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T J Voneida

Publications and source records attributed to T J Voneida.

16 recordsLinked to original sources
PubMed1992

Use of computer-assisted courseware in teaching neuroscience: the Graphic Brain.

We describe the development of a computer-assisted instructional tool for the neurosciences. Designed to run on readily available MS-DOS computers, the Graphic Brain utilizes computer-generated static and animated images and accompanying text to assist in instruction of neuroanatomy and neurophysiology. We have used the Graphic Brain in our medical neuroscience course and report that, as measured anecdotally and by test scores, it facilitates student comprehension of the space- and time-varying aspects of anatomy and physiology. When the Graphic Brain is used as an adjunct to lecture, we find that we can cover the same material in 75% of the time required using traditional methods.

Brain↗
PubMed1990

Changes in instrumentally and classically conditioned limb-flexion responses following inferior olivary lesions and olivocerebellar tractotomy in the cat.

Lesions were placed in various parts of the inferior olivary nucleus and olivocerebellar tract in an attempt to define further the role of the inferior olive in the performance of a conditioned limb-flexion response (LFR) in cats. Thirty-two cats were trained to make an LFR using either classical or instrumental conditioning. The conditioned stimulus (CS) was a tone, and the unconditioned stimulus (US), a shock to the forelimb. Following training, lesions were placed in various parts of the inferior olivary nucleus in 20 animals (radio frequency lesions, 17; electrolytic lesions, 3). Midline section of the olivocerebellar tract was carried out in 12 animals. The degree of conditioned-response (CR) loss resulting from a given lesion was closely related to the precise locus of the lesion. Rostromedial olivary lesions, which included the spino- and cortico-olivary forelimb projection zones and the olivocerebellar projection area, resulted in varying degrees of CR loss (from partial to near total), deregulation of response latency, and a significant reduction of response amplitude. The CR deficit and degree of post-operative CR recovery were directly related to the extent of damage to this part of the rostromedial olive. Lesions restricted to the caudal olive or to caudal levels of the olivo-cerebellar tract resulted in no postoperative CR deficits. Animals with caudal lesions, however, showed more severe general motor deficits postoperatively than did those with rostromedial lesions and loss of the CR. Prolonged training of animals with the most complete CR deficits resulted in some relearning, but response patterns were typified by long-latency, low-amplitude CRs and a highly unstable response pattern.

Animals↗
PubMed1979

Efferent projections of the dorsal ventricular ridge and the striatum in the Tegu lizard. Tupinambis nigropunctatus.

A H3 proline-leucine mixture was injected into the dorsal ventricular ridge (DVR) and striatum of the Tegu lizard in order to determine their efferent projections. The brains were processed according to standard radioautographic technique, and counterstained with cresyl violet. DVR projections were generally restricted to the telencephalon, while striatal projections were limited to diencephalic and mesencephalic structures. Thus the anterior DVR projects ipsilaterally to nuclei sphericus and lateralis amygdalae, striatum (ipsilateral and contralateral) ventromedial nucleus of the hypothalamus, nucleus accumbens, anterior olfactory nucleus, nucleus of the lateral olfactory tract and lateral pallium. Posterior DVR projections enter ipsilateral anterior olfactory nucleus, lateral and interstitial amygdalar nuclei, olfactory tubercle and bulb, nucleus of the lateral olfactory tract and a zone surrounding the ventromedial hypothalamic nucleus. Labeled axons from striatal injections pass caudally in the lateral forebrain bundle to enter (via dorsal peduncle) nuclei dorsomedialis, medialis posterior, entopeduncularis anterior, and a zone surrounding nucleus rotundus. Others join the ventral peduncle of LFB and enter ventromedial nucleus (thalami), while the remaining fibers continue caudally in the ventral peduncle to the mesencephalic prerubral field, central gray, substantia nigra, nucleus intercollicularis, reticular formation and pretectal nucleus posterodorsalis. These results are discussed in relation to the changing notions regarding terminology, classification and functions of dorsl ventricular ridge and striatum.

Amygdala↗
PubMed1978

The cat's response to stimulus difference as attention focus and cue.

