PubMed Health⌕ Search

Biomedical subjects

R Hassler

Publications and source records attributed to R Hassler.

At least 19 recordsLinked to original sources
PubMed1985

Architectonic differentiation of the lateral geniculate body of the cat.

The cell layers of the lateral geniculate nucleus (LGN) of the cat have been reinvestigated in relation to the localization of the degeneration of optic terminals. After unilateral enucleation the degenerated crossed and uncrossed optic terminals form five continuous alternate strips in all the five layers of the LGN with the Fink-Heimer method. The crossed terminals end in the layers A, B0, and B2, and the uncrossed terminals in the layers A1, and B1 without overlapping. The cyto- and myeloarchitectonic study of complete frontal, sagittal, and horizontal serial sections has shown that the former B layer and the nuclei interlaminares centralis pars ventralis and medialis of Thuma built up three continuous parallel layers, which we propose to call B0, B1, and B2. The layer B0 containing large cells and more single fibers than the layers A and A1, extends on the medial, ventral and caudal side of layer A1. The layer B1 containing smaller cells and less single fibers than the layer B0, surrounds the layer B0 from medial, ventral and caudal. It comprises in the medial part of the ventral extent a pale spot with especially small nerve cells. The layer B2 containing medium-sized cells in less dense arrangement and many small dark fiber bundles split up from optic tract extends medially and ventrally of layer B1. The caudal pole of the LGN is covered cap-like by the layers B0, and B1 and incompletely by B2. This new interpretation of the LGN's layers in the cat is more regular and easier to compare with the stratification of the LGN of other species including primates.

Animals↗
PubMed1979

Locally evoked potentials in slices of rat neostriatum: a tool for the investigation of intrinsic excitatory processes.

Field potentials, extracellular unitary discharges and intracellular potentials evoked by intrastriatal stimulation were recorded from slices (thickness 200-400 micron) of rat neostriatum maintained in an artificial medium. The field potentials consisted of two negative waves appearing at latencies of 0.5-1.5 ms (N-1) and 2-4 ms (N-2). Extracellular unitary records showed two typed of discharges, one with short but constant latencies at threshold level stimulation and the other with longer and variable latencies. In intracellular recordings the late discharge was seen to arise from EPSPs. Based on the intra- and extracellular unitary records, N-1 was identified as the population spike of antidromically or directly activated unitary discharges and N-2 as that of orthodromically activated discharges. This interpretation was substantiated by the fact that the N-2 potential was blocked in a perfusion medium containing a lower Ca++ or a higher Mg++ concentration than the standard solution. Neither interruption of ascending neostriatal inputs nor decortication 14 days prior to recording altered the configuration of the locally evoked potentials or the probability of synaptically driven discharge occurrence. Thus by intrastriatal stimulation, neostriatal neurons are activated antidromically or directly and/or orthodromically through intrinsic excitatroy synapses. Since the intracellular recordings showed that neostriatal neurons can be well preserved, this preparation can be regarded as a useful tool for electrophysiological and neuropharmacological investigations on intrinsic excitatory processes in the neostriatum.

Afferent Pathways↗
PubMed1978

Selective degeneration of two out of the nine types of synapses in cat caudate nucleus after cortical lesions.

In the cat caudate nucleus the same nine types of synapses are found as in putamen and fundus striati. The three parts of the striatum in the strict sense do not differ in the morphological differentiation of synapse types but only in their quantitative distribution. One-third of all synapses in the caudate nucleus are axo-spinous type IV synapses with a curved and divided asymmetric contact. This strongly suggests that the caudate nucleus interneuronal apparatus is dominated by centre-median input, in contrast to the putamen which is controlled by the cortico-striatal input to its internuncial cells and by its strong intrastriatal feedback mechanism. Extensive destruction of the convexity of the cortex and the medial cortex in one hemisphere results in dark degeneration of a large proportion of two of the nine types of caudate synapses: a) the axo-dendritic type VII synapses exciting the large spiny caudate neurons and b) the axo-spinous type III synapses making contact with the small spiny neurons of the interneuronal cell apparatus.

