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 811 records · Page 45Linked to original sources
PubMedDate not supplied

Interhemispheric integration: II. Symmetry and convergence of the corticostriatal projections of the left and the right principal sulcus (PS) and the left and the right supplementary motor area (SMA) of the rhesus monkey.

The relationship between the termination zones of projections from paired homotopic areas of the frontal lobes was examined in the caudate nucleus and the putamen of the macaque monkey. Injections of WGA-HRP and tritiated amino acids were made in topographically matched regions of the principal sulcus (PS) or of the supplementary motor area (SMA) in each hemisphere, such that the projections from the same area on each side were differentially labeled in the same animal. Adjacent sections through the neostriatum were processed for the respective tracers, permitting the relationship between the converging projections to be defined. The topographic distribution and strength of ipsilateral corticostriatal projections observed for separately labeled left and right hemispheres were strikingly similar. Projections from the left and the right PS terminated preferentially in central parts of the left and right neostriata, respectively, while projections of the left and right SMAs terminated preferentially in dorsolateral parts of respective left and right neostriata. Therefore, little evidence for asymmetry of corticostriatal projections was found. The projections of the left and the right PS to the same neostriatum were also compared. Remarkably, whether in the left or right hemisphere, projections from the left and the right PS were in precise register in topographically specific territories of the caudate and putamen. Likewise, projections of the left and right SMAs converged in both the left and right neostriata. Such convergence allows for a remarkable degree of interhemispheric integration in the descending corticostriatal networks.

Animals↗
PubMed2001

Evaluation of 60 continuous quality improvement projects in French hospitals.

OBJECTIVE: To evaluate the feasibility of implementing continuous quality improvement (CQI) projects in French health care organizations. DESIGN: The French Ministry of Health issued two calls for CQI projects (in 1995 and 1996). ANAES was commissioned to monitor and evaluate the projects, and to provide advice. SETTING: ANAES in collaboration with French public hospitals. STUDY PARTICIPANTS: A jury selected 64 projects from 483 submissions. The first series of projects related to safety issues (e.g. blood transfusions), the second related chiefly to patient management. INTERVENTIONS: ANAES instructed project leaders in process analysis (modified four-step FOCUS-PDCA model), convened regular meetings between leaders and performed on-site visits. MAIN OUTCOME MEASUREMENTS: Objective outcomes: goal achievement, extension of projects to other topics and departments, allocation of resources. Subjective outcomes: changes in attitudes. Statistics were obtained from two questionnaires completed by project leaders. RESULTS: Four projects were discontinued; 82% (49 out of 60) met more than half their objectives. The CQI method was adopted by other departments in 65% and 50% (1st and 2nd series respectively) of cases. Hospital management often chose to provide continued support (81%/88%), offer training (59%/80%), create a CQI unit (62%/73%), and allocate a budget (61%/65%). A positive impact on staff attitudes was noted in over 75% of projects. CONCLUSION: ANAES' co-ordinated initiative to acquaint a hard core of French public hospitals with CQI proved successful. Identification of the factors for success and of potential hurdles helped pave the way for the national hospital accreditation procedure currently underway.

Attitude of Health Personnel↗
PubMedDate not supplied

Visualization modes for CT colonography using cylindrical and planar map projections.

PURPOSE: The purpose of this study was to demonstrate the limitations to the effectiveness of CT colonography, colloquially called virtual colonoscopy (VC), for detecting polyps in the colon and to describe a new technique, map projection CT colonography using Mercator projection and stereographic projection, that overcomes these limitations. METHOD: In one experiment, data sets from nine patients undergoing CT colonography were analyzed to determine the percentage of the mucosal surface visible in various visualization modes as a function of field of view (FOV). In another experiment, 40 digitally synthesized polyps of various sizes (10, 7, 5, and 3.5 mm) were randomly inserted into four copies of one patient data set. Both Mercator and stereographic projections were used to visualize the surface of the colon of each data set. The sensitivity and positive predictive value (PPV) were calculated and compared with the results of an earlier study of visualization modes using the same CT colonography data. RESULTS: The percentage of mucosal surface visualized by VC increases with greater FOV but only approaches that of map projection VC (98.8%) at a distorting, very high FOV. For both readers and polyp sizes of > or =7 mm, sensitivity for Mercator projection (87.5%) and stereographic projection (82.5%) was significantly greater (p < 0.05) than for viewing axial slices (62.5%), and Mercator projection was significantly more sensitive than VC (67.5%). Mercator and stereographic projection had PPVs of 75.4 and 78.9%, respectively. CONCLUSION: The sensitivity of conventional CT colonography is limited by the percentage of the mucosal surface seen. Map projection CT colonography overcomes this problem and provides a more sensitive method with a high PPV for detecting polyps than other methods currently being investigated.

