Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “vertical connectivity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2025

Contrasting Patterns of Connectivity Between Populations of Euphotic and Mesophotic Hydroids in Reunion Island Support the Deep Reef Refuge Hypothesis.

In the context of coral reef decline, mesophotic coral ecosystems (MCEs, 30-150 m) offer hope for the recovery of degraded euphotic reefs. The Deep Reef Refuge Hypothesis (DRRH) postulates the potential of mesophotic reefs to reseed euphotic reefs. This hypothesis needs to be further tested by estimating connectivity along the depth gradient. Mesophotic data are lacking worldwide, particularly in the southwestern Indian Ocean (SWIO). Here, using a total of 2218 samples collected at depths ranging from 10 to 103 m, we estimated the connectivity of 7 hydroid species sampled at euphotic, upper, and lower mesophotic depths around Reunion Island using a multi-species comparative framework. Population genetic analyses using 8-17 microsatellite markers per species (80 markers in total) as well as Bayesian inference were performed to estimate population structure and contemporary migration rates to highlight connectivity patterns and directionality of gene flow between depths. The results revealed three main genetic patterns depending on the species: a horizontal stepping stone pattern between areas around the island, a vertical stepping stone pattern between adjacent depths, and a quasi-panmictic pattern. Each species showed some specificity within these patterns, but overall, at least 4 of the 7 species support the assumption of vertical connectivity from the Deep Reef Refuge Hypothesis, highlighting the importance of studying multiple species. The existence of vertical connectivity between euphotic and mesophotic depths in the southwestern Indian Ocean confirms the importance of mesophotic coral ecosystems for conservation efforts and our global understanding of coral reef ecosystem dynamics.

Animals↗
PubMed1978

Interlaminar connections of the visual cortex in the hedgehog (Paraechinus hypomelas).

The contribution of each cortical lamina to intracortical circuitry was studied in the visual neocortex of the Pakistani hedgehog. Punctate laminar lesions were made electrolytically within the visual cortex, and after five to seven days the brains were processed and stained with the Fink-Heimer technique. The results of this study suggest that both horizontal and vertical connections are important to the organization of visual cortex in the hedgehog. The horizontal projections originate at three distinct cortical depths. Lesions in layer II reveal projections that traverse the inner one-half of layer I; lesions in layers III and IV reveal projections that traverse layer IV and that enter the cortical white matter; lesions in layers V and VI reveal projections that traverse the outer one-half of layer VI and that enter the cortical white matter. The vertical projections are oriented perpendicular to the pial surface. Layers II and III project to underlying layer V. Layers V and VI in turn contribute to a reciprocal projection back to all superficial cortical laminae. This anatomical data about intracortical circuitry is discussed with reference to the functional organization of visual cortex.

Animals↗
PubMed1978

Intracortical connectivity of architectonic fields in the somatic sensory, motor and parietal cortex of monkeys.

