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PubMed1989

Projections of enteric peptide-containing neurons in the rat.

In order to understand better the neuronal circuitry involved in the regulation of gut functions, we have studied the distribution and projections of those enteric neurons in the rat intestines that contain vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), galanin, substance P (SP), calcitonin gene-related peptide (CGRP), gastrin releasing peptide (GRP), somatostatin and enkephalin. The origin of the peptide-containing nerve fibers was examined by immunocytochemistry after extrinsic denervation. Most of them were found to be intramural in origin, each population displaying its own characteristic topographic distribution. The projections of each neuronal population were studied immunocytochemically by examining the subsequent axonal degeneration after local severing of nervous pathways. This study revealed that myenteric neurons issue predominantly descending projections to other myenteric ganglia and to the muscle layers. Submucous neurons project to other submucous ganglia and to the mucosa and submucosa. Most of these neurons issue both ascending and descending projections. The projection distances varied considerably between the different neuronal populations, the majority being in the range of 4-10 mm. Myenteric GRP and galanin neurons in the small intestine issued the longest projections, 20 and 15 mm, respectively. The shortest projections were those issued from myenteric VIP/NPY neurons and submucosal galanin and GRP neurons in the small intestine and from submucosal VIP neurons in the large intestine (2 mm in length). On the whole our results on the projections of enteric neurons in the rat agree with observations in the guinea pig and dog. However, there are species differences that remain to be explained.

Animals↗
PubMed2004

Projection-based needle segmentation in 3D ultrasound images.

Needles are used extensively in interventional procedures such as biopsy and brachytherapy. To deliver radioactive seeds to pre-planned positions or sample lesions from the region that may contain cancer cells, the 3D position of the needle must be determined accurately and quickly. Three-dimensional ultrasound (US) image guidance is an efficient technique used to perform this task. In this paper, we describe the development of a projection-based needle segmentation method comprising three steps. First, the 3D image is projected along an initial direction perpendicular to the approximate needle direction determined from the 3D imaging system. The needle is then segmented in a projected 2D image. Using the projection direction and the detected 2D needle direction, a plane containing the needle--called the needle plane--is determined. Secondly, the 3D image is re-projected in the direction perpendicular to the normal of the needle plane and step 1 is repeated. If the needle direction in the projected 2D image is horizontal, the needle plane is correct; otherwise, steps 1 and 2 are repeated until a correct needle plane is found. Thirdly, the 3D image is projected along the normal direction of the needle plane and the needle endpoints in the projected 2D image are determined. Using the relationship between the 3D projection and the 3D volume coordinate systems, the coordinates of the endpoints of the needle in the 3D US coordinate system are determined. Experiments with agar and turkey phantom 3D US images demonstrated that our method could segment the needle from 3D US images with an average accuracy of 0.7 mm in position and 1.2 degrees in orientation with a speed of 13 fps on a 1.3-GHz PC. In addition, experiments illustrated that our method is robust to variations in the initial estimated needle direction, the size of the cropped volume, and the ray-casting transfer function parameters used in pre-processing.

Algorithms↗
PubMed1999

Differential projections to the intralaminar and gustatory thalamus from the parabrachial area: a PHA-L study in the rat.

The organization of projections from the parabrachial (PB) area to the ventral posterior parvicellular (VPpc) "gustatory" and intralaminar nuclei of the thalamus was studied in the rat by using microinjections of Phaseolus vulgaris leucoagglutinin (PHA-L), into subregions of the PB area. The present study is a follow-up of three former studies (Bernard et al. [1993] J. Comp. Neurol. 329:201-229; Aldén et al. [1994] J. Comp. Neurol. 341:289-314; Bester et al. [1997a] J. Comp. Neurol. 383:245-281) that examined PB projections onto the amygdala, the bed nucleus of the stria terminalis, and the hypothalamus. Our data showed that (1) the region centered in the internal lateral PB subnucleus projects densely with a bilateral and symmetric pattern to the caudal portion of the paracentral and, to a lesser extent, to the adjacent portion of the central and parafascicular medial thalamic nuclei; (2) the mesencephalic PB region centered in the ventral lateral subnucleus and scattered neurons in the subjacent brachium conjunctivum project primarily, although diffusely, to the central medial thalamic nucleus. The third region includes two subgroups: (3a) the medial subgroup, including the medial, the waist area, and the ventral lateral subnuclei of the pontine PB area, projects bilaterally but with a weak ipsilateral predominance to the VPpc, terminals bearing large varicosities. Additionally, a diffuse projection with small varicosities spreads in the area between the two VPpc nuclei and the central medial nucleus. (3b) The lateral subgroup, centered in the external medial subnucleus, projects with a contralateral predominance in the periphery of the VPpc nuclei, most terminals being located around the dorsomedial tip. It is suggested that the PB projections to the intralaminar nucleus could be involved in cortical limbic arousal processing in relation with nociceptive, (somatic, visceral, and intraoral) and gustatory aversive stimuli. The projection with large varicosities inside the VPpc could process gustatory discrimination.