Animals↗
PubMed1978

The normal seminal vesiculogram.

Vasoseminal vesiculography was performed on 69 asymptomatic men. Considerable variability in the appearance of the normal adult seminal tract was seen. On the left, the normal seminal vesicle averaged 5.6 cm long, 2.0 cm wide, and 0.6 cm in luminal diameter; on the right, it averaged 5.0 cm long, 2.0 cm wide, and 0.6 cm in luminal diameter. The normal ejaculatory duct averaged 16.0 mm long and 1.5 mm wide on the left and the same on the right. Criteria for normality are presented and the radiographic techniques reviewed.

Adult↗
PubMed1978

[Demonstration of intrastriatal types of synapses and axon-collaterals by experimental isolation of fundus striati from all extrastriatal connections (author's transl)].

After columnar isolation of the cat's fundus striati with a survival time of 2 days or 2 or 4 weeks all axospinous boutons (type I, III And iv) and most axo-dendritic (or axo-somatic) boutons (type II, VI and VII) undergo dark degeneration. All specimens of axo-somatic (or axodendritic) type IX bouton (containing large, round vesicles in a clear axoplasm) and most specimens of type V bouton (with pleomorphic and some dense core vesicles) are unaltered. Many type VIII boutons (dindritic terminals containing scattered, small, sphrical vesicles suspended between the filaments of many microtubules in clear dendroplasm) are almost preserved, in the fundus more than in the caudate nucleus. After 2 or 4 weeks, some perikarya and many dendrites have undergone an electron-dense retrograde degeneration resulting from interuption of the efferent axons of the large striatal cells. The type IX synapses are interpreted as intrinsic between the small spiny and the large efferent striatal neurons; the type V as intrastriatal axon-collaterals of the large efferent neurons and the type VIII as dendritic terminals of intrastriatal Golgi type II nerve cells (possibly dwarf cells).

Animals↗
PubMed1977

Electron microscopic study of terminal degeneration in the anterodorsal thalamic nucleus of the cat.

The ultrastructure and synaptic organization of the anterodorsal nucleus (AD) of the thalamus were investigated under normal and experimental conditions. The large glomeruli are composed of an extensive central dendrite, probably arising from a projecting neuron, and of various terminal boutons. Besides the typical small bouton (RS) filled with round vesicles, two specializations of the large bouton (RL) containing round vesicles are found. The larger one (RL1) is characterized by a looser arrangement of synaptic vesicles and many mitochondria; it undergoes dark degeneration following unilateral lesions of the mamillary body in both AD. The intermediate type (RL2) is distinguished by a denser arrangement of vesicles; it undergoes dark degeneration following lesions of the midline nuclei of the thalamus. The two types of terminal boutons (F1 and F2) which contain flattened or pleomorphic vesicles do not degenerate following lesions of the mamillary body and midline nuclei; they belong to Golgi type II interneurons.

Animals↗
PubMed1977

Degeneration of two of nine types of synapses in the putamen after center median coagulation in the cat.

The cat putamen contains the identical nine types of synapses and the same proportion of axo-dendritic (or axo-somatic) synapses as described for the fundus striati. However, type III (cortico-striatal) (31:16%) and type V Caxon-callateral) (13:1%) occur much more frequently and type I (nigro-striatal) much less frequently (14:34%) in the putamen than in the fundus striati. Of the axo-spinous synapses only type IV, with densely arranged small round vesicles and interrrupted, asymmetric contact, shows a dark degeneration after center median lesions, mainly in the parvocellular part. Of the six axo-dendritic (or axo-somatic) synapses, only type VII, with densely packed small round vesicles and asymmmetric contact, is degenerated after the same lesion in the center median nucleus. However, after such lesions type VII synapses are much more frequently degenerated in the putamen than those of type IV.