Anterograde and retrograde transport methods were used to study the corticocortical connectivity of areas 3a, 3b, 1, 2, 5, 4 and 6 of the monkey cerebral cortex. Fields were identified by cytoarchitectonic features and by thalamic connectivity in the same brains. Area 3a was identified by first recording a short latency group I afferent evoked potential. Attempts were made to analyze the data in terms of: (1) routes whereby somatic sensory input might influence the performance of motor cortex neurons; (2) possible multiple representations of the body surface in the component fields of the first somatic sensory area (SI). Apart from vertical interlaminar connections, two types of intracortical connectivity are recognized. The first, regarded as "non-specific," consists of axons spreading out in layers I, III and V-VI from all sides of an injection of isotope; these cross architectonic borders indiscrimininately. They are not unique to the regions studied. The second is formed by axons entering the white matter and re-entering other fields. In these, they terminate in layers I-IV in one or more mediolaterally oriented strips of fairly constant width (0.5--1 mm) and separated by gaps of comparable size. Though there is a broadly systematic topography in these projections, the strips are probably best regarded as representing some feature other than receptive field position. Separate representations are nevertheless implied in area 3b, in areas 1 and 2 (together), in areas 3a and 4 (together) and in area 5; with, in each case, the representations of the digits pointed at the central sulcus. Area 3b is not connected with areas 3a or 4, but projects to a combined areas 1 and 2. Area 1 is reciprocally connected with area 3a and area 2 reciprocally with area 4. The connectivity of area 3a, as conventionally identified, is such that it is probably best regarded not as an entity, but as a part of area 4. Areas identified by others as area 3a should probably be regraded as parts of area 3b. Parts of area 5 that should be more properly considered as area 2, and other parts that receive thalamic input not from the ventrobasal complex but from the lateral nuclear complex and anterior pulvinar, are also interconnected with area 4. More posterior parts of area 5 are connected with laterally placed parts of area 6. A more medial part of area 6, the supplementary motor area, occupies a pivotal position in the sensory-motor cortex, for it receives fibers from areas 3a, 4, 1, 2 and 5 (all parts), and projects back to areas 3a, 4 and 5.

Animals↗
PubMed1979

Significance of free-dorsiflexion of the toes in walking.

Dissection reveals that the ball of the foot contains a connective tissue framework with transverse, vertical, and sagittal fibers, all connecting the skin with the proximal phalanges of the toes. Dorsiflexion of the toes tightens the framework and thereby restricts passive movements of the skin, enabling shear forces to be transferred to the skeleton. An electromechanical oscillator was constructed that applied oscillatory shear forces of constant amplitude (+/- 0.2 N) to the skin and at the same time measured the resulting motions. It was found that the toes should be dorsiflexed by 35--40 degrees to restrict skin mobility to 50 per cent and by 50 degrees to restrict it maximally. The results were compared to actual dorsiflexions of toes during walking. These dorsiflexions were measured on slow motion film and with still pictures with light tracks formed by light emitting diodes. Maximal dorsiflexion during push off was found to be 60 degrees for feet walking without shoes, 45--50 degrees for feet walking in soft shoes, and 25--30 degrees for feet walking in a stiff shoe of the minus-heel type. Dorsiflexion was further found significant for arch support and for the mechanics of the forefoot during push-off.

Biomechanical Phenomena↗
PubMed1979

Laminar origins and terminations of cortical connections of the occipital lobe in the rhesus monkey.

Cortical connections within the occipital lobe (areas 17, 18 and 19) of the rhesus monkey are investigated with the autoradiographic and horseradish peroxidase procedures. Two efferent systems, each with a specific laminar organization, are observed. (1) Rostrally directed connections, from area 17 to 18, area 18 to 19 and area 19 to the inferotemporal region (area TE), originate from neurons in layer IIIc (and, in area 19, from a small complement of neurons in layer Va), and terminate in and around layer IV. (2) In contrast, connections in the reverse direction ('caudally directed' connections), from area TE to 19, area 19 to 18, and area 18 to 17, originate from neurons in layers Vb, VI and, to a lesser extent, IIIa, and terminate mainly in layer I. In addition, the laminar organization of several intrinsic and callosal connections are observed. In trinsic connections within areas 18 and 19 originate from neurons in layers IIIc and, to a lesser extent, Va, and terminate in vertical bands in layers I to IV. Callosal connections from areas 18, 19, and the caudal inferotemporal region originate from neurons mainly in layer IIIc. From areas 18 and 19, these callosal connections terminate in vertical bands in layers I through IV. Thus, different cortical projection systems are characterized by specific laminar distributions of efferent terminations as well as of their neurons of origin.

Animals↗
PubMed1979

Fucntional specialization and binocular interaction in the visual areas of rhesus monkey prestriate cortex.

