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K Grottel

Publications and source records attributed to K Grottel.

At least 55 records · Page 3Linked to original sources
PubMed1990

The course of motor unit twitch in dependence on muscle stretching force. Studies on medial gastrocnemius muscle of the rat.

Studies were performed on 46 units of medial gastrocnemius muscles in 23 rats. In the examined population, three types of motor units were distinguished: fast fatigable (FF), fast resistant (FR) and slow (S) units. The studied muscle was stretched with force gradually increasing from 0.5 to 10 g. Most of FF units and some of FR units reached the highest twitch force when the muscle was stretched with 4 to 7.5 g. The remaining fast units and almost all slow units reached the highest twitch force at 10 g stretching of the muscle. In some fast units, twitch force even decreased slightly at stretching of the muscle with 10 g force. On the other hand, contraction time and half-relaxation time were getting prolonged in the whole process of stretching the muscle. Most pronounced changes in contraction time and half-relaxation time took place in S type units while the least pronounced ones - in FF type units. The prolongation of half-relaxation times in motor units of all three types was more pronounced than the prolongation of contraction times.

Animals↗
PubMed1989

Topographic and zonal pattern of olivocerebellar projection to the paramedian lobule in the rabbit: an experimental study with an HRP retrograde tracing method.

Distribution of neurons in the inferior olive (IO) projecting to the paramedian lobule (PML) was studied in rabbits by means of retrograde transport of horseradish peroxidase (HRP). HRP was injected into various regions of different folia of the PML. Findings indicate zonal and to some extent topographic organization in olivocerebellar projections to PML folia. The neurons in corresponding areas of dorsal (dlPO) and ventral lamina (vlPO) of the principal olive (PO) project to composite zones D (D1 + D2) in sublobule f: medial, intermediate and lateral. In addition, the caudal part of the medial accessory olive (MAO) projects to the most laterally located zone (C2-lateral) and the caudal part of the dorsal accessory olive (DAO) to the most lateral zone (C3) in sublobule f. The middle part of the DAO sends projections to zone C1 located medially in sublobules d-a. The rostral and caudal parts of the DAO send projections to zone C3 in sublobules a and f, respectively. The rostral, middle and adjacent caudal parts of MAO, with no clear topographic organization, project to broad zone C2 in sublobules e-b. The neurons in restricted areas of the caudomedial part of the dlPO and vlPO, probably intermingled with those supplying the composite medial zone D in sublobule f, project to sublobules e-b to terminate in zones D1 and D2, respectively.

Animals↗
PubMed1989

Do the same subdivisions of the nucleus reticularis tegmenti pontis project onto longitudinal zones of the paramedian lobule? An anatomical study in the rabbit with retrograde tracing technique (HRP).

Rabbits were subject to iontophoretic injections of HRP into various sites of mediolateral extent of the cerebellar paramedian sublobules (PML). The distribution of retrogradely HRP-labelled neurons was mapped within the subdivisions of the pontine reticular tegmental nucleus (NRTP). Clear evidence for absence of correlation between the distribution of labelled cells within the NRTP longitudinal subdivisions and mediolateral location of HRP injection sites in PML has been obtained. The present findings suggest that there is no longitudinal compartmentalization of the NRTP-PML connectivity and the same NRTP longitudinal subdivisions project onto several sagittal zones of the PML.

Animals↗
PubMed1988

The pontocerebellar efferents from the pontine reticular tegmental nucleus in the rabbit: differential projections to the paramedian sublobules as revealed with tracing of retrograde axonal transport of horseradish peroxidase.

