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 577 records · Page 32Linked to original sources
PubMed2005

Successful healthcare programs and projects: organization portfolio management essentials.

Many healthcare organization projects take more time and resources than planned and fail to deliver desired business outcomes. Healthcare IT is a major component of many projects and often undeservedly receives the blame for failure. Poor results are often not a result of faulty healthcare IT or poor project management or poor project execution alone. Many projects fail because of poor portfolio management--poor planning and management of the portfolio of initiatives designed to meet an organization's strategic goals. Because resources are limited, portfolio management enables organizations to more strategically allocate and manage their resources so care delivery, service delivery, and initiatives that advance organizations toward their strategic goals, including healthcare IT initiatives, can be accomplished at the levels of quality and service desired by an organization. Proper portfolio management is the essential foundation for program and project success and supports overall organization success. Without portfolio management, even programs and projects that execute flawlessly may not meet desired objectives. This article discusses the essential requirements for porfolio management. These include opportunity identification, return on investment (ROI) forecast, project prioritization, capacity planning (inclusive of human, financial, capital, and facilities resources), work scheduling, program and project management and execution, and project performance and value assessment. Portfolio management is essential to successful healthcare project execution. Theories are drawn from the Organizational Project Management Maturity Model (OPM3) work of the Project Management Institute and other leading strategy, planning, and organization change management research institutes.

Delivery of Health Care↗
PubMed1989

Topographic organization of the cerebello-olivary projection in the albino rat: an autoradiographic orthograde tracing study.

The topographic organization of the cerebello-olivary projection was investigated in the albino rat using an autoradiographic orthograde tracing method. The results indicate that the cerebello-olivary fibers are topographically organized and terminate primarily in the contralateral inferior olive. Only the caudoventral part of the medial cerebellar nucleus projects to the caudal part of the medial accessory olive (MAO). The anterior and posterior interpositus nuclei project mainly to the dorsal accessory olive and the rostral part of the MAO, respectively. In addition, the medial part of the posterior interpositus nucleus projects to the ventral lamella of the principal olive (PO) and the dorsomedial cell column (dmcc), and the lateral part of the anterior interpositus nucleus projects to the dmcc. The dorsolateral hump also projects to the dmcc. The lateral cerebellar (dentate) nucleus projects to the PO. The dentato-olivary projection is topographically organized. In a rostrocaudal direction, the rostral dentate projects to the caudal PO, while the caudal dentate projects to the rostral PO. The medial and lateral dentates project to the ventral and dorsal lamellae of the PO, respectively, and also the dorsal and ventral dentates project to the medial and lateral parts of the PO, respectively. A few cerebello-olivary fibers, except those arising from the medial cerebellar nucleus, terminate in the area of the ipsilateral olive symmetric to the contralateral projection.

Animals↗
PubMed1977

Ascending projections of the locus coeruleus in the rat. II. Autoradiographic study.

The ascending projections of the locus coeruleus were studied using an autoradiographic method. The major projection of locus coeruleus neurons ascends in a dorsal pathway traversing the midbrain tegmentum in a position ventrolateral to the periaqueductal gray. At the caudal diencephalon the locus coeruleus axons descend to enter the medial forebrain bundle at a caudal tuberal hypothalamic level. They are jointed in the medial forebrain bundle by a much smaller locus coeruleus projection which takes a ventral course through the midbrain tegmentum and enters the medial forebrain bundle via the mammillary peduncle and ventral tegmental area. Terminal projections are evident in the midbrain to the periaqueductal gray, tegmentum and raphe nuclei. There are widespread projections to the dorsal thalamus. The heaviest of these are to the intralaminar nuclei, the anteroventral and anteromedial nuclei, the dorsal lateral geniculate and the paraventricular nucleus. In the hypothalamus the largest projections are to the lateral hypothalamic area, periventricular nucleus, supraoptic nucleus and paraventricular nucleus. As the locus coeruleus projection ascends in the medial forebrain bundle, fibers leave it to traverse the lateral hypothalamus and zona incerta and enter the internal capsule, the ventral amygdaloid bundle and ansa peduncularis. These appear to terminate in the amygdaloid complex and, via the external capsule, in the lateral and dorsal neocortex. At the level of the septum 4 projections are evident. One group of fibers enters the stria medullaris to terminate in the paraventricular nucleus and habenular nuclei. A second group joins the stria terminalis to terminate in the anygdaloid complex. The third group turns into the diagonal band and medial septum; some fibers terminate in the septal nuclei and others continue into the fornix to termimate in hippocampus. A large component continues around the corpus callosum into the cingulum to terminate in the cingulate and adjacent neocortex, the subiculum and hippocampus. The remaining fibers continue rostrally in the medial forebrain bundle to terminate in olfactory forebrain and frontal neocortex. Commissural projections arise at 4 locations. The first decussation occurs in the dorsal tegmentum just below the central gray rostral to the locus coeruleus. The crossing fibers enter the contralateral dorsal bundle. A second group of fibers leaves the ipsilateral dorsal pathway, crosses in the posterior commissure and enters the contralateral dorsal pathway at the level. The third commissural projection arises more rostrally and crosses in the dorsal supraoptic commissure to enter the contralateral medial forebrain bundle. The fourth commissural projection is through the anterior commissure. The termination of the contralateral projection appears similar to that of the ipsilateral projection.

