The "Di.S.Co." project: a community-based comprehensive control project of chronic diseases. Time change in intervention strategy. The "Di.S.Co." Research Group.
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Adult↗
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Project management, Part III. Budgets for projects.
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Budgets↗
[Administration of the "Healthy School" project].
INTRODUCTION: The term of project management is commonly used to describe the work of a team that is handling a special program. In this type of management, a form of leadership which creates environment, enables fast movement of participants through different work phases achieving the common aims, is used [1-4]. The "Healthy School" Project, launched in almost all European countries, has been taking place in Yugoslavia since the end of 1991 [5]. The project developed within the country designed as a health promotion-education intervention study in primary schools. The network of 13 schools on 11 locations representing typical economic, cultural and social environments, was established to cover the country. Although the proposed methodological approach from WHO was followed [6], the specific situation in the country (economic crisis, break down of Yugoslav Federation, the war and international blockade) distated the particular modification. The management of the Healthy School Project in general, and in Yugoslavia particularly, is based upon project management structure (Scheme 1). The objective of this research was to assess the Healthy School project management in Yugoslavia, by measuring causal, intervening and output variables. METHOD: In the process of assessing the management in general, three groups of criteria are commonly used: (a) causal (those that influence the course of developments in the Project), (b) intervening (representing the current condition of the internal state of the Project), and (c) output (that reflect the Project achievements). (a) For the purpose of this study the causal criteria were measured by analyzing the overall management strategy and the level of agreement in objectives of the Project itself, the Project Coordinators and main participants in the Project. (b) The intervening criteria used in this assessment were: the time spent on different project activities, the estimate of the severity of the problems in different aspects of project management, the level of personal influence on different aspects of Project development and overall work motivation and satisfaction of all participants. (c) The outcomes of the given management attempts were analyzed by the following output variables: the number of different types of meetings held, the number of seminars, mass media presentation and articles, the amount of money raised and the number of questionnaires administered. Triangular method was used to gather the data: (1) direct observation, (2) four types of questionnaires and (3) project reports and documentation. Four types of specially designed questionnaires were used to examine four groups of participants (Project Coordinators, School Project Managers, Directors and Project Co-operators). The questionnaires were different in the questions concerning examinees' project tasks and types of external communication, while the questions referring to personal characteristics, general features of the project (goals, common jobs, participation in decision making, motivation and satisfaction) were the same for all groups. RESULTS: The average age of the project participants was 45.50 ranging from 25 to 60 years of age. The oldest group was the group of School Directors, while the youngest were School Co-operators. The project has been run mostly by women, while men were predominantly represented in the group of School Directors. The teaching occupation is presented by 61.8%, the rest being health professionals, mostly of preventive orientation. The analysis and classification of participants goals verify that the personal goals of all participants correspond with the main Project goals. Certain groups have also some additional motives which support their successful and affective movement towards the overall Project goals. The largest problem in all groups appear to be in the field of financing the Project activities (Figure 1). (ABSTRACT TRUNCATED)
Administrative Personnel↗
Participation in programs designed to improve employment outcomes for persons with psychiatric disabilities: evidence from the New York WORKS demonstration project.
