Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Projection”

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 1,243 records · Page 69Linked to original sources
PubMed2001

Ontogeny of modulatory inputs to motor networks: early established projection and progressive neurotransmitter acquisition.

Modulatory information plays a key role in the expression and the ontogeny of motor networks. Many developmental studies suggest that the acquisition of adult properties by immature networks involves their progressive innervation by modulatory input neurons. Using the stomatogastric nervous system of the European lobster Homarus gammarus, we show that contrary to this assumption, the known population of projection neurons to motor networks, as revealed by retrograde dye migration, is established early in embryonic development. Moreover, these neurons display a large heterogeneity in the chronology of acquisition of their full adult neurotransmitter phenotype. We performed retrograde dye migration to compare the neuronal population projecting to motor networks located in the stomatogastric ganglion in the embryo and adult. We show that this neuronal population is quantitatively established at developmental stage 65%, and each identified projection neuron displays the same axon projection pattern in the adult and the embryo. We then combined retrograde dye migration with FLRFamide-like, histamine, and GABA immunocytochemistry to characterize the chronology of neurotransmitter expression in individual identified projection neurons. We show that this early established population of projection neurons gradually acquires its neurotransmitter phenotype complement. This study indicates that (1) the basic architecture of the known population of projection inputs to a target network is established early in development and (2) ontogenetic plasticity may depend on changes in neurotransmitter phenotype expression within preexisting neurons rather than in the addition of new projection neurons or fibers.

Animals↗
PubMed2001

Searching excellence in project management.

A main outcome of this paper is supposed to be a model of an effective management of projects in specific conditions of foreign aid programmes funded by the European Union. It was decided to fund three basic projects focused on the Health Care Financing, Health Management and Privatisation. All these projects were completed by the end of 2000 with a different level of success. Different projects' results were achieved in dependence on both the internal management system and external factors. Based on a theory examined, empirical, practical and evidence-based experience from the above projects the paper discusses particularly those aspects of project management that may influence a successful implementation of projects and may lead to the excellence in managing projects. (Ref. 25.)

Efficiency, Organizational↗
PubMed2003

Ultrasonographic projection of a pathologic site on the anterior abdominal wall. Our own experience.

INTRODUCTION: The success of any operation depends to a great extent on how well the optimal surgical approach is chosen. The purpose of the present study was to propose a method of sonographic projection of an abdominal pathologic site on the anterior abdominal wall which can facilitate the selection of an optimal surgical approach. MATERIAL AND METHODS: The study included 26 patients aged 20 to 65 years operated on in the Clinic of Thoracic and Abdominal Surgery in the Medical University, Plovdiv between January 1996 and December 2001. Using ultrasonography we projected a pathologic site located in the abdomen on the anterior abdominal wall. A strip of adhesive band was placed on the scanning surface of a 3.5 MHz linear transducer to cast an acoustic shadow and thus draw the outlines of the site on to the anterior abdominal wall. RESULTS: Patients with liver hydatid cysts (primary and recurrent) and with recurrent calculous cholecystitis were predominant (20/26, 76.9%). The surgical approach in the cases of primary liver hydatid cysts was in the right hypochondriac region; after laparotomy it was extended in both directions. In the patients with recurrent liver hydatid cysts (6/26, 23.07%) the incision was made on the projected image, directly over the site; it was less traumatic and associated with less blood loss. In eight patients with chronic calculous cholecystitis (30.7%) the projection was used for minilaparotomy (up to 6 cm); in two patients the projection suggested that we should use the transrectal approach as optimal instead of the subcostal approach. The right subcostal approach was used in one patient with chronic calculous cholecystitis and retroperitoneal cyst instead of median laparotomy. In patients with retroperitoneal tumours and intra-abdominal non-organ echinococcosis the projection had confirmatory character. According to the review of the literature we made, such sonographic projection of pathologic sites on the anterior front wall for the purpose of selecting an optimal surgical approach has been done for the first time. CONCLUSIONS: 1. The sonographic projection of a pathologic site located in the abdomen on the anterior abdominal wall creates a direct visual association between intra-abdominal lesions and superficial structures (body constitution, subcutaneous fat, operative cicatrices). 2. This direct visual association, as well as the information provided about the depth, size and relation to adjacent organs helps the surgeon to choose the most appropriate surgical approach.