Adult↗
PubMed2005

Comparison of early performance indicators for screening projects within the European Breast Cancer Network: 1989-2000.

In 1989 the European Breast Cancer Network (EBCN) was established by the first pilot projects for breast cancer screening, co-funded by the Europe Against Cancer programme. We report early performance indicators for these EBCN projects while taking into account their organizational setting. Out of 17 projects in the network, 10 projects from six European countries contributed aggregated data on number of invitations, screening examinations, and breast cancers detected over the period 1989-2000. Results were summarized separately for projects in centralized versus decentralized health care environments. The European Guidelines for quality assurance in mammography screening provided reference values for the performance indicators. The most prominent finding in this study was the higher participation rate in centralized versus decentralized projects (average participation in 1998: 74 versus 33%; P<0.001), whereas the invitation system and screening policy in these projects were similar. Detection rates and characteristics of cancers detected at initial and subsequent screening examinations showed no significant differences between centralized and decentralized projects. Even though early performance indicators for centralized versus decentralized projects were similar, the impact of breast screening on mortality from this disease at the population level will differ since the decentralized projects reach only part of the target population.

Adult↗
PubMed2004

Evidence for an elastic projection mechanism in the chameleon tongue.

To capture prey, chameleons ballistically project their tongues as far as 1.5 body lengths with accelerations of up to 500 m s(-2). At the core of a chameleon's tongue is a cylindrical tongue skeleton surrounded by the accelerator muscle. Previously, the cylindrical accelerator muscle was assumed to power tongue projection directly during the actual fast projection of the tongue. However, high-speed recordings of Chamaeleo melleri and C. pardalis reveal that peak powers of 3000 W kg(-1) are necessary to generate the observed accelerations, which exceed the accelerator muscle's capacity by at least five- to 10-fold. Extrinsic structures might power projection via the tongue skeleton. High-speed fluoroscopy suggests that they contribute less than 10% of the required peak instantaneous power. Thus, the projection power must be generated predominantly within the tongue, and an energy-storage-and-release mechanism must be at work. The key structure in the projection mechanism is probably a cylindrical connective-tissue layer, which surrounds the entoglossal process and was previously suggested to act as lubricating tissue. This tissue layer comprises at least 10 sheaths that envelop the entoglossal process. The outer portion connects anteriorly to the accelerator muscle and the inner portion to the retractor structures. The sheaths contain helical arrays of collagen fibres. Prior to projection, the sheaths are longitudinally loaded by the combined radial contraction and hydrostatic lengthening of the accelerator muscle, at an estimated mean power of 144 W kg(-1) in C. melleri. Tongue projection is triggered as the accelerator muscle and the loaded portions of the sheaths start to slide over the tip of the entoglossal process. The springs relax radially while pushing off the rounded tip of the entoglossal process, making the elastic energy stored in the helical fibres available for a simultaneous forward acceleration of the tongue pad, accelerator muscle and retractor structures. The energy release continues as the multilayered spring slides over the tip of the smooth and lubricated entoglossal process. This sliding-spring theory predicts that the sheaths deliver most of the instantaneous power required for tongue projection. The release power of the sliding tubular springs exceeds the work rate of the accelerator muscle by at least a factor of 10 because the elastic-energy release occurs much faster than the loading process. Thus, we have identified a unique catapult mechanism that is very different from standard engineering designs. Our morphological and kinematic observations, as well as the available literature data, are consistent with the proposed mechanism of tongue projection, although experimental tests of the sheath strain and the lubrication of the entoglossal process are currently beyond our technical scope.

