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Biomedical subjects

T J Voneida

Publications and source records attributed to T J Voneida.

At least 19 recordsLinked to original sources
PubMed2000

The effect of brachium conjunctivum transection on a conditioned limb response in the cat.

Seven cats were trained to perform a forelimb conditioned response to a paired tone conditioned stimulus (CS)/shock unconditioned stimulus (UCS). Brachium conjunctivum section ipsilateral to the trained limb was carried out following criterion conditioned response (CR) performance. Lesion sites were identified histologically and further confirmed by observation of cellular changes in the dentate and interpositus nuclei ipsilateral to the section. The brachium conjunctivum was found to have been sectioned in four of the seven subjects. Each of these animals demonstrated a total or near-total loss of the CR. Extended postoperative training resulted in no increase in CR performance levels. The unconditioned response (UCR) remained unaffected, as did limb placing, accuracy of striking at moving objects, grooming, running and walking. The results are discussed in the context of an earlier report by McCormick et al. [Bull Psychonom Soc 1981;18:103-5], in which section of the superior cerebellar peduncle was found to abolish a conditioned nictitating membrane response in the rabbit. Taken together, they support the contention of Lavond [Annu Rev Psychol 1993;44:317-42], Thompson [In: Sprague JM, Epstein AN, editors. Progress in Psychobiology and Physiological Psychology. New York: Academic Press 1983, pp. 167-96], Yeo et al. [Behav Brain Res 1984;13:261-66; Exp Brain Res 1985;60:87-98; Exp Brain Res 1985;60:99-113; Exp Brain Res 1992;88:623-38.] and others that the cerebellum represents a critical site for acquisition and retention of a conditioned memory trace.

Animals↗
PubMed1999

The effect of rubrospinal tractotomy on a conditioned limb response in the cat.

Five cats were trained to perform a forelimb conditioned response to a paired tone CS/shock UCS. Rubrospinal tract section ipsilateral to the trained limb was carried out following criterion CR performance. Lesion sites were identified histologically and further confirmed by observation of cellular changes in the red nucleus contralateral to the trained limb. Tractotomy resulted in total or near-total loss of the CR. Prolonged postoperative training resulted in no increase in CR performance levels. The UCR remained unaffected, as did limb placing, accuracy of striking at moving objects, grooming, running and walking. Training of the opposite limb in two subjects resulted in mean scores of 90 and 85% within three sessions. Control lesions in those subjects resulted in no changes in CR performance scores. The red nucleus receives a substantial input from sensorimotor cortex and cerebellum, both of which have been shown to represent essential parts of the brain circuitry involved in associative learning and memory. Since pyramidotomy has no effect on limb CR performance [Vonedia TJ. Exp Neurol 1976;19:483-493], the possible role of the red nucleus/rubrospinal tract is discussed in terms of a critical trigger area for the expression of a learned motor response.

Animals↗
PubMed1998

Sperry's concept of mind as an emergent property of brain function and its implications for the future of humankind.

Sperry's proposal that subjective experience plays a major role in brain function and in the emergence of mind, consciousness and human values represent a challenge to behaviorism as the dominant force in psychology. Mind is viewed as an emergent property of the brain, generated from and dependent upon neural activity, but nonetheless separate from it. Macrodeterministic factors result in the evolution of human values, which represent a critical key to world change. Two major conferences resulted from Sperry's challenge to the scientific community. The Trieste Conference led to a 'Declaration of Human Responsibilities', presently under consideration by the United Nations as a corollary to the 'Declaration of Human Rights'. The Japan Conference inspired work toward a Network University of the Green World, in which computer networking will support international communication in areas of environmental concern.

Brain↗
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↗
PubMed1982

Indirect visual cortical input to the deep layers of the hamster's superior colliculus via the basal ganglia.