Animals↗
PubMed1999

Spinal cord-projecting vasopressinergic neurons in the rat paraventricular hypothalamus.

The paraventricular hypothalamic nucleus (PVH) is a key structure for the maintenance of homeostasis. Homeostatic regulation includes modulation of signaling in the spinal cord. This may be exerted by neurons in the PVH with spinal projections. However, the PVH is not a homogeneous structure, but consists of anatomically and functionally distinct subdivisions. In this study, we have analyzed the distribution of spinal cord-projecting PVH neurons that express vasopressin, an important neuropeptide in autonomic regulation. Vasopressinergic neurons were identified with a radiolabeled riboprobe complementary to vasopressin mRNA combined with immunohistochemical labeling of retrogradely transported cholera toxin subunit b in spinally projecting neurons. More than 40% of the spinally projecting neurons in the PVH of naive Sprague-Dawley rats were found to express vasopressin mRNA. The lateral parvocellular subdivision and the ventral part of the medial parvocellular subdivision contained the densest distribution of spinal cord-projecting vasopressin mRNA-expressing neurons. The magnocellular subdivisions displayed large numbers of vasopressin mRNA-expressing neurons, but very few of those projected to the spinal cord. The dorsal parvocellular subdivision contained a large number of spinally projecting neurons, but very few of those expressed vasopressin mRNA. These findings show that the PVH gives rise to a major vasopressinergic projection to the spinal cord and that the spinal cord-projecting vasopressinergic neurons are parceled into anatomically distinct cell groups. This provides an anatomical basis for a selective activation of functionally different groups in the PVH as part of a behaviorally adaptive response, including modulation of autonomic activity and pain processing at the spinal level.

Animals↗
PubMed1999

Organization of projections to the lateral amygdala from auditory and visual areas of the thalamus in the rat.

Projections to the amygdala from the auditory thalamus have been implicated in the associative conditioning of fear responses to acoustic stimuli. Thalamo-amygdala auditory projections enter the amygdala via the lateral nucleus (LA). It is well documented that these projections originate in the medial division (MGm) of the medial geniculate nucleus (MGN), the posterior intralaminar nucleus (PIN), and the suprageniculate nucleus (Sg). It is not known, however, whether these thalamic projections terminate in a topographic fashion within the LA. We therefore used several retrograde tract tracing techniques to determine whether the terminations of thalamo-amygdala fibers have a topographic organization within the LA. These tracers were injected into various locations within the LA, and the distribution of the retrogradely labeled cells throughout the thalamus was analyzed. In general, rostral to caudal distinctions in the thalamus are maintained in the LA, such that projections from throughout the MGN terminate in the anterior part of the LA, whereas the caudal part of the MGN projects to the caudal part of the LA. Furthermore, the density of cells that give rise to thalamo-amygdala projections varies within each thalamic nucleus along the rostro-caudal axis. The patterns of thalamo-amygdala connectivity observed support previous parcellation schemes that segregate the LA into dorsal, medial, and lateral areas, and suggest that the LA should be further divided into anterior and posterior parts. In addition to the well-known projections to the LA originating from PIN, MGN, and Sg, we also found substantial projections from the dorsal portion of the MGN (MGd) and the lateral posterior thalamic nucleus (LP). These findings suggest that some of the functional segregation in the thalamus may be preserved in the LA, and that the role of the MGd and LP in thalamo-amygdala transmission should be reconsidered.

Amygdala↗
PubMed2000

Unequal representation of the temporal and nasal retina in an anomalous projection to the lateral thalamus.