Acceleration↗
PubMed1995

The corticotectal projection of the rat in vitro: development, anatomy and physiological characteristics.

In this study, the formation of the corticotectal projection of the rat in organotypic slice culture was investigated, using both anatomical and physiological approaches. The establishment of fibre connections from visual cortex to superior colliculus explants was monitored after 3, 6, 14, 20 and 30 days in vitro by cortical injections of Dil. As in cortical cultures without cocultured colliculus, fibres anterogradely labelled by this procedure spread radially from the injection site into the surroundings of the explant, without displaying any directional preference. Especially, layer V pyramidal cells could be seen to extend processes not only to the collicular target, but also in the opposite direction, suggesting that no axonal guidance was exerted by the projection target. The total number of fibres projecting in the direction of the colliculus was not higher than of those projecting in the opposite direction. However, fibres projecting into the colliculus were significantly longer. This was also the case when the colliculus was placed next to the pial side of the cortical explant, indicating that outgrowth direction was not related to this observation. We therefore assume a chemotrophic rather than a chemotactic influence of the projection target on cortical axons, which is based on direct contact of axons to the target tissue. It cannot be excluded, however, that the failure to detect chemotactic guidance was caused by the lack of diffusion gradients in our culture system. Innervation of the collicular slice exclusively originated from layer V pyramidal cells, irrespective of the position of the collicular target. Fibre courses suggested that discrimination of the projection target was achieved upon encounter with the collicular surface by direct membrane contact. Inside the collicular tissue, fibre arborizations occurred preferredly in up to three layers perpendicular to the surface. Even after the smallest tracer injections, termination fields were diffusely distributed over the collicular slice. Also, the spatial distribution of retrogradely stained projection neurons did not differ statistically from an equal distribution. Thus, a high degree of convergence and divergence was observed anatomically in the corticotectal projection formed in vitro, corresponding to the immature state in vivo. The functionality of the corticotectal projection was assessed by intracellular recordings from collicular neurons. Electrophysiological properties, such as membrane potential (-68 +/- 11 mV), membrane resistance (35.4 +/- 27.7 M omega) and the time constant (3.0 +/- 2.1 ms) were comparable to reference values, confirming the viability of our culture preparation. The functionality of corticotectal transmission was revealed by intracellularly recorded responses of collicular cells to extracellular cortical stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Projections from the hippocampal region to the mammillary bodies in macaque monkeys.

A combination of anterograde and retrograde tracers mapped the direct hippocampal and parahippocampal inputs to the mammillary bodies in two species of macaque monkey. Dense projections arose from pyramidal cells in layer III of the subiculum and prosubiculum, and terminated in the medial mammillary nucleus. While there was no evidence of an input from the dentate gyrus or fields CA1-3, a small contribution arose from the presubiculum and entorhinal cortices. All of the hippocampal and parahippocampal projections to the mammillary bodies appeared to use the fornix as a route. The caudal portions of the subiculum and prosubiculum contained the greatest numbers of cells projecting to the mammillary bodies. A light contralateral projection to the medial mammillary nucleus was also observed, although this appeared to arise primarily from the more rostral portions of the subiculum and prosubiculum. There was a crude topography within the medial mammillary nucleus, with the caudal subicular projections terminating in the mid and dorsal portions of the nucleus while the rostral subicular and entorhinal projections terminated in the ventral and lateral portions of the medial nucleus. Light ipsilateral projections throughout the lateral mammillary nucleus were sometimes observed. Comparisons with related studies of the macaque brain showed that the dense hippocampal projections to the mammillary bodies arise from a population of subicular cells separate from those that project to the anterior thalamic nuclei, even though the major output from the mammillary bodies is to the anterior thalamic nuclei. Other comparisons revealed underlying similarities with the corresponding projections in the rat brain.

Amino Acids↗
PubMed1992

Struggling with self: the personal projects of students seeking psychological counseling.