Abdomen↗
PubMed1992

The retinal distribution of ganglion cells with crossed and uncrossed projections and the visual field representation in the opossum.

The retinal distribution of ganglion cells with crossed and uncrossed projections in the South American opossum, Didelphis marsupialis, was revealed by delivering HRP to one optic tract or to retinal targets of one hemisphere. The cells with uncrossed projections are restricted to the temporal retina, comprising 1/3 of the total retinal area, with a sharp transition at the naso-temporal boundary. Besides being distributed over the nasal 2/3 of the retina, cells with crossed projections are intermingled with those with uncrossed projections over the entire temporal retina. Quantitative analysis about the representation of the horizontal meridian on four specimens revealed that the maximum density of cells with uncrossed projections is on the average located at 3.2 mm (SD = 0.21), i.e. 34.8 deg, temporal to the optic disk, falling to 10% at 2.1 mm (SD = 0.14) or 22.8 deg. On the other hand, the peak for cells with crossed projections is more nasally placed at 1.8 mm (SD = 0.18), i.e. 19.6 deg. Between these two maxima, the site wherein the densities of cells with crossed and uncrossed projections are about equal is on the average about 2.7 mm (SD = 0.25) form the optic disk, i.e. 29.3 deg. This estimate supports the hypothesis that the retinal intersection of the vertical meridian lies within the region of split representation of crossed and uncrossed ganglion cells. In addition, it was observed that the opossum's retina has a large contingent of cells with uncrossed projections temporal to an eccentricity of 2.7 mm from the optic disk, where it represents roughly 2/3 of the ganglion cells. These data corroborate the relevance of the opossum as a non-primate model for visual work.

Animals↗
PubMed2003

Detection of gaps in the spatial coverage of coral reef monitoring projects in the US Caribbean and Gulf of Mexico.

As part of the US Coral Reef Task Force's National Program to Map, Assess, Inventory, and Monitor US Coral Reef Ecosystems, a comprehensive survey of projects/programs monitoring coral reef ecosystems and related habitats (i.e., seagrass beds and mangroves) in the US Caribbean and Pacific was undertaken. Information was gathered on a total of 296 monitoring and assessment projects conducted since 1990 in the US Caribbean and the Gulf of Mexico. Substantial gaps in monitoring coverage of US coral reef ecosystems were revealed through geographic information system (GIS) analysis of survey metadata. Although southern Florida contains approximately two-thirds of all marine monitoring projects found in the US Caribbean and Gulf of Mexico, we were unable to identify any ongoing projects that monitor coral reefs along Florida's western coast and off of the Florida Middle Grounds. Additionally, Florida is covered by approximately 1 900 km2 of mangroves, yet there were only four ongoing projects that monitor this ecosystem, leaving gaps in coverage in the Lower and Middle Keys and along the eastern and western coasts. The Flower Garden Banks National Marine Sanctuary, located offshore of the Texas/Louisiana border, has an integral long-term monitoring program, but lacks a monitoring project that gathers long-term, quantitative data on reef lish abundance and certain water quality parameters. Numerous coral reef monitoring projects in Puerto Rico are concentrated on the island's southwestern coast surrounding La Parguera, while far fewer monitoring projects are conducted along the northern and southeastern coasts and around Vieques Island. In the US Virgin Islands, the paucity of monitoring projects in large areas of St. Croix and St. Thomas contrasts with monitoring activity in three marine protected areas (MPAs), where 66% of the US Virgin Islands' coral reef monitoring sites were found. Only a series of assessments have been conducted at Navassa, a small, uninhabited island located 55 km west of Haiti and 137 km northeast of Jamaica. In order to better understand changes in coral reef communities and to produce a series of biennial reports on the status of US coral reef ecosystems, the National Oceanic and Atmospheric Administration (NOAA) is developing a national coral reef monitoring network. This network has already begun to fill some of these gaps in monitoring coverage through issuing cooperative grants to states and territories to build long-term monitoring capacity.