Study of an anomalously regenerated, nontopographically organized retinal projection in the frog olfactory cortex revealed that the temporal retina is the main source of this projection, suggesting the existence of specific temporal fiber-directed attractant or trophic influences. In the present study, we examined the organization of an anomalous retinal projection that forms in the frog thalamus after ablation of the optic tectum. The projections from different sectors of the retina were studied by means of the anterograde transport of biotinylated dextran-amine (BDA) delivered to incisions made across the nerve fiber layer in frogs surviving ablation of the contralateral tectal hemisphere for 13-46 weeks. The projections from nasal retinal sectors were always lightly constructed in the aberrant terminal field, whereas their projections to the lateral geniculate complex remained reasonably strong. In contrast, the projections from temporal retinal sectors, though also weak initially, in time became robust and filled the aberrant field over most of its extent. The specific amplification of the temporal fiber projection now observed in two foreign targets provides further evidence for the existence of target-based, attractant/trophic molecules with functional specificity for temporal retinal fibers. That such agents can exist or be inducible in a foreign area would suggest that they belong to a family of molecules having natural biological activity in normal development or regeneration. However, the possibility that the augmented role of the temporal retina in these projections is a result of experience-based plasticity is also discussed.

Animals↗
PubMed2000

Ballistic seed projection in two herbaceous species.

We found that the majority of ballistic seeds tested [N = 74 of 78 in Vicia sativa ssp. nigra (Fabaceae); N = 25 of 27 in Croton capitatus var. capitatus (Euphorbiaceae)] were projected at angles that would yield a greater distance than the average of seeds with the same initial speed projected at random angles. In addition, the median of fractional distance error (maximum distance - seed distance)/(maximum distance), of the seeds were 0.11 and 0.04 for V. sativa and C. capitatus, respectively. Seed projection distance was modeled by using initial projection angle, initial speed, and measured drag, along with other seed data. We improved upon previous such studies by using dual-angle high-speed stroboscopic photography to determine initial projection angle and speed. We also measured seed drag in a low-turbulence wind tunnel. Seed projection positions on the plant, which also affect seed projection distance, were found to be primarily from the top of the plant, with 98 of 137 and 407 of 407 fruits in the upper half of the plant for V. sativa and C. capitatus, respectively. Our findings are significant because they suggest that in addition to the ballistic projection mechanism itself, the species studied have additional adaptations that result in enhanced seed projection distance from the parent plant.

Journal Article↗
PubMedDate not supplied

Neonatal skin care: evaluation of the AWHONN/NANN research-based practice project on knowledge and skin care practices. Association of Women's Health, Obstetric and Neonatal Nurses/National Association of Neonatal Nurses.

OBJECTIVE: To develop and evaluate an evidence-based clinical practice guideline for assessment and routine care of neonatal skin, educate nurses about the scientific basis for practices recommended in the guideline, and design procedures that facilitate implementation of the project guideline into clinical practice. DESIGN: Descriptive report of the collaborative neonatal skin care research-based practice project of the Association of Women's Health, Obstetric and Neonatal Nurses and the National Association of Neonatal Nurses. SETTING: Neonatal intensive-care unit (NICU) and special-care nurseries and well-baby nurseries in 51 hospitals located throughout the United States. PARTICIPANTS: Member site coordinators (N = 51), nurses who work at the selected sites, and the neonates observed during both the pre- and postimplementation phases of the project (N = 2,820). METHOD: An evidence-based clinical practice guideline was developed, sites were selected from all respondents of the call for sites, site coordinator training was provided, data collection was facilitated by project-specific data collection tools, and the project was evaluated by the science team. MAIN OUTCOME MEASURES: Diversity and numbers of sites represented, patient representation, site coordinator knowledge of neonatal skin care pre- and postimplementation, use of project-designed implementation tools, satisfaction with project guideline and the data collection process, changes in practices and product use, and site coordinators' experiences during guideline implementation. RESULTS: Fifty-one sites completed the project, representing NICU, special-care, and well-baby nurseries in both academic and community hospital settings in 27 states. Registered nurses working in these sites totaled 4,754 full-time equivalent positions (FTEs) (in NICU/special-care and well-baby nurseries). Site coordinators demonstrated increased knowledge of research-based neonatal skin care and satisfaction with the implementation tools and data collection process. Product use changed, reflecting acquisition of new knowledge. Barriers to implementation of the guideline were identified. CONCLUSIONS: The AWHONN/NANN Neonatal Skin Care Research-Based Practice Project demonstrated increased knowledge among site coordinators who received training, facilitated changes in neonatal skin care as defined by the practice guideline, and thus advanced evidence-based clinical practice.