Afferent Pathways↗
PubMed1987

Local circuitry of identified projection neurons in cat visual cortex brain slices.

The relationship between pyramidal cell morphology and efferent target was investigated in layer 6 of cat primary visual cortex (area 17). Layer 6 has 2 projections, one to the lateral geniculate nucleus (LGN) and another to the visual claustrum. The cells of origin of each projection were identified by retrograde transport of fluorescent latex microspheres. The labeled cells were visualized in brain slices prepared from area 17, using an epifluorescence compound microscope modified for intracellular recording. Individual retrogradely labeled cells were penetrated and intracellularly stained with Lucifer yellow to visualize the patterns of axons and dendrites associated with each projection. The neurons that give rise to the 2 projections had very different patterns of dendrites and local axonal collaterals, but the patterns within each group were highly stereotyped. The differences between their axonal collaterals were particularly dramatic. Claustrum projecting cells had fine, horizontally directed collaterals that arborized exclusively in layer 6 and lower layer 5. Most LGN projecting cells had virtually no horizontal arborization in layer 6. Instead, they sent widespread collaterals vertically, which arborized extensively in layer 4. The apical dendrites of the 2 groups also differed markedly. Claustrum projecting cells had apical dendrites reaching to layer 1, with branches in layer 5 only, while LGN projecting cells never had an apical dendrite reaching higher than layer 3, with side branches in layers 5 and 4. Therefore, each efferent target must receive inputs from neurons whose synaptic connections within area 17 are significantly different from those of neurons projecting to other targets. This further suggests that distinct visual response properties should be associated with each projection. In addition to the claustrum and LGN projecting cells, about 20% of layer 6 pyramidal neurons lacked an efferent axon. Morphologically, most resembled LGN projecting neurons, but a few had characteristics of claustrum projecting cells. These neurons may represent cells that either failed to make an efferent connection or cells that lost an efferent axon during development. Their frequency suggests that such intrinsic, presumably excitatory, neurons may play a significant role in cortical processing.

Animals↗
PubMed1984

Methods and issues in the projection of population health status.

The discussion of strategies for forecasting health status changes in human populations often becomes immersed in efforts to utilize simple projection strategies that will produce crude projections. The motivation behind this effort is that simple projection strategies have limited data requirements and the crude projection strategies will be, in some ill-defined sense, robust (i.e., insensitive to assumptions). Actually there is a wide range of projection tools available. It seems appropriate to appraise the nature and attributes of each when considering the uses to which the projections will be put. For example, simple models are not necessarily more robust than more sophisticated procedures, especially for longer term temporal projections. Clearly we have many examples in developed countries where the use of simple actuarial or demographic projections has underestimated the true cost of a health programme by factors of 200-300%. The reason why the failures of such simple projection efforts become so rapidly manifest is that the programmes, once implemented, are expanded to meet the population's needs. In projecting only health services or utilization one has nearly a self-fulfilling prophecy--that resource constraints or the actual organization of the programme will directly determine the course of the level and mixture of health services consumption. Therefore failure to base the projections on a detailed model of underlying population needs leads in such cases to grossly inaccurate results. Clearly, projecting a population's health needs requires even more data than projecting health service requirements. Such information constraints require the use of a model to organize data from multiple objective and subjective sources, and to reflect the best scientific understanding of the processes involved. This article briefly discussed the application of 2 such models. One was designed for the analysis of discrete state health changes using population and vital statistics data, the other described both discrete and continuous changes using data from longitudinally followed community populations. One is designed to work only with detailed aggregate data with heavy inputs from scientific experts; the other deals with relatively information-rich measurements. Both can be modified on the basis of expert judgement to deal with simulations of a multiplicity of possible interventions. Both appropriately calculate the relative costs and benefits of select health initiatives.(ABSTRACT TRUNCATED AT 400 WORDS)