The New York WORKS demonstration project was designed to improve employment outcomes for persons with psychiatric disabilities receiving Supplemental Security Income (SSI) disability payments. This article shows how the individual characteristics of participants were related to outcomes at each stage of the multistage recruitment process used in the project and how those characteristics contributed to enrollment. The findings are important to program administrators who are interested in ensuring that SSI recipients receive equal access to employment-related services and who want to improve recruitment strategies for future demonstration projects. The New York WORKS recruitment process used administrative records from the Social Security Administration (SSA) to identify the population of over 68,000 SSI recipients with a diagnosis of a psychiatric disability in Erie County and New York City. Staff involved in the project documented the results of each stage of the recruitment process. The New York WORKS project included four stages: (1) the provision of information (sending a letter and information packet); (2) demonstrated awareness of the project (response to a letter containing an overview of the project); (3) expression of interest (indication of interest in the project, using a postmarked form returned to New York WORKS project staff); and (4) participation (actual enrollment in the program). The project staff members were also able to identify data from administrative records that described the characteristics of the population, including age, sex, type of psychiatric diagnosis, the number of months that the person collected benefits before the recruitment process, employment experience before the recruitment process, and annual earnings in the year before the recruitment process. The data on outcomes at each stage of the recruitment process and the characteristics of SSI recipients were analyzed using an empirical method recently suggested by Heckman and Smith. The analysis identified the relationship between the characteristics of SSI recipients and the outcomes at each stage of the recruitment process and demonstrated how those characteristics contributed to the overall likelihood of enrollment. Demographic characteristics, information about diagnosis, and characteristics related to work history had different effects on outcomes at different stages of the recruitment process. For example, younger SSI recipients were less likely to reply to the information letter but more likely to express an interest in the project and more likely to enroll, given that interest. This result suggests that there may be an information barrier for the younger group of SSI recipients during the early recruitment stages. There were also interesting differences by psychiatric diagnosis and by recent employment experience at each stage of the process. Most notably, persons with anxiety disorders were less likely to express an interest in the project and less likely to enroll in the project if they expressed an interest. This finding suggests that project administrators may need to examine more effective methods to accommodate persons with an anxiety disorder at the enrollment stage of the recruitment process. Persons with relatively low earnings in the year before the project were more likely to respond, to express interest in the project, and to enroll than were those with no earnings and those with relatively high earnings. This finding suggests that the recruitment strategy used by the New York WORKS project is more effective at enrolling a subset of the population that has some demonstrated work capacity and that, of those with a demonstrated work capacity, New York WORKS is enrolling those who are likely to have the most to gain from the project. This finding has implications for the development of sample designs for other demonstration projects, in particular the SSA-proposed mental health treatment study. A number of strategies may lead to improvements in future evaluations of participation in SSA projects and programs. For example, the New York WORKS data did not contain information for all SSI recipients on race, education, or literacy. These factors have been shown to be important in the Job Training Partnership Act literature and are likely to play a role in participation. The inclusion of these data in future evaluations may provide important information on participation in SSA projects. Another useful strategy for future evaluations includes the identification of random samples of those who choose not to enroll at different stages in the process and the collection of information on the reason for the decision. These additional data may help project administrators to gain a clearer description of the reasons for differences in outcome that occur at each stage of the process, assess the overall performance of the recruitment process, and improve the recruitment processes used in future projects.
Adult↗
The organization of the projection from the cerebral cortex to the striatum in the rat.
The detailed organization of the corticostriate projection has been investigated in the brain of the rat using the technique of retrograde transport of horseradish peroxidase following the placement of small, iontophoretic injections of horseradish peroxidase conjugated to lectin throughout all major regions of the striatum (caudate-putamen, nucleus accumbens and olfactory tubercle). The results demonstrate that all major regions of the cerebral cortex project to the striatum on both sides of the brain with an ipsilateral predominance. The cells of origin of both the ipsilateral and contralateral corticostriate projections lie mainly in lamina V (especially lamina Va) with very small numbers in lamina III of the neocortex and mesocortex, and in the deep laminae of the allocortex. The results show that each striatal locus receives inputs from several cortical regions, i.e. there is extensive overlap in the corticostriate projection, and that, in general terms, each cortical region projects onto a longitudinally oriented region of the striatum. In particular, the major subdivisions of the cerebral cortex--the neocortex, mesocortex and allocortex--project onto defined but partially overlapping regions of the striatum: the neocortex projects to the caudate-putamen; the mesocortex projects mainly to the medial and ventral regions of the caudate-putamen but also to the ventral striatum (nucleus accumens and olfactory tubercle); and the allocortex projects mainly to the ventral striatum but also to the medial and ventral parts of the caudate-putamen. Within each of these major projection systems there is a further organization, with the constituent parts of each major cortical region projecting to smaller longitudinal components of the major projection fields. Each neocortical area projects to a longitudinal region of the dorsal striatum (caudate-putamen): the sensory and motor areas project topographically onto the dorsolateral striatum such that the rostral sensorimotor cortex (head areas) projects to central and ventral regions and the more caudal sensorimotor cortex (limb areas) projects to dorsal regions of the dorsolateral striatum; the visual area projects to the dorsomedial striatum; and the auditory area projects to the medial striatum. Each mesocortical area projects to a longitudinal area of the striatum: the most posteromedial mesocortex (the retrosplenial area) projects to the dorsomedial striatum; more anterior and lateral parts of the mesocortex project to more ventral parts of the striatum: and the most lateral mesocortex (the agranular insular and perirhinal areas) project to the ventrolateral striatum.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Thalamic connections with limbic cortex. I. Thalamocortical projections.