The cat's response to visual difference targets in figure-ground and figure-figure arrays (a unique target figure in a field of contrasting identical figures) was studied. Subjects approached the targets of the figure-ground arrays readily when they were presented in a training series, learning to use them as cues to the location of a food reward, and showing no disturbance when stimulus aspects of the arrays were reversed. Response to the figure-figure targets during training was more variable. Some were approached promptly, but others, especially those involving interchanging of target and background elements, required considerable training before consistent approach was achieved. Subjects selected the target with significant frequency in test series with novel figure-ground arrays, even after only brief training; they did not, however, select the target in novel figure-figure arrays until they had extended experience with training stimuli.

Animals↗
PubMed1976

A comparative neuroanatomic study of retinal projections in two fishes: Astyanax hubbsi (the blind cave fish), and Astyanax mexicanus.

Retinofugal projections in the blind cave fish A. hubbsi and in the highly visual A. mexicanus were studied with both reduced silver and autoradiographic methods. Contrary to what has been reported for other teleosts, ipsilateral, as well as the generally accepted contralateral, projections were found in A. mexicanus. Bilateral retinofugal projections were traced to the dorsolateral thalamic nucleus and area pretectalis. Contralateral projections were traced to the lateral geniculate nucleus, nucleus pretectalis, accessory optic nucleus, nucleus corticalis, nucleus opticus hypothalamicus and the superficial layers of the optic tectum (strata opticum, fibrosum and griseum superficiale, and the cellular zone of griseum centrale). Retinal efferents in the blindfish, A. hubbsi, are sparse and totally crossed. Areas receiving a retinal projection include nucleus opticus hypothalamicus, lateral geniculate and the superficial layers of the medial third of the optic tectum. Preliminary behavioral studies are described and discussed in relation to the possible visual potential of this teleost.

Animals↗
PubMed1976

Tectal efferents in the blind cave fish Astyanax hubbsi.

Suction lesions were placed in the optic tecta of 36 blind cave fish. Three main bundles of tectal efferents were observed. A large, caudally directed fascicle distributes to the ipsilateral torus semicircularis, nucleus isthmi, and lateral tegmental areas of the mesencephalon and pons via the ipsilateral tectobulbar tract. Contralaterally, this fascicle descends to pontine levels as the contralateral tectobulbar tract. A second, rostrally directed bundle exits from the tectum at two levels. A small fascicle leaves from the caudal tectum and ascends rostrally as the commissura transversa. This bundle then joins with more rostrally exiting fibers and the combined fascicles collect in the area of the medial optic tract. They remain in this position until the level of the postoptic commissure where they decussate. Subsequently, this bundle moves caudally and enters the contralateral tectum at its most rostral extreme. The third bundle of tectofugal efferents leaves the tectum medially, at the level of the lesion, and enters the tectal commissure, through which it is distributed to the ipsilateral torus longitudinalis and contralateral optic tectum.

Animals↗
PubMed1975

Interhemispheric projections of the optic tectum in pigeon.

The anatomical patterns of intertectal pathways in pigeon (Columba livia) were studied with modifications of the Nauta-Gygax silver technique following discrete unilateral tectal lesions. No homotopic connections between the two optic tecta were found. The data do not support an anatomical basis for the behavioral observation of interhemispheric reversal of left-right mirror-image patterns in monocularly trained pigeons. Degenerated fibers of passage were identified in the tectal commissure, the posterior commissure, the ventral tegmental decussation and the supraoptic decussations. Preterminal fields were identified in the contralateral substantia grisea perinventricularis of the tectum, lateral mesencephalic reticularnuclei, area pretectalis, nucleus linearis caudalis, nuclues posteroventrialis, and lateral geniculate nucleus, pars ventralis. The possible significance of these findings is discussed with reference to behavioral, electrophysiologic and neuroanatomic studies.

Animals↗
PubMedDate not supplied

Fetal rat cerebellar fragment transplantation into adult rat forebrain lesion cavities.

Fragments of fetal rat cerebellar tissue were grafted into forebrain cortical lesion cavities of adult rats. After a survival ranging from 12-151 days, no graft was found to fill the cavity completely. Large neurons, occasionally grouped into nests, were identifiable from the 22nd day. Myelinated graft fibers, first seen at 32 days, failed to enter host brain. Although grafts demonstrated elements resembling cerebellar tissue, overall organization did not resemble that of the cerebellum.

Animals↗