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At least 19 recordsLinked to original sources
PubMed1975

Stereotaxic coordinates for the Rhesus monkey thalamus and mesencephalon referencing visual afferents and cytoarchitecture.

When using a stereotaxic instrument for visual field stimulation we found that electrode placements in the thalamus and mesencephalon of prone rhesus monkeys with the aid of avaiable atlases showed considerable errors. As these animals are valuable for primate visual system reseach an atlas was constructed with methods that have not been used before for rhesus. In addition, the specific connections from the visual cortices, superior colliculus and retina to the thalamus and mesencephalon are also shown. Anesthetized monkeys of specific body dimensions had a matrix of pins inserted into the brain before fixation. A matrix was used so that the penetrations seen in the sectioned brain could be cross related as a control for accurate measurements of the stereotaxic planes throughout the brain. The surface of the whole brain frozen blocks were photographed on the microtome just before a cut section was taken. These calibrated pictures formed the "floor plan" of the atlas as they represent more accurately the brain geometry than individual sections which are distorted by cutting, staining and mounting. Cytoarchitectural (Nissl stain) and axonal connectional (Fink-Heimer stain) information was transferred and adjusted onto the block pictures from their corresponding stained sections. Follow up experiments showed that the present coordinates are accurate for these monkeys of restricted body dimensions. In addition, referencing visual axonal projections onto the same cytoarchitectural map in stereotaxic coordinates provides an atlas for localizing areas of the thalamus, on a basis other than cytoarchitecture, which receive combinations of visual inputs for further anatomical and physiological studies of the rhesus monkey visual system. The atlas further demonstrates that projections do not necessarily follow the cytoarchitectural definition of an area, but rather redefine the thalamus on the basis of specific axonal connections.

Animals↗
PubMed1978

Amygdaloid projections to the mesencephalon, pons and medulla oblongata in the cat.

Amygdalotegmental projections were studied in 26 cats after injections of horseradish peroxidase (HRP) in the diencephalon, midbrain and lower brain stem and in 6 cats after injection of 3H-leucine in the amygdala. Following HRP injections in the posterior hypothalamus, periaqueductal gray (PAG) and tegmentum many retrogradely labeled neurons were present in the central nucleus (CE) of the amygdala, primarily ipsilaterally. Injections of HRP in the posterior hypothalamus and mesencephalon also resulted in the labeling of neurons in the basal nucleus, pars magnocellularis. Following 3H-leucine injections in CE and adjacent structures autoradiographically labeled fibers were present in the stria terminalis and ventral amygdalofugal pathways. In the mesencephalon heavily labeled fiber bundles were located lateral to the red nucleus. Labeled fibers and terminals were distributed to the mesencephalic reticular formation, substantia nigra, ventral tegmental area and PAG. In the pontine and medullary tegmentum the bulk of passing fibers was located laterally in the reticular formation. Many labeled fibers and terminals were distributed to the parabrachial nuclei, locus coeruleus, nucleus subcoeruleus and lateral tegmental fields. Many terminals were also present in the solitary nucleus and dorsal motor nucleus of the vagus nerve. The location of the cells of origin and the distribution of the terminals of the amygdalotegmental projection suggest that this pathway plays an important role in the integration of somatic and autonomic responses associated with affective defense.

Amygdala↗
PubMed1977

Topographical distribution of acetylcholinesterase and butyrylcholinesterase in the diencephalon and mesencephalon of the garden lizard (Calotes versicolor).

The present report incorporates the histochemical mapping of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) among the various nuclei and fiber tracts of the diencephalon and mesencephalon of Calotes veriscolor. The various nuclei, for both enzymes, present varying degrees of staining, ranging from negative nuclei, on the one hand, to mild and intense staining on the other hand. Almost all of the fiber tracts reveal intense activity in BChE preparations, while they demonstrate mild and moderate activities for AChE. The nature of the various nuclei in relation to enzymatic patterns is discussed.

Acetylcholinesterase↗
PubMed1976

Chemo-architectonic studies in a submammalian brain. Adenosine triphosphatase and simple esterase in the diencephalon and mesencephalon.

The present report deals with the histo-enzymological mapping of adenosine triphosphatase and simple esterase in the diencephalon and mesencephalon of Uromastix hardwickii. The enzymatic make-up, in both cases, does not differ markedly in the various nuclei; few variations, of course, occur in some midbrain areas like pretectal nuclei. The latter are intensely positive for ATPase, while these nuclei are moderate to simple esterase. Nevertheless, one of the most interesting results pertaining to simple esterase activity is of a high order in the fiber tracts in comparison to ATPase. The other interesting feature relates to the fact that generally intensely positive nuclei, in ATPase preparations, are those which have extensive efferent fibres. The metabolic significance of high degree of ATPase activity vis-a-vis extensive efferent connections has been exhaustively discussed, besides the possible significance of the general data obtained.

Adenosine Triphosphatases↗
PubMed1975

Effects of electrical stimulation of the mesencephalon and diencephalon on the paradoxical phase of sleep.

During paradoxical sleep electrical stimulation of the mesencephalic reticular formation and emotiogenic structures in the mesencephalon and diencephalon produced depression or an increase in the theta rhythm of the hippocampal and entorhinal electrical activity. However, stimulation not involving behavioral arousal did not cause a transition from paradoxical phase into slow wave sleep. The cessation of stimulation restored the normal structure of the paradoxical phase. Stimulation of the reticular formation causing the depression of the hippocampal and entorhinal theta rhythm without behavioral arousal did not affect duration of the paradoxical phase, which was shortened, however, by electrical stimulation of the emotiogenic structures evoking an increase in the hippocampal and entorhinal theta rhythms. Stimulation of ventromedial hypothalamus or septum (during wakefulness inhibiting motivational behavior and emotional stress) caused transition from the paradoxical into slow wave sleep. This is probably caused by a decrease in emotiogenic stress, which during the paradoxical phase is usually on a high level.

