No description available.

Dissertation (Ph.D.)--Auburn University, 2009. / Abstract. Includes bibliographic references.

Thesis (Ph. D.)--University of Chicago, Committee on Neurobiology, March 1999. / Includes bibliographical references. Also available on the Internet.

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.

No description available.

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

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.

Food cleaning behavior has been observed among laboratory squirrel monkeys. A Wilcoxon signed-ranks test showed that significantly more cleaning behavior occurred when hard monkey chow pellets and soft fruit were coated with edible debris. Monkeys removed fewer pieces of fruit from a food crock containing fruit coated with edible debris in a timed test. A principal component analysis of the food cleaning behaviors showed two underlying correlated factors. The first factor was the use of the body to clean food. The second factor was the use of the environment to clean food. Two groups of squirrel monkeys, one without previous learners and one with previous learners, were subjects in a fishing study. The presence of previous learners in the social group was not significant for monkeys fishing in water filled crocks. But there was a significant difference in the number of fishing attempts made by the No Previous Learners Group when fishing in wading pools. The Previous Learners group did not make significantly more fishing attempts fishing in wading pools than in crocks. A significant difference was observed in fishing attempts during Phase 1 and Phase 2 of the wading pool experiment for both groups. All monkeys in the group fishing experiments ate fish when it could be obtained. Monkeys who did not learn to fish successfully learned alternative behaviors to obtain fish. The Previous Learners group in the wading pool experiment were subjects in a more difficult fishing test. Significantly fewer fishing attempts were made but the number of monkeys that caught fish was larger. Caged squirrel monkeys scored a lower percentage of fishing attempts than squirrel monkeys living in a social group. While Cebus monkeys caught fish, unlike squirrel monkeys, they did not attempt to eat them.

No description available.

Six squirrel monkeys were tested on short-term memory tasks assessing ability to suppress perseverative responses that had been previously reinforced. Each trial was divided into three parts: Initial Preference Assay (IPA), Bias-Conditioning (BC), and Reversal Conditioning (RC), and alternated between two conditions: experimental and control. Strength of response bias (based on choices of response during IPA) exceeded chance levels for each monkey. Eighty-four percent of responses to BC of the experimental trials were made to the response loci chosen in IPA even though that response was not rewarded. Monkeys made 38% correct responses during RC but shifted from making most errors during control trials in the beginning of the experiment to making most errors during experimental trials by the end of the experiment. Monkeys had developed a strategy of persevering from IPA to BC and then shifting to the other, not previously chosen window on RC, which led to correct responses in the experimental trials. (Abstract shortened with permission of author.)