When different development rates for psychological processes such as those in spatial memory exist, they can be linked to relevant brain areas via their different developmental rates. The hippocampus and caudate nucleus have been implicated in allocentric and egocentric spatial behavior changes found in youth and old age. Variation in allocentric and egocentric behavior in squirrel monkeys due to age was examined using a quadruple T-maze and animals in three age groups: 0.3 - 4 year olds, (n = 12), 5 - 10 year olds (n=12) and 11 - 17 year olds (n = 12). Subjects were trained to go to one of three goals in the maze from one of two training release locations. When they reached criterion for consistent responding, they were given probe trials pseudorandomly interspersed with the training trials in which they were released from one of the three other locations. The 12 test sessions were divided into three phases consisting of four sessions each. A 3 (age groups) x 3 (probe sites) x 3 (phases) mixed design ANOVA with repeated measures on the second and third factors revealed only a significant effect for probe site (F(1,33) = 14.55, p < .01) sing the Geisser-Greenhouse correction for heterogeneity of variance. The pattern of responding most clearly resembled route and was stable over testing. Age was not significant although there was a trend toward random behavior in young and more route-like behavior in older animals. Intrinsic maze cues effects on responding were examined. These data were analyzed using a 3 (age groups) x 2 (training groups) x 3 (probe sites) mixed design ANOVA with repeated measures on the last factor, and again revealed only a significant probe site effect (F(1,33) = 14.55, p < .01). Thus cues intrinsic to the maze did not affect response pattern. Only 13 subjects clearly used one of the three spatial strategies: 6 route, 3 direction, and 4 place. Of the remaining 23 animals 11 were young, 5 were adult and 7 were mature. Two used a variation of place, three used a combination of strategies, four were idiosyncratic, 10 used proto-route (route-like, but not systematic enough to be route) and three were random. The use of place strategy by animals as young as 4 and as old as approximately 17 implicates hippocampal changes occurring outside this age range.

Animal foraging behavior is shaped by patterns and processes that operate on several temporal and spatial scales. In chapter 1, I briefly review the meaning and importance of temporal and spatial scales. In chapter 2, I examine the foraging behavior of the Long Jawed spider (Tetragnatha elongata). In North Carolina, the spider exhibits the counter intuitive behavior of relocating its web daily in rich habitats, but rebuilding its web on the same site for many days in a row in poor habitats. I test a risk-sensitive foraging model of this behavior, but its predictions were not met. I develop an alternative hypothesis to explain the behavior of Long Jawed spiders: that the higher density of spiders in rich habitats results in more frequent interactions between spiders, and that these interactions provoke spiders to relocate more often in rich habitats. I report the results of density-reduction experiments, which corroborate my hypothesis. In chapter 3, I examine the foraging and storing strategy of the Eastern Gray Squirrel (Sciurus carolinensis). The squirrels ate most of the white oak (WO) acorns, and buried most of the red oak (RO) acorns, confirming my prediction. I also present the results of an experiment designed to reveal whether squirrels used tannin and/or fat content of acorns to distinguish between acorns of different species. The results of this experiment were inconclusive. In another experiment, I buried a large number of acorns, and assessed samples of acorns retrieved at intervals through the fall/winter season. I found that tannin levels in RO acorns did not decline during their interment, rendering an alternative hypothesis untenable. Further, I confirmed an earlier assumption: stored WO acorns do suffer more insect damage than RO acorns. I hypothesize that the storing and foraging strategy of squirrels may affect the distribution of oaks, and review evidence from the literature that supports this hypothesis. Finally, I argue that Clark's Nutcracker (Columbiana nucifraga) may employ the same strategy as it forages for pine seeds, and again review evidence from the literature to support this hypothesis. (Abstract shortened by UMI.)

No description available.

This thesis investigated whether a food-storing mammal, the eastern grey squirrel (Sciurus carolinensis), uses social cognitive skills in relation to its caching behaviour and explored whether social cognition really is a specialized adaptation that differs from other cognition by examining how social and non-social learning differ. The influence of social factors on the natural caching behaviour of wild squirrels was studied in the field and the effects of conspecific presence on specific aspects of caching behaviour (learning, memory and recovery) were investigated by testing captive squirrels in the laboratory on social learning and one-trial learning tasks. The squirrels were found to be able to learn by observing a conspecific and learned to make a logical choice more readily than an illogical one. They showed no such bias in a comparable non-social task. They responded flexibly to the presence of conspecifics both in the wild and in the laboratory but the results can be interpreted in terms of responses to observable cues rather than as evidence of higher cognitive skills. In total, this thesis suggests that squirrels use unsophisticated social cognitive strategies in relation to their caching but, the difference found in learning under social and non-social conditions suggests that, although not a highly social species, grey squirrels are particularly prepared to form certain associations with social cues. This offers some support to the theory that factors other than social complexity may lead to the development of the ability to process social information highly effectively.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1934. / Reprinted from American journal of anatomy, vol. 54, no. 3 (15 May 1934). Title from title screen (viewed Mar. 22, 2007). Includes bibliographical references (p. 506). Online version of the print original.