Anterograde and retrograde tracing techniques were employed to delineate the organization of a visual cortical input to the deep layers of the hamster's superior colliculus which may be mediated by links in the striatum and substantia nigra. Autoradiographic experiments showed that areas 17, 18a, and the cortex medial to area 17 (areas 18b and 29) all projected to the dorsocaudal part of the ipsilateral striatum. This projection was organized so that the rostrocaudal axis of the visual cortex was represented along the antero posterior axis of the striatum. Large posterior neocortical injections which included all of these areas also revealed a weak, crossed corticostriatal pathway. Such injections also demonstrated clear discontinuities in the terminal distribution of the visual corticostriatal projection, similar to those which have been noted after injections of tracers into the motor and premotor cortices. Retrograde tracing experiments showed that the cells of origin of the visual cortical projections to the striatum were medium-sized pyramidal neurons located primarily in the upper portion of lamina V. Anterograde transport of [3H]-leucine and HRP showed that the portion of the striatum heavily innervated by the visual cortex projected to the part of substantial nigra, pars reticulata immediately adjacent to the cerebral peduncle. Injections in the rostral striatum labeled more medial portions of this nucleus. The cells of origin of the striatonigral pathway measured between 13 and 20 micrometers in diameter and they were located primarily in the dorsal and lateral parts of the striatum. Anterograde tracing after substantia nigra, pars reticulata injections revealed a projection to both superior colliculi. The uncrossed pathway terminated primarily as a series of patches throughout the mediolateral and rostrocaudal extents of the lower stratum griseum intermediale and stratum album intermedium. Labeling was also visible in the lateral portion of the stratum griseum profundum. The crossed nigrotectal pathway terminated primarily in the rostrolateral stratum griseum profundum. The cells of origin of the nigrocollicular pathway were fusiform or multipolar cells and were located primarily adjacent to the cerebral peduncle throughout the rostral half of the substantias nigra, par reticulata.

Animals↗
PubMed1981

Anatomical and electrophysiological demonstration of tectotectal pathway in the golden hamster.

Both the retrograde transport of horseradish peroxidase (HRP) and extracellular single unit recording have been employed to demonstrate the existence of an intertectal pathway in the golden hamster. The cells of origin of this projection are located primarily in the stratum griseum intermediate and stratum griseum profundum of the anterior one-half of the colliculus and respond, in most cases, only to somatosensory stimuli. These findings cast doubt on the recently proposed generalization [13] that this pathway may be rudimentary or even absent in animals with limited collicular binocularity or a small ipsilateral hemifield representation in the colliculus.

Animals↗
PubMed1981

The origin of the hippocampal commissure in the rat.

The present study was designated to determine the origin of commissural axons in the hippocampus. One hippocampus of 94 rats was pressure injected with 40% horseradish peroxidase (Sigma VI), or with 2-4% wheat germ agglutinin HRP (E-Y Labs). Injections (0.001 to 0.1 microliter) were made through glass micropipettes with fitted plungers. Pipettes were positioned stereotaxically, and by electrophysiological monitoring through the injection syringe. An ipsilateral stimulating electrode activated CA3 and CA1 cells via Schaffer collaterals. Population potentials were monitored as the recording pipette was advanced from the cortical surface into the hippocampus. Wave forms of monosynaptically elicited field potentials provided an accurate indicator of its position. Following survival periods of 24 hours, the brains were processed according to the Mesulam method. Forty-micron sections were serially mounted and counterstained. Injection sites and filled cells were plotted manually on a standard set of coronal sections. Our results indicate that field CA1 receives input from contralateral subfields CA1a and c, as well as from all CA3 subfields. In addition, rostral CA1 injections resulted in labeling of cells in the contralateral subiculum and entorhinal cortex. Homotopic connections exist between subfields CA3a and b; it appears that a major input to CA3c is from the contralateral polymorph cells of the dentate hilus. Commissural input to the dentate granule cells appears to be the giant polymorph and CA3c cells of the contralateral dentate hilus. With respect to the question of homotopicity, our results suggest that commissural connections are predominantly homotopic in the mediolateral plane, although CA1 and CA3 injections also resulted in contralateral labeling of hippocampal cells caudal to the levels of injection.

Animals↗
PubMed1981

Efferent projections of the septum in the Tegu lizard, Tupinambis nigropunctatus.

A H3 proline or H3 leucine mixture was injected into the septal region of the Tegu lizard in order to determine its efferent projections. The brains were processed according to standard autoradiographic technique and counterstained with cresyl violet. Septal projections were limited to either telencephalic or diencephalic areas. Intratelencephalic projections consisted of efferents to medial pallium, nucleus accumbens, bed nucleus of the anterior commissure, preoptic area and septum itself. Fibers entering the diencephalon projected to medial habenular nucleus, dorsomedial thalamic nucleus, dorsolateral thalamic area, periventricular nucleus of the hypothalamus, lateral hypothalamic area and mammillary nucleus. The results are discussed in relation to the efferent projections of the septum in other vertebrates.

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↗