Personal projects can be described as self-articulated goals and related sequences of actions. In order to investigate what kind of personal projects people with psychological problems have, and how they work on them, 28 counselling client students, 44 students of psychology, and 45 students of technology completed a Finnish version of Little's (1987) Personal Project Inventory. The results showed that the clients scored lower on project accomplishment than other groups. Their personal projects were frequently self-related, while those of the technology students were often task-related. The higher their sense of coherence, self-esteem, mental health and life satisfaction, the more subjects expected to accomplish their projects, the more frequently they described task-related projects, the less negative affect they reported, and the less frequently they described self-related projects. These results suggest that psychologically distressed individuals struggle with self-related projects and have problems in accomplishing their projects.

Adult↗
PubMed1978

The cortical projections of foveal striate cortex in the rhesus monkey.

1. The cortical projections of the foveal and extrafoveal parts of the striate cortex have been compared, using conventional degeneration techniques, as well as combinations of anatomical methods. While both foveal and extrafoveal striate cortex share a common pattern of projections (to areas V2, V3 and the visual area in the medial part of the posterior bank of the superior temporal sulcus), foveal striate cortex was found to have an additional projection (to part of the cortex of the fourth visual areas, V4). The latter projection includes the posterior lip of the inferior occipital sulcus which, on anatomical grounds, is regarded as the ventral extension of V4. 2. Anatomical studies using double tracers were employed to clarify the nature of the projections from the striate cortex and from V2 to V4. In one such experiment, tritiated proline was injected into extra-foveal striate cortex and a small lesion was made in that part of V2 receiving a direct projection from the region of the striate cortex into which the radioactive tracer was injected. Only degenerating fibres (due to the lesion), and no radioactive label, was found in V4. Such an experiment showed that, unlike foveal striate cortex, the projections from extrafoveal striate cortex to V4 are not direct, but through V2. 3. In another type of anatomical experiment using double tracers, the corpus callosum was sectioned and tritiated proline was injected into foveal striate cortex. Such an experiment allowed a more accurate determination of the extent of V4, as judged from its callosal connexions, to which foveal striate cortex projects. 4. Considering the projections of V1 to areas V2, V3 and the visual area in the medial part of the posterior bank of the superior temporal sulcus, and considering the differences in the projections of foveal and extrafoveal striate cortex, it is suggested that, among other functions, the striate cortex acts as a distribution centre for the information coming over the retino-geniculo-cortical pathways, parcelling this information out to different visual areas of the prestriate cortex for further analysis.

Animals↗
PubMed2002

Nicotinic ACh receptor subtypes on gastrointestinally projecting neurones in the dorsal motor vagal nucleus of the rat.

To determine the predominant nicotinic ACh receptor (nAChR) located on neurones in the dorsal motor nucleus of the vagus (DMV) that project to the gastrointestinal tract, we used the rat brainstem slice preparation and whole-cell recordings of DMV neurones identified by retrograde DiI tracing to pharmacologically characterize nAChRs. Pressure ejection of acetylcholine (ACh, 250 microM for 200 ms) from a patch pipette placed approximately 10-20 microm from the surface of the recorded cell produced an inward current in most DMV neurones sampled. The average currents for neurones projecting to the fundus, antrum and caecum were 149 +/- 38 (n = 25), 115 +/- 18 (n = 29) and 117 +/- 23 pA (n = 6), respectively. Blockade of the alpha7 subtype of nAChR with either alpha-bungarotoxin (alpha-BGT) or methyllycaconitine (MLA) counteracted 60-75 % of the ACh-evoked current in DMV neurones projecting to the fundus, antrum and caecum. In neurones projecting to the fundus and the antrum, currents resistant to alpha-BGT were significantly blocked by dihydro-beta-erythroidine (10-20 nM), an antagonist of the alpha4beta2 subtype of nAChR. In neurones projecting to the caecum, currents resistant to alpha-BGT were significantly depressed by a low concentration of mecamylamine (1 microM). Cytisine (100 microM), an agonist of nAChRs that contain the alpha7 or the beta4 subunit, evoked significant currents in caecum-projecting neurones that were previously exposed to alpha-BGT. In contrast, cytisine had no effect on DMV neurones previously exposed to alpha-BGT that project to the fundus or antrum. Our data indicate that the prevailing nAChR subtype in DMV neurones projecting to the GI tract is the alpha7 subtype. In addition, we obtained evidence for the co-expression of the alpha4beta2 nAChR subtype on DMV neurones projecting to the fundus and antrum, and the alpha3beta4 nAChR subtype on DMV neurones projecting to the caecum.

