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At least 19 recordsLinked to original sources
PubMed1978

[Embryonic development of the brain of Scyliorhinus canicula (L.). III. The optical system and adjacent nuclei in the tegmentum mesencephali].

The ontogenesis of the optic system in the brain has been studied with reference to the general biology of the embryo and to the cytoarchitecture of the optic tectum. 1. Sharks vary in terms of retinal structure (Franz 1931). Scyliorhinus shows densely packed and large cellular layers alternating with thin fiber layers. 2. The optic tracts, which are not excessively large, cross in the optic chiasm by approximately 95%. The optic fibers, forming a medial and a lateral tract, enter the tectum in zones 9 and 11. 3. The eye muscle nuclei do not differ from the general vertebrate pattern. The oculomotor nucleus represents the largest portion; the abducens nucleus is small. 4. The nucleus interstitialis of the fasciculus longitudinalis medialis is remarkably developed and consists of large neurons. Together with the interpreduncula nucleus it receives fibers of fasciculus retroflexus.

Abducens Nerve↗
PubMed1978

A radioautographic study of retinal projections in type I and type II lizards.

The retinofugal projections of 5 species (Acanthodactylus boskianus, Scincus scincus, Tarentola mauritanica, Uromastix acanthinurus and Zonosaurus ornatus) belonging to 5 different families of Type I and Type II lizards have been examined by means of the radioautographic method. In the 5 species the retinal ganglion cells project to the contralateral hypothalamus (nucleus suprachiasmaticus), thalamus (nucleus geniculatus lateralis pars ventralis, nucleus geniculatus lateralis pars dorsalis), pretectum (nuclei lentiformis mesencephali, geniculatus pretectalis, postero-dorsalis griseus tectalis), tectum opticum (layer 2 to layer 6 of the stratum griseum et fibrosum superficiale) and tegmentum mesencephali (nucleus opticus tegmenti). Ipsilateral optic fibers were never observed in Uromastix acanthinurus, whereas an uncrossed quota was visible in both nucleus geniculatus lateralis pars dorsalis and nucleus postero-dorsalis in the other species. An ipsilateral retinotectal projection was observed only in Tarentola mauritanica. With the exception of the nucleus griseus tectalis the contralateral optic centers identified in this material have to a large extent been observed in other reptiles belonging to the different orders. The presence in reptiles of a general pattern of contralateral visual projections indicates that these were established very clearly in the course of evolution. Similarities become apparent when this plan is compared with that observed in birds. In marked contrast the ipsilateral component in reptiles is unstable and mutable in nature. This ipsilateral retinotectal projections do not appear to be a feature restricted to Type I lizards. On the other hand, the presence of this optic component cannot be linked solely to nocturnal habits.

Animals↗
PubMed1978

Topographic projections between the nucleus isthmi and the tectum of the frog Rana pipiens.

The connections between the nucleus isthmi and the tectum in the frog have been determined by several anatomical techniques: iontophoresis of horseradish peroxidase into the tectum, iontophoresis of 3H-porline into the nucleus isthmi and the tectum, and Fink-Heimer degeneration staining after lesions of the nucleus isthmi. The results show that the nucleus isthmi projects bilaterally to the tectal lobes. The ipsilateral isthmio-tectal fibers are distributed in the superficial layers of the tectum, coincident with the retionotectal terminals. The contralateral isthmio-tectal fibers travel anteriorly adjacent to the lateral optic tract and cross the midline in the supraoptic ventral decussation, where they turn dorsally and caudally; upon reaching the tectum, the fibers end in two discrete layers, layers 8 and A of Potter. The tectum projects to the ipsilateral nucleus isthmi and there is a reciprocal topographic relationship between the two structures. Thus, a retino-tecto-isthmio-tectal route exists which may contribute to the indirect ipsilateral retinotectal projection which is observed electrophysiologically. The connections between the nucleus isthmi and the tectum in the frog are strinkingly similar to the connections between the parabigeminal nucleus and the superior colliculus of mammals.

Animals↗
PubMed1979

Topological analysis of the brain stem of the lungfish Lepidosiren paradoxa.