Animals↗
PubMed2006

[Eco-value level classification model of forest ecosystem based on modified projection pursuit technique].

To optimize the projection function and direction of projection pursuit technique, predigest its realization process, and overcome the shortcomings in long time calculation and in the difficulty of optimizing projection direction and computer programming, this paper presented a modified simplex method (MSM), and based on it, brought forward the eco-value level classification model (EVLCM) of forest ecosystem, which could integrate the multidimensional classification index into one-dimensional projection value, with high projection value denoting high ecosystem services value. Examples of forest ecosystem could be reasonably classified by the new model according to their projection value, suggesting that EVLCM driven directly by samples data of forest ecosystem was simple and feasible, applicable, and maneuverable. The calculating time and value of projection function were 34% and 143% of those with the traditional projection pursuit technique, respectively. This model could be applied extensively to classify and estimate all kinds of non-linear and multidimensional data in ecology, biology, and regional sustainable development.

Ecosystem↗
PubMed1991

Intraluminal projection of descending thoracic aorta and intraaortic balloon pump catheter examined by transesophageal echocardiography in patients undergoing coronary artery bypass surgery.

The thoracic descending aorta (DTA) was examined in 57 patients undergoing coronary artery bypass grafting (41 men and 16 women: 63.0 +/- 10.6 years old) using two-dimensional transesophageal echocardiography. An intraaortic balloon pump (IABP) was instituted in ten patients. A short-axis view of DTA was examined for intraluminal projection from the diaphragm level to the aortic arch level. In a frozen-frame image, the area and the height of the projection at each clockwise direction was measured. Four patients with preoperative insertion of an IABP catheter were excluded from the analysis. Seventy projections were found in 40 of 53 patients (75.5%), most frequently found at the 3 to 6 o'clock position. The tip of the IABP catheter was also located in the area between 3 and 6 o'clock of the aortic lumen in 6 of 10 patients. In one case, the area of projection was reduced from 1.1 cm2 to 0.7 cm2. In two of four patients with preoperative institution of an IABP catheter, projections were found near the catheter tip. Both intraluminal projections and IABP catheter tip were most commonly located in the same region of the DTA, suggesting a possible dislodging of the projection while advancing the catheter. This was demonstrated in one case. The catheter tip may damage the aortic intima and/or cause a formation of abnormal projection. We conclude that intraoperative examination of DTA in addition to routine monitoring can provide useful information which is helpful for minimizing complications at the time of insertion of an IABP catheter.

Aged↗
PubMed1990

Alternative projections of the U.S. population.

The U.S. Bureau of the Census recently released a set of population projections that include middle and high projections that we argue are too conservative. The projections discount the possibility of future baby booms and assume slow rates of mortality decline and low levels of immigration. In this article we explore the impact on the size and age composition of the U.S. population of alternative scenarios of plausible fertility, mortality, and immigration assumptions. We conclude that (1) the Census Bureau's highest projection might be interpreted as a reasonable middle projection, (2) a reasonable high projection would yield a U.S. population in 2080 some 300 million persons larger than the Bureau's highest projection, with the population 85 and older more than twice the Bureau's greatest estimate, and (3) uncertainty about the pace of population growth is substantially greater than the Bureau's projections suggest.

Age Factors↗
PubMed1989

[Organization of the projections of the cortex of the sulcus cruciatus to the centromedian and parafascicular nuclei in cats].