Acetylcholine↗
PubMed2005

Synaptic input of rat spinal lamina I projection and unidentified neurones in vitro.

Spinal lamina I projection neurones that transmit nociceptive information to the brain play a pivotal role in hyperalgesia in various animal models of inflammatory and neuropathic pain. Consistently, activity-dependent long-term potentiation can be induced at synapses between primary afferent C-fibres and lamina I projection neurones but not unidentified neurones in lamina I. The specific properties that enable projection neurones to undergo long-term potentiation and mediate hyperalgesia are not fully understood. Here, we have tested whether lamina I projection neurones differ from unidentified neurones in types or strength of primary afferent input and/or action potential-independent excitatory and inhibitory input. We used the whole-cell patch-clamp technique to record synaptic currents in projection and unidentified lamina I neurones in a transverse lumbar spinal cord slice preparation from rats between postnatal day 18 and 37. Lamina I neurones with a projection to the parabrachial area or the periaqueductal grey were identified by retrograde labelling with a fluorescent tracer. The relative contribution of NMDA receptors versus AMPA/kainate receptors to C-fibre-evoked excitatory postsynaptic currents of lamina I neurones significantly decreased with age between postnatal day 18 and 27, but was independent of the supraspinal projection of the neurones. We did not find a significant contribution of kainate receptors to C-fibre-evoked excitatory postsynaptic currents. Lamina I projection and unidentified neurones possessed functional GABAA and glycine receptors but received scarce action potential-independent spontaneous GABAergic and glycinergic inhibitory input as measured by miniature inhibitory postsynaptic currents. The miniature excitatory postsynaptic current frequencies were five times higher in projection than in unidentified neurones. The predominance of excitatory synaptic input to projection neurones, taken together with the previous finding that their membranes are more easily excitable than those of unidentified neurones, may facilitate the induction of synaptic long-term potentiation.

Action Potentials↗
PubMed2005

A technique for on-board CT reconstruction using both kilovoltage and megavoltage beam projections for 3D treatment verification.

The technologies with kilovoltage (kV) and megavoltage (MV) imaging in the treatment room are now available for image-guided radiation therapy to improve patient setup and target localization accuracy. However, development of strategies to efficiently and effectively implement these technologies for patient treatment remains challenging. This study proposed an aggregated technique for on-board CT reconstruction using combination of kV and MV beam projections to improve the data acquisition efficiency and image quality. These projections were acquired in the treatment room at the patient treatment position with a new kV imaging device installed on the accelerator gantry, orthogonal to the existing MV portal imaging device. The projection images for a head phantom and a contrast phantom were acquired using both the On-Board Imager kV imaging device and the MV portal imager mounted orthogonally on the gantry of a Varian Clinac 21EX linear accelerator. MV projections were converted into kV information prior to the aggregated CT reconstruction. The multilevel scheme algebraic-reconstruction technique was used to reconstruct CT images involving either full, truncated, or a combination of both full and truncated projections. An adaptive reconstruction method was also applied, based on the limited numbers of kV projections and truncated MV projections, to enhance the anatomical information around the treatment volume and to minimize the radiation dose. The effects of the total number of projections, the combination of kV and MV projections, and the beam truncation of MV projections on the details of reconstructed kV/MV CT images were also investigated.

Humans↗
PubMedDate not supplied

A pseudo-Poisson noise model for simulation of positron emission tomographic projection data.