The thalamocortical projections to limbic cortex in the cat have been studied with retrograde and anterograde axonal transport techniques. Five limbic cortical areas were identified on the basis of cytoarchitecture. The five areas are the anterior limbic area, the cingular area, the dorsal and ventral retrosplenial areas, and the presubiculum. Each of these cortical areas received small injections of horseradish peroxidase, and the afferent thalamic nuclei were identified by retrograde labelling of cells. The cortical projection of each of the anterior thalamic nuclei and the lateral dorsal nucleus was determined autoradiographically. Each of the anterior thalamic nuclei and the lateral dorsal nucleus projects to limbic cortex by two pathways. One group of fibers leaves the rostral thalamus by the fornix, pierces the corpus callosum, joins the cingulate fasciculus to reach limbic cortex. The other group travels through the lateral thalamic peduncle and internal capsule. The anterior ventral nucleus projects primarily to the dorsal retrosplenial area, particularly to layer I, the deep portion of layer II, and superficial portion of layer III. Sparse projections also exist to the ventral retrosplenial area, the cingular area, and the presubiculum. Very sparse projections to the anterior limbic area are seen. The anterior dorsal nucleus projects primarily to the ventral retrosplenial area, particularly layers I, the deep portion of layer II, and superficial layer III. sparse projections exist to the dorsal retrosplenial area and presubiculum, but apparently no projections exist to the cingular or anterior limbic area. The anterior medial nucleus projects primarily to layers I and superficial III of the ventral retrosplenial area. sparse projections exist to each of the other limbic cortical areas. The lateral dorsal nucleus projects extensively onto limbic cortex. Prominent projections occur to layer I, the external granular layer and lamina dessicans of the presubiculum, layers I and III-IV of the dorsal retrosplenial area, and layers I, III, and IV of the cingular area. Sparse projections occur to the ventral retrosplenial area and the anterior limbic areas. Thalamocortical projections also originate in the midline and intralaminar nuclei including the central medial, reuniens, rhomboid, paracentral, central lateral, and central dorsal nuclei. These data indicate that the anterior thalamic nuclei project upon limbic cortex in a complex manner. Further, the projections to limbic cortex from the anterior nuclei overlap with projections from the lateral dorsal nucleus. This overlap of thalamic projections onto limbic cortex suggests a convergence of information from nonprimary sensory systems with information from the classical limbic system.
Animals↗
Topographic organization of subcortical projections to the anterior thalamic nuclei in the rat.
Subcortical projections to the anterior thalamic nuclei were studied in the rat, with special reference to projections from the mammillary nuclei, by retrograde and anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase. The medial mammillary nucleus (MM) projects predominantly ipsilaterally to the entire anterior thalamic nuclei, whereas the lateral mammillary nucleus projects bilaterally to the anterodorsal nucleus (AD) of the anterior thalamic nuclei. A topographic relationship was recognized between the MM and the anterior thalamic nuclei. The dorsal region of the pars mediana of the MM projects to the interanteromedial nucleus (IAM), whereas the ventral region projects to the rostral part of the anteromedial nucleus (AM). The dorsal and the ventral regions of the pars medialis project to the dorsomedial part of the AM at its caudal and rostral levels, respectively. The dorsomedial region of the pars lateralis projects to the ventral AM. The ventrolateral region of the pars lateralis projects to the ventral part of the anteroventral nucleus (AV) in such a manner that rostral cells project rostrally and caudal cells project caudally. The pars basalis projects predominantly ipsilaterally to the dorsolateral AV and bilaterally to the AD. The rostrolateral region of the pars posterior projects to the lateral AV, whereas the medial and the caudal regions of the pars posterior project to the dorsomedial AV. The rostrodorsal part of the nucleus reticularis thalami was found to project to the anterior thalamic nuclei; cells located rostrally in this part project to the IAM and AM, whereas cells located caudodorsally project to the AV and AD. The laterodorsal tegmental nucleus projects predominantly ipsilaterally to the AV, especially to its dorsolateral part. The present study demonstrates that subdivisions of the subcortical structures are connected to the subnuclei of the anterior thalamic nuclei, with a clear-cut topography arranged in the dorsoventral and the rostrocaudal dimensions.
