Source: Dissertation Abstracts International, Volume: 40-07, Section: B, page: 3476. / Thesis (Ph.D.)--The Florida State University, 1979.

Source: Dissertation Abstracts International, Volume: 41-07, Section: B, page: 2820. / Thesis (Ph.D.)--The Florida State University, 1980.

A cross-cultural investigation of a male-male competition hypothesis regarding the evolution of male homosexual behavior was conducted using the Human Relations Area Files Probability Sample. Nine predictions pertaining to the incidence of homosexual behavior within cultures and consequences of the male-male competition hypothesis were tested. In addition, statistical control procedures were incorporated so as to evaluate the predicted relationships while minimizing bias. Seven of the nine predicted relationships received at least tentative support from the analyses, with two relationships receiving unqualified support. Of particular importance was the strong, positive correlation between the level of male homosexual behavior within cultures and the degree of polygyny within those cultures. Two predictions based on other proposed models for the evolution of homosexual behavior (kin-selection and bonding) resulted in non-significant world-wide correlations. Thus, it is suggested that factors which universally contribute to variability in the intensity of male-male competition may produce differences in the likelihood of the expression of homosexual behavior, while the particular advantages which may accrue to the individuals involved in this behavior have yet to be identified empirically. These advantages may be specific to certain cultural and personal situations rather than being universal. / Source: Dissertation Abstracts International, Volume: 44-11, Section: B, page: 3566. / Thesis (Ph.D.)--The Florida State University, 1983.

Three groups of laboratory rats were presented with water, laboratory chow, and a sugar solution for 23 hours and their eating and drinking patterns were quantified. Each group received either a glucose, fructose or maltose solution. The concentration of the sugar solution was systematically increased (4%, 8%, 16%, 32%) with a single concentration being presented to rats in four day blocks. For all three sugars, total intake (ml) of sugar solution increased with concentration, reaching a peak at 8% and then decreased with further rises in concentration. Calories consumed from sugar monotonically increased with concentration, reaching an asymptote at 8% for both glucose and maltose and at 16% for fructose. As calories consumed from sugar increased with rising concentration, chow intake decreased. The decrease in chow intake was due primarily to a reduction in feeding bout frequency. As the concentration of sugar increased, the day to night ratio of sugar intake approached unity. This was attributed to an increase in the incentive value of the sugar solution, provoking ingestion during the daytime, with postingestional inhibition limiting nighttime intake. Fluid bout volume increased with sugar concentration up to 8% and then either remained the same or dropped when the concentration was raised from 8% to 16% depending on the sugar. All groups decreased their fluid bout volume when the concentration was raised from 16% to 32%. These data suggest that caloric density is an important factor in the limitation of bout volume. Since caloric intake within a sugar drinking bout progressively increased with each rise in sugar concentration, the asymptotic portion of the curve describing calories consumed from sugar was attributable to alterations of drinking bout frequency and not drinking bout size. This finding also suggests that caloric load is not the sole factor / responsible for the limitation of bout volume. Bout drinking rate (ml/min) monotonically increased with concentration reaching an asymptote at 8% for glucose and at 16% for fructose and maltose. This finding supports the claim that the incentive value of sugar solutions does not decrease with high sugar concentrations. / Source: Dissertation Abstracts International, Volume: 45-08, Section: B, page: 2730. / Thesis (Ph.D.)--The Florida State University, 1984.

Visual masking was measured in two human psychophysical experiments which showed that the contrast threshold to a grating test stimulus and the increment threshold to a spatially homogeneous (flash) test stimulus were elevated when they were preceded, respectively, by a grating or flash masking stimulus over a range of stimulus onset asynchronies (SOAs) from 55 to 200 milliseconds. The amplitude of the visual evoked cortical potential (VECP) to a test stimulus was then measured in anesthetized, paralyzed cats under the stimulus conditions used in the psychophysical experiments. The amplitude of the VECP was reduced when the test stimulus was presented after the masking stimulus at SOAs shown to produce masking in the psychophysical experiments. It was concluded that the reduction in VECP amplitude could be used as a physiological measure of visual masking and experiments were conducted to identify the properties and neural locus of the masking effects. / Visual masking was produced by both monoptically and dichoptically presented gratings and flashes. Masking produced dichoptically must be attributed to cortical mechanisms. However, the degree of masking was significantly weaker for dichoptically presented stimuli, suggesting that masking produced monoptically was both peripheral and central in origin. / Masking produced by monoptically presented gratings was greatest when the contours of the masking and test stimuli had the same spatial phase and orientation and was reduced by half when the orientation of the contours differed 6(DEGREES) to 15(DEGREES). A cortical neural locus for orientation-selective masking was demonstrated by simultaneous recordings of evoked potentials in the optic tract and visual cortex, which showed the degree of masking measured in the optic tract was independent of test stimulus orientation. / The findings support an integration theory of masking which posits that masking results when the masking and test stimuli evoke responses in the same neural elements and produce a degradation of the response to the test stimulus. Masking and test stimuli with contours differing in orientation would excite separate populations of orientation-selective cortical neurons and thereby produce little masking. / Source: Dissertation Abstracts International, Volume: 44-02, Section: B, page: 0643. / Thesis (Ph.D.)--The Florida State University, 1983.