If is is believed that neural mechanisms mediating stereoscopic vision may be localized in specific areas of the visual cortex, then it becomes necessary to be able to define these areas adequately. This is no easy matter in the rhesus monkey, an animal close to man, where the cytoarchitecturally uniform prestriate cortex is folded into deep sulci with secondary gyri. One way around this awkward problem is to use the callosal connections of the prestriate cortex as the anatomical landmarks. Callosal connections are restricted to regions at which the vertical meridian is represented. Since the visual fields, including the vertical meridian, are separately represented in each area, each has its own callosal connections. These are of great help in defining some of the boundaries of these areas, since the boundaries often coincide with the representation of the vertical meridian. With the visual areas thus defined anatomically, it becomes relatively easy to assign recordings to particular areas. Studies of binocular interactions in these areas reveal that most cells in all prestriate areas are binocularly driven. Hence, theoretically, all of the prestriate areas are candidates for stereoscopic mechanisms. The degree of binocular interaction varies from cell to cell. At the two extremes are cells which either respond to monocular stimulation only and are inhibited by binocular stimulation or ones which respond to binocular stimulation only. Changing, as opposed to fixed, disparity is signalled by two types of cells. In one category are cells activated in opposite directions for the two eyes. Such cells are always binocularly driven. In the other category are cells, some of which are monocularly activated, that are capable of responding to changing image size. In the monkey, both these categories of cells have so far been found in the motion area of the superior temporal sulcus only.

Animals↗
PubMed1978

The third visual complex of rhesus monkey prestriate cortex.

1. Two independent but neighbouring visual areas, V3 and V3A, sharing a common cytoarchitectural plan, but in each one of which the visual fields are separately represented, have been studied anatomically, functionally, and in combined anatomico-physiological experiments. 2. The properties of single cells in the two areas are so similar, judged by the techniques used in this study, that it is often impossible to tell whether any one penetration was sampling from cells in V3 or V3A. This is especially so if the cells have receptive fields in the lower hemi-quadrants, since the vertical meridian of the lower visual fields is represented along the V3-V3A boundary and since a transition from V3 to V3A along this border is not accompanied by a shift in receptive field positions of cells. 3. Since the visual fields, including the vertical meridian, are separately represented in these two areas, and since regions of vertical meridian representation are callosally connected, a simple and certain method of specifying the boundary between V3 and V3A is to examine the degeneration following section of the callosal splenium. A heavy patch of degeneration then marks the V3-V3A boundary. Within this patch, however, is a sub-patch containing fewer callosal fibres, or none at all. The boundary between V3 and V3A was taken to be at this subpatch. 4. Since the horizontal meridian is represented at the V2-V3 boundary, and since V1 projects to both these areas, sending coarse fibres to V3 and fine fibres to V2, it was found that the boundary between V2 and V3 could be precisely drawn by making a lesion in the horizontal meridian representation in V1 and noting where, in the prestriate cortex, fine fibres give way to coarse ones, without an intervening gap. 5. Double tracer anatomical experiments, in which tritiated proline was injected into V1 of animals whose callosal splenium had been sectioned, showed that whereas V3 receives a direct input from V1, V3A does not. V3A, instead, was found to receive an input from V3. Double tracer anatomical experiments were undertaken to study a possible input from V2 to V3A. Although such experiments did not reveal a direct input from V2 to V3A, they were not entirely conclusive. 6. The vast majority of cells in V3 and V3A were binocularly driven, without obvious monocular preferences. Some cells, however, though responding to stimulation of the individual eyes, summated their responses to binocular stimulation. Others responded only when both eyes were simulataneously stimulated. In any oblique penetration, cells preferring binocular stimulation only occurred either singly or in groups. 7. In an oblique penetration, the shift from a cell responding to binocular stimulation only to one responding equally well to stimulation of either eye was not necessarily accompanied by a shift in orientational preferences, shifts in the former...

Animals↗
PubMed1978

New apparatus for exercising a monkey seated in a primate chair.