The ventricular sulcal pattern and the cellular structure of the brain stem of the lungfish Lepidosiren paradoxa have been studied in transversely cut Nissl and Bodian stained sections. Five longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis and the sulcus medianus superior could be distinguished. In the isthmus region a number of obliquely oriented sulci is present. One of these, designated here as sulcus d, continues as a longitudinal groove into the mesencephalon. In Lepidosiren most neuronal perikarya are contained within a diffuse periventricular gray. However, 24 separate cell masses could be delineated. Six of these are primary efferent nuclei, six are primary afferent center, six nuclei are considered to be components of the reticular formation and the remaining six may be interpreted as "relay" nuclei. The distribution of the cell masses and their relations to the ventricular sulci were studied with the aid of the graphical reconstruction procedure termed tolopogical analysis (cf. Nieuwenhuys, '74, and fig. 11). This analysis yielded the following results. In the rhombencephalon the gray matter is arranged in four longitudinal columns or areas which have been termed the area ventralis, area intermedioventralis, area intermediodorsalis and area dorsalis. In many places the sulcus intermedius ventralis, the sulcus limitans and the sulcus intermedius dorsalis mark the boundaries between these morphological entities. These longitudinal areas coincide largely, but not entirely, with so-called functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the nucleus of the solitary tract, two non-visceral sensory cell masses, namely the magnocellular and parvocellular vestibular nuclei. The four longitudinal zones cannot be distinguished in the mesencephalon nor can the sulcus limitans be recognized here. Functionally, however, the medial part of the tegmentum mesencephali may be considered the rostral extreme of the somatic motor column, whereas the remainder of the midbrain contains a number of somatic sensory centers.

Animals↗
PubMed1978

Behavior and electrical brain stimulation in the green iguana, Iguana iguana L. II. Stimulation effects.

Behavioral responses were electrically elicited in the brains of 21 green iguanas. At 518 stimulation sites, a limited number of behaviors could be reliably elicited. Except for some motor responses which had a forced appearance, they corresponded to the basic activity of green iguanas, exploratory behavior, display, defensive and escape-related behavior. Head-nodding displays were reliably elicited post stimulation when imminent escape was prevented experimentally but rarely during stimulation. Goal-directed behavior, i.e., feeding, drinking, mating and fighting behavior, were not elicited. The stimulation sites of frequently elicited behavioral responses revealed regional differences and some structural correlations. The majority of sites yielding defensive display responses were found in the hypothalamus, while dewlap display was more readily and widely elicited. Axial rotation and head-raising were elicited in a ventrothalamic zone extending into the tegmentum mesencephali. Tongue-flicking response sites were mostly concentrated in ventromedial areas of the tel-, di- and mesencephalon. Most escape-related responses were distributed unspecifically but the sites of violent flight responses were confined to the dorsal and lateral mesencephalon.

Animals↗
PubMed1975

[The primary optical projection in albino and pigmented rats].

1. We have studied by silver degeneration methods in transversal and horizontal brain series the pathways and the terminal nuclei of the primary optic system in albino and pigmented rats. 2. About 90% of the retinal axons are crossing in the Chiasma opticum. Differences between albino and pigmented rats are small. At the level of the lateral geniculate body (l.g.b.) the axons ramify. One branch is going in the optic tract or in the transversalsystem to the pretectum and tectum. The other branch goes as a collateral in the longitudinal system of the dorsal l.g.b. and ends here. 3. The optic fibers project--especially contralateral--to the following nuclei: veutral l.g.b. (lateral half), dorsal l.g.b., nucleus of the optic tract, Nc. olivaris praetectalis, Ncc. praetectales anterior et posterior and superior colliculus (laminae I-III). In the nuclei of the pretectal region are ipsilateral only a few degenerating fibers. 4. Especially in the dorsal l.g.b. but also in the superior colliculus the pigmented rats show ipsilateral an larger retinal input. 5. The ipsilateral fibers project to a special region in the dorsal l.g.b. This region is also innervated by contralateral axons. 6. In both the albino and pigmented rats the dorsal l.g.b. shows no lamination in the cytoarchitectonical picture and the ipsi- and contralateral input regions overlap. Therefore in the rat we can not speak from a laminated dorsal l.g.b. We have here--prepoperantly functional caused--a simple form of l.g.b. 7. The accessory optic system is only decussated. It includes the Fasciculus inferior tr. opt. accessorius, who projects only and direct to the median terminal nucleus and the Fasciculus superior tr. opticus accessorius. The last goes off from the optic tract at the level of the pretectal region and innervates all the 3 accessory optic nuclei. 8. In a few preparates we found references for a direct retino-hypothalamic connection (Nc. suprachiasmaticus and Nc. arcuatus hypothalami).

Albinism↗
PubMed1976

Regional serotonin levels in brain: a comparison of depressive suicides and alcoholic suicides with controls.