The thesis is divided into four parts;<p> 1.The implantation of the blastodermic vesicle,<p> 2.The method of amnion formation in Citillus,<p> 3.The anatomy and foetal membranes of a 25 mm. embryo,<p> 4.The brain of a 9 mm. foetus.

The thesis is divided into four parts;<p> 1.The implantation of the blastodermic vesicle,<p> 2.The method of amnion formation in Citillus,<p> 3.The anatomy and foetal membranes of a 25 mm. embryo,<p> 4.The brain of a 9 mm. foetus.

Thesis (Ph. D. in Physics)--Vanderbilt University, Dec. 2007. / Title from title screen. Includes bibliographical references.

M. Tech. Electrical Engineering. / Investigates the mathematical modelling, analysis and simulation of a six-phase squirrel cage induction machine. This dissertation is the report of the analysis and simulation of this machine through three methods, namely: The direct-quadrature axis (dqxy0102) based on generalised theory of electric machines, which enabled the machine to be mathematically modelled in the arbitrary reference frame; the classical magnetic field distribution analysis; and the finite element method (fem). The resulting models of the analysis of the six-phase squirrel cage induction machine are implemented by simulation using appropriate software. The simulations generate unique results of the steady-state and the dynamic performance characterising the performance of the six-phase squirrel cage induction machine. Tests are conducted on a 1.5 kW experimental machine whereby the performance characteristics of the theoretical analysis and simulations are validated with the experimental results. The results of the three are compared among themselves, and also with the experimental results to appraise the suitability of each method for the modelling and analysis of the hpo machine.Even though six-phase machine is considered in this study it is believed that the methods as applied in this work are generally applicable to hpo squirrel cage induction machine of any number of phases.

Six naive capuchin monkeys (Cebus appella) and six naive squirrel monkeys (Saimiri sciureus) were tested on an 8 second indirect delayed-response task in a modified Wisconsin General Test Apparatus (WGTA). Six experimental conditions were used to vary the lighting conditions during the 8 second delay between the termination of the 5 second cue light behind a door panel and the raising of a 2-way mirror screen which allowed the subject to respond to one of the two panels. These six conditions were altered by timers which controlled a small light located in the top of the test cage. The six experimental conditions were (1) light in test cage remained on for the entire 8 seconds; (2) light went off immediately following the termination of the cue light and remained off for the entire 8 seconds at which time the light came on simultaneously with the raising of the 2-way mirror screen; (3) light on for 4 seconds and then off for 4 seconds; (4) light off for 4 seconds then on for 4 seconds; (5) light on for 2 seconds, off for 4 seconds and on for 2 seconds; and, (6) light off for 2 seconds, on for 4 seconds and off for 2 seconds. A randomized 6 x 6 Latin Square was used to assign subject and condition per day. Testing was conducted six days per week which allowed each condition to be presented to each subject every week. The 6 x 6 Latin Square was then repeated five times for a total test period of 30 weeks or 180 days. The 30 weeks were divided into 3 blocks of 10 weeks each. The results were analyzed with the Sequential State Theory (SST) which was developed by King and Fobes and is a two-stage theory of learning. The two stages are defined as attention which is followed by an associative stage of bias free learning. The results indicated that, to the contrary of some recent research, proactive inhibition was a significant source of error under all conditions and for both species. There were no significant species differences as a function of the different lighting condition during the period of delay. The Sequential State Theory hypothesizes a triphasic model for the acquisition of a complex learning task. When the learning task is sufficiently difficult there are three clearly identifiable curves in the acquisition of learning. First, the animal exhibits error tendencies such as position perseveration. This tendency is followed by an increase in random responding. Finally, detect responses emerge which are manifested by attending to the relevant dimensions of the stimulus object. The data for both the capuchin monkeys and squirrel monkeys supported this model of learning with the response curves emerging in the predicted manner.