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Biomedical subjects

P Cornwell

Publications and source records attributed to P Cornwell.

34 records · Page 2Linked to original sources
PubMed1980

Subtotal lesions of the visual cortex impair discrimination of hidden figures by cats.

Cats with partial or nearly total ablation of areas 17, 18, and 19 were assessed on the discrimination of hidden figures and other visually guided behaviors to determine whether such insults produce deficits like those that follow lateral striate lesions in monkeys. Cats with destruction limited to the representation of central vision (Group M) were impaired at discriminating patterns complicated by extraneous cues, but they were less impaired than cats with more complete lesions (Group MS). The deficit was not a general one in visual learning since animals in both Groups M and MS learned simple pattern discriminations as rapidly as controls. It is suggested that the loss of geniculocortical functions representing central vision produces similar deficits in cats and monkeys but that to have this effect in cats, damage must extend beyond area 17.

Animals↗
PubMed1978

Extent of recovery from neonatal damage to the cortical visual system in cats.

Cats that received either marginal or marginal plus extramarginal lesions as 3-day-old kittens were assessed on a series of tests of visually guided behavior. These cats were not conspicuously different from normal controls in avoiding obstacles or in activity level. Yet these same operated cats were severely impaired in performance on the visual cliff and in visual discrimination learning, even when the lesions were limited to the geniculocortical portion of the visual system. However, maximum losses in pattern and form discrimination learning were observed only in cats with severe retrograde degeneration in both the lateral geniculate nucleus and the complex of the pulvinar and nucleus lateralis posterior. Photically evoked potentials were recorded in the lateral regions of the neocortex more reliably from operated cats that had made fewer errors in discrimination learning than from more severely debilitated cases; this relation was present even among cases with nearly equivalent amounts of retrograde degeneration in the visual thalamus. These findings suggest that in the cat (a) recovery of vision is incomplete after neonatal lesions of the visual cortex and (b) a cortical system lateral to the geniculocortical projections may be involved in pattern vision.

Animals↗
PubMed1976

Performance on the visual cliff by cats with marginal gyrus lesions.

Lesions in 12 cats that destroyed almost all of area 17 (Group MS) abolished differential responding on the visual cliff. Performance was not impaired in 9 cats in which regions of the striate cortex were spared in the depths of the splenial sulcus or in 23 cats with damage to extramarginal areas. There were 37 controls. Additional experiments indicated that the deficit in performance by MS cats was not reduced either by the administration of amphetamine or by increases in cues for motion parallax. Monocularly occluded normal cats preferred the shallow surface of the visual cliff, demonstrating that the deficit was not due solely to removal of neurons sensitive to binocular disparity. The findings were discussed in light of electrophysiological evidence that lesions of the visual cortex disrupt functions of the superior colliculus.

Amphetamine↗
PubMed1976

Marginal and extramarginal cortical lesions and visual discrimination by cats.

Seventy-five cats learned a shape discrimination with zero, one, or two irrelevant cues. They were then subjected to sham operations (n = 34), ablation of the marginal and splenial gyri (n = 9), or lesions in the extramarginal (EM) cortex. The 32 EM cats comprised four groups, three with small (EM1, n = 9), intermediate (EM2, n = 10), and large (EM3, n = 9) decortications, and a fourth group with both EM lesions and heavy degeneration in the lateral geniculate nucleus (LGN, n = 4). The cats with marginal or extensive extramarginal lesions were severely impaired in shape and size discrimination. Two lines of evidence indicate that their behavioral defects resulted from different neural dysfunctions. (a) The errors made by marginal gyrus cases increased sharply as a function of the number of irrelevant cues present in shape discrimination training; no other group, including Group EM3, was affected by this variable. (b) Cats with extramarginal ablations and strong LGN degeneration were no more severely impaired than were subjects with comparable extramarginal damage and little or no LGN degeneration. While the nature of the two kinds of deficits remains unclear, they seem parallel to those following posterior cortical lesions in monkeys.

Animals↗
PubMedDate not supplied

Survival and death of neurons in cortical area PMLS after removal of areas 17, 18, and 19 from cats and kittens.