Actuarial Analysis↗
PubMed2002

Evaluating the participatory process in a community-based heart health project.

This paper presents the evaluation of a participatory research process used in a community-based heart health project, the British Columbia Heart Health Demonstration Project. The project utilized both a population heart health approach and a community mobilization model for taking action on heart health. A participatory evaluation plan was selected to: allow for participation in decision-making, incorporate the community perspective, enhance utilization of data, increase skills and capacities at the community level and enhance the responsiveness of the project team to emerging issues. Six elements common to participatory research were synthesized from the literature and rating scales were developed. Project participants across three project levels (investigative team, community project management committee members, community and provincial project coordinators) were asked to rate each of the elements and then explain their ratings during a focus group interview. Ratings were averaged and plotted on a 'sextagram' to illustrate the extent of participation in the research project. Patterns and themes that emerged from the transcripts and fieldnotes, regarding issues that influenced each rating, were categorized according to the framework of participatory research. Ratings and descriptions of participation on each element varied across project levels. The ratings of participation for the elements of sustainability and resource mobilization were uniformly low reflecting the large dependence on external funds. Participants involved at the community level perceived a greater level of participation in the identification of need and definition of goals and activities. Critical issues identified were related to the predominance of the external funding source, the imposition of funding agency guidelines on the communities, the amount of guidance by experts and the data collection methods. The analysis highlighted the responsiveness of the project to feedback over time and increases in the capacity of communities over time. Critical issues in the evaluation of participation were: differentiating stakeholder participation in program activities from research activities, variations in the meaning of community and participation among interviewees, the complexity of evaluating the extent of participation in a multi-level project and the evolution of participation over a 5 year time span. A definitive conclusion about the level of participation was elusive, however, the methodology afforded a contextual understanding of the assessments of participation and of participation itself and provides a foundation for evaluating and improving future participatory research initiatives.

British Columbia↗
PubMedDate not supplied

The Human Genome Project in the United States: a perspective on the commercial, ethical, legislative and health care issues.

The Human Genome Project represents a government supported effort to map and sequence the human genome. Governmental support for the Project should include increased emphasis on grants and contracts to industry. This is particularly true for small highly innovative biotechnology companies that can rapidly integrate and use technology as a base for product development. Private industry must be integrated as a partner into the Project, as it will be in Japan and Europe. There is a consensus in industry that the Genome Project is, at this stage at least, a science research project funded by government and not, at present, a commercial project. It is not seriously expected to have any substantial widespread commercial impact in the near future. The ultimate commercial benefits of the Human Genome Project, in terms of definable health care products, may not be realized until well into the next century. Yet, there are a few companies for which the Genome Project affords immediate commercial opportunities in certain niche areas. The Genome Project can be expected to have a significant impact upon medical knowledge and treatment. Though the Genome Project is just beginning, much of the type of medical knowledge expected to be gained from the Project is already present and even being exploited, albeit on a small scale. The application of genetic understanding to practical applications raises ethical, medical and legal issues central to the Genome Project. Unfortunately, emotion and sensationalism sometimes dominate and prevent a constructive discussion of ethical and social issues pertaining to genetics. To answer public concerns about human gene transfer experiments, the medical and biotechnology communities must constructively discuss the medical realities, the benefits to human health and the adequacy of the current governmental oversights. These presentations must be understandable by the lay public and must address their fears. Failure to assuage public fears and concerns, no matter how abstract or unrealistic they may be to the medical/scientific community, will lead to increased governmental controls and regulatory burdens.