Although radioactive decay obeys Poisson statistics, because of the corrections that are applied to the projection data prior to reconstruction, the noise in positron emission tomography (PET) projections does not follow a Poisson distribution. Use of Poisson noise when simulating PET projections in order to test the performance of reconstruction and processing techniques is therefore not appropriate. The magnitude of PET projection noise was observed to be as much as 10 to 100 times greater than Poisson noise in some instances. A quadratic function was found to fit the relationship between noise power spectral density and total projection count. The coefficients of the quadratic function were determined for projections of different tracer distributions and types. Using these observations, a method of simulating PET projections was developed based on a pseudo-Poisson noise model. Projections simulated according to this method are good approximations to real projection data and take into account the characteristics of individual PET cameras and particular tracer distributions. Such simulated projections have been valuable in predicting the performance of reconstruction algorithms. This approach can also be applied to single photon emission tomography.

Computer Simulation↗
PubMed1983

Connections of midbrain periaqueductal gray in the monkey. II. Descending efferent projections.

1. We have defined the descending efferent projections of the midbrain periaqueductal gray (PAG) by injecting small amounts of [3H]leucine into the various regions of the squirrel monkey PAG. 2. Despite the fact that different regions of the PAG were injected in separate animals, the majority of the brain stem areas labeled remained constant. 3. The PAG exhibited a dense projection to the superior colliculus, the nucleus cuneiformis, and the locus ceruleus. Parts of the reticular formation (nucleus reticularis: pontis oralis, pontis caudalis, gigantocellularis, magnocellularis, and ventralis) received a projection from the PAG, as did the nucleus parabrachial pars lateralis, ambiguous, the nucleus raphe magnus, and raphe pallidus. 4. In contrast to the brain stem, the deep laminae of the nucleus caudalis and the deep laminae of the cervical spinal cord were labeled only after injections of the lateral aspect of the PAG. 5. The main route for the PAG leads to brain stem projections is through the lateral edge of the paramedian reticular formation. The great majority of the anterograde labeling was ipsilateral to the injection although a small contralateral projection was present. 6. These results indicate that the PAG projects to the brain stem and spinal cord in the monkey. Many of the brain stem areas that the PAG projects to are known to project to the spinal cord. These secondary spinal projections coupled with the direct PAG leads to spinal projection provide a wide variety of routes through which the PAG may influence spinal cord activity.

Animals↗
PubMed1997

Properties of individual embryonic primary afferents and their spinal projections in the rat.

Embryonic (E19-E20) and early postnatal (P2) spinal cords with intact saphenous and sciatic nerves were isolated and placed in aerated artificial cerebral spinal fluid (CSF). Intracellular recordings were made from cells in the L2-L6 dorsal root ganglia using microelectrodes filled with 3 M potassium acetate or 5% neurobiotin (NB) in 1 M potassium acetate. Several physiological properties of adequately impaled cells were measured, including peripheral conduction velocity, action potential (AP) amplitude and duration, duration of afterhyperpolarization (AHP), input impedance, rheobase, presence of inward rectifying current, and maximum somal firing frequency. The extent to which these properties are correlated also was determined. One cell per ganglion was injected with NB. Stained somata and their central projections in the spinal cord were visualized in serial 50 microm sections. Cell size was determined and the central morphology of the central projections examined. Although some fibers were in the process of growing into the spinal cord, others had established projections over several millimeters in the dorsal columns. Although most of these fibers supported projections in the gray matter, 22% only maintained fibers in the dorsal columns. Fibers with projections in the dorsal horn exhibited three types of morphology: projections confined to the superficial dorsal horn (laminae I, II); terminals confined to laminae III-V; and projections spanning laminae II-V. In addition, some embryonic fibers maintained projections to the dorsal horn that extended over five lumbar segments. Somal APs could be divided into two groups: broad spikes with inflections on their falling phase and narrow spikes without inflections. On average, cells with broad spikes (BS) had the following characteristics: slower peripheral conduction velocity, larger amplitude, higher rheobase and input impedance, longer AHP duration, and lower maximum firing frequency. There were significant correlations between conduction velocity and several of the physiological properties. Conduction velocity was negatively correlated with AP duration, rheobase, and input impedance and positively correlated with maximum firing frequency. Comparisons between spike shape and central morphology revealed that cells lacking collaterals in the gray matter and those with projections in the superficial dorsal horn always had broad somal spikes with inflections. Those with projections confined to laminae III-V always had narrow somal spikes (NS).