Animals↗
Projections from the red nucleus and surrounding areas to the brainstem and spinal cord in the cat. An HRP and autoradiographical tracing study.
HRP injections at the C2, T1 and S1 spinal levels and in the medullary lateral tegmental field revealed that the contralaterally projecting rubro-bulbospinal neurons are located not only in the caudal but also to a certain extent in the rostral red nucleus (RN). These RN projections are somatotopically organized. Neurons projecting to the sacral cord are located in the ventrolateral RN, those projecting to the upper part of the spinal cord lie in the dorsomedial RN and those projecting to the medullary lateral tegmentum were found in the dorsal portions of the RN. These last neurons are smaller than many of the other RN neurons. The HRP results also revealed that the RN does not project to the caudal raphe nuclei. The autoradiographical results confirmed the HRP findings. They further indicated that the contralateral RN projections to the caudal brainstem precerebellar nuclei (nucleus corporis pontobulbaris, lateral reticular nucleus, lateral cuneate nucleus) and the dorsal column nuclei are also somatotopically organized. This was also true for the RN projections to the dorsomedial and intermediate facial subnuclei and the caudal pontine and medullary lateral tegmental field. These areas receive afferents from mainly the dorsal portions of the RN. Regarding the RN projections to the spinal cord, the autoradiographical tracing results revealed somatotopically organized contralateral RN projections to laminae V, VI and VII. Moreover, a small but distinct RN projection to a dorsolaterally located group of motoneurons at the C8-T1 level was demonstrated. Ipsilaterally a minor projection to the cervical and upper thoracic lateral intermediate zone was observed. Finally, strong ipsilateral projections from the rostral mesencephalon to the inferior olive were seen. These projections were derived from various rostral mesencephalic areas, including the nucleus of Darkschewitsch, the nucleus accessorius medialis of Bechterew, the interstitial nucleus of Cajal and the area of the rostral interstitial nucleus of the medial longitudinal fasciculus. In the cat it was difficult to define which of the mesencephalic areas projecting to the inferior olive represented the parvocellular RN. A new subdivision of the RN is proposed based on its projections and not on the size of its cells. In this concept the first group is formed by the RN neurons projecting contralaterally to the caudal brainstem and spinal cord. The second group consists of RN neurons projecting to the inferior olive.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
The thalamostriatal projection in the cat.
The organization of the projections from the intralaminar and other thalamic nuclei to the caudate nucleus (CD), putamen (PU), nucleus accumbens (Acc), and olfactory tubercle (TO) were examined in the cat by autoradiography after deposits of 3H-amino acids in individual thalamic nuclei and by retrograde cell labeling after intrastriatal deposits of wheat-germ-conjugated horseradish peroxidase. All of the rostral intralaminar nuclei, here considered to include the central lateral (CL), paracentral (PC), central medial (CeM), and rhomboid nuclei (Rh), project to the striatum. Projections closely associated with those of the rostral intralaminar group arise from cells of the paraventricular nucleus (PV) and a region lateral to the stria medullaris. These nuclei, which roughly form a ring around the mediodorsal nucleus, project in a highly particular, but loosely arranged topographic pattern to all parts of the striatum. The medially located cells in Rh, PV, and those alongside the stria medullaris project mainly to medial parts of Acc and CD; the dorsolaterally located cells of CL project mainly to the dorsolateral parts of CD and PU; cells in PC and CeM project to progressively more ventral and medial parts of CD and PU, and the lateral part of Acc. Superimposed on this projection from the rostral intralaminar region is the projection from the caudal intralaminar group including the centromedian (CM), parafascicular (PF), and subparafascicular nuclei (subPF). Together these nuclei project in a loosely but specifically organized topography to the entire striatum. The lateral and dorsal parts of CD and PU receive fibers mainly from CM. Ventral and medial parts of CD and PU and Acc receive fibers mainly from PF; TO receives fibers from subPF and the ventral part of PF. Several nuclei in the lateral nuclear mass of the thalamus also project to particular parts of the striatum. Thus, cells in the rostromedial part of the ventral anterior nucleus project to the head of CD and some cells in the rostral part of the ventromedial nucleus project to the head of CD and to PU. Several cells scattered in the lateral posterior complex project to lateral parts of the head of CD, and cells in the rostral extension of the medial subdivision of the posterior nuclear complex project to lateral parts of the head and body of CD. Finally, several cells of the paratenial nucleus project selectively to Acc. These data provide a detailed map of the total thalamostriatal projection in the cat and, hence, form a basis for more specific functional questions about this poorly understood system.