Projections from the nucleus reticularis tegmenti (NRTP) pontis to the cerebellar paramedian lobule were studied using a horseradish peroxidase retrograde transport technique. The rabbit's NRTP consists of a medial principal part (the nucleus papillioformis: PLF) and smaller lateral part (the processus tegmentosus lateralis: PTL). The PLF can be subdivided into a dorsomedial part--zone A, a ventrolateral part--zone C, and a main part--zone B. Zone B is furthermore divisible into the subzones: B1, B2, and B3. In addition, some cells of zone B3 invade the fiber bundles of the medial lemniscus. Experimental data have indicated a topographically organized bilateral projection from the NRTP to the anterior, the middle and the posterior folia of the paramedian lobule with some degree of contralateral dominance. In contrast to an earlier report in cats we find that not only the ventral, but also the dorsal region of the NRTP send projections onto the paramedian lobule. The neurons sending axons to the paramedian lobule are localized mainly in the middle and to a some degree in the posterior thirds of the NRTP. Zones A, B1 and B3 project onto all of sublobules of the paramedian lobule. While zone A projects primarily onto the anterior sublobules (e, f), zone B1 emanates to the middle paramedian sublobules (c, d), Zone B3 sends fibers mainly into the posterior sublobules (a, b) and to a some degree to the middle paramedian sublobules. Zone B2 distributes a few axons exclusively to the middle folia of the paramedian lobule, while the middle part of the PTL gives rise to small bilateral projection to sublobules c and d of the paramedian lobule. Neurons of zone C send projections into the middle folia of the paramedian lobule. These findings are discussed in relationship to other morphological and physiological data on neurons of the pontine reticular tegmental nucleus.

Animals↗
PubMed1988

Afferent fiber connections from the raphe nuclei to the cerebellar paramedian lobule. A histochemical study in the rabbit utilizing horseradish peroxidase as a retrograde marker.

The distribution of labelled cells within the raphe nuclei has been studied after iontophoretic injections of horseradish peroxidase into various folia of the cerebellar paramedian lobule. Retrogradely marked neurons of all sizes and shapes were found in more caudally located raphe nuclei: obscurus, pallidus, magnus and pontis, as well as single neurons in nucleus centralis superior and dorsal raphe nucleus. The nuclei raphe pontis and obscurus send the greatest number of fibers to the paramedian lobule. Most of the projection takes origin from raphe neurons located in midline and ipsilaterally. Folia c and d are the recipients of most afferents from the raphe nuclei (pallidus, obscurus, pontis, magnus). On the other hand, folia f and e appear to receive contribution from nuclei raphe pontis and pallidus, while folia a and b from nuclei obscurus and magnus. Additionally single neurons in nucleus raphe dorsalis contribute to the projection onto the folia f and e, and from nucleus centralis superior to the folia c, d and occasionally to the sublobule a. The studies are discussed in relation to other investigations of afferent-efferent connections and already known functional role of the raphe nuclei.

Animals↗
PubMed1988

Twitch force and action potentials of single motor units in medial gastrocnemius muscle of the rat.

On the basis of a sag test in unfused tetanus we classified fast and slow motor units (MUs) in medial gastrocnemius muscle of the rat. The following parameters of motor units were investigated: single twitch force, duration of the action potentials, maximum-minimum amplitude time (M-MAT), action potentials amplitude and their latencies after stimulus (to the onset of potentials) and the diameter of MU territory in muscle medio-lateral direction. Differences were found between fast and slow MUs in all of the properties. A correlation was found between MU twitch forces and the diameters of territories and amplitudes of action potentials in the whole investigated MU population, as well as between the duration and the M-MAT of the action potentials.

Action Potentials↗
PubMed1986

Neuronal group connecting the nucleus retroambiguus with nucleus ambiguus.

The nucleus retroambiguus is connected to the ambiguus rostrally to the crossing pyramidal fibers and laterally to the crossing lemnisces. The lateral reticular nucleus is positioned laterally and ventrally to the neurons of the connection. The neurons belonging to the connection are medium-sized. Their long dendrites are directed mainly medially, dorsally and ventrally. Medially directed dendrites ascend into the central nucleus of the medulla oblongata. Fibers of the lateral vestibulobulbospinal tract pass through the area of the connection. The tracts of the corticobulbar and medial reticular formations are found in the vicinity of the neuronal group described above. It is not impossible, however, that other, as yet unknown, tracts also pass in the neighbourhood.