A new apparatus and method for exercising a monkey seated in a primate chair are described. The apparatus consists of a set of hand and foot bars mounted at either end of a rocker arm that pivots in a vertical plane. This arm is connected by a steel cable to a wooden box that houses lead weights. By simultaneously pushing the foot bar and pulling the hand bar, the monkey lifts a weight and triggers a microswitch which releases a banana-flavored food pellet into a well close to the animal's mouth. The amount of work performed is varied by changing the a) amount of weight to be lifted, b) distance the weight must be lifted, or c) number of times that the animal lifts the weight for a single reward. During 30 min of exercise, the heart rate of a given monkey rose 120 beats/min, respiratory rate 24/min, and colonic temperature 1.2 degrees C above base-line values. Total work performed in 30 min varied from 250 to 360 kpm. Major advantages of this apparatus over a treadmill or bicycle ergometer are that the animal 1) is restrained sufficiently to permit the delicate experimental manipulations and physiological measurements, 2) can be exercised strenuously in a quantitative fashion, and 3) is readily trained to perform the task in a short time.

Animals↗
PubMed1977

[Studies on the halfside comparison of heterotopic transplantation of mucosa with and without epithelium].

In patients with symmetric recessions in their canine and premolar regions, one side was supplied with an epithelium-containing and the other with an epithelium-free graft from the hard palate. Both sides were studied and compared. After six months, the size of the connective tissue transplants was reduced by 50% (that of the epithelium transplants by 0%). Within half a year, the width of the attached gingiva had decreased by 36% in the case of connective tissue transplants (epithelium transplants by 15%) and the vertical graft width by 60% (epithelium transpltnas 17%). Our clinical and histological findings suggest that grafting of heterotopic connective tissue transplants is not equal to epithelium-containing transplants.

Adolescent↗
PubMed1979

[Pathology of the bone pocket].

Inflammatory periodontal destruction includes periodontal bone destruction. In addition to etiologic factors which contribute to the formation of gingival pockets, cell-mediated immune reactions apparently play a special role in osteoclastic processes. Apart from coincidental events, the form of osteoclasia is influenced in the beginning by the form and position of the tooth. Vertical osteoclasia, a variant form, is more frequently observed in connection with juvenile periodontitis. Occlusal periodontal trauma and general primary diseases may possibly also influence the pattern of periodontal bone destruction.

Bacterial Toxins↗
PubMed1979

Vestibular mechanisms.

It is apparent from this and other reviews of the subject that our knowledge of vestibular function is most complete for the primary canal and otolithic afferents. Relatively little progress has been made in the understanding of receptor mechanisms and the functional importance of the efferent vestibular system. Since most of it has been summarized previously the latter were not considered here. Considerably more knowledge has accumulated in the field of central vestibular mechanisms, particularly those related to eye movements. Recent advances in functional synaptology of direct and indirect vestibuloocular pathways are described. It appears that the indirect pathways are essential for the central integration of the peripheral head velocity into a central eye position signal. Candidates for the neural integrator are presented and discussed and their connectivity described both for the horizontal and the relatively poorly studied vertical eye movement system. This field will certainly be studied extensively during the next years. Another interesting field is the role of the cerebellum in the control the vestibuloocular reflex. Recent data and hypotheses, including the problem of cerebellar plasticity, are summarized and evaluated. That the vestibular nuclei are by no means a simple relay system for specific vestibular signals destined for other sensory or motor centers is evidenced in this review by the description of multiple canal-canal, canalotolith, and visual-vestibular convergence at the nuclear level. Canal-otolith and polysensory convergence in vestibular neurons enables them to correct for the inherent inadequacies of the peripheral canal system in the low frequency range. The mechanisms of polysensory interaction in the central vestibular system will undoubtedly be an important and interesting field for future research.

Abducens Nerve↗
PubMedDate not supplied

[Degree of homogeneity of the forms of statistical relationship between the EEG and spike currents of neurons].