Animals↗
Projections from the anterodorsal and anteroventral nucleus of the thalamus to the limbic cortex in the rat.
The present study characterized the projections of the anterodorsal (AD) and the anteroventral (AV) thalamic nuclei to the limbic cortex. Both AD and AV project to the full extent of the retrosplenial granular cortex in a topographic pattern. Neurons in caudal parts of both nuclei project to rostral retrosplenial cortex, and neurons in rostral parts of both nuclei project to caudal retrosplenial cortex. Within AV, the magnocellular neurons project primarily to the retrosplenial granular a cortex, whereas the parvicellular neurons project mainly to the retrosplenial granular b cortex. AD projections to retrosplenial cortex terminate in very different patterns than do AV projections: The AD projection terminates with equal density in layers I, III, and IV of the retrosplenial granular cortex, whereas, in contrast, the AV projections terminate very densely in layer Ia and less densely in layer IV. Further, both AD and AV project densely to the postsubicular, presubicular, and parasubicular cortices and lightly to the entorhinal (only the most caudal part) cortex and to the subiculum proper (only the most septal part). Rostral parts of AD project equally to all three subicular cortices, whereas neurons in caudal AD project primarily to the postsubicular cortex. Compared to AD, neurons in AV have a less extensive projection to the subicular cortex, and this projection terminates primarily in the postsubicular and presubicular cortices. Further, the AD projection terminates in layers I, II/III, and V of postsubiculum, whereas the AV projection terminates only in layers I and V.
Animals↗
Stream restoration and enhancement projects: is anyone monitoring?
Declines in salmon stocks and general watershed health in Washington State, USA, have led to an increase in stream restoration and enhancement projects initiated throughout the state. The increasing number of projects has also raised questions regarding the monitoring of these efforts. Project managers receiving hydraulic project approvals (HPAs) were surveyed to determine whether monitoring was taking place on their projects. About half the project managers surveyed reported the collection of baseline data and the use of biological, physical, chemical, or other water quality measures for their projects. Of those who reported collection of monitoring data, only 18% indicated that monitoring was required. Respondents were also asked to rank the importance of various project goals on a Likert scale. Project managers with projects focusing on "engineering" goals (e.g., roadbed stabilization) were less likely than other project managers to collect baseline monitoring data. Project managers with projects focusing on "restoration/ecological" or "fisheries" goals were more likely than other project managers to collect monitoring measures. Although monitoring appears to be taking place in slightly more than half of the projects surveyed, the nature of the data collected varies widely across projects, and in most cases the monitoring effort is voluntary. This suggests that project sponsors, funders, and managers must consider the issues involved in requiring appropriate monitoring, establishing standardized monitoring guidelines, the time frames in which to monitor, providing other incentives for conducting monitoring, and ensuring adequate funding for monitoring efforts.
Animals↗
Perirhinal and parahippocampal cortices of the macaque monkey: projections to the neocortex.
We investigated the topographic and laminar organization of the efferent cortical projections of the perirhinal and parahippocampal cortices. Area 36 of the perirhinal cortex projects preferentially to areas TE and TEO, whereas area TF of the parahippocampal cortex projects preferentially to the posterior parietal cortex and area V4. Area TF projects to many regions of the frontal lobe, whereas area 36 projects mainly to the orbital surface. The insular and cingulate cortices receive projections from areas 36 and TF, whereas only area TF projects to the retrosplenial cortex. Projections to the superior temporal gyrus, including the dorsal bank of the superior temporal sulcus, arise predominantly from area TF. Area 36 projects only to rostral levels of the superior temporal gyrus. Area TF has, in general, reciprocal connections with the neocortex, whereas area 36 has more asymmetric connections. Area 36, for example, projects to more restricted regions of the frontal cortex and superior temporal sulcus than it receives inputs from. In contrast, it projects to larger portions of areas TE and TEO than it receives inputs from. The efferent projections of areas 36 and TF are primarily directed to the superficial layers of the neocortex, a laminar organization consistent with connections of the feedback type. Projections to unimodal visual areas terminate in large expanses of the cortex, but predominantly in layer I. Projections to other sensory and polymodal areas, in contrast, terminate in a columnar manner predominantly in layers II and III. In all areas receiving heavy projections, the projections extend throughout most cortical layers, largely avoiding layer IV. We discuss these findings in relation to current theories of memory consolidation.