Animals↗
PubMed1976

[Interaction between the systems involved in fast pain perception and in slow, persistent pain (author's transl)].

A single pinprick triggers both a pang, the "1st pain" and after a pause of 0.5 s, a spreading burning feeling, the "2nd pain". The 2nd pain is delayed because it is conducted by unmyelinated C-fibers at a rate of less than 1 m/s, 20 times slower than conduction of the 1st pain. In the spino-thalamic tract the myelinated fibers of the 1st pain conduct much faster than those of the 2nd pain, and terminate in the parvocellular ventroposterior (VP) thalamic nucleus, which projects to area 3b in the postcentral gyrus. The slow C-fibers of the 2nd pain terminate in cortex-independent thalamic nuclei like limitans, which project to the outer segment of the pallidum. This subcortical pain pathway is disinhibited after destruction of the cortical pathway of the 1st pain, so that the patients suffer from spontaneous agonizing pain feeling (thalamic pain). Unbearable pain in cases of thalamic softening, in anaesthesia dolorosa and in phantom pain can be relieved by stereotactic coagulation of the thalamic nuclei involved in the 2nd pain. Normally they are inhibited by the cortical pathway of the 1st pain.

Analgesia↗
PubMed1976

Degenerated boutons in the fundus striati (nucleus accumbens septi) after lesion of the parafascicular nucleus in the cat.

An attempt has been made to reveal which of the nine different types of synapses in the fundus striati, discriminated in a previous study, degenerate following experimental lesions in the parafasciculo-center median complex of the cat. Two types of synaptic contacts were found to be degenerated two days after the lesion was performed: (1) the axo-spinous type IV, characterized by densely-packed, small, round vesicles and a strong asymmetric thickening, and (2) the axo-dendritic or axo-somatic type VII, again characterized by small, round vesicles in a dense accumulation and an asymmetric thickening. After two days of survival the original characteristics of the boutons could still be recognized in both types of synapses. A positive correlation exists between the location and extent of the coagulation foci in the parafascicular nucleus and the appearance of degenerated boutons in the fundus striati. Therefore, the conclusion that the parafasciculofundus neurons terminate as type IV or type VII boutons is entirely justified. Additionally, the role of the special types of boutons in the synaptic organization of the fundus striati has been discussed.

Animals↗
PubMed1976

The discrimination of nine different types of synaptic boutons in the fundus striati (Nucleus accumbens septi).

An attempt has been made to discriminate additional types of synapses than have been previously described in the nucleus accumbens septi of the cat, which can, according to Brockhaus (1942), justifiably be termed the fundus striati due to the fact that it possesses all of the morphological and some of the neurochemical features of the striatum. This was undertaken in order to correlate at least one type of synapse with each different afferent pathway. Nine distinct types of synapses could be differentiated electron microscopically: Type I: axo-spinous synapses with sparse, small, round vesicles which seemed to be the nigro-striatal endings (35%). Type II: axo-somatic or axo-dendritic en passant synapses containing small, round vesicles (3%). Type III: axo-spinous synapses filled with densely-packed, small, round vesicles displaying strong postsynaptic thickenings which seem to be cortico-striatal (17%). Type IV: large axo-spinous synapses with densely-arranged, small, round vesicles contacting larger spines branching off a pedicle (9%). Type V: axo-somatic or axo-dendritic synapses containing large pleomorphic vesicles, probably axon collaterals (1%). Type VI: axo-somatic or axo-dendritic synapses with elongated small vesicles (20 X 45 nm) (3%). Type VII: large axo-somatic or axo-dendritic synapses filled by densely-packed, small, round vesicles (11%). Type VIII: large axo-somatic or axo-dendritic synapses containing loosely-arranged, small, round vesicles (8%). Type IX: axo-somatic or axo-dendritic synapses containing large, round vesicles in a translucent axoplasm (13%).

Animals↗