Cost-Benefit Analysis↗
PubMed1996

Neurochemical, morphologic, and laminar characterization of cortical projection neurons in the cingulate motor areas of the macaque monkey.

The primate cingulate gyrus contains multiple cortical areas that can be distinguished by several neurochemical features, including the distribution of neurofilament protein-enriched pyramidal neurons. In addition, connectivity and functional properties indicate that there are multiple motor areas in the cortex lining the cingulate sulcus. These motor areas were targeted for analysis of potential interactions among regional specialization, connectivity, and cellular characteristics such as neurochemical profile and morphology. Specifically, intracortical injections of retrogradely transported dyes and intracellular injection were combined with immunocytochemistry to investigate neurons projecting from the cingulate motor areas to the putative forelimb region of the primary motor cortex, area M1. Two separate groups of neurons projecting to area M1 emanated from the cingulate sulcus, one anterior and one posterior, both of which furnished commissural and ipsilateral connections with area M1. The primary difference between the two populations was laminar origin, with the anterior projection originating largely in deep layers, and the posterior projection taking origin equally in superficial and deep layers. With regard to cellular morphology, the anterior projection exhibited more morphologic diversity than the posterior projection. Commissural projections from both anterior and posterior fields originated largely in layer VI. Neurofilament protein distribution was a reliable tool for localizing the two projections and for discriminating between them. Comparable proportions of the two sets of projection neurons contained neurofilament protein, although the density and distribution of the total population of neurofilament protein-enriched neurons was very different in the two subareas of origin. Within a projection, the participating neurons exhibited a high degree of morphologic heterogeneity, and no correlation was observed between somatodendritic morphology and neurofilament protein content. Thus, although the neurons that provide the anterior and posterior cingulate motor projections to area M1 differ morphologically and in laminar origin, their neurochemical profiles are similar with respect to neurofilament protein. This suggests that neurochemical phenotype may be a more important unifying feature for corticocortical projections than morphology.

Animals↗
PubMed1998

Organization of the intrinsic connections of the monkey amygdaloid complex: projections originating in the lateral nucleus.

We have used the anterograde tracer, Phaseolus vulgaris-leucoagglutinin (PHA-L) to study the intrinsic projections of the lateral nucleus of the Macaca fascicularis monkey amygdaloid complex. A reanalysis of the monkey lateral nucleus indicated that there are at least four distinct cytoarchitectonic divisions: dorsal, dorsal intermediate, ventral intermediate, and ventral. The major projections within the lateral nucleus originate in the dorsal, dorsal intermediate, and ventral intermediate divisions and terminate in the ventral division. The ventral division also projects to itself but does not project significantly to the other divisions of the lateral nucleus. Thus, the ventral division appears to be a site of convergence for information entering all other portions of the lateral nucleus. There are substantial regional and topographic differences in the projections from each of the lateral nucleus divisions to other amygdaloid nuclei. The dorsal division projects to all divisions of the basal and accessory basal nuclei, to the periamygdaloid cortex, the nucleus of the lateral olfactory tract, the dorsal division of the amygdalohippocampal area, and the lateral capsular nuclei. The dorsal intermediate division projects to the intermediate and parvicellular divisions of the basal nucleus, to the parvicellular division of the accessory basal nucleus, and to the periamygdaloid cortex. The ventral intermediate division projects to the magnocellular division of the accessory basal nucleus and to the parvicellular division of the basal nucleus. The major projections from the ventral division are directed to the parvicellular division of the basal nucleus, the parvicellular division of the accessory basal nucleus, the medial nucleus, and the periamygdaloid cortex. Projections from all portions of the lateral nucleus to the central nucleus are generally very light. It appears, therefore, that each division of the lateral nucleus originates topographically organized projections to the other amygdaloid areas that terminate in distinct portions of the target regions. The topographic organization of intrinsic amygdaloid projections raises the possibility that serial and parallel sensory processing may take place within the amygdaloid complex.