Amino Acids↗
The cortical projections of the mediodorsal nucleus and adjacent thalamic nuclei in the rat.
The mediodorsal nucleus of the rat thalamus has been divided into medial, central and lateral segments on the basis of its structure and axonal connections, and these segments have been shown by experiments using the autoradiographic method of demonstrating axonal connections to project to seven distinct cortical areas covering most of the frontal pole of the hemisphere. The position and cytoarchitectonic characteristics of these areas are described. The medial segment of the nucleus projects to the prelimbic area (32) on the medial surface of the hemisphere, and to the dorsal agranular insular area, dorsal to the rhinal sulcus on the lateral surface. The lateral segment projects to the anterior cingulate area (area 24) and the medial precentral area on the dorsomedial shoulder of the hemisphere, while the central segment projects to the ventral agranular insular area in the dorsal bank of the rhinal sulcus, and to a lateral part of the orbital cortex further rostrally. (The term "orbital" is used to refer to the cortex on the ventral surface of the frontal pole of the hemisphere.) A ventral part of this orbital cortex also receives fibers from the mediodorsal nucleus, possibly its lateral segment, but the medial part of the orbital cortex, and the ventrolateral orbital area in the fundus of the rhinal sulcus receive projections from the paratenial nucleus and the submedial nucleus, respectively. All of these thalamocortical projections end in layer III, and in the outer part of layer I. The basal nucleus of the ventromedial complex (the thalamic taste relay) has been shown to have a similar laminar projection (layer I and layers III/IV) to the granular insular area immediately dorsal to, but not overlapping, the mediodorsal projection field. However, the principal nucleus of the ventromedial complex appears to project to layer I, and possibly layer VI, of the entire frontal pole of the hemisphere. The anteromedial nucleus does not appear to project to layer III of the projection field of the mediodorsal nucleus, although it may project to layers I and VI, especially in the anterior cingulate and medial precentral areas. A thalamoamygdaloid projection from the medial segment of the mediodorsal nucleus to the basolateral nucleus of the amygdala has also been demonstrated, which reciprocates an amygdalothalamic projection from the basolateral nucleus to the medial segment. The habenular nuclei also appear to project to the central nucleus of the amygdala. These results are discussed in relation to the delineation and subdivision of the prefrontal cortex in the rat, and to amygdalothalamic and amygdalocortical projections which are described in a subsequent paper (Krettek and Price, '77).
Amygdala↗
Alterations of the crossed parabigeminotectal projection induced by neonatal eye removal in rats.
Projections of the parabigeminal nucleus to the contralateral superior colliculus and dorsal lateral geniculate nucleus were examined in normal adult pigmented rats and in adult rats from which one or both eyes had been removed at birth. In normal rats the crossed parabigeminotectal projection is restricted to the superficial layers in anterior and medial areas of colliculus, regions innervated also by the lower temporal portion of the ipsilateral retina. In unilaterally enucleated animals the crossed parabigeminotectal projection to the "denervated" colliculus is expanded, as is the retinal projection from the ipsilateral eye. In addition, there is a crossed parabigeminal projection to the "denervated" dorsal lateral geniculate nucleus in these rats. In bilaterally enucleated animals the parabigeminotectal projection is expanded, but not as greatly as in unilateral enucleation cases; there is a crossed parabigeminothalamic projection in these animals as well. The corresponding termination patterns of the contralateral parabigeminal nucleus and the ipsilateral retina in the normal superior colliculus may indicate a functional and/or developmental interdependence between the projections from these two regions. The existence of an expanded parabigeminotectal projection in bilaterally enucleated rats shows that a sustained ipsilateral retinotectal projection is not necessary for the establishment of a crossed parabigeminotectal projection, but points to the possibility that ipsilateral retinal input may constrain the parabigeminal projection to terminate within certain boundaries. The even greater expansion of the projection from the parabigeminal nucleus to the colliculus which receives an expanded projection from the ipsilateral retina of unilaterally enucleated rats suggests that the functional organization of the ipsilateral retinotectal projection may be capable of restricting the size of the terminal field of the crossed parabigeminotectal projection.