Clinical Nursing Research↗
PubMed2000

Divorced women at retirement: projections of economic well-being in the near future.

The Modeling Income in the Near Term (MINT) data system projects retirement income for persons retiring in the 1990s through 2020. Using those data, we examine the economic well-being of divorced women at retirement. The MINT data system improves upon previous estimates of Social Security benefits by: Measuring and projecting years of marriage to determine if the 10-year requirement has been met, Projecting lifetime earnings until retirement and eligibility for Social Security retirement benefits, and Estimating lifetime earnings of former spouses. MINT also makes independent projections of each retiree's income from pensions, assets, and earnings (for working beneficiaries). As a result of changes in marital patterns, MINT projects that the proportion of women who are divorced will increase. At the same time, the proportion of those women who are eligible for auxiliary benefits is projected to decrease, for two main reasons. First, changes in women's earnings and work patterns result in more women receiving retired-worker benefits based on their own earnings. Second, an increased number of divorced women will not meet the 10-year marriage requirement for auxiliary benefits. Despite the projected decrease over time in eligibility rates for auxiliary benefits, the level of Social Security benefits is projected to change little between the older and younger birth cohorts of divorced women entering retirement. According to the MINT data, the most vulnerable of divorced women will be those who have not met the 10-year marriage requirement. Poverty rates will be higher for them than for all other divorced women. This group of divorced women is projected to grow as more and more women divorce from shorter marriages. With more women divorcing and with fewer divorced women meeting the 10-year marriage requirement, the proportion of economically vulnerable aged women will increase when the baby boom retires. Further research is warranted on this long neglected subject. Analyses of divorced women's economic well-being by major socioeconomic characteristics such as race and ethnicity and education are of particular interest. Such analyses can be supported by the MINT data system.

Age Factors↗
PubMed2001

Dendritic arborizations of the rat substantia nigra pars reticulata neurons: spatial organization and relation to the lamellar compartmentation of striato-nigral projections.

The cerebral cortex provides a major source of inputs to the basal ganglia. As has been well documented, the topography of corticostriatal projections subdivides the striatum into a mosaic of functionally distinct sectors. How information flow from these striatal sectors remains segregated or not within basal ganglia output nuclei has to be established. Electrophysiologically identified neurons of the rat substantia nigra pars reticulata were labeled by juxtacellular injection of Neurobiotin, and the spatial organization of their dendritic arborizations was analyzed in relation to the projection fields of individual striatal sectors. Thirty-nine nigral neurons located in the projection territory of the distinct striatal sensorimotor sectors were reconstructed. The data show that the dendritic arborizations of nigral neurons conform to the geometry of striato-nigral projections. Like striatal projections, the arborizations formed a series of curved laminas enveloping a dorsolaterally located core. Although dendritic fields of the neurons lying in the laminae were flat, those located in the core were spherical or cylindrical, thereby conforming to the shape of the striatal projection fields. This remarkable alignment between the dendritic arborizations of nigral neurons and the projection fields from individual striatal districts supports the concept of a parallel architecture of the striato-nigral circuits. However, pars reticulata neurons usually extend part of their dendrites within adjacent striatal projection fields, thereby ensuring a continuum between channels. The extension of the dendritic arborizations within the striatal projection fields suggests that nigral neurons integrate the information that is relevant for the completion of the specific motor behavior they control.

Action Potentials↗
PubMed1991

Elimination of the transient ipsilateral retinotectal projection is not solely achieved by cell death in the developing chick.