The levels of 5-hydroxytryptamine have been measured in 33 areas of the human brain and these levels compared in depressed suicides, in alcoholic suicides, and in controls. The values obtained for control brains ranged from 5.3 mumole 5-HT/kg wet weight in substantia nigra to 0.4 mumole 5-HT/kg wet weight in frontal gray. No significant differences were found among diagnostic groups in any of the areas studied.

Adult↗
PubMedDate not supplied

[Study of the connections of the thalamus in Rana temporaria frogs by the peroxidase method].

In frogs, on the base of the axonal transport of horseradish peroxidase, the connections ascending to the primordial hippocamp were shown from the ipsi- and contralateral pyriform pallium, contralateral primordial hippocamp, ispilateral amygdala and nucleus accumbens, as well as from rostral parts of the postero-central thalamic nucleus (bilaterally). The ascending connections from the dorsal column nuclei were followed with reliability till the rostral parts of the contralateral mesencephalic tegmentum, but very likely they reach also the dorsal thalamus.

Animals↗
PubMed1975

[Synkinesis of head and eye movements evoked by brainstem stimulation in the alert monkey].

The synkinesis of head and eye movements evoked by electrical stimulation of the tectum and tegmentum in the alert monkey is described. In positions where both head and eye movements can be evoked, the two are almost always parallel in direction and they are superimposed on rather than substituted for each other. The directiion of movement depends on the stimulated positions: tilt and turn reactions are distributed according to laterality, direction of vertical movements depends more on the stimulus parameter than the electrode position. Head movements release vestibulo-ocular reflexes, which are superimposed on the electrically evoked eye movements.

Animals↗
PubMed1977

Progesterone metabolism in the pineal, brain stem, thalamus and corpus callosum of the female rat.

Specific brain regions, namely, thalamus, tectum, tegmentum, cerebellum, medulla and pineal, from five proestrous rats were incubated for 30 min with [3H]progesterone. After reverse isotopic dilution analysis, the following metabolites were identified in all incubations by purification to constant specific activity, derivative formation and/or gas liquid chromatography trapping: [3H]5alpha-pregnane-3, 20-dione (10-20% of the starting substrate except pineal -- 0.7%), [3H]3alpha-hydroxy-5alpha-pregnan-20-one (1.6-3.8% except for pineal -- 0.5%) and [3H]20alpha-hydroxy-4-pregnen-3-one (0.05-0.11%). Preliminary results from the corpus collosum incubation indicated the presence of the same metabolites. Although some apparent constant specific activities were obtained for 20alpha-hydroxy-5alpha-pregnan-3-one and 5beta-pregnane-3, 20-dione, the low levels of 3H associated with these steroids did not permit a definitive identification. The results indicate the presence of at least delta1-steroid 5alpha-reductase, 3alpha-hydroxysteroid dehydrogenase and 20alpha-hydroxysteroid dehydrogenase activities with progesterone as substrate in the brain regions examined.

Animals↗
PubMed1979

[Enzyme histochemical study of the brain of Chthonerpeton indistinctum (Gymnophiona, Amphibia)].

In the brain of the Caecilian species Chthonerpeton indistinctum the following enzymes have been demonstrated by means of histochemical techniques: acid phosphatase, alpha-naphthylacetate esterase, acetylcholin esterase. Acid phosphatase occurs in the cytoplasm of the neurons in 4 different types of localization. Its activity in the ventral parts of the brain is markedly higher than in the dorsal ones. Of particularly high activity are: the motor neurons in the tegmentum, the nucleus mesencephali trigemini, individual large neurons in the marginal zone of the grey matter of the telencephalon, which seems to be a special character of the Caecilians among the Amphibia. The ependyma exhibits local differences in respect of acid phosphatase activity. alpha-Naphthylacetate esterase marks in particular the secretory neurons of the hypothalamus, the large perikarya of the nucleus mesencephali trigemini and the motor neurons of the tegmentum. In the telencephalon the alpha-naphthylacetate esterase activity corresponds to that of acid phosphatase. Acetylcholin esterase marks--with certain restrictions--cholinergic neurons. These predominate in Chthonerpeton in the caudal parts of the brain. In the telencephalon amygdala, septal area striatum and the mitral cells are of comparatively high activity. The neurosecretory neurons of the hypothalamus are particularly rich in this enzyme. As an anurans the cholinergic fasciculus retroflexus as asymmetric. The tectum opticum is of secondary simplicity and does not exhibit a clearly recognizable stratification.

