Yarlparu: on sorrow and grief.
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Attitude to Death↗
Biomedical subjects
J Dineen
Publications and source records attributed to J Dineen.
Parasol and midget ganglion cells of the human retina.
Golgi-impregnated ganglion cells were studied in two flat-mounted human retinas. A number of different morphologic forms were observed, and those showing a thickly branching dendritic field with terminals that stratified within a narrow zone of the inner plexiform layer were selected for further investigation. When the dendritic field diameter of these cells was plotted against distance from the fovea, the scatter diagram showed two distinct clusters. At any given eccentricity, there was no overlap between the cell group with large dendritic fields and the group with small dendritic fields. Those with the larger dendritic fields also tended to have larger somas and thicker axons than the group with the smaller dendritic fields. The dendritic fields of both groups tended to be elongated, and the orientation and degree of this elongation were quantified by determining the best-fitting ellipse for each dendritic field. The degree of elongation was independent of eccentricity. The orientation of the dendritic field (major axis of the ellipse) of a cell did not appear to be independent of its position on the retina. To test whether the major axes tended to be directed toward any particular point on the retina, the positions of the cells on the retinal flat mount were transformed to relative positions on the retinal hemisphere, and the orientations of the dendritic fields were expressed in a spherical coordinate system for this hemisphere. A search was made for the position on the hemisphere which minimized the mean square deviation of the orientations from this point. The group with the large dendritic fields showed a significant tendency to be radially oriented toward a specific location on the retinal hemisphere, and that location lay within a few degrees of the fovea. Leventhal and Schall ('83) have reported a similar finding for ganglion cells of the cat retina. For the group with small dendritic fields, the retinal location that minimized the mean square deviation was also near the fovea; however, the set of orientations showed no greater tendency for mutual alignment than did a randomized set. The cell group with the large dendritic fields appears to correspond to Dogiel's (1891) type II cells, to Polyak's ('41) parasol cells, to the A cells of the monkey retina described by Leventhal et al. ('81), observed following HRP injection to the magnocellular layer of the LGN, and to the P alpha cells of the monkey retina, observed by Perry and Cowey ('81), following HRP uptake by cut axons of the optic nerve.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
Alterations of retinal inputs following striate cortex removal in adult monkey.
The morphology of the retina and central retino-recipient nuclei was studied in two monkeys that had undergone total bilateral striate cortex removal as adults. These animals had been behaviorally tested for two years after lesioning and had demonstrated significant recovery of pattern vision. Light and electron microscopy and autoradiography were done on the central retino-recipient nuclei following a monocular intravitreal injection of 3H-proline. Light microscopic analysis of retinal ganglion cell number showed a 30% loss in the parafoveal retina due to retrograde trans-synaptic degeneration. The most striking central change in retinal axon distribution was in the dorsal lateral geniculate nucleus (dLGN) where the parvocellular but not the magnocellular region showed a marked reduction in retinal input. Despite the loss of almost all dLGN neurons through retrograde degeneration, at the EM level both parvocellular and magnocellular regions contained islands of neuropil made up of retinal and several other types of synaptic terminals as well as small dendrites and pale unidentified processes. Approximately equal numbers of retinal terminals were identified by EM autoradiography in both regions of dLGN, which did not explain the apparent differences in labeling between the two regions seen in the light microscope. A second change in central retinal pathways was found in the olivary pretectal nucleus where a significant loss of retinal input also occurred. A third change, but in the opposite direction, was found in the pregeniculate nucleus (PGN) where the area of retinal terminals appeared enlarged. The remaining central retino-recipient nuclei had the same distribution of retinal input as the control animals.
Animals↗
The primate visual system after bilateral removal of striate cortex. Survival of complex pattern vision.
This study examined the strategies used by monkeys lacking striate cortex to perform visual pattern discriminations. Complete bilateral removal of area 17 initially produced severe visual impairment with recovery of even rudimentary visual capacities (e. g., flux discrimination) dependent on gradually retraining the monkeys through a set of increasingly more complex pattern discriminations. After extended periods of postoperative testing, however, three of five monkeys lacking striate cortex were able to discriminate a number of complex visual patterns even when such local stimulus cues as amount of contour and number of elements were equal. Further testing demonstrated that these animals could distinguish a pattern's spatial organization. They were also able to transfer good performance to tasks with novel patterns.
Animals↗
Relationship of age and hypertension to neuropsychological test performance.
Young adult (X- = 29) and middle aged (X- =50) hypertensive and normotensive subjects were compared with respect to seven neuropsychological test scores derived from tests on the Halstead-Reitan battery. Age main effects, with inferior performance for the middle aged subjects, were observed for the localization and time portions of the Tactile Performance Test (TPT) and for the Trail Making A test. The multivariate age effect was significant for the composite of seven scores. A multivariate blood pressure main effect was obtained and main effect blood pressure was significant for the category test; hypertensives made more errors than normotensives. A blood pressure by age interaction was observed for finger tapping scores and the TPT-Memory scores with larger differences between hypertensives and normotensives for the younger than for the middle aged group. Results were discussed in terms of previous studies of age and hypertension with the WAIS, the Primary Mental Abilities Test and serial reaction time measures. The poor prediction of hypertensive status from individual neuropsychological test scores was emphasized and readers were cautioned not to conclude that essential hypertensives, as a group, can be characterized as brain damaged.
Adult↗
Effects of altered responsibility, congnitive set, and modeling on physical aggression and deindividuation.
This laboratory investigation using 64 college students as subjects assessed the role of three disinhibiting variables in producing both physical aggression and an internal state of deindividuation. Altered responsibility, congnitive set, and modeling were manipulated in a factorial design, and all three variables significantly increased physical aggression. No interaction produced significant results. The increase due to altered responsibility and varying cognitions supports Zimbardo's theory of deindividuation which relates certain input variables to wild, impulsive behavior. Questionnaire data indicated that the increase in aggression was not accompanied by internal mediational factors such as reduced self-awareness. It appears that disinhibiting forces may produce increases in antisocial behavior without necessarily producing a deindividuated internal state.
Aggression↗