Joseph Zappia - Academia.edu (original) (raw)

Papers by Joseph Zappia

Behavioural Brain Research, 1987

The study examined the effect of testosterone on the asymmetry of visual discrimination performan... more The study examined the effect of testosterone on the asymmetry of visual discrimination performance of young chicks. Two-week-old chicks were tested on the pebble floor visual discrimination task. Male chicks were found to have brain asymmetry for visual discrimination learning~ since chicks tested binocularly, or tested monocularly using their right eye system, have superior learning performance compared to chicks tested monocularly using their left eye system. Control female chicks were not found to have brain asymmetry. Testosterone treatment (12.5 mg of testosterone oenanthate on day 2 posthatch) reversed the pattern of brain asymmetry observed in control males but not females. In addition, asymmetry of visual discrimination learning is demonstrated in both male and female chicks after unilateral intracranial treatment with monosodium glutamate.

Developmental Brain Research, 1987

A cell suspension of the optic tecta of 3-day-old chick embryos was injected into the vitreal cha... more A cell suspension of the optic tecta of 3-day-old chick embryos was injected into the vitreal chamber of 2-day-old posthatch chicks. After a 14-21-day survival period, examination of eyeballs showed that all implants survived and, in 50% of cases, were attached to the pecten. The implants had proliferated and showed a laminated pattern of organization, with small cells in the superficial regions and large cells in the deep regions of the implant. The implants also contained a well-developed neuropil with mature synapses. The host retina was not affected by the presence of the implant. We suggest that the avian pecten represents a highly amenable structure for studies involving the response(s) by damaged retinae to neural implants.

Current Eye Research, 1989

This study examines the effects of excitotoxic amino acids on eye growth and retinal morphology. ... more This study examines the effects of excitotoxic amino acids on eye growth and retinal morphology. Day old chicks received a single intraocular injection of either 200 nmoles kainic acid (KA), 200 nmoles quisqualic acid (QUIS) or 400 nmoles N-methyl-D,L-aspartate (NMDA). Following survival periods of 7, 14 and 21 days, eyeballs were removed and weighed. Measurements of axial length, equatorial length, anterior chamber depth and corneal diameter were taken. Treatment with KA increased eye weight and equatorial length. Treatment with QUIS increased the anterior chamber depth but decreased the equatorial length. Treatment with NMDA increased anterior chamber depth, but to a lesser extent than QUIS. The effects of QUIS and NMDA could be distinguished from those of KA since the former excitotoxins resulted in a marked increase in anterior chamber depth with no enlargement of vitreal chamber. Changes in eye size were evident by day 7 and were sustained throughout the duration of the experiment. Examination of retinae revealed that KA lesions amacrine cells, bipolar cells, some ganglion cells and photoreceptors. Exposure to QUIS lesions amacrine cells, horizontal cells and causes mild disruption of photoreceptor outer segments. In contrast, NMDA predominantly lesions amacrine cells. The results demonstrate that these neurotoxins have different effects on eye growth, which may be associated with differences in retinal pathology. It is proposed that photoreceptors are ideally suited to play a role in the control of eye growth.

Neuroscience Letters, 1989

In the chick forebrain, the hyperstriatum accessorium (HA), receives an orderly ascending project... more In the chick forebrain, the hyperstriatum accessorium (HA), receives an orderly ascending projection from the dorsolateral thalamus, a primary visual centre. The study examines the topography of the descending projection from HA to the ventral lateral geniculate nucleus (GLv), another retino recipient region of the diencephalon. Discrete injections of horseradish peroxidase-labelled wheat germ agglutinin were placed in the HA, and reaction product was assessed in terminals within the GLv. The rostrocaudal axis of HA undergoes a 180 ° rotation and is represented along the caudorostral axis of GLv. A comparison with other inputs to GLv, retina and optic rectum, shows that all inputs are in visuotopic register.

Developmental Brain Research, 1983

Key words: functional lateralization --chicken forebrain --glutamate --attack and copulation -lig... more Key words: functional lateralization --chicken forebrain --glutamate --attack and copulation -light exposure --embryonic development

Neuroscience Letters, 1985

Key words: glutamate kainic acid retinotoxicity visual behavior chick After intraocular treatment... more Key words: glutamate kainic acid retinotoxicity visual behavior chick After intraocular treatment with kainate or glutamate, chicks were tested for visual discrimination performance, pecking aim, bead detection, optokinetic response and pupillary response. Kainate at an amount of 6 nmol per eye impaired performance in all of the tests except pupillary response. No effects were seen after 0.6 nmol of kainic acid. Glutamate at 6000 nmol impaired performance on all tests but the optokinetic and pupillary response. Although glutamate caused less severe deficits in visual behaviour than the high dose of kainate, cellular organization of the retina, at least in some regions, was more disrupted in these animals. Glutamate at 600 nmol caused a late onset defect in visual discrimination performance but no effects on optokinetic response.