Amygdala↗
PubMed2000

Organization of projections from the inferior olive to the cerebellar nuclei in the rat.

The detailed organization of projections from the inferior olive to the cerebellar nuclei of the rat was studied by using anterograde tracing. The presence of a collateral projection to the cerebellar nuclei could be confirmed, and a detailed organization was recognized at the nuclear and subnuclear level. Olivary projections to the different parts of the medial cerebellar nucleus arise from various parts of the caudal half of the medial accessory olivary nucleus. The interstitial cell groups receive olivary afferents from the intermediate part of the medial accessory olive and from the dorsomedial cell column. A mediolateral topography was noted in the projections from the rostral half of the medial accessory olive to the posterior interposed nucleus. Olivary projections to the lateral cerebellar nucleus are derived from the principal olive according to basically inversed rostrocaudal topography. Projections from the dorsomedial group of the principal olive to the dorsolateral hump were found to follow a basically rostrocaudal topography. The anterior interposed nucleus receives olivary afferents from the dorsal accessory olive. Its rostromedial parts are directed to the lateral part of the anterior interposed nucleus and its caudolateral part reach the medial anterior interposed nucleus. No terminal arborizations in the cerebellar nuclei were found to originate from (1) the dorsal fold of the dorsal accessory olive, which resulted in projections to the lateral vestibular nucleus and (2) the dorsal cap of Kooy. It was noted that the olivary projection to the cerebellar nuclei is strictly reciprocal to the nucleo-olivary projection as described by Ruigrok and Voogd (1990). Moreover, it is suggested that the olivonuclear projection adheres to the organization of the climbing fiber projection to the cerebellar cortex and to the corticonuclear projection, thus, establishing and extending the detailed micromodular organization of the connections between inferior olive and cerebellum.

Animals↗
PubMed2000

Morphology, axonal projection pattern, and responses to optic nerve stimulation of thalamic neurons in the salamander Plethodon jordani.

In the salamander Plethodon jordani, the morphology and axonal projections of thalamic (TH) neurons and their responses to electrical optic nerve stimulation were determined by intracellular recording and biocytin labeling under in vitro, whole-brain conditions. Based on their axonal projections, labeled neurons (n = 76) were divided into the following groups: TH1 neurons, with mostly ipsilateral projections to the striatum; TH2 neurons, with ipsilateral or bilateral projections to the medial amygdala and nucleus accumbens; TH3 neurons, with bilateral projections to the medial and dorsal pallium; TH4 neurons, with mostly ipsilateral projections to the striatum and ipsilateral projections to the tectum opticum, tegmentum, and rostral medulla oblongata; and TH5 neurons, with ipsilateral projections to the tegmentum, medulla oblongata, and rostral spinal cord without (TH5.1) or with (TH5.2) additional projections to the optic tectum. TH1-TH4 neurons are found in the dorsal thalamus and around the sulcus medialis, and TH5 neurons are found in the ventral thalamus. Labeled neurons with ascending projections, i.e., the more dorsally situated TH1-TH4 neurons, are mostly inhibited by electrical stimulation of the optic nerve and have significantly longer latencies (mean +/- S.D., 42.1 +/- 11.6 msec) than neurons with exclusively descending projections, i.e., the ventrally located TH5 neurons (8.5 +/- 6.1 msec), which receive the bulk of retinal afferents and show excitation at electrical optic nerve stimulation. Neurons recorded without labeling in the dorsal thalamus likewise exhibit mostly inhibition and have significantly longer latencies (35.7 +/- 18.9 msec) than those recorded in the ventral thalamus (10.9 +/- 7.7 msec), which mostly show excitation. None of the neurons recorded in the dorsal thalamus followed repetitive stimulation of the optic nerve. Thus, neurons situated in the dorsal thalamus and projecting to pallial or subpallial telencephalic targets are unlikely to receive monosynaptic or oligosynaptic, excitatory retinal input. Accordingly, no retino-thalamo-telencephalic pathway homologous to that found in amniotes appears to exist in salamanders.

Action Potentials↗
PubMed2004

A comparative reappraisal of projections from the superficial laminae of the dorsal horn in the rat: the forebrain.