In order to study the HRP retrograde axonal transport, injections of horseradish peroxidase (HRP) were made in the centromedian and parafascicular nuclei of the cat. The centromedian nucleus receives more cortical projections than the parafascicular nucleus. After centromedian and parafascicular nuclei injections, retrograde labeling was more abundant in the ventral bank of the cruciate sulcus than in its dorsal bank. Area 4 projects preferentially to the centromedian nucleus. These projections arise mainly in sector gamma of area 4. Projections from area 6 a beta to the centromedian and parafascicular nuclei are slightly more numerous than those arising in 6 a alpha. Projections from the sectors of motor and premotor areas located in the depth of the cruciate sulcus are scanty. These projections, however, are mainly directed to the centromedian nucleus and the lateral portions of the parafascicular nucleus. Cortical neurons projecting to centromedian and parafascicular nuclei are mainly situated in the superficial and intermediate sublayers of layer V. Only scarce projections arise from neurons located in layer VI.

Animals↗
PubMed1989

[Hippocampus-cerebellar cortex-cerebellar nuclei projection in the rat: electrophysiological and HRP studies].

The spatial distribution of the hippocampus-cerebellar projection and the connection between the projection area of hippocampus in the cerebellum and cerebellar nuclei were studied by means of electrophysiological and HRP labelling techniques. Polysynaptic responses of Purkinje cell's simple and complex spike in the lobule VI could be evoked by stimulation of the area CA1/CA3 of the dorsal hippocampus. These results suggest that there are polysynaptic projections from CA1 and CA3 areas of dorsal hippocampus to the lobule VI of cerebellar cortex, and the last relay fibers for these projections are mossy fiber and/or climbing fiber. It is also shown that this hippocampus-cerebellar projection predominantly terminates at the lobule VI of cerebellar cortex, 0.8-1.4 mm lateral to the midline. The projection from CA1 area is mainly contralateral, whereas the projection from CA3 area is mainly ipsilateral. The results with HRP labelling indicate that the projection area of hippocampus is an interpositus zone of the lobule VI. Reciprocal connections may exist between this cortical area and the interpositus nucleus.

Animals↗
PubMed1985

Development of the ipsilateral retinothalamic projection in the frog Xenopus laevis. III. The role of thyroxine.

The ipsilateral retinothalamic projection in Xenopus laevis normally first appears at about stage 54, at a time when a number of other changes known to be dependent on a rise in circulating levels of thyroxine begin to occur. We have investigated the role of thyroxine in the development of the ipsilateral retinothalamic projection by studying retinal projections and patterns of retinal histogenesis in tadpoles whose ability to produce thyroxine was blocked by treatment with propylthiouracil (PTU), and in similar tadpoles in which thyroxine was restored by injection of small amounts of thyroxine into one eye. PTU-reared tadpoles continue to grow and to add neurons to the retina in a symmetric pattern like that of normal tadpoles at early developmental stages. The PTU-reared tadpoles remained by external criteria at stage 54. Like normal stage 54 tadpoles, the PTU-reared tadpoles either lacked an ipsilateral projection entirely or had an extremely sparse projection. Injection of thyroxine into one eye of PTU-reared tadpoles resulted in the production of substantial ipsilateral projections from the treated eyes as well as shifts to the asymmetric pattern of retinal cell addition which normally begins after stage 54. Such changes were much more prominent in hormone-treated than in untreated eyes, suggesting that they are caused by local action of thyroxine on the treated eyes. With low doses, thyroxine-induced effects on the development of the ipsilateral projection and on retinal histogenesis were restricted to the treated eye. These results suggest that the presence of thyroxine in one eye alone is sufficient to cause the development of the ipsilateral projection.

Animals↗
PubMed1986

Topographic targeting errors in the retinocollicular projection and their elimination by selective ganglion cell death.