Animals↗
Laminar and areal differences in the origin of the subcortical projection neurons of the rat somatosensory cortex.
Fluorescent retrograde tracing techniques were employed in a double-labelling paradigm to determine the distribution of corticospinal, corticotectal, and corticotrigeminal projection neurons in layer Vb of the adult and neonatal rat somatosensory cortex. The double-labelling paradigm allowed a direct comparison of the cortical distribution of neurons projecting to each target and identification of neurons projecting to more than one target. In the adult rat, each population of projection neurons was found to have a unique laminar and/or areal distribution. Corticospinal projection neurons were located throughout the width of layer Vb in the medial granular portion of somatosensory cortex, while corticotrigeminal projection neurons were distributed throughout the width of layer Vb in the more laterally located dysgranular portion of somatosensory cortex. Corticotectal projection neurons were located more superficially in layer Vb than either corticospinal or corticotrigeminal projection neurons and found scattered throughout both dysgranular and granular somatosensory cortex. Each combination of subcortical injections also resulted in double labelling a small percentage of uniquely distributed neurons. These distribution differences coupled with measurements of cell size allowed us to identify the parent population of the dual projection neurons. Subpopulations of corticotectal neurons also project to the brainstem trigeminal complex and to the spinal cord. Subpopulations of corticotrigeminal neurons also project to the spinal cord, and a proportion of corticotrigeminal neurons projects to at least two targets within the brainstem trigeminal complex (nucleus principalis and subnucleus interpolaris). In the adult rat, corticospinal neurons (as defined by either laminar position or somal size) did not appear to give off collaterals to either the superior colliculus or brainstem trigeminal complex. In the neonatal rat, double-labelled neurons which project to both the spinal cord and the tectum are distributed throughout the full width of layer Vb, rather than restricted to the superficial portion of the layer as in the adult rat. Further, it appears as if the ontogenetic change in the laminar distribution of corticospinal and tectal projection neurons is achieved by mechanisms of selective process elimination rather than cell death. These results are discussed in terms of both the developmental factor which may contribute to the discrete distribution of cortical projection neurons found in the adult and the functional significance of bifurcating projection neurons.
Animals↗
Cerebellar nucleo-olivary projections in the rat: an anterograde tracing study with Phaseolus vulgaris-leucoagglutinin (PHA-L).
In order to evaluate the reciprocity of olivo-cerebellar and cerebello-olivary connections, a detailed description of the cerebellar nucleo-olivary projection in the rat is presented using small, iontophoretic injections of the anterograde tracer Phaseolus vulgaris-leucoagglutinin. Sparse projections were found to arise from the rostral part of the medial cerebellar nucleus toward the lateral part of the caudal medial accessory olive. Its medial parts receive a projection from the dorsolateral protuberance of the medial cerebellar nucleus. Caudal and lateral regions of the medial cerebellar nucleus project to the "beta" group and dorsomedial cell column. Heavy olivary projections to circumscribed parts of the inferior olive were found after injections in the remaining cerebellar nuclei. The medial part of the posterior interposed nucleus connects to caudolateral areas of the rostral half of the medial accessory olive, whereas lateral areas project to more rostromedial parts. The most ventromedial part of the lateral cerebellar nucleus projects to the ventrolateral outgrowth. Adjacent medial, ventral, and caudal regions connect to the ventral leaf of the principal olive. The cerebellar origin of the projection to its dorsal leaf is located in lateral, dorsal, and rostral parts of the lateral cerebellar nucleus. The dorsolateral hump projects to the dorsomedial group of the rat inferior olive. Rostromedial projections to the dorsal accessory olive originate from the lateral part of the anterior interposed nucleus, whereas its medial parts project to more lateral and caudal regions of this olivary subnucleus. The dorsal fold of the dorsal accessory olive does not receive a projection from the cerebellar nuclei but from the lateral vestibular nucleus. No cerebellar projections were found to the dorsal cap. Relatively strong ipsilateral projections, which were the mirror images of the contralateral projections, were observed in the dorsomedial group, rostral medial accessory olive, and ventral leaf of the principal olive. When both the inferior olive and the cerebellar nuclei are considered as folded but continuous sheets of grey matter, the complete nucleo-olivary projection can be described as a simple transformation.