During development of the projection from the retina to the brain in the chick, a transient ipsilateral retinotectal projection forms and disappears. This disappearance is coincident with a wave of ganglion cell death in the retina. The contribution of cell death to the disappearance of this projection, as opposed to another mechanism such as axon retraction, was examined. Retinal ganglion cells with a projection to the ipsilateral tectum were retrogradely labeled by injection of long-lasting fluorescent dyes into the tectum prior to the onset of ganglion cell death. Large injections of fast blue labeled approximately 1800 ganglion cells in the ipsilateral retina before the period of cell death began. If the injected embryos were allowed to survive past the peak period of ganglion cell death, the average number of labeled ganglion cells in the ipsilateral retina was reduced by somewhat more than half. It is possible that the remaining labeled ganglion cells projected only to nontectal visual nuclei and were labeled by fast blue that had diffused out of the tectum. This was tested by repeating the study using very localized injections of 1,1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate or fluorescent microspheres into the tectum. These small injections confirmed that cells with transient projections to the ipsilateral tectum survived past the elimination of this projection. Thus, ipsilaterally projecting ganglion cells have, at most, a slightly greater propensity for death than the average ganglion cell, and elimination of the transient ipsilateral retinotectal projection in chick can be explained only, in part, by the mechanism of cell death.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Tangential projection for depiction of the anterior regions of the jaws performed with the dental X-ray set].

The tangential projection represents an extraoral projection which with success can be performed with the dental X-ray set. The film is placed lateral to the angle of the mouth in a vertical position level with either the maxilla or the mandible. If a view of the midline is wanted the film is placed parallel with the sagittal plane; if e.g. the canine region is of interest the film is angulated. The central X-ray is directed horizontally and perpendicularly to the film passing (as a tangent) the anterior surface of either the maxilla or mandible. The beam area used for periapical projections is ideal also for this projection. The tangential projection is indicated as a supplemental projection for three-dimensional localization of e.g. supernumerary teeth in the maxillary anterior region and for the buccolingual position of an impacted canine. It is also very useful in combination with frontal projections in the planning of insertion of dental implants. According to the Danish legislation it is not allowed to use the dental X-ray set for extraoral projections unless intensifying screens are used. However, the Danish Institute of Radiation Hygiene has accepted tangential projections using dental X-ray films and omitting intensifying screens in edentulous patients due to their better resolution, which is of particular importance in the planning of implant insertion.

Humans↗
PubMed1990

Prenatal specification and target induction underlie the enrichment of calcitonin gene-related peptide in the trigeminal ganglion neurons projecting to the cerebral vasculature.

The neurotransmitter calcitonin gene-related peptide (CGRP) is enriched in the adult rat trigeminal visceral projection to the cerebral arteries compared both to other neurotransmitters in this projection and to the percentage of CGRP-positive trigeminal cells projecting to cutaneous targets. In colchicine-treated ganglia approximately 30% of adult trigeminal ganglion cells projecting to the middle cerebral artery contain CGRP. Several possible developmental mechanisms underlying this enrichment were investigated. Some of this enrichment is accounted for by a prenatal selection of CGRP cells in the cerebrovascular projection. The remainder of the enrichment can be explained by a late (postnatal days 55-90) target-induced expression of CGRP in some trigeminal neurons innervating cerebral arteries. Most surprisingly, the massive postnatal regression in the trigeminal projection to the cerebral arteries (between postnatal days 5 and 55, cell death and axon retraction delete 3/4 of the neurons that innervate the middle cerebral artery neonatally) has no role in the CGRP enrichment in the cells remaining at maturity in this projection. These regressive events appear to affect equally the CGRP-positive and CGRP-negative populations. However, axon retraction is involved in the postnatal loss of CGRP enrichment seen in 1 small subpopulation of the trigeminal projection. Each trigeminal cell in this population sends axon collaterals to both the cerebral artery and the forehead skin neonatally, and then later most of these dually projecting neurons retract only their artery collaterals but do not die. A low percentage of CGRP-containing neurons does not appear to predate artery collateral retraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

[Central afferent projections from the rat sternocleidomastoid and trapezius muscles. A study using transganglionic transport of horseradish peroxidase].