The correlation between the spike activity and the waves of surface ECoG was studied in the visual and motor cortex of alert non-immobilized rabbits. A comparison was made between the forms of the obtained correlation functions for the cells with different horizontal and vertical distances between them. The analysis revealed the similarity of such functions in neurones of V-VI cortical layers, situated vertically under each other along the microelectrode track. Similar in form statistic connections between the ECoG and the background spike activity were also found, beginning with the depth of 1.000 mc, in the neurones situated at the same horizontal cortical level; however, with the increased distance between the cells the degree of similarity of these connections decreases in a non-linear way. On the basis of the obtained data a conclusion is made that the tangential sizes of the background functional ensembles of the cortical neurones are within the range of 140-300 mc.

Animals↗
PubMed1977

Anomalous pulmonary venous connection of entire left lung with intact atrial septum.

Three cases of total unilateral pulmonary venous connection of the left lung with intact atrial septum are described. All patients were acyanotic and had findings of volume overload of the right side of the heart. An anomalous vertical vein in the superior mediastinum and large pulmonary arteries were visible on the plain chest radiograph, similar to what is seen in cases of total anomalous pulmonary venous connection. Selective pulmonary angiography delineated the anomalous connection of the left pulmonary veins and documented the absence of an atrial septal defect.

Adult↗
PubMed1978

The teratogenic effects of 5-fluoro-2-desoxyuridine (F.U.D.R.) on the Wistar rat fetus with particular reference to cleft palate.

The teratogenic effects of 5-fluoro-2-desoxyuridine on Wistar rat fetuses were studied macroscopically, microscopically and ultrastructurally. In no case did palatal shelf elevation occur, and a palatal shelf elevating force could not be demonstrated in freshly-removed fetuses. The shelves, like the connective tissues generally, showed clear evidence of depressed mucopolysaccharide synthesis. The shelves eventually ossified in the vertical position, and in some cases their free edges fused with the lateral wall of the oral cavity (palato-oral fusion). The results were consistent with the mucopolysaccharide-turgor hypothesis advanced by the author in a previous paper to account for normal shelf elevation. Phocomelia, brain and limb bud haemorrhages, gross subcutaneous oedema, hyperextension of the cranial base, fused vertebrae, detached epithelia, bizarre brain abnormalities (including some remarkable attempts at neural reconstitution) and growth and ossification of the mandible in the virtual absence of Meckel's cartilages were also noted in these fetuses.

Abnormalities, Drug-Induced↗
PubMed1979

Anatomy of musculus levator veli palatini in the 15-week human fetus.

The morphology of musculus levator veli palatini in the 15-week fetus was analyzed using 30-micrometer subserial sections. The sample included 26 specimens, of which 9 each were sectioned coronally and sagittally while 8 were sectioned in the transverse plane. At this stage of development m. levator veli palatini takes a general attachment to the precursor of the petrous part of the temporal bone, and, in some cases, auxiliary attachments to the auditory tube complex were also observed. At its origin, the muscle is located anterior to the tube. It then runs medially, passing beneath the auditory tube prior to entering the velum. As it nears the region of the lateral pharyngeal wall, a small fascicle trails posteriorly and inferiorly to the main muscle mass and occasionally runs into the upper margin of m. constrictor pharyngis superior. The levator muscle is more localized within the velum at this stage of development than it has been reported to be in the adult, being confined here to the central third of the soft palate. Most of the fibers of the muscle appear to form a sling within the central 20% of the velum, although some were seen to take attachment to loose connective tissue and the palatine raphe. Upon its entry into the velum, m. levator veli palatini is intersected vertically by bundles of both mm. palatoglossus and palatopharyngeus.

Female↗
PubMed1976

[Vertical vergence pathways].

Two pathways for vertical vergence probably exist: the cortical one carrying a psycho-optical reflex, the other sub-cortical connected to the vestibular apparatus and more probably to the otolith system. The sub-cortical pathway is essentially a vestibulo-cerebellar oculomotor pathway; but in addition there certainly exist direct vestibulo-oculomotor connections and long tracts passing through the interstitial nucleus of Cajal and the reticular formation.