Animals↗
PubMedDate not supplied

[Transitory ischemia of the mesencephalon caused by vertebral angiography].

Vertebral angiography, performed using catheterization according to Seldinger, is followed by a transitory Weber syndrome. The Authors maintain that the vessel spasm of the vertebro-basilar territory, visible during the angiography, is the main cause of the transitory ischemic attach at the base of the mesencephalon.

Adult↗
PubMed1979

Effects of intraventricular and intra-aquaductal 6-hydroxydopamine on monoamine containing neurons of the fowl paleostriatum, diencephalon and mesencephalon.

The effects of a single intraventricular or intra-aquaductal infusion of 6-hydroxydopamine (6-OHDA) on monoamine fluorescence in the paleostriatum augmentatum, diencephalon and mesencephalon were studied. Present experiments have enable us to better characterize the distribution of catecholaminegic axons in the paleostriatum augmentatum, preoptic area, hypothalamus, median eminence, periventricular areas as well as of cell-bodies and axons exbiting green fluorescence in the n. mesencephalicus properties and other mesencephalic nuclei.

Animals↗
PubMed1979

Ascending projection from the respiratory centre to mesencephalon and diencephalon.

The brainstem reticular formation, subthalamus and thalamus were explored in a search for units modulated by the respiratory centre. Experiments were performed on cats under local anesthesia, in which respiratory center oscillation was independent of movement of the lungs and thorax. A large proportion of units firing tonically showed an increasing frequency, phase related to phrenic nerve activity. Respiration related units (RRUs) rostral to the pneumotaxic centre were concentrated in definite areas of the brainstem reticular formation, subthalamus and thalamus. Respiratory modulation disappeared rostral to a section performed at the ponto-mesencephalic junction.

Animals↗
PubMed1975

[Histochemical evidence of aminotransferases. III. Localization of aminotransferases in the mesencephalon, diencephalon, cortex cerebri and in the peripheral nervous system (author's transl)].

The histochemical distribution of some aminotransferases at various levels through the midbrain and cerebrum and in the peripheral nervous system of the rat has been described. The selective localization of the reaction product in the neurons and the neuropil was the same for the aminotransferases studied. There was a difference in the intensity of the enzyme activity. The white matter was negative, and only the glial cells and the blood vessels exhibit transaminase activity. Some nuclei showed an intensive reaction in the neurons and neuropil: nuel. ruber, substantia nigra, hypothalamic nuclei, Ammon's horn. A high activity was observed in the ganglion cell, and the nerve fibres were negative. There was a great similarity between the pattern of distribution for aminotransferases and that for some dehydrogenases.

Animals↗
PubMed1979

Single unit activity in the mesencephalon of Sternarchus.

Action potentials evoked in a phase-locked 1 : 1 relationship by natural electric organ discharges (EOD) were recorded extracellularly and intracellularly from single mesencephalic magnocellular nucleus units in the high frequency electric fish Sternarchus albifrons (Gymnotidae). This activity has been shown to be the result of an extrinsic feedback of the electrosensory system and is probably important for the socalled jamming avoidance response triggered artificial electric pulses when delivered into the water in a 1 : 1 relationship at intensities higher than the EOD. In the same way, artificial pulses of frequency near EOD could either drive or, due to beats, greatly disturb the regular firing of the units. More insight into the neural mechanism was yielded by single EOD-triggered shocks provoking a failure in firing of certain action potentials of the series and causing long-lasting (10-20 ms) accelerations and decelerations of the regular EOD-evoked firing (transient disturbance). Intracellular stimulations show similar effects. The biological significance of this neural mechanism for the fish's electroperception and JAR is discussed.

Action Potentials↗
PubMed1979

[Cell proliferation and migration in the roof of the mesencephalon (tectum) in Xenopus laevis tadpoles and adult frogs normally and in brain injury. II. Cell proliferation and differentiation of the tectum in frogs].

The proliferation and directions of cell differentiation in tectum opticum were studied in the young frogs under the conditions of normal development and upon brain trauma by means of 3H-thymidine autoradiography. The same types of cells were shown to be able of proliferation in both the cases: cells of the ventricle zone and glioblasts (gliocytes) in all other tectum layers. A study of directions of the tectum proliferating cells' differentiation in the frogs has shown that the proliferating cells differentiate mainly in the ependyme tanicytes in the ventricle layer 1 and gliocytes in the other tectum layers. The trauma did not change the direction of proliferating cells' differentiation towards the formation of neurons. The complete regeneration is observed in the tectum layer 1 only.

Animals↗
PubMed1976

[Quantitative growth analysis of limbic nuclei areas fresh volume in diencephalon and mesencephalon of an albino mouse ontogenic series. II. Corpus mammillare].

The fresh volumes of the Nucl. medialis and of the Nucl. lateralis corporis mammillaris of 52 white mice aged between 17 and 60 days of ontogenesis have been determined. The fresh volume of the left Nucl. lateralis is significantly larger than that of the right side. The data of the Nucl. laterales have been fitted by a 3parametric logistic function. The data of the Nucl. medialis have been fitted by a sum of logistic functions. This sum has an increasing and a decreasing component and it shows a maximum of the sum of both components near 32 days of ontogenesis. The degree of maturity and the growth-rate of maturity have been discussed. Both nuclei belong to the group of brain regions in white mice with an early development. The growth of different brain regions is asynchronous. There is a need for further quantitative analyses.

Age Factors↗