Projections to the forebrain from lamina I of spinal and trigeminal dorsal horn were labeled anterogradely with Phaseolus vulgaris-leucoagglutinin (PHA-L) and/or tetramethylrhodamine-dextran (RHO-D) injected microiontophoretically. Injections restricted to superficial laminae (I/II) of dorsal horn were used primarily. For comparison, injections were also made in deep cervical laminae. Spinal and trigeminal lamina I neurons project extensively to restricted portions of the ventral posterolateral and posteromedial (VPL/VPM), and the posterior group (Po) thalamic nuclei. Lamina I also projects to the triangular posterior (PoT) and the ventral posterior parvicellular (VPPC) thalamic nuclei but only very slightly to the extrathalamic forebrain. Furthermore, the lateral spinal (LS) nucleus, and to a lesser extent lamina I, project to the mediodorsal thalamic nucleus. In contrast to lamina I, deep spinal laminae project primarily to the central lateral thalamic nucleus (CL) and only weakly to the remaining thalamus, except for a medium projection to the PoT. Furthermore, the deep laminae project substantially to the globus pallidus and the substantia innominata and more weakly to the amygdala and the hypothalamus. Double-labeling experiments reveal that spinal and trigeminal lamina I project densely to distinct and restricted portions of VPL/VPM, Po, and VPPC thalamic nuclei, whereas projections to the PoT appeared to be convergent. In conclusion, these experiments indicate very different patterns of projection for lamina I versus deep laminae (III-X). Lamina I projects strongly onto relay thalamic nuclei and thus would have a primary role in sensory discriminative aspects of pain. The deep laminae project densely to the CL and more diffusely to other forebrain targets, suggesting roles in motor and alertness components of pain.

Amygdala↗
PubMed1977

Topographic organization of the projections from cortical areas 17, 18 and 19 onto the thalamus, pretectum and superior colliculus in the cat.

The distribution of cortical projections from areas 17, 18 and 19 to the lateral thalamus, pretectum, and superior colliculus was investigated with the autoradiographic tracing method. Cortical areas 17, 18 and 19 were demonstrated to project retinotypically and in register upon the dorsal lateral geniculate nucleus, medial interlaminar nucleus, lateral zone of the lateral posterior complex, nucleus of the optic tract and superior colliculus. Area 19 was shown to project retinotopically upon the pulvinar nucleus. Clear retinotopic organization was not demonstrable in the projections of areas 17, 18 and 19 to the reticular complex of the thalamus and ventral lateral geniculate nucleus, or in the projection of area 19 to the anterior pretectal nucleus. The cortical projections were employed to define the retinotopic organization of the nucleus of the optic tract, pulvinar nucleus, and later zone of the lateral posterior complex. The cortical projections show the vertical meridian to be represented caudally, with the lower visual field represented laterally, and the upper visual field medially, within the nucleus of the optic tract. The projections of area 19 to the pulvinar nucleus demonstrate the lower visual field to be represented rostrally and the upper field caudally in this mucleus; the vertical meridian to be represented at the lateral border and the visual field periphery to be represented at the medial border of the pulvinar nucleus. Cortical projections to the lateral zone of the lateral posterior complex demonstrate the lower visual field to be represented rostrally and the upper visual field caudally; the vertical meridian to be represented at the medial limit and the visual field periphery at the lateral border of the termination zones. On the basis of the experimental findings a new terminology is introduced for the feline lateral posterior complex. Divisions are proposed which correspond to zones with demonstrably distinct afferent input. The pulvinar nucleus is defined by the distribution of projections from area 19. Three flanking divisions are defined within the lateral posterior complex; a lateral division recipient of projections from area 17, 18 and 19, and interjacent division recipient of projections of the superficial layers of the superior colliculus, and a medial division flanking the tectorecipient zone medially.

Animals↗
PubMed1978

Morphological and electrophysiological characteristics of projection neurons in the nucleus interpositus of the cat cerebellum.