Animals↗
Topographical and topological organization of the thalamocortical projection to the striate and prestriate cortex in the marmoset (Callithrix jacchus).
In eleven hemispheres of nine marmoset monkeys (Callithrix jacchus), we have investigated the thalamo-cortical organization of the projections from the pulvinar to the striate and prestriate cortex. In each experiment, single or multiple injections of various retrograde fluorescent tracers were injected into adjacent regions or areas. In two experiments, horseradish peroxidase (HRP) was injected into the lateral geniculate nucleus (LGN) and the lateral pulvinar, respectively. The results show that the thalamo-cortical projection from LGN to striate cortex and from pulvinar to the prestriate cortex are similarly organized, but the geniculo-striate projection is more precise than the pulvinar-prestriate projection. The pulvinar-prestriate projection is topographically organized and preserves topological neighbourhood relations. Projection zones to the various visual areas are concentrically wrapped around each other. The projection zone to area 18 constitutes a central core region. It begins ventro-laterally in PuL where the pulvinar is in contact with the LGN. This contact zone we called the hilus region of the pulvinar. The area 18-projection zone stretches as a central cone into the posterior pulvinar through PuL and into PuM. It is surrounded by the projection zone to the posterior belt of area 19 and this in turn is surrounded by the projection zone to the anterior belt of area 19. The projection zones to area 19 are then surrounded medially and dorsally by zones projection to the temporal and parietal association cortex, respectively. The projection zone to area MT is located medio-ventrally in the posterior pulvinar (PuIP and surrounding nuclei) and coincides with a densely myelinated region. Area 17 also receives input from the pulvinar but probably predominantly in the region of the central visual field. The pulvinar zone projecting to area 17 is located ventrolaterally from the central core region projecting to area 18 and is contiguous laterally with the LGN. If the positions of the vertical and the horizontal meridian in the pulvinar correspond to those in the respective cortical projection zones, a second order visual field representation such as found in area 18, with the horizontal meridian split at an eccentricity of about 7-10 degrees, can also be recognized in the pulvinar.
Acetylcholinesterase↗
Functional organization of the direct and indirect projection via the reticularis thalami nuclear complex from the motor cortex to the thalamic nucleus ventralis lateralis.
The projection systems which arise from the motor cortex to reach the nucleus ventralis lateralis (VL) were investigated in the rat. They included a direct as well as an indirect projection via the reticularis thalami nuclear complex (RT). The investigation was performed in two steps: i) the former concerned the projection to the VL as well as to the RT from individual cortical foci electrophysiologically identified by the motor effects evoked by electrical stimulation; the second step concerned the projection from the RT to functionally defined regions of the VL. The direct projection from the motor cortex to the VL is somatotopically arranged. The projection reciprocates the fiber system directed from the VL to the motor cortex. Thus cortical zones controlling the motor activity of the proximal segments of the limbs project onto the regions of the VL that project back to these same cortical areas. With regard to cortical zones controlling the motor activity of the distal segments of the limbs, they not only project to the region of the VL specifically related to them, but also to the region of the VL associated with the cortical areas responsible for movements of the proximal parts of the same limb. In that case fiber terminals were more dense in the VL region controlling the proximal segment than in the region controlling the distal segment of the same limb. This organization suggests that proximal adjustments may be automatically provided by the motor activity of the distal segments of the same limb. The motor cortex projects to the rostral region of the RT with a precise topographical organization. In particular, the projection shows a dorsoventral organization in the RT in relation to the caudorostral body representation in the motor cortex. The projection which arises from the rostral region of the RT also reaches the VL with a topographical arrangement. It discloses a rostrocaudal organization in the VL in relation to a dorsoventral displacement in the RT. Comparing the projection from the motor cortex to the RT and that from this nuclear complex to the VL it was shown that the regions of the VL and their receptive cortical areas were associated with the same regions of the RT. It was therefore concluded that the motor cortical projection to the VL relayed by the RT is somatotopically organized. In both direct and relayed pathways the projections from "hind-" and "forelimb" motor area are segregated, whereas the "head" projection overlaps, at least partially, the "forelimb" terminal field.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