visible after 7 days, but appreciable shrinking of the stained area does not appear to occur until after 4 days. 2. The first signs of labeling of olivary neurons are seen after 5-10 hours, after 7 days there are no labeled cells. The rate of retrograde transport in olivocerebellar fibers is calculated to be between 50 and 100 mm/day. Labeling of cells appears to require staining of the molecular layer of its projection areas in the cerebellum. 3. For studies of the olivocerebellar projection survival times of 2-3 days and injections of 0.5 mul of a 50% HRP suspension seem in general to be well suited. Best results are obtained with animals weighing 1-3 kg. There is a clearcut correlation between the site of staining of the cortex of a particular part of the cerebellum and the site(s) and extension of olivary area(s) containing labeled cells. 4. Anterograde transport in axons of Purkinje cells has been observed. Electron microscopically the axons of these fibers contain HRP labeled tubules and vesicles as do their terminal boutons in the nuclei. 5. In cases where the injected fluid has spread to the cerebellar nuclei, localized parts contain neurons which are labeled as are the cells in the injected cerebellar cortex.

Afferent Pathways↗
PubMed1976

An autoradiographic identification of Purkinje axon terminals in the cat.

The Purkinje axon boutons terminating in nuclei fastigii and interpositus in the cat have been identified after injection of 3H leucine into the cerebellar cortex overlying the nuclei. The animals survived from 4-48 h after injection of the isotope. Semithin and ultrathin sections were coated and exposed for 3 and 14 weeks, respectively. The electron micrographs showed labelling over myelinated axons down to a diameter of 0.8 mum, and over boutons. Fifty labelled boutons were used for identification of the shape of their synaptic vesicles. The statistical analysis including the test for skewness showed that 39 boutons (78%) fall in one group. Most of the synaptic vesicles in this group are elliptical (ration from 1:1.1 - 1:1.7). Slightly ovoid vesicles (ration up to 1:1.3) are frequent, but flattened vesicles (ration above 1:1.7) are relatively few in this group of boutons. 8% of the boutons have a rather homogeneous vesicle population (prevalence of round vesicles, ratio 1:1). Synaptic specializations of Gray's type II or of an intermediate type were found in the boutons belonging to the first group (78% of the boutons). Specializations of Gray's type I were found in the other bouton groups (8% of the boutons).

Animals↗
PubMed1975

The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase.

The distribution of labeled cells in the inferior olive of the cat has been mapped following injections of small amounts of horseradish perosidase in the paramedian lobule of the cerebellum. The distribution of labeled cells was plotted in drawings of approximately serial transverse sections. The findings in each case were transferred to a standard diagram of the olive to facilitate comparison of cases. Previous studies of the distribution of retrograde cell loss in the inferior olive following cerebellar lesions (Brodal, '40b) showed that fibers ending in the paramedian lobule come from the caudal part of the ventral lamella of the principla olive. This was confirmed with the peroxidase method, but in addition three other separate and well circumscribed area of the olive showed labeling: one in the dorsal accessory olive, another in the rostral part of the medial accessory olive, a third in the caudal part of the dorsal lamella of the principal olive (fig. 7). There is some degree of topical arrangement within the projection of each of these olivary areas to the paramedian lobule. It is particularly striking that the projection areas of the caudal one-third of the lobule are different from and overlap only little with those of the orstral two-thirds. On account of diffusion of the injected perosidase solution in the folia it could not be decided whether the different olivary areas project to particular longitudinal zones in the paramedian lobule. The main findings can be correlated with the physiological observations of Armstrong et al. ('74). Some of the "paramedian" olivary areas are labeled also following peroxidase injections in other cerebellar parts, among them the nuclei interpositus anterior and posterior. The findings are compatible with the notion that olivocerebellar fibers branch to supply more than one cerebellar region. It is confirmed that the olivocerebellar projection, including that of the nuclei, is almost completely crossed. In the discussion it is emphasized that afferents from several sources converge on all four olivary regions projecting onto the paramedian lobule. The olivocerebellar projection obviously allows for divergence as well as convergence of impulses from the olive to the cerebellum. For further insight into the anatomical organization of the inferior olive, the entire olivocerebellar projection has to be mapped with the peroxidase methods, and further studies of the afferents to the olive are needed. In such studies, as well as in physiological ones, it is essential that findings are described with meticulous reference to the topography of the olivary subdivisions.

Animals↗
PubMed1975

Studies on the cerebellar projections from the main and external cuneate nuclei in the cat by means of retrograde axonal transport of horseradish peroxidase.

The cerebellar projections from the main and external cuneate nuclei in the cat have been studied by means of retrograde axonal transport of horseradish peroxidase. The main projection from the external cuneate nucleus (ECN) is to the intermediate and, possibly, the small lateral part of lobule V and to the paramedian lobule on the ipsilateral side. The projection from the ECN to the cerebellar regions mentioned is topographically organized. Cells in the caudal part of the ECN send their axons to the caudal parts of lobule V and to the rostral part of the paramedian lobule. Cells in the rostral part of the ECN project to the rostralmost part of lobule V and to the folia in the caudal part of the paramedian lobule. The experimental study also shows that cells in the main cuneate nucleus (MCN) send their axons to the cerebellum. These axons, like those from the ECN, terminate in the intermediate part of lobule V of the anterior lobe and in the paramedian lobule. However, the axons of the cells in the MCN terminate only in the superficial parts of the folia, whereas those from the ECN terminate in the depth of the folia in these two cerebellar areas. The present study also gives evidence that cells in the ventral part of the gracile nucleus send their axons to lobules I and II of the anterior lobe vermis. The observations referred to here are to our knowledge the first anatomical findings demonstrating a projection from the main cuneate and gracile nuclei onto the cerebellar cortex. The observations confirm previous physiological studies.

Animals↗
PubMed1975

The reticulovestibular projection in the cat. An experimental study with silver impregnation methods.

The distribution of degeneration in the vestibular nuclei (VN) has been studied in transversely cut sections from 9 cats with stereotaxically performed lesions in the main reticular formation (RF) of the brain stem (Nauta of Fink and Heimer method). No projection was found from the mesencephalic reticular formation (R.mes.) and nucleus reticularis ventralis (R.v.). However, the reticular nuclei gigantocellularis (R.gc.), parvocellularis (R.p.c.) and pontis oralis (R.p.o.) were found to project bilaterally onto the 4 main vestibular nuclei with an ipsilateral overweight. By far the greates contribution comes from the R.gc. and R.p.c. In cases with R.gc. lesions some degeneration was found in the small cell groups x and f. The latter is also supplied from the R.p.c. The distribution of degeneration within the vestibular complex is rather diffuse, but a certain pattern can be discovered. After R.p.c. lesions the maximal terminal field in the VN is found within the superior nucleus, while the lateral and medial nuclei are preferred sites of termination of fibers from R.gc. and R.p.c. The projections of the R.gc. and the R.p.c. may be more different than appears from our findings since lesions of one of them will most likely have affected some ascending or descending fibers emanating from the other. Since the areas of RF projecting to VN receive afferents from many sources, these sources have possibilities to act on the VN even if they do not possess direct connections with this nuclear complex. These possibilities should be remembered in physiological studies of responses in the VN following stimulation of many parts of the CNS.

Animals↗