Afferent Pathways↗
PubMed1975

Variability of dermal elastin visualized ultrastructurally with iron hematoxylin.

The Verhoeff iron hematoxylin-lead citrate (VIH-LC) method demonstrated vertical elastic fibers that were often composed only of microfibrillar component extending into the epidermal basement membrane in human skin. These fibers connected with a network of trabeculae composed of microfibrils and elastin fibrils in varying proportions. The large elastic fibers in the deep two thirds of the dermis consited mainly of compact bundles of small elstin fibrils in infants and of solid elastin cores with a fimbriated periphery in adults; Dermis of a 6-month-old fetus contained very few small elastic fibrils except around blood vessels. Skin of an elderly subject revealed exteme proliferation of unusual reticulated elastic fibers in various areas and disclosed abnormal nodules of elastin or collagen fibrils in finely particulate matter. Small elastin fibrils, abundant microfibrils, and intermixed individual collagen fibrils comprised an adventitial collar between sweat glands and fibroblasts. Elastin fibrils were absent from this collar in the fetus and increased with the subject's age. A permanganate-high iron diamine sequence appeared to impart density to the microfibrillar component of elastic fibers.

Adolescent↗
PubMed1979

A Golgi study of the ventral tegmental area of Tsai and interfascicular nucleus in the rat.

The ventral tegmental area of Tsai (VTA) and interfascicular nucleus of the adult rat brain has been studied with two variants of the Golgi method in three planes of section. Neurons were studied in relation to the cytoarchitectural groupings of the VTA. Dendritic organisation and dendritic fields were mapped out for each cytoarchitectural subgroup and cell types within each subgroup were classified on the basis of cell size and dendritic morphology. In each subnucleus of VTA, neurons had distinct characteristics. In nucleus paranigralis neurons were small to medium in size and their dendritic fields organised in an approximately horizontal plane orientated in an anteromedial direction and slanting dorsally over the interpeduncular nucleus and fossa. Neurons of the parabrachial group were small to medium sized with no preferential orientation. In nucleus linearis raphe caudalis small neurons were strongly orientated in the plane of the nucleus in a dorso-ventral direction slanting forwards. Neurons in the interfascicular group were small to very small and their maximum dendritic extents were seen in the horizontal plane. In frontal section they formed a compact ball of cells in the midline and were separated on either side from the larger neurons in the medial edge of nucleus paranigralis. In general VTA neurons tended to fall into one of two morphological categories. Type 1 were small to medium, and had two to four primary dendrites which divided into varicose secondary dendrites. Type 2 were medium sized, with two to five primary dendrites. Both primary and secondary dendrites and the cell soma of Type 2 neurons were moderately spiny. Secondary dendrites were not varicose. Forms also occurred which were intermediate between Types 1 and 2. In the nucleus paranigralis, Type 1 was more common medially, while Type 2 was more common laterally, particularly in the ventrolateral paranigral region. Only neurons of Type 1 were seen in nucleus linearis raphe and interfascicular nuclei. Local axon circuits were observed to arise from the primary dendrites of Type 1 neurons and to ramify close to neighbouring neurons. Axon swellings from such circuits were observed to make apparent contact with primary dendrites of nearby neurons and clusters of axon swellings were observed near cell somas of neighbouring impregnated neurons of similar type. The results are discussed and particular attention is paid to the similarities and differences between VTA and the substantia nigra pars compacts (SNC). The major difference appears to be that, whereas in SNC dendrites are organised in vertical as well as horizontal planes, in the VTA no long ventrally directed dendrites were observed. Combining these results with known cytoarchitecture and connections of VTA and SNC, it appears that fundamental differences occur between VTA and some neurons of the SNC, both in the nature of their morphology and intrinsic organisation, and in the organisation of their efferent and afferent connections.

Animals↗