Animals↗
PubMed2001

Physiology and morphology of intratelencephalically projecting corticostriatal-type neurons in pigeons as revealed by intracellular recording and cell filling.

Much of the Wulst and dorsal ventricular ridge (DVR) in birds, which together make up the part of the avian telencephalon functionally resembling mammalian cerebral cortex, projects to the striatum. Those connections arise from neurons projecting additionally to the brainstem as well as from neurons projecting only within the telencephalon. As part of an effort to further characterize corticostriatal-type projection neurons in birds, we recorded intracellularly from neurons of the outer DVR, identified neurons projecting to the striatum by antidromic stimulation from the ipsilateral rostromedial striatum or subsequently by their axonal projection, characterized these neurons physiologically and then filled them with biocytin. As neurons in the outer DVR only project within telencephalon, neurons within it projecting to the striatum are of the intratelencephalically projecting (IT) type. Our studies suggest that: (1) the membrane potentials of avian IT-type neurons fluctuate between two preferred subthreshold values, and action potentials occur only in the 'up' state, (2) avian IT-type neurons show a time-dependent inward rectification in response to hyperpolarization and regular firing in response to constant current injection, (3) the conduction velocity of avian IT-type neurons is slow (about 0.2 m/s), (4) avian IT-type neurons possess radially disposed densely spiny dendrites but no apical dendrite, (5) avian IT-type neurons have local and distant collateral projections within the DVR, and (6) individual avian IT-type neurons give rise to an extensive terminal field within the striatum. Aside from the shape of their dendritic tree, IT-type neurons in birds closely resemble IT-type corticostriatal neurons in mammals in these various aspects, although it is presently uncertain whether this neuron type has been inherited in common by birds and mammals from stem amniotes.

Animals↗
PubMed1978

The vestibular nuclei in the domestic hen (Gallus domesticus). IV. The projection to the spinal cord.

Horseradish peroxidase was injected at various levels of the spinal cord of the hen and the cells in the brain stem, labeled due to retrograde transport of the tracer enzyme, were mapped with particular reference to the vestibular nuclear complex. The Deiters' nuclei project ipsilaterally to the spinal cord. The projection from the nucleus Deiters ventralis reaches down to the lumbosacral spinal cord. The spinal projection from the nucleus Deiters dorsalis is somatotopically organized. Cells localized rostrally within the nucleus project to upper parts of the spinal cord cells localized caudally project to the lumbosacral spinal cord. The medial and the descending nucleus contain labeled cells in two compartments of the nuclei. In each of them a rostral one projects to the upper cervical cord, a caudal one projects to the thoracical spinal cord. In addition, labeled cells are observed in the reticular formation, mainly in the pons and the medulla oblongata, in the red nucleus, in the raphe nuclei and in the periaqueductal grey. Very few labeled cells are observed in the locus ceruleus, the nucleus intercalatus and in the nucleus of the solitary tract. In some cases, the number of labeled cells in the various nuclei in the brain stem projecting to the spinal cord was counted to get an impression of the quantitative importance of the vestibulospinal projection relative to afferents to the spinal cord from the other nuclei. The findings are discussed in the light of what is known of the vestibulospinal projection in mammals.

Animals↗
PubMed1995

Organization of the sources of reticulospinal projections in the chicken by means of a confocal laser scanning microscope.

To investigate the manner of reticulospinal projections in chickens, two different fluorescent dyes (Fast-Blue and Diamidino-Yellow) were injected into the lumbar and sacral segments. Results showed that the main projections to the spinal segments are clearly different for the pons and medulla. The main source of the medulospinal projections was in the ventral reticular formation, and the projections from the dorsal reticular formation were sporadic. On the other hand, the main pontine projections arose from the dorsolateral tegmentum and they projected to the sacral segments. In contrast, projections to the lumbar segments were somewhat more dominant in the ventromedial tegmentum than in the dorsolateral tegmentum. Double projection neurons were observed in the ventrolateral reticular formation and dorsolateral tegmentum where there were many cells of origin of the spinal descending projections. The reticulospinal projections manner of birds was organized dorsoventrally, and it was comparable with that of mammals.

Amidines↗