The populations of neurons in the nucleus interpositus (IP) of the cat cerebellum which project to the ventral lateral nucleus of the thalamus (VL), the red nucleus (RN), the nucleus reticularis tegmenti pontis (NRTP), the pontine nuclei (PN), the inferior olive (IO), and the cerebellar cortex were identified by intracellular and extracellular injections of HRP and studied electrophysiologically. When HRP was simultaneously injected into the VL, RN, and IO, over 95% of the neurons in the IP nuclei were labeled; indicating that there are few, if any, local circuit neurons. The vast majority (86%) of the larger IP neurons (soma length greater than or equal to 20 micrometer) project rostrally to the RN and thalamus. These neurons typically have long, relatively spine free dendrites and axons which in a few cases gave rise to recurrent collaterals. Two intracellularly stained projection neurons which had exceptionally long spiny dendrites had axons which gave rise to nucleocortical collaterals in addition to several local collaterals. IP neurons projecting to the NRTP and PN were located primarily in the lateral aspect of the nucleus interpositus anterior. Electrophysiological experiments established that neurons projecting to the NRTP also project to the VL. The IP neurons projecting to the IO have small fusiform or multipolar somata, long thin dendrites, and receive excitatory inputs from the IO. At least 73% of the small neurons in the IP project to the IO, and some of these, in addition, project to the VL. There are at least three morphologically distinguishable populations of projection neurons, small IO projections neurons, and neurons with nucleocortical collaterals. The projection of the IP to diverse regions of the brain is accomplished mainly by axon collateralization, but regional and morphological specialization also play a role in the organization of the output of the IP.

Animals↗
PubMed1979

Projections of the cerebellar and dorsal column nuclei upon the inferior olive in the rhesus monkey: an autoradiographic study.

Projections from the cerebellar and dorsal column nuclei to the inferior olive of the rhesus monkey were traced with anterograde autoradiographic methods. The cerebellar nuclei give rise to a massive projection which reaches the contralateral inferior olivary complex by way of the descending limb of the superior cerebellar peduncle. Dentato-olivary fibers project exclusively upon the principal olivary nucleus (PO) and observe a strict topography. The dorsal, lateral, and ventral dentate project respectively to the dorsal, lateral, and ventral lamellae of the PO. Within the lamellae, the dentato-olivary fibers are related point for point in the medio-lateral axis. By contrast, the rostro-caudal topography is reversed so that the rostral pole of the dentate projects to the caudal PO and the caudal dentate to the rostral PO. These connections are predominantly crossed but a small ipsilateral component recrosses the midline at the olivary commissure and mirrors the topography on the opposite side. The anterior interpositus projects only to the medial half of the DAO and the posterior interpositus projects only to the rostral two thirds of the MAO. The ipsilateral component is minor in comparison with the contralateral projection, but appears to be more substantial than the ipsilateral projection to the PO arising from the dentate nucleus. The fastigial nucleus does not project upon the olivary complex. The dorsal column nuclei project topographically upon the contralateral accessory nuclei with the gracile nucleus sending fibers primarily to the lateral half of the DAO and the cuneate nucleus projecting to rostral cell groups of the MAO. The present results when compared with other olivary connections described by previous studies in a variety of species suggest that regions of the MAO and DAO receiving sensory information from the periphery may lie outside the influence of cerebellar feedback loops.

Animals↗
PubMed1980

Ascending projections of the inferior colliculus in the cat: an autoradiographic study.

The ascending projections of the inferior colliculus (IC) in the cat were traced by the autoradiographic method, with special reference in the differenial projections of each subnucleus of IC. The laminated ventrolateral part of the central nucleus of IC (CNv) projects to the ventral and medial divisions of the ipsilateral medial geniculate body (MGB). The projections to the ventral division are topographically organized in the mediolateral direction, the terminals being arranged in the form of lamina, while those to the medial division are diffuse. The unlaminated dorsomedial part of the central nucleus of IC (CNd) sends fibers to every division of the ipsilateral MGB, particularly to the dorsal division and the ventromedial portion of the ventral division. It is noteworthy that the external nucleus of IC (EN) projects to the superior colliculus, part of the pretectum, and the anterior extremity of MGB ipsilaterally, in addition to the ventral and medial divisions of MGB. The posterior cap of IC, regarded as the pericentral nucleus of IC (PC), projects ipsilaterally to the ventral part of the caudal tip of MGB and the posterior part of the suprapeduncular nucleus. In addition of these projections, the parabrachial region and interstitial nucleus of the brachium of IC (BIC) are identified as common targets of projections of each nucleus of IC on the ipsilateral side. Contralaterally, every subnucleus of IC except for PC projects via the commissure of IC to areas corresponding to the targets of the ipsilateral projections, such as the ventral and medial divisions of MGB and the parabrachial region and the interstitial nucleus of BIC, although these contraleral projections are in general much sparser than those ipsilateral. Intrinsic and commissural connections within IC are also revealed in this study, providing characteristic configurations of each subnucleus of IC. It is concluded that the ascending projections of IC in the cat are highly differentially organized according to its subnucleus.