Animals↗
PubMed1986

Evidence for cerebellar efferents to the ventral lateral geniculate nucleus and the lateral terminal nucleus of the accessory optic system in the rabbit. A morphological study with comments on the organizational features of visuo-oculomotor-trunco-cerebellar loops.

The efferent ascending connections of the cerebellar nuclei and afferent optic projections to the ventral lateral geniculate nucleus and the terminal nuclei of the accessory optic tract were traced in the 26 rabbits using the technique of experimental anterograde degeneration. Following eyeball enucleation, within the ventral lateral geniculate nucleus terminal degeneration was found mostly contralaterally and was restricted to both the sublayers (external and internal) of the lateral division, while ipsilaterally only scanty and confined to the dorsal region of the external sublayer of the lateral (sector alpha) division. After cerebellar lesions degeneration was found within the ventral region of the medial division (sector gamma) of the contralateral LGv and within contralateral LTN. From the localization of the lesions in the cerebellar nuclei, as well as from the distribution of degenerations in the area of the LGv, it was postulated that the parent neurons for the cerebello-LGV fibers are located in the contralateral posterior interposed nucleus, although the anteroventral lateral cerebellar nucleus, the Y group and the infracerebellar nucleus have been not excluded. Within the all terminal nuclei of the accessory optic tract the retinal fibers were found to terminate bilaterally with contralateral preponderance, mostly in the MTN, while ipsilateral fibers terminate most extensively in the lateral terminal nucleus of the accessory optic tract (LTN). In this means the retinal afferents of both sides seem to subserve the contralateral lateral cerebellar nucleus control. Taken together, the findings indicate that the extrageniculate visual inputs might be subjected to direct reciprocal cerebello-nuclear control. The visual extrageniculate cerebellopetal pathways and their correlations with the vestibulo-ocular and optokinetic reflex loops are discussed.

Animals↗
PubMed1986

The nucleus "k" of Meessen and Olszewski efferents to the cerebellar paramedian lobule: a retrograde tracing histochemical (HRP) study in the rabbit and the cat.

The group "k" of Meessen and Olszewski (1949) was identified in the brain stems of normal rabbits and cats. In the rabbit, a topographical subdivision of the group "k" into the well defined cell aggregations k1, k2 and k3 was found. In the cat, the nucleus corporis pontobulbaris was subdivised into a posterodorsal and a anteroventral part. The former was located ventrally to the motor and principal sensory trigeminal nuclei, the latter was wedgeshaped and situated more anteriorly at the lateroventral margin of the pons. In 9 rabbits and 7 cats the neurons of origin for cerebellar paramedian lobule afferents were identified with retrograde transport of horseradish peroxidase within the nucleus "k" and nucleus corporis pontobulbaris, respectively. In both species, most projections to the paramedian lobule were seen as originating ipsilaterally with only a small contralateral component. The study suggests that there are certain segregated projections of the nucleus "k" or the nucleus corporis pontobulbaris to the cortex of the anterior and posterior parts of the paramedian lobule, with some valid species differences. In the cat, the whole projection was found to originate in the more anterior and ventral parts of the nucleus "k" (nucleus corporis pontobulbaris). The posterior part of the paramedian lobule in the rabbit receives afferents from the homolateral subdivisions k3 and, to a minor degree, from k2; while in the cat, afferents are bilateral with an ipsilateral preponderance and originate from the posterior cellular group of the nucleus corporis pontobulbaris dispersed among and medially to the exiting motor root of the trigeminal nerve. The anterior part of the paramedian lobule afferents in the rabbit originates bilaterally within subdivision k1, to a minor degree ipsilaterally in the dorsal region of subdivision k3, and occasionally in subdivision k2, whereas in the cat afferents originate from the anterior and posterior levels of the corpus pontobulbaris. Additionally, some afferents for the rabbit anterior paramedian lobule originate within the homolateral nucleus "n". No evidence for a longitudinal zonal pattern of the projection onto the paramedian lobule was found. The study is discussed in the light of present information on the connections of the nucleus "k" (nucleus corporis pontobulbaris).