Acetylcholinesterase↗
PubMed1979

Connections of the tectum of the rattlesnake Crotalus viridis: an HRP study.

We have studied the connections of the tectum of the rattlesnake by tectal application of horseradish peroxidase. The tectum receives bilateral input from nucleus lentiformis mesencephali, posterolateral tegmental nuclei, anterior tegmental nuclei and periventricular nuclei; ipsilateral input from nucleus geniculatus pretectalis, and lateral geniculate nucleus pars dorsalis; and contralateral input from dorso-lateral posterior tegmental nucleus and the previously undescribed nucleus reticularis caloris (RC). RC is located on the ventro-lateral surface of the medulla and consists of large cells 25--45 micrometer in diameter. Efferent projections from the tectum can be traced to the ipsilateral nucleus lentiformis mesencephali, the ipsilateral lateral geniculate region, anterior tegmental region and a wide bilateral area of the neuropil of the ventral tegmentum and ventral medualla. We have not found any direct tectal projections from the sensory trigeminal nuclei including the nucleus of the lateral descending trigeminal tract (LTTD). We suggest that in the rattlesnake, RC is the intermediate link connecting LTTD to the tectum.

Animals↗
PubMed1976

Physiological aspects of visual perception. II. The subcortical visual direction of behavior.

The second part of the Bennett Lecture for 1975 by Denny-Brown examined the subcortical representation of the dissociation of function described by Denny-Brown and Chambers. Complete removal in the macaque monkey of the corticomesencephalic fibers where they pass from pulvinar to colliculus, and of the colliculus, resulted in the same loss of visual object identification, binocular fixation, and visuosocial behavior that followed removal of area 17. Vision for peripheral movement and spatial orientation ("panoramic vision") remained excellent, with release of catatonia. Conversely, unilateral electrolytic lesions of the mesencephalic tegmentum produced visuospatial distortion, asymmetry of optic righting, and directional difficulties in eye movement (Parinaud syndrome and skew deviation). When bilateral, tegmental lesions produced great constriction of visual field with release of convergence and fixation spasm. Suppression of peripheral attention resulted from perceptual rivalry.

Animals↗
PubMed1977

Möbius syndrome due to brain stem tegmental necrosis.

Möbius syndrome undoubtedly results from a variety of disorders affecting central or peripheral portions of appropriate cranial nerves or their target muscles. Pathological alterations observed in cranial nuclei are most often viewed as aplastic or dysplastic lesions. Two patients with Möbius syndrome with associated facial and skeletal malformations showed mineralized necrotic foci in multiple brain stem nuclei. Prenatal encephalomalacic lesions represent the pathological basis for some cases of congenital static Möbius syndrome.

Cranial Nerves↗
PubMed1978

Combined nuclear and supranuclear defects in ocular motility. A clinicopathologic study.

A 65-year-old man suffered a midbrain infarct after coronary artery bypass surgery. He was left with a severe neuro-ophthalmologic deficit consisting of paralysis of upward and downward vertical gaze, weakness of adduction of the left eye, a dilated fixed left pupil, and partial right Horner's syndrome. He died 31 months after the episode. Postmortem examination disclosed an infarct involving parts of both oculomotor nuclei as well as supranuclear structures thought to be involved in the mediation of vertical eye movements.

Aged↗
PubMed1977

The effect of large unilateral cortical lesions on rubrospinal tract sprouting in newborn rats.

Many previous reports have demonstrated the development of aberrant neural connections in response to neonatal brain lesions. This investigation was undertaken to study possible alterations, particularly axonal sprouting, in rodent rubrospinal projections after neonatal destruction of the corticospinal tract through frontal cortical ablation. The neonatal ablations were made by aspiration in 1 to 2-day-old rats under hypothermic anesthesia. At three to six months after neonatal surgery, the rubrospinal tracts were ablated bilaterally in these small animals as well as in controls, by stereotaxically transecting the ventral tegmental decussation. Animals were killed two to six days after adult surgery, and rubrospinal projections were demonstrated using the Fink-Heimer degeneration stain. No differences in the pattern of rubrospinal projections were observed between animals with neonatal cortical lesions and controls. In all animals rubrospinal projections were located primarily in Rexed's lamina VI with a slight distribution into lamina V and the dorsal portion of lamina VII. Various hypotheses explaining the lack of rubrospinal sprouting after neonatal cortical lesions are presented, along with possible experiments to test these hypotheses.

Animals↗