In adult rats, as in other rodents, the retinocollicular projection is topographically organized in a very precise manner. Experiments involving the use of the retrogradely transported fluorescent dye fast blue as either a short- or long-term marker in neonatal rats indicate that the precision of this retinotopic projection does not arise ab initio, but rather is brought about by the preferential elimination of those ganglion cells whose axons project to topographically inappropriate regions of the colliculus. Such topographic targeting errors have been identified along both the rostrocaudal and mediolateral axes of the colliculus, and their elimination occurs during the period of naturally occurring ganglion cell death, which is completed by about postnatal day 10. When impulse activity in the retinal ganglion cell axons is blocked by repeated intraocular injections of the sodium channel-blocking agent tetrodotoxin (TTX) throughout the postnatal period of ganglion cell death, the preferential loss of the incorrectly projecting ganglion cells does not occur in the activity-blocked eye, although, as reported elsewhere, the overall loss of ganglion cells is comparable to that seen in normal animals. This supports the notion that the mechanism for selecting against incorrectly projecting ganglion cells is based on impulse activity among the competing ganglion cell axons. However, under activity-block conditions, the aberrantly projecting axons appear to retract from the caudal margin of the colliculus. The death of retinal ganglion cells during development thus seems to serve 2 purposes: It provides for the quantitative matching of the ganglion cell population to the needs of its central projection fields, and, at the same time, it serves to selectively eliminate those cells whose axons project to inappropriate targets or to inappropriate regions within the correct target fields.

Amidines↗
PubMed1985

Telencephalic afferent projections from the diencephalon and brainstem in the pigeon. A retrograde multiple-label fluorescent study.

The sites of origin of ascending projections to the telencephalon in the pigeon (Columba livia) were studied by means of the retrograde fluorescence technique following the injection of various tracers (Evans Blue, Fast Blue, Nuclear Yellow) concomitantly into different regions of topographically distinct areas of one hemisphere: hyperstriatum (HY), ectostriatum-paleostriatum (EP), posterior neostriatum (PN). The distribution of retrograde neuronal labeling observed within diencephalic and midbrain structures revealed systems providing unique projections to either a single or a multiple combination of the different telencephalic sites sampled. Single projections to HY arise from numerous dorsal thalamic nuclei including: ipsilaterally-dorsolateralis anterior pars medialis, dorsointermedius posterior, dorsomedialis anterior and posterior and bilaterally-dorsolateralis anterior and superficialis parvocellularis. Single ipsilateral projections upon either the ectostriatum or the caudal neostriatum arise from the nucleus (n.) rotundus/n. triangularis complex and the n. ovoidalis respectively. Multiple ipsilateral afferents to both HY and the neostriatum intermedium stem from rostral and caudal portions of the n. dorsolateralis posterior respectively, whereas the n. subrotundus projects to all of the telencephalic sites examined. Within midbrain/caudal brainstem regions, the area ventralis-Tsai sends afferents to HY and EP and multiple projections upon the latter in addition to the PN site originate in ipsilateral: zona perinervus oculomotorius, the lateral and medial mesencephalic reticular formation, n. tegmenti pedunculo-pontinus pars compacta and bilateral: zona peri-fasciculus longitudinalis medialis, substantia grisea centralis, n. locus coeruleus, n. annularis, n. linearis caudalis. In the case of the latter structures, the multiple-label procedure also made it possible to demonstrate differential distributions of the component populations of neurons whose axons terminate within distinct telencephalic sites and those which display multiple projections via collateral axon branching. Various neuronal systems projecting to the avian telencephalon are compared to those of other vertebrates and possible homologies in telencephalic afferent organization are discussed.

Afferent Pathways↗
PubMed1980

Retinal projections in lamprey (Lampetra fluviatilis).