Afferent Pathways↗
PubMed1983

[Effect of bromfenvinphos (IPO-62) on changes in the apical dendritic spines of the cortical pyramidal neurons of the rat].

The rats (control group--6 animals, experimental group I--13, experimental group II--8) of inbred Wistar/W Bog strain, were orally administered 84,6% technical concentrate IPO-62 (bromphenvinphose) dissolved in olive oil and next the spines on apical cortex dendrites were evaluated. Statistically significant loss of dendritic spines was found both in group I (IPO-62 daily dose from 3 to 12 mg per 1 kg of body weight during 58 days) and in group II (IPO-62 daily dose--12 mg per 1 kg/body weight for 5 days and 18 mg/kg body weight for 4 days).

Animals↗
PubMed1981

Dendritic topography of neurons of the retroambiguus nucleus in cat.

In 18 cats of different ages the topography of dendrites of the retroambiguus nucleus was established with Golgi impregnation method. The large and medium neurons of the nucleus send their longest dendrites mainly into dorsomedial and ventrolateral directions. The former dendrites enter the nervous tract area such as pyramidal, medial vestibulo-bulbo-spinal, ponto-bulbo-spinal and tecto-bulbo-spinal. The ventrolaterally directed dendrites reach the area in which pass lateral vestibulo-bulbo-spinal tract and fibers of the lateral reticular system. The dendrites always project outside of the center (nucleus). Thus, the term center should comprise not only perikaryons but also the area of dendritic tree which receives most of the afferent fibers. It is suggested to introduce two terms, viz., the "input area" which is formed by dendritic tree of the neurons belonging to the nucleus in the section and the "input space" as the dendritic tree considered in the three dimensions.

Aging↗
PubMed1978

Dendritic range of the neurons of the intermediate gray at the levels of the first and second lumbar segment of the spinal cord in the cat 1. The range dendrites of the central region neurons.

Spinal cords of kittens and mature cats were examined at the levels of L1 and L2 segments. Using Golgi impregnation method it has been stated that dendrites of the small and medium neurons lying in the central region of the intermediate gray ramify mainly within the region in question. Some of them, however, penetrate the neighbouring regions. The dendrites of large neurons reach the lamina III (according to Rexed's division), paramedially the white commisure, the intermediomedial as well as the thoracic nuclei. These dendrites reach even the lateral horns of the spinal cord (laterally) and the motor nuclei (ventrally).

Animals↗
PubMed1978

Dendritic range of the neurons of the intermediate gray at the levels of the first and second lumbar segment of the spinal cord in the cat. 2. The range of dendrites of the paramedial region neurons.

The lumbar segments (L1 and L2) of spinal cords in 8 kittens and 6 mature cats were examined using several modifications of Golgi method. Within the paramedial region two groups of neurons were distinguished (besides the thoracic nucleus), i.e. the intermediomedial nucleus and paracommissural neuronal group. Small cells of the both groups send their dendrites in the relatively short distances over the nuclei. Medium cells dendrites of the intermediomedial nucleus penetrate the thoracic nucleus, the central region of the intermediate gray, the lamina VII, and the white commissure. Dendrites of the paracommisural cells penetrate the lateral horn as far as motor nuclei, the intermediomedial nucleus, sometimes the thoracic nucleus, the central and lateral regions of the intermediate gray as well as the white commissure. Possible afferent connections of these neurons with various centers of the cord, with supraspinal centers as well as with peripheral afferents are discussed.

Animals↗