Electric taste may be described as the perception of a taste produced by passing a small current through the tongue. These studies were undertaken to gain some insight into its mechanism on both a neurophysiological and biophysical basis by recording electrophysiologically from the chorda tympani nerve of the rat in response to both electrical and chemical stimulations of the tongue. / The response profiles of chemical and electrical stimulations saturated at the same maximum response for each individual salt tested (LiCl, NaCl, KCl, and CaCl(,2)) indicating an ion specificity for electric taste. This observation supports the idea of iontophoresis of ions at these curent densities ( 300 microamps/sq. cm.). If the taste cells of the tongue were inactivated with either Iodoacetic acid or N - ethyl maleimide or removed with collagenase, then responses from the chorda tympani could only be obtained at these higher current densities. / A mechanism was proposed for electrical stimulations which accounts for the responses as a result of ion accumulation around the state receptor membranes. The membrane, acting as an anion exchanger, selectively accumulates cations to anodal current countering the charge with anions from the cell's interior. The magnitude of this accumulation is proposed to be a balance of ions being accumulated by the current and diffusing away, down their concentration gradient, into the bulk solution. / Source: Dissertation Abstracts International, Volume: 44-02, Section: B, page: 0641. / Thesis (Ph.D.)--The Florida State University, 1983.

Albino rats were maintained in varying illuminances of cyclic light (12L:12D) from birth through 15 weeks. Upon sacrifice, several retinal parameters were tested for differences between animals raised in one illuminance and another. These parameters were: (1) dark-adapted whole retina rhodopsin level, (2) steady-state whole retina rhodopsin level, (3) rod outer segment length throughout the retina, (4) photoreceptor cell density throughout the retina, (5) in situ rhodopsin absorbance throughout the retina, and (6) rhodopsin regeneration rate in vivo. The range of illuminances in the animals' habitats was 3 lux to 800 lux. / Results proved that albino rats were able to change a combination of the above parameters in order to adapt to the illuminance of their environment. Specifically, there was four times more rhodopsin in the whole retina extract of dark-adapted animals which were raised in 3 lux than those raised in 400 lux. Changes in the transverse absorbance, determined by microspectrophotometry, and the length of outer segments accounted for this difference. The microspectrophotometry was carried out on fixed and frozen sections of retina. The transverse absorbance measures were the absorbance in small volumes of the outer segment layer, and took into account both the density of cells and the density of pigment within cells. The change in dark-adapted rhodopsin content, coupled with the ability to alter their pigment regeneration rate, allowed the animals to control the amount of pigment in their retinas at steady-state bleach. By altering this amount, the rats controlled the number of photons their retinas caught each day with great accuracy. Animals raised in cyclic illuminances ranging from 3 to 400 lux caught a statistically equal number of photons (2.03 (+OR-) 0.2 x 10('16)) during the light period. / This study detailed a continuum of adaptation over a wide range of cyclic illuminances and revealed a retinal plasticity previously unknown in vertebrates. The possible evolutionary significance of this plasticity was briefly considered. / Source: Dissertation Abstracts International, Volume: 45-09, Section: B, page: 3109. / Thesis (Ph.D.)--The Florida State University, 1984.

A technique was developed for obtaining odor psychophysical data from pigeons. Each pigeon was phyically restrained so that its beak was held within the stimulus air steam and it was required to make one response in the presence of odor and another in the presence of clean air. Absolute thresholds to amyl acetate were between 10('-3.4) and 10('-3.6) of vapor saturation for each of three pigeons tested. / Following the determination of absolute threshold the olfactory nerves were bilaterally sectioned in each animal, and each was tested after this operation in an attempt to monitor the return of olfactory sensitivity due to reconstitution of the olfactory nerve. One pigeon regained preoperative levels of sensitivity within 20 days. Another pigeon showed nearly complete recovery 10 weeks after sectioning, after which its threshold increased by approximately .7 log unit and remained stable at this level. A third pigeon failed to exhibit any postoperative odor-air discrimination during 99 days of testing. / These results demonstrate that normal behavioral sensitivity to an odorant is possible with reconstituted nerves and that the recovery process following nerve sectioning may occur in less than three weeks. Possible explanations are given for the high degree of variability found across subjects. This study represents an initial step toward quantifying the relationship between the degree replacement of olfactory axons with reconstitution and the degree of recovery of specific olfactory capacities. / Source: Dissertation Abstracts International, Volume: 41-05, Section: B, page: 1967. / Thesis (Ph.D.)--The Florida State University, 1980.

Source: Dissertation Abstracts International, Volume: 41-01, Section: B, page: 0401. / Thesis (Ph.D.)--The Florida State University, 1979.

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