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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

EFFECTS OF VISUAL DEPRIVATION ON THE TEMPORAL MODULATION SENSITIVITY OF THE OPTIC TRACT, LATERAL GENICULATE NUCLEUS, AND VISUAL CORTEX OF THE CAT

Unknown Date (has links)
Source: Dissertation Abstracts International, Volume: 41-01, Section: B, page: 0400. / Thesis (Ph.D.)--The Florida State University, 1980.
22

ROLE OF CENTRAL VISUAL PROJECTIONS IN EFFECTS OF LIGHT AND DARK ON NEUROENDOCRINE FUNCTION AND BEHAVIOR

Unknown Date (has links)
Several lines of evidence suggest that the central visual pathways have rather distinct and separate functions in the mediation of the various influences of light on animals. To investigate this further, the effects of selective visual system lesions on a number of light-induced changes in behavior and physiology were studied. / In one experiment, the effects of primary and accessory optic system lesions on drinking behavior and estrous cycles under light-dark (LD) and constant light (LL) conditions were investigated. Neither lesions of the primary optic tract (POT) nor lesions of the inferior accessory tract and substantial portions of medial terminal nucleus (MTN) had permanent effects on the estrous cycles of female albino rats on LD 12:12. The nocturnality (relative proportion consumed in the dark) of water intake under LD 12:12 was significantly reduced by MTN lesions. POT lesions were without effect on drinking in LD. / A 2-month exposure to LL caused an immediate and sustained depression of water intake and a gradual development of constant vaginal estrus (CE) in intact rats. The reduction in water intake was still observed in rats with POT lesions. MTN lesions on the average attenuated the inhibitory effect of LL on drinking, but resulted in a wide range of individual responses. In contrast, the development of LL-induced CE was accelerated following POT lesions, but was unaffected by MTN lesions. These results suggest that the primary optic system is involved in the mediation of LL-effects on estrous cycles but not on drinking. Conversely, the accessory optic system appears to be involved in the light regulation of water intake but not in the estrus response to LL. / In a second experiment, the roles of the visual pathways in determining the distribution of rapid eye movement (REM) sleep, slow wave sleep (SWS) and arousal within the LD cycle were investigated. Ablation of the POT or of the superior accessory optic terminal nuclei did not affect the distribution of sleep and arousal on 24-hr LD cycles. MTN lesions increased the nocturnality of REM sleep while leaving the distribution of SWS and arousal unchanged. Lesions of the suprachiasmatic nuclei, including the terminals of the retinohypothalamic tract (RHT) abolished the circadian rhythm of sleep-wakefulness and its entrainment to the LD cycle. These results confirm and extend those of others which indicate that the RHT is solely responsible for the entrainment of circadian rhythms by light. / The occurrence of REM sleep during darkness was significantly increased when intact rats were transferred from a 24-hr LD cycle to a 1-hr LD cycle. This effect of short LD cycles on sleep patterns was not abolished by selective ablation of either the primary optic, accessory optic, or retinohypothalamic projections, although rats with POT lesions showed significantly more REM sleep in the light periods than the other groups. In addition, MTN lesions accentuated dark enhancement of REM sleep such that virtually no REM sleep occurred during the short light periods. The data suggest that this response to short LD cycles is mediated by some hitherto undescribed retinal projection, or alternatively, can be mediated by several retinal projections ("mass action"). / The results of these experiments, along with those of other studies, indicate that the functions of the central visual pathways are not completely separate and mutually exclusive, and that a given retinal projection may be involved in a variety of photic-induced changes in behavior and physiology. / Source: Dissertation Abstracts International, Volume: 41-03, Section: B, page: 1155. / Thesis (Ph.D.)--The Florida State University, 1980.
23

The interaction of the sensory organs (olfactory placode and optic vesicles) with brain in Xenopus embryos

Unknown Date (has links)
Previous experiments in Xenopus laevis have shown that transplantation of an olfactory placode can result in the connection of the transplanted olfactory placode with different portions of the brain where hypertrophy and hyperplasia occurs. This project intended to ascertain the morphological interactions of the olfactory placode with the central nervous system and to compare this with the interaction of the eye primordium with the CNS in young embryos of Xenopus. Normal development of the olfactory placode was also studied to describe the morphological sequence of events involved in the development of the olfactory placode. / The olfactory placode and optic vesicle of two different species of Xenopus(laevis and borealis) were transplanted between the species at stage 23 to exploit the differential nuclear straining with quinacrine of Xenopus borealis. The chimerae enabled us to recognize where the donor cells are located among the host cells. / The olfactory organ first appears at stage 23 as a paired thickening of the two ectodermal layers: the superficial non-nervous layer (NNL) and the inner nervous layer (NL). Receptor cells differentiate from the NL and the supporting cells develop from the NNL. Sensory axons reach the brain at stage 32. Primitive synaptic contacts first appear at stage 37/38. / The transplanted placode in place of the removed eye usually fuses with the host's ipsilateral olfactory placode producing a large and irregularly shaped olfactory organ. With the passage of time the cells of the fused olfactory placode acquire a staining pattern that is entirely characteristic of the host. From the transplanted placode a nerve develops and reaches the diencephalon which is not its normal target or at times the telencephalon. Many placodal cells migrate along this nerve and penetrate the brain. These cells form small aggregates in the host brain. The donor cells remain in the host CNS up to premetamorphic stages when my experiments terminated. / The eye transplanted in place of the excised olfactory placode develops well with all the retinal layers and lens, however, it grows into a large, irregular organ. From the eye transplant, a cellular bridge develops and specifically connects with the diencephalon which is its normal target. The cellular bridge consists of donor cells and fibers. Some of the donor cells penetrate the rostral diencephalon mixing with the host cells. / The transplanted olfactory placode shows plasticity in that it connects with unconventional targets. Many cells from the transplanted olfactory placode migrate and incorporate into the non-olfactory area of the host brain. As opposed to the olfactory organ, the transplanted eye specifically reaches its normal target in spite of the two host eyes. The retinal cells that migrate through the tissue bridge incorporate into the host diencephalon. / Source: Dissertation Abstracts International, Volume: 50-08, Section: B, page: 3752. / Major Professor: Pasquale P. C. Graziadei. / Thesis (Ph.D.)--The Florida State University, 1989.
24