The long-term morphological consequences on laminar thickness and neuron survival were assessed in cerebral cortical area PMLS following excision of visual cortical areas 17, 18, and 19 from adult and adolescent cats and from neonatal kittens. Following excisions from kittens, layers III, V, and VI in area PMLS were reduced in thickness and there was a significant loss of neurons from layers III and VI. Following excisions from adolescent cats, layers V and VI were thinner than normal, whereas excisions from adult cats resulted in a detectable thinning only of layer V and no neuron loss from any layer. In a parallel study, the configuration of projections between area PMLS and areas 17, 18, and 19 in adult cats and newborn kittens was analyzed and related to the patterns of neuron survival and death in area PMLS following the excisions. In adult cats, projections from areas 17, 18, and 19 terminate in all layers, but they are heaviest into layer III in area PMLS. Layers III and VI contain the largest number of neurons that form the origin of the reciprocal projections back to areas 17, 18, and 19. In area PMLS of the newborn kitten, the laminar distribution of cells projecting to areas 17, 18, and 19 resembles the pattern in the adult cat, although the laminar pattern of the terminations is poorly differentiated. The pattern of cell death following the excisions from the kittens can be most easily explained on the basis of the mature configuration of the reciprocal pathways and on the neurons' maturational status at the time areas 17, 18, and 19 were removed. Thus, immature cortical neurons that are deprived of their targets and inputs undergo degenerative changes. These changes are most severe in infancy, and they can be predicted on the basis of the final patterns of projections the neurons would have developed with the damaged region. This loss of neurons in early-lesioned animals in regions of cortex anatomically connected to the damaged tissue implies that there may be cognitive deficits associated with the secondary degeneration in addition to the deficits caused by the primary lesion.

Aging↗
PubMedDate not supplied

Perceptual and cognitive visual functions of parietal and temporal cortices in the cat.

We used reversible cooling deactivation to compare the functions of cortices lining the middle suprasylvian (MS) sulcus and forming the ventral portion of the posterior suprasylvian (vPS) gyrus. A battery of attentional, motion and mnemonic processing tasks were used and performance was examined during deactivation of each region. The results show a clear dissociation of functions. Deactivation of MS cortex resulted in profound deficits on a visual orienting task and on the discrimination of direction of motion, whereas deactivation of vPS cortex severely impaired both retention and learning of novel and overlearned object discriminations. In addition, deactivation of either MS or vPS cortex impaired discrimination of learned patterns when components of the patterns were in motion, whereas only deactivation of vPS cortex impaired the discrimination when all components were static. Together, these results show that a region of parietal cortex contributes to the processing of visual motion and to attentional processes, whereas a region of temporal cortex contributes to the learning and recognition of three-dimensional objects and two-dimensional patterns. This functional dissociation is linked to differences in underlying visual pathways, which have many features in common with the parietal and temporal visual processing streams previously identified in monkeys and humans. Furthermore, the broad similarity in neural operations carried out in parietal and temporal cortices of cats, monkeys and humans suggests the existence of a common plan for cortical processing machinery within mammals with well developed cerebral cortices.

Animals↗
PubMedDate not supplied

Topical lidocaine in the treatment of partial-thickness burns.

The analgesic properties and systemic absorption of topical lidocaine in the treatment of partial-thickness burns were evaluated by applying a 5% lidocaine cream to the burn wound at a concentration of 1 mg/cm2. The plasma lidocaine level was measured in 24 patients 15, 30, 60, 120, and 240 minutes after application. Systemic analgesics were given 30 minutes before application of the lidocaine cream. The Visual Analog Scale was used to record pain intensity in 30 patients just before and 30 minutes after application of the lidocaine cream. The maximal area treated was 28% total body surface area partial-thickness burn with application of 4.5 gm of lidocaine, resulting in a plasma level of 5.8 micrograms/ml. The plasma lidocaine level was constant during the 4-hour experiment and was associated with a significant decrease in pain. No infectious, allergic, or cardiovascular complications were observed. Our results indicate that topical lidocaine cream offers significant pain relief of long duration without associated systemic side effects.

Absorption↗
PubMedDate not supplied

Proactive psychosocial care of blood or marrow transplant patients.

PURPOSE: The authors describe a proactive model of psychosocial care for patients undergoing blood or marrow transplantation and their families. DESCRIPTION OF PROGRAM: This program for blood or marrow transplantation patients, developed at the Center for Cancer Treatment and Research, Richland Memorial Hospital, and the University of South Carolina School of Medicine in Columbia, South Carolina, involves pretransplant comprehensive psychosocial assessment; development and implementation of an individual psychosocial treatment plan; monitoring and medical management of neuropsychiatric problems; and psychotherapeutic sessions with a psychiatrist. These functions are achieved through the use of a multidisciplinary psychosocial team and ongoing consultation-liaison with the entire blood or marrow transplantation team. CLINICAL IMPLICATIONS: This positive, proactive model demonstrates significant benefit to patients, families, and the blood or marrow transplantation healthcare team. Benefits of this model are derived from psychosocial assessment during work-up, subsequent planning, and communication with the entire team, thus allowing early identification of problems and avoiding escalation and the likelihood of negative outcomes. Less energy is exerted and less resources expended when problems are resolved with early intervention rather than with intensive interventions during transplant. The psychosocial staff members develop strong relationships with patients and families before transplant, increasing the power of interventions and receptivity of the patient. The blood or marrow transplantation team benefits from the ongoing presence of psychosocial staff and the consistency of approaches offered by team members. An integral part of this approach is teaching psychosocial care to all staff members and modeling approaches to problems. Other blood or marrow transplantation centers and centers providing other intensive anticancer therapies may benefit by adapting this model into the day-to-day care of their patients.

Blood Transfusion↗