Primary afferent fibers from the sternocleidomastoid and trapezius muscles were transganglionically labeled with HRP, using rats anesthetized with urethane. All labelings were found ipsilaterally; retrogradely labeled cells were located in the C2 to C4 spinal ganglia, and transganglionic labelings in the C1 to the rostral C6 spinal segments and in the medulla oblongata. Labeled terminal fields were the lamina VI, the central cervical nucleus and the ventral horn in the cervical spinal cord, and in the medulla oblongata, many labeled fibers projected to the lateral (Cul) and medial cuneate nuclei (Cum), with a few of them projecting to the vestibular nucleus and the intermediate nucleus of Cajal. In the lateral cuneate nucleus, the terminal field was located in the medial portion at rostral levels, but it gradually shifted laterally as traced caudally; in the medial cuneate nucleus, the terminal field was located rostrally in the dorsolateral portion, but caudally in the ventrolateral portion. Although the sternocleidomastoid and trapezius muscles displayed a similar afferent projection pattern, the projection from the former muscle differed from that of the latter in the following respects: 1) Levels of projections to the spinal ganglia and the cervical spinal cord were located slightly more rostrally. 2) The terminal field in the lamina VI was located slightly more medially. 3) In the ventral horn, the sternocleidomastoid muscle afferents projected rostrally to the dorsomedial portion and caudally to the ventrolateral portion, but the trapezius muscle afferents projected solely to the ventrolateral portion at more caudal levels. 4) The terminal fields in the external cuneate nucleus were more extensive. 5) The projection area in the rostral medial cuneate nucleus was located slightly more medially, and projection to the ventromedial portion of the caudal medial cuneate nucleus and that to the intermediate nucleus were considerably fewer.

Animals↗
PubMed1985

Comparison of the distributions of ipsilaterally and contralaterally projecting corticocortical neurons in cat visual cortex using two fluorescent tracers.

Using the retrograde fluorescent tracers Fast Blue and Diamidino Yellow we have studied the callosal and ipsilateral corticocortical connections between the cat's area 17/18 border region and the posteromedial lateral suprasylvian visual area (PMLS), as well as the callosal connections of each of these regions with its contralateral homologue. The main goal was to determine whether single cortical neurons project with branching axons to more than one cortical target. In addition, the double-labeling technique enabled us to examine, within a single section of cortical tissue, the relative distributions of neurons with different cortical targets. Most corticocortical neurons labeled in the area 17/18 border region and in area PMLS projected to only one of the cortical injection sites tested. When two callosal neuron types were labeled in the same area, no double-labeled neurons were found. When ipsilateral corticocortical and callosal neurons were labeled in combination, a few double-labeled neurons were found in both cortical regions examined. The most common type of double-labeled neuron was located in area PMLS and projected bilaterally to the area 17/18 border region. Our findings regarding the laminar distributions of ipsi- and contralaterally projecting neurons are in agreement with previous studies. In addition, we have found that, for callosal neurons within the upper layers of areas 17 and 18, neurons projecting to the contralateral area 17/18 border are located in the lower half of layer II/III and in upper layer IV, whereas neurons projecting to contralateral area PMLS are restricted to the lower portion of layer II/III. In addition, for callosal neurons within the deep layers of area PMLS, neurons projecting to contralateral area PMLS are located throughout layers V and VI, whereas neurons projecting to the contralateral area 17/18 border are restricted to layer VI. There are numerous other possible targets for axon collaterals not examined in this paper. However, the scarcity of neurons with multiple projections demonstrated in this study reflects the high degree of specificity of cortical connectivity. This anatomical organization may be the basis for a precise channeling of differential information at the single neuron level.

Amidines↗
PubMed1983

Acoustic chiasm: efferent projections of the lateral superior olive.

The efferent connections of the cat's lateral superior olive (LSO) were examined first with kainic acid-induced anterograde degeneration and tritiated leucine autoradiography and then by systematic repetition of HRP and fluorescent dye retrograde tract-tracing techniques. The results show that virtually all LSO cells have axons ascending either contralaterally or ipsilaterally to high pontine and midbrain levels of the brainstem. Most terminate in the ventrolateral division of either the ipsilateral or contralateral central nucleus of the inferior colliculus, some terminate in the ipsilateral or contralateral dorsal nucleus of the lateral lemniscus, and a small number terminate in the ipsilateral intermediate nucleus of the lateral lemniscus. Only a small proportion (less than 5%) of LSO cells project to both sides via axon collaterals. The ipsilateral, contralateral, and bilateral projections arise from three overlapping subpopulations of cells within LSO: Those projecting ipsilaterally are concentrated in its lateral limb; those projecting contralaterally are concentrated in its medial limb; the few projecting bilaterally are thinly scattered throughout. Therefore, a lateral-medial gradient is present across LSO based on the laterality of its cell's efferent targets. This gradient parallels LSO's tonotopic gradient: The higher the characteristic frequency of an LSO cell, the more likely it is to project contralaterally. This arrangement of LSO's ascending projections, with most of its lateral cells projecting ipsilaterally and most of its medial cells projecting contralaterally, is similar to the arrangement of the optic chiasm in animals with overlapping eye-fields. Its presence seems to provide an anatomical basis for some recent electrophysiological and behavioral reports of chiasm-like properties of the superior olivary complex.