Visual projections in lamprey were investigated using two methods,--one by revealing transport of horseradish peroxidase, and the other by silver impregnation of degenerating axons and terminals after enucleation of the eye. Both methods produced similar results. The chiasm showed incomplete crossing of retinal fibres, the major part of which, as an optic tract, proceed along the contralateral thalamus up to the entry into the optic tectum, while the smaller part takes the same course on the ipsilateral side. Besides, from the posterior part of the optic chiasm an axial optic tract branches off, which proceeds through the central part of the contralateral thalamus up to the pretectal nucleus, individual fibres of which enter the central grey layer of the optic tectum. On the contralateral side, the visual projections are localized in the lateral geniculate body, pretectal nucleus, in the three upper layers of the optic tectum, in the ventrolateral area of the optic tectum and as solitary diffuse projections in the mesencephalic tegmentum. Innervation of thalamic and pretectal nuclei are realized by two tracts--the tractus opticus proper, and tractus opticus axialis. On the ipsilateral side visual projections, excepting the optic tract, are scarce and in the thalamus appear as small areas of the lateral geniculate body and pretectum adjacent to the optic tract. Solitary visual projections were found in two upper layers of the rostral optic tectum and in larger numbers in the 3rd and 4th layers of the caudal part and in ventrolateral area of the optic tectum. Projections in mesencephalic tegmentum were single. Diffuse visual projections in the lateral part of hypothalamus could be revealed only by the silver impregnation method. Using the peroxidase method two types of cells were observed in mesencephalic tegmentum where, possibly, the centrifugal fibres proceeding to retina, originate. A comparison is made of central visual projections in lampreys and other representatives of nonmammalian vertebrates.

Animals↗
PubMed1983

Intrinsic organization of the cat's medial geniculate body identified by projections to binaural response-specific bands in the primary auditory cortex.

The area of the cat's primary auditory cortex (AI) within which high frequency sounds are represented can be subdivided using functional criteria. Within each subdivision, or "binaural interaction band," all recorded neurons display similar responses to binaural stimulation. The current study distinguishes the thalamic sources of input to these subdivisions of AI and characterizes the topography within the thalamic projection to each class of bands. The borders of binaural bands in AI were mapped using microelectrode recording with diotic tonal stimulation, then injections of one to three retrograde tracers were introduced into identified bands. Within the ventral division (V) of the medial geniculate body (the major thalamic source of input to AI), the neuronal populations that projected to different classes of binaural bands were strictly segregated from each other. This segregation of class-specific thalamic sources constitutes a laminar organization within an axis of V that is orthogonal to the previously described tonotopic organization. Excitatory/excitatory (EE) binaural neurons in AI were found to be segregated from excitatory/inhibitory (EI) neurons in alternating "bands." We consistently identified: (1) a ventral pair of rostrocaudally continuous EI and EE bands, (2) a middle area within which the pattern of binaural subdivisions was more variable and within which bands often were discontinuous rostrocaudally, and (3) a dorsal zone (DZ) within which the responses of neurons differed in binaural properties and in frequency specificity from the response patterns that were characteristic of neurons elsewhere in AI. Each EI band apparently derived input that converged from three thickened laminae of cells in V that were oriented approximately horizontally. The most ventral of these laminae encompassed the ovoidal part of V (Vo), suggesting that EI bands are the only recipients in AI of a projection from Vo. All of the EE bands and DZ derived their input from a single continuous structure which included the dorsal two-thirds of the rostral pole of V and a horizontal lamina interposed between the two dorsalmost EI-projecting laminae. Restricted portions of the complex EE-projecting structure in V projected preferentially to particular EE subdivisions of AI. The V-to-AI thalamocortical topography exhibited a high degree of convergence and divergence within the projections to each cortical binaural band and within the projections to each class of bands. These observations indicate that the high frequency representation in AI and its principal thalamic source of input, the ventral division of the medial geniculate body, may be thought of as assemblies of spatially discrete, functionally distinguishable subunits. The significance of this intrinsic organization is discussed in regard to the requirements for analysis of sound stimuli.

Animals↗
PubMed1983

Observations on the projection from the perihypoglossal nuclei onto the cerebellum in the macaque monkey.