Behavioural Brain Research, 1987

The study examined the effect of testosterone on the asymmetry of visual discrimination performan... more The study examined the effect of testosterone on the asymmetry of visual discrimination performance of young chicks. Two-week-old chicks were tested on the pebble floor visual discrimination task. Male chicks were found to have brain asymmetry for visual discrimination learning~ since chicks tested binocularly, or tested monocularly using their right eye system, have superior learning performance compared to chicks tested monocularly using their left eye system. Control female chicks were not found to have brain asymmetry. Testosterone treatment (12.5 mg of testosterone oenanthate on day 2 posthatch) reversed the pattern of brain asymmetry observed in control males but not females. In addition, asymmetry of visual discrimination learning is demonstrated in both male and female chicks after unilateral intracranial treatment with monosodium glutamate.

Developmental Brain Research, 1987

A cell suspension of the optic tecta of 3-day-old chick embryos was injected into the vitreal cha... more A cell suspension of the optic tecta of 3-day-old chick embryos was injected into the vitreal chamber of 2-day-old posthatch chicks. After a 14-21-day survival period, examination of eyeballs showed that all implants survived and, in 50% of cases, were attached to the pecten. The implants had proliferated and showed a laminated pattern of organization, with small cells in the superficial regions and large cells in the deep regions of the implant. The implants also contained a well-developed neuropil with mature synapses. The host retina was not affected by the presence of the implant. We suggest that the avian pecten represents a highly amenable structure for studies involving the response(s) by damaged retinae to neural implants.

Current Eye Research, 1989

This study examines the effects of excitotoxic amino acids on eye growth and retinal morphology. ... more This study examines the effects of excitotoxic amino acids on eye growth and retinal morphology. Day old chicks received a single intraocular injection of either 200 nmoles kainic acid (KA), 200 nmoles quisqualic acid (QUIS) or 400 nmoles N-methyl-D,L-aspartate (NMDA). Following survival periods of 7, 14 and 21 days, eyeballs were removed and weighed. Measurements of axial length, equatorial length, anterior chamber depth and corneal diameter were taken. Treatment with KA increased eye weight and equatorial length. Treatment with QUIS increased the anterior chamber depth but decreased the equatorial length. Treatment with NMDA increased anterior chamber depth, but to a lesser extent than QUIS. The effects of QUIS and NMDA could be distinguished from those of KA since the former excitotoxins resulted in a marked increase in anterior chamber depth with no enlargement of vitreal chamber. Changes in eye size were evident by day 7 and were sustained throughout the duration of the experiment. Examination of retinae revealed that KA lesions amacrine cells, bipolar cells, some ganglion cells and photoreceptors. Exposure to QUIS lesions amacrine cells, horizontal cells and causes mild disruption of photoreceptor outer segments. In contrast, NMDA predominantly lesions amacrine cells. The results demonstrate that these neurotoxins have different effects on eye growth, which may be associated with differences in retinal pathology. It is proposed that photoreceptors are ideally suited to play a role in the control of eye growth.

Neuroscience Letters, 1989

In the chick forebrain, the hyperstriatum accessorium (HA), receives an orderly ascending project... more In the chick forebrain, the hyperstriatum accessorium (HA), receives an orderly ascending projection from the dorsolateral thalamus, a primary visual centre. The study examines the topography of the descending projection from HA to the ventral lateral geniculate nucleus (GLv), another retino recipient region of the diencephalon. Discrete injections of horseradish peroxidase-labelled wheat germ agglutinin were placed in the HA, and reaction product was assessed in terminals within the GLv. The rostrocaudal axis of HA undergoes a 180 ° rotation and is represented along the caudorostral axis of GLv. A comparison with other inputs to GLv, retina and optic rectum, shows that all inputs are in visuotopic register.

Developmental Brain Research, 1983

Key words: functional lateralization --chicken forebrain --glutamate --attack and copulation -lig... more Key words: functional lateralization --chicken forebrain --glutamate --attack and copulation -light exposure --embryonic development

Neuroscience Letters, 1985

Key words: glutamate kainic acid retinotoxicity visual behavior chick After intraocular treatment... more Key words: glutamate kainic acid retinotoxicity visual behavior chick After intraocular treatment with kainate or glutamate, chicks were tested for visual discrimination performance, pecking aim, bead detection, optokinetic response and pupillary response. Kainate at an amount of 6 nmol per eye impaired performance in all of the tests except pupillary response. No effects were seen after 0.6 nmol of kainic acid. Glutamate at 6000 nmol impaired performance on all tests but the optokinetic and pupillary response. Although glutamate caused less severe deficits in visual behaviour than the high dose of kainate, cellular organization of the retina, at least in some regions, was more disrupted in these animals. Glutamate at 600 nmol caused a late onset defect in visual discrimination performance but no effects on optokinetic response.