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Biomedical subjects

R E Foster

Publications and source records attributed to R E Foster.

61 records · Page 4Linked to original sources
PubMed1978

The organization of central auditory pathways in a reptile, Iguana iguana.

The present experiments were designed to trace the central auditory pathways in an extant reptile, the New Worlkd lizard--Iguana iguana, utilizing anterograde axonal degeneration stained by the Fink-Heimer ('67) method and the retrograde axonal transport of horseradish peroxidase (LaVail and LaVail, '74). Beginning with the projections of the auditory portion of the VIIIth nerve, the ascending pathways were traced through successive relay nuclei to the telencephalon. The auditory portion of the VIIIth nerve projects to two nuclei in the dorsomedial medulla-nucleus angularis and nucleus magnocellularis medialis. These two nuclei together with a third cll group, nucleus magnocellularis lateralis (intercalated between nucleus angularis and nucleus magnocellularis medialis), have been referred to as the auditory tubercle in previous studies (cf. Miller, '75). The axonal degeneration following large lesions of the auditory tubercle and small lesions of nucleus angularis demonstrated the second order auditory pathways. Fibers leave nucleus angularis ventrally and travel to the ventral surface of the medulla where they cross the midline and ascend to the midbrain in pathways resembling the trapezoid body and the lateral lemniscus of mammals. Along these pathways, terminal arborizations of some fibers were seen in three lower brainstem nuclei while other fibers ascent to the midbrain and terminate in the central nucleus of the torus semicircularis. Experiments in which horseradish peroxidase injections were made in the torus semicircularis demonstrated that nucleus angularis is a primary source of second order auditory fibers to the midbrain and, in addition, that two of the lower brainstem targets of the auditory tubercle project to the torus semicircularis. These lower brainstem pathways were shown to be associated with the auditory system by electrophysiologically recording sound-evoked responses from clusters of cells in the torus semicircularis. Ascending fibers arising from the central nucleus of the torus semicircularis were followed rostrally where they entered the dorsal thalamus and terminated throughout nucleus medialis. Finally, a thalamotelencephalic auditory pathway was traced from nucleus medialis into the lateral forebrain bundle. Terminations of this pathway from nucleus medialis were seen in the medial dorsal ventricular ridge and in the striatum. It was concluded that the ascending auditory pathways of the iguana bear a remarkable resemblance to both the mammalian and avian auditory pathways from the level of the first order neurons in the VIIIth nerve to the level of the telencephalon. At the same time, there are important specializations of the auditory system in birds and mammals such as the development of particular lower brainstem nuclei. Nevertheless, a basic plan for the organization of the auditory system in terrestrial vertebrates can be recognized which invites comparisons with the vertebrate classes that remained in aquatic habitats...

Animals↗
PubMed1977

Acquisition of modified American sign language by a mute autistic child.

An attempt was made to teach a modified version of American Sign Language to mute 5-year-old boy who had been diagnosed autistic and who had a Merrill-Palmer IQ of 65. Previous attempts to teach imitative spoken language had failed, and baseline data indicated that the child's signing vocabulary was also nonexistent. Data were collected during 20 structured sessions involving presentation of stimuli, prompting and manual guidance when necessary, and reinforcement. Continuous use of signs as communication in class and at home was emphasized. The child had mastered 12 signs at the end of the study. Spontaneous signing frequency as recorded by parents and teachers during several 48 hour periods rose from 15 to 42 emitted signs over the 3 months of the study. The child made 6 months' developmental progress during this time, as measured by a sign-language adaptation of the Alpern-Boll Communication Scale. However, the child made no apparent progress in acquiring spoken language.

Autistic Disorder↗
PubMed1975

The connections and laminar organization ofthe optic tectum in a reptile (lguana iguana).

The goals of this study were: (1) to describe the total pattern of projections from the optic tectum of Iguana iguana and Pseudemys scripta; and (2) to describe the contributions of particular lamina of the Iguana's optic tectum to this total pattern. Lesions were made in the optic tectum of the Iguana which damaged either all or only certain tectal laminae and, for comparison with the Iguana, lesions in the turtle's optic tectum were made which involved all laminae. The anterograde degeneration resulting from these lesions was stained with the Fink-Heimer ('67) method. The total pattern of projections from the optic tectum in the Iguana and the turtle is similar to that reported for representatives of other vertebrate classes. That is, the optic tectum gives rise to ipsilateral ascending projections to pretectal nuclei, to nucleus rotundus and to nucleus geniculatus lateralis pars ventralis of the diencephalon and, in addition, to a contralateral ascending pathway which courses via the supraoptic decussation to the contralateral diencephalon. Tectotectal connections and several descending pathways were also recognized in each species. The descending pathways include ipsilateral tectobulbar and tecto-isthmi pathways and a contralateral predorsal bundle. Lesions which damaged only certain tectal laminae in the Iguana revealed a laminar organization of the efferent projections. A lesion restricted to the superficial retinal-recipient layers, stratum griseum et album superficiale, resulted in degeneration in only nucleus isthmi pars magnocellularis and nucleus geniculatus lateralis pars ventralis. A lesion which involved both the retinal-recipient layers and stratum griseum centrale resulted in degeneration in only one additional structure, nucleus rotundus. A small lesion involving the deep periventricular layers as well as the superficial layers produced degeneration in the predorsal bundle and the ipsilateral tectobulbar tract as well as in the structures receiving input from the more superficial layers. These results are compared to the results of similar analyses of the superior colliculus in mammals.

Animals↗
PubMedDate not supplied

An unusual ocular manifestation of discoid lupus erythematosus.

BACKGROUND: Discoid lupus erythematosus is a chronic skin disease characterized by well-demarcated papules and plaques. Mucous membrane changes are common; however, conjunctival involvement is unusual. We report a case of unilateral, chronic, isolated discoid lupus erythematosus of the conjunctiva. OBSERVATIONS: A 32-year-old man presented for evaluation of chronic conjunctivitis of the right eye that had persisted for 9 years. A biopsy of the bulbar conjunctiva revealed a mixed mononuclear cellular infiltrate distributed along the epithelial basement membrane zone and around the stromal blood vessels. Immunohistopathologic examination revealed a diffuse, granular pattern of fluorescence corresponding to immunoglobulins and complement components along the epithelial basement membrane zone and in the walls of the stromal blood vessels. Electron microscopy demonstrated changes in the epithelial basal lamina consistent with discoid lupus erythematosus, including areas that were multilayered. Immunoelectron microscopy identified sub-basal lamina deposits of immunoglobulin G. CONCLUSIONS: Discoid lupus erythematosus should be a suspected cause of chronic conjunctival inflammation; the diagnosis is substantiated by immunopathologic and ultrastructural studies.

Adult↗