The occurrence and distribution of retrogradely labeled cells in the perihypoglossal nuclei of the monkey were mapped after injections of horseradish peroxidase in various cerebellar cortical regions. In general the findings are in accord with those made in the cat. The flocculus receives a heavy bilateral projection from the nucleus prepositus, particularly from its caudoventral part, and from the nucleus of Roller. There is an apparently scanty projection from the nucleus intercalatus. The uvula receives a rather similar projection, but in the prepositus the cells projecting to the uvula are on the whole situated more dorsally and rostrally than those supplying the flocculus. The projection to lobules VII-VIII is distinct. More scanty projections have been found to the paramedian lobule and the anterior lobe. The different but partially overlapping sites of origin in the prepositus of fibers to the flocculus and uvula indicate the presence of a topical pattern within the perihypoglosso-cerebellar projection, as in the cat (34). In the monkey the two regions of origin appear to coincide with two particular cell collections in the prepositus (12). Both small and middle sized cells project to the cerebellum, as they do in the cat (9, 48). The nucleus supragenualis nervi facialis in the macaque is morphologically different from the corresponding nucleus in most other mammalian species (12), but it contains labeled cells after injections in the flocculus, uvula and other cerebellar regions. A considerable number of cells in the abducent nucleus are labeled after injections in the flocculus and the posterior vermis.

Animals↗
PubMed1981

Spreading of hemiretinal projections in the ipsilateral tectum following unilateral enucleation: a study of optic nerve regeneration in Xenopus with one compound eye.

Right compound eyes were formed in Xenopus embryos at stages 32-33 by the fusion of two nasal (NN), two ventral (VV) or two temporal (TT) halves. Shortly after metamorphosis the optic nerve from the compound eye was sectioned and the left intact eye removed. The retinotectal projections from the compound eye to the contralateral and ipsilateral tecta were studied by [3H]proline autoradiography and electrophysiological mapping between 6 weeks and 5 months after the postmetamorphic surgery. The results showed that NN and VV eyes projected to the entire extent of both tecta. In contrast, optic fibre projection from TT eyes, although more extensive than the normal temporal hemiretinal projection, failed to cover the caudomedial portion of the tecta. The visuotectal projections in all three combinations corresponded to typical reduplicated maps to be expected from such compound eyes, where each of the hemiretinae projected across the contralateral and ipsilateral tecta in an overlapping fashion. The rapid expansion of the hemiretinal projections of the compound eyes in the ipsilateral tectum following the removal of the resident optic fibre projection suggests that tectal markers may be carried and deployed by the incoming optic fibres themselves.

Action Potentials↗
PubMed1981

Cerebellar projections to the superior colliculus in the cat.

The projections from the cerebellar nuclei to the superior colliculus of the cat have been studied by injecting small amounts of horseradish peroxidase into the colliculus and charting the distribution of the labeled neurons in the cerebellar nuclei. The results show that the cerebellar nuclei project to the deep layers of the superior colliculus, especially contralaterally. Of the deep cerebellar nuclei, the lateral sends the most conspicuous projection to the superior colliculus. This projections is topographically organized in a rostrocaudal sense, ending principally in the intermediate layers, and is most dense in the rostral half of the contralateral superior colliculus. The lateral nucleus also projects to the rostral part of the ipsilateral superior colliculus. The nucleus interpositus anterior projects to the rostromedial part of the stratum griseum intermedium of the contralateral colliculus. The caudal pole of the fastigial nucleus projects to the strata grisea intermedium and profundum, mainly to the latter and specifically in the caudal half of both superior colliculi. These results demonstrate that, apart from the possible existence of direct cerebellar connections to the oculomotor nuclei, the visual cerebellum modulates, through monosynaptic projections, the activity of the deep layers of the superior colliculus which is related directly to the regulation of the eye- and head-orienting movements.

Afferent Pathways↗