Animals↗
PubMed1981

Organization of corticothalamic projections from parietal cortex in cat.

Corticothalamic projections from areas 5a, 5b, and 7 of cat parietal cortex were studied with autoradiographic techniques. Each cortical area was identified by its cytoarchitectural characteristics and the patterns of termination were related to the thalamic nuclear groups. Injections of 3H-leucine in cortical area 5a were associated with terminal labeling primarily in the spinal recipient zone of the ventral lateral nucleus (VLsp) and the medial division of the posterior group (POm). The corticothalamic projections of area 5a are loosely topographically organized; medial parts of 5a project heavily to rostral and lateral parts of VLsp and sparsely to POm, while lateral parts of 5a project to more medial and caudal parts of VLsp and heavily to POm. Cortical area 5b projects primarily to the rostral portions of the lateral posterior nucleus (LP). These projections also appear to be topographically organized. The part of area 5b on the marginal gyrus projects to more ventral parts of rostral LP, while area 5b on the middle suprasylvian gyrus projects to more dorsal and lateral parts of rostral LP. Cortical area 7 projects to LP and the pulvinar (Pul). Rostral parts of area 7 project heavily to dorsal and lateral parts of LP and lightly to Pul; more caudal portions of area 7 projects relatively more heavily to Pul. The reticular, central lateral, and paracentral nuclei also receive projections, especially from the suprasylvian gyrus. The results are discussed with regard to putative sensory response characteristics of these cortical areas and to general thalamocortical organization.

Animals↗
PubMed1981

Projections from the pontine nuclei proper and reticular tegmental nucleus onto the cerebellar cortex in the cat. An autoradiographic study.

After injections of 0.5 microliter of tritiated leucine and/or proline into various parts of the pontine nuclei proper or the pontine tegmental reticular nucleus (N.r.t.) of 34 cats, labeled terminals of pontocerebellar fibers were found in the cerebellar cortex. Fibers from the pontine nuclei and N.r.t. terminate as mossy fibers in the granular layer of the cerebellum, and no evidence is obtained of labeled fibers in the molecular layer. The pontocerebellar projection is, in general, bilateral with a contralateral preponderance, and a complex organization has been shown to exist in the cat. Clear evidence of divergence of this projection from a small pontine area has been demonstrated. Thus, the dorsolateral nucleus has a heavy projection to lobule VII, besides modest projections to lobules VI, VIII, and IX, crus I and II, paraflocculus, and paramedian lobule. On the other hand, a particular cerebellar region receives afferent fibers from several pontine regions, confirming previous HRP studies. For example, lobule VII receives heavy projections from parts of the dorsolateral, peduncular, and paramedian nuclei, less heavy projections from the lateral part of the lateral nucleus, and some from other parts of the pontine nuclei. This is a convergent feature of the pontocerebellar projections. In addition, small adjoining areas within a pontine subdivision have different patterns of cerebellar projections, shwing preferential sites of terminations. This suggests some degree of localization within the pontine nuclei. The cerebellar projection from the N.r.t. shows an essentially similar organization as the projection from the pontine nuclei proper, an apparent difference being only that the former is more extensive in the fields of termination than the latter. Some evidence for a parasagittal termination of pontocerebellar projections to the paramedian lobule has been found in this study. However, this is not as clear-cut as such patterns in the cerebellar projections from the spinal cord, cuneate nucleus, and lateral reticular nucleus shown recently in rat and cat.

Amino Acids↗