Psychophysiological assessment of conditioned responses to drug stimuli among cocaine and heroin addicts

Unknown Date (has links)
The purpose of this research was to examine more closely the conditioning factors that are assumed to be operating in heroin and cocaine addiction. The goal of this study was to determine the specific nature of psychophysiological responses of cocaine and heroin addicts when they are exposed to drug-related stimuli, to investigate whether classical conditioning occurs through association with the positive intoxicating effects or the aversive withdrawal symptoms of each drug, and whether this conditioning of psychophysiological symptoms to environmental stimuli occurs in cocaine addiction in a manner analogous to that seen in heroin addiction. / Multivariate analysis of variance procedures were employed to determine whether the addicts differed from matched control subjects on physiological measures of heart rate, skin conductance level, peripheral skin temperature, and on subjective ratings of craving, withdrawal-like, and high-like symptoms. Results indicate that heroin addicts in this sample experienced significantly greater withdrawal-like symptoms, and high-like symptoms, while cocaine addicts experienced significantly greater withdrawal-like symptoms high-like symptoms, and craving in response to the drug-related stimuli than did the control subjects. / The results are discussed in terms of the classical and operant conditioning paradigms, and treatment implications are examined. / Source: Dissertation Abstracts International, Volume: 51-02, Section: B, page: 1034. / Major Professor: Jack G. May, Jr. / Thesis (Ph.D.)--The Florida State University, 1989.
25

Connections of the auditory midbrain: Efferent projections of the dorsal nucleus of the lateral lemniscus, the nucleus sagulum, and the origins of the gabaergic commissure of Probst

Unknown Date (has links)
The efferent projections of the Cat's dorsal nucleus of the lateral lemniscus (DLL) were examined first with kainic acid-induced anterograde degeneration and $\sp3$H-leucine autoradiography, then by systematic repetition of horseradish peroxidase and fluorescent dye retrograde tract-tracing techniques. Biochemical properties of DLL neurons and their projections were studied first by immunohistochemical methods using antibodies directed against GABA and glycine, then by retrograde transport of $\sp3$H-GABA and $\sp3$H-glycine. / The results show that DLL projects axons to the ipsilateral inferior colliculus, and projects axons through the commissure of Probst to contralateral inferior colliculus and contralateral DLL. Approximately half of DLL projections to contralateral structures (IC and DLL) arise from axon collaterals. DLL's ipsilateral and contralateral projections are topographically and tonotopically organized. / Immunohistochemical studies show a large proportion (61-83%) of DLL neurons are immunolabeled by antibodies to GABA, few by antibodies to glycine. Furthermore, DLL neurons retrogradely transport $\sp3$H-GABA but not $\sp3$H-glycine from injections into the inferior colliculus. / The results also show that the commissure of Probst originates primarily (80%) from DLL, the remainder (20%) originates from nucleus sagulum. Orthograde transport studies show the nucleus sagulum projects to the inferior colliculus and medial geniculate body bilaterally, and to the nucleus sagulum of the opposite side. / Source: Dissertation Abstracts International, Volume: 49-08, Section: B, page: 3496. / Major Professor: Karen Kircher Glendenning. / Thesis (Ph.D.)--The Florida State University, 1988.
26

TEMPORAL MODULATION SENSITIVITY IN THE PIGEON

Unknown Date (has links)
Source: Dissertation Abstracts International, Volume: 38-06, Section: B, page: 2929. / Thesis (Ph.D.)--The Florida State University, 1977.
27

PARALLEL AUDITORY PATHWAYS MEDIATING REFLEXIVE HEAD ORIENTATION TO SOUND

Unknown Date (has links)
Source: Dissertation Abstracts International, Volume: 37-12, Section: B, page: 6397. / Thesis (Ph.D.)--The Florida State University, 1976.
28

EXOGENOUS MODULATION OF DRINKING RHYTHMS IN THREE STRAINS OF RATS

Unknown Date (has links)
Source: Dissertation Abstracts International, Volume: 37-12, Section: B, page: 6398. / Thesis (Ph.D.)--The Florida State University, 1976.
29

HINDBRAIN ORIGINS OF AUDITORY FIBERS ASCENDING TO THE CENTRAL NUCLEUS OF THE INFERIOR COLLICULUS AND THE NUCLEI OF THE LATERAL LEMNISCUS: A HORSERADISH PEROXIDASE STUDY IN THE CAT

Unknown Date (has links)
Source: Dissertation Abstracts International, Volume: 39-03, Section: B, page: 1534. / Thesis (Ph.D.)--The Florida State University, 1977.
30

ONSET OF PUBERTY AND SEXUAL BEHAVIOR IN FEMALE RATS AFTER NEONATAL MODIFICATION OF MONOAMINERGIC NEUROTRANSMITTERS

Unknown Date (has links)
Source: Dissertation Abstracts International, Volume: 38-09, Section: B, page: 4528. / Thesis (Ph.D.)--The Florida State University, 1977.

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