Animals↗
PubMedDate not supplied

The School Health Curriculum Project: a study of frequency of participation to impact.

In response to the increase in teenage cigarette smoking in the United States, the federal government funded an innovative school health education curriculum titled the School Health Curriculum Project. The purpose of this study was (1) to determine the cigarette smoking attitudes and behaviour of eighth-grade students who participated in the Project, and (2) to identify whether or not significant differences existed among students who participated in one or more R units of the Project. Three grade units of the Project were examined: the fifth grade lung unit, sixth grade heart unit, and seventh grade brain unit. The independent variable was the type and number of Project units received. The teenage self-test, supplemented with a number of behavioural items, was used to measure cigarette smoking attitudes and behaviours and served as the dependent variable. The analysis of variance indicated that significant mean differences did not exist between the combination of one or more units of the Project and smoking attitudes. Although those students who participated in all three units had higher mean scores on 4 of the 8 attitude scales, none were significant at the designated alpha level (.05). Based upon the findings one can see that changes in cigarette smoking attitudes and behaviour were not proportionate to intensity and frequency of the intervention. However, this does not indicate the Project was ineffective. It may be that one unit is enough to create an impact on cigarette smoking attitudes and behaviour and that successive units will help maintain that behaviour. Since the Project covers numerous health topics, future investigations of the relationship between the Project and health behaviour need to be analyzed.

Adolescent↗
PubMed1993

Olfactory and nonolfactory projections in the river lamprey (Lampetra fluviatilis) telencephalon.

The projections of the olfactory bulb, the primordial dorsal, piriform and hippocampal pallia, and of the dorsal thalamus were studied in the lamprey Lampetra fluviatilis using horseradish peroxidase (HRP) and HRP coupled to the wheat germ agglutinin (WGA-HRP). There was obtained an experimental morphological evidence of the presence of the direct thalamo-telencephalic projections in this vertebrate species. The anterior and posterior parts of the dorsal thalamic nucleus, the nucleus of Bellonci, the primordial geniculate bodies, the rostral part of the midbrain were identified as the sources of the telencephalic afferents. These connections may serve as a morphological substrate for transmission of nonolfactory impulses to the telencephalon of the lamprey. The projections of the nucleus of Bellonci into the primordial hippocamp were compared to the limbic thalamo-hippocampal pathways of other vertebrates. We have established, that the fibers ascending from the dorsal thalamus were distributed in the same areas, as those descending from the olfactory bulb. These are: mainly the primordial hippocamp and only a few fibers reach the dorsal and piriform pallia, as well as an area free of olfactory projections--the dorsal part of the subhippocampal lobe. We have also demonstrated that, the secondary olfactory fibers mainly projected ipsilaterally to the primordial dorsal and piriform pallia. A lesser dense bulbar projection has been observed ipsilaterally in the primordial hippocamp and in the ventral part of the subhippocampal lobe. Only few olfactory projections were found in the pallial areas and in the subhippocampal lobe contralaterally. The olfactory fiber terminals were also observed ipsilaterally in the septum, striatum, preoptic area and in the contralateral olfactory bulb. Bilateral bulbofugal projections also occur in the diencephalon, namely in the ventral thalamus and in the hypothalamus. Caudally, the secondary olfactory fibers can be traced up to the area of the posterior tuberculum. Afferents to the olfactory bulb in the river lamprey originate in the subhippocampal lobe, in all three pallial formations and probably in the dorsal thalamus. These structures are at the same time the target zones for the olfactory bulb efferent projections, thus being connected reciprocally with the olfactory bulb.

Afferent Pathways↗