Split chiasm developmentally induced in kittens: plasticity of interhemispheric transfer in visual cortex cells

Summary Visual callosal transfer during development was studied in order to reveal plasticity-related compensation for the absence of direct contralateral inputs. The optic chiasm was midsagittally sectioned in 6–8 weeks old kittens (OCK) and for comparison, in adult cats (OCA). Unit recording was made during adulthood in the border area between visual cortex areas 17 and 18, namely the callosal projection zone. The proportion of cells showing interhemispheric transfer in the OCK group, as indicated by the presence of visual input from the contralateral eye was 10.5%; in the OCA cats their proportion was 4.0%. Moreover, 2.3% of the cells showed a pure transfer of input from the contralateral eye in the OCK, although none was seen in the OCA cats. Thus, during the developmental period, a plasticity induced process, albeit limited, takes place in the enhancement of interhemispheric transfer of visual information.     

The Ultimate Rejection: Helping the Survivors of Teen Suicide Victims

Each year, teens who commit suicide leave behind more than 25,000 survivors. In addition to feelings of depression, anger, and guilt, the survivors must cope with societal attitudes toward suicide. Few resources are available to deal with the problem. This paper discusses the impact of teen suicide on survivors, and outlines educational and administrative postincident intervention guidelines for schools.     

Optic chiasm split and binocularity diminution in cortical cells of acute and of chronic operated adult cats

Summary The ocular dominance, responsiveness level and receptive field properties of single cortical cells were studied in 12 acute and chronic split chiasm adult cats (729 cells) and in 13 normal controls (544 cells). Recording was made from the border between visual areas 17/18. Responsive cells in the operated cats were obtained exclusively (87.1%) following stimulation of the ipsilateral eye, except for a very few cells (2.5%) which were binocularly driven. In comparison, only few (10.9%) of the cells in the normal control cats were driven ipsilaterally and the majority of them (74.5%) were binocularly driven. Relatively small proportions of cells (46.1%) were visually responsive in the acute (< 1 week postoperatively) and in the most chronic (> 6 months) cats, in comparison to the normal cats (87.3%). No consistent change was found in the responsiveness level of cortical cells as function of length of the survival time (correlation coefficient: –0.45). Only a very slight tendency for a relative increase in binocularly driven cells with survival time was found as well as a reduction in the proportion of nonspecific cells. However, in view of the general absence of binocularity and responsivity in these cats, it was concluded that no recovery was found, even long after the elimination of the contralateral inputs.     

Cocaine alters opiate receptor binding in critical brain reward regions

Brain reward systems are thought to be involved in the reinforcing effect of both cocaine and opiates. In vitro receptor autoradiography was used to determine the effect of chronic, continuous cocaine exposure of 2 weeks duration on [3H]naloxone binding in various regions of rat brain. Although cocaine action in the central nervous system is usually associated with altered dopamine function, we observed that opiate receptor density as labeled by [3H]naloxone was altered by chronic cocaine exposure in critical brain reward regions, including the nucleus accumbens, ventral pallidum, and lateral hypothalamus. Endogenous opioid activity at opiate receptors in these critical regions may be associated with the reinforcement induced by both cocaine and opiates.     

Clinical aspects of progressive systemic scleroderma (PSS). Multicenter studies of 194 patients

Patients from five German Departments of Dermatology (Düsseldorf, Erlangen, Frankfurt am Main, Hamburg and Munich) affected with progressive systemic scleroderma (PSS) were classified and examined. The results of the clinical investigations are presented. In order to guarantee a uniform classification of all patients, the patients were divided into three groups according to the distribution of the affected skin: type I consisted of those with acrosclerosis distal to the wrist, type II had scleroderma extending along the wrist in a proximal direction, and type III had diffuse scleroderma beginning on the trunk. Altogether, 194 patients with PSS were investigated, and the following distribution was found: type I, 32%; type II, 60%; type III, 7%; 1% of the patients could not be classified. The distribution according to the patients' sex and age was in good agreement with published reference data. The incidence, significance, and localization of the major symptoms were investigated. The Raynaud symptom could be identified as being the main clinical symptom in 90% of the patients. Joint involvements (10%-73% depending in the applied parameters), dysphagia (51%), and rest dyspnea (30%) contributed to the main internal symptoms. The extensive clinical, chemical, and immunological results are summarized. In 80% of the cases, high ANA titers could be detected, but these were not correlated to the type of disease.     

Fluid collections in the intraperitoneal and extraperitoneal spaces: comparison of MR and CT

Fourteen patients with abnormal subdiaphragmatic fluid collections (eight intraperitoneal, two extraperitoneal, and four intra- and extraperitoneal) were examined with computed tomography (CT) and magnetic resonance (MR) imaging. MR and CT provided equivalent information concerning the presence and extent of fluid collections in 13 of the 14 cases. Image acquisitions with two different repetition times (TRs) and two echo times (TEs) were necessary, in most cases, to detect and discriminate between different types of pathologic fluids. Transudative ascites demonstrated long T1 and T2 relaxation times, whereas abscesses, phlegmon, pancreatic pseudocyst, exudative pancreatitis, and chronic hematoma demonstrated an intermediate or short T1 and a long T2.     

The organization of pyramidal cells in area 18 of the rhesus monkey

The aim of this study was to investigate the vertical organization of axons and pyramidal cells in area 18, and to compare it with that in area 17. In area 18 there are regularly spaced vertical bundles of myelinated axons that have an average center-to-center spacing of 21 microns. This arrangement of axons resembles that in area 17. Pyramidal cells in area 18 and their apical dendrites are less regularly arranged. The apical dendrites of the pyramidal cells of layer 6A aggregate with those from layer 5 pyramids to form swathes of apical dendrites that pass into layer 4. There they are joined by the apical dendrites of the small layer 4 pyramids, so that much of the neuropil of layer 4 is occupied by apical dendrites. Most of these apical dendrites form their terminal tufts in layer 3. Very few of them reach layer 1, which is dominated by the apical dendrites of layer 2/3 pyramids. Thus, there are two tiers of apical dendrites and their apical tufts, a deep one formed by the layer 4, 5 and 6 apical dendrites that terminate in layer 3, and a second one formed by the apical dendrites of layer 2/3 pyramids that terminate in layer 1. In contrast, in area 17 the apical dendrites of layer 5 pyramids form discrete clusters that have a center-to-center spacing of 23 microns. These clusters are joined by the apical dendrites of the layer 2/3 pyramids and all of these apical dendrites form their apical tufts in layer 1. Based upon the dispositions of the apical dendrites of the pyramidal cells in area 17 and 18, we speculate that the influences of, and the interactions between, the feed-forward and feed-back signals in the two areas are quite different, because in the two areas different postsynaptic targets are available to these afferents.