The Role of the Hippocampus in the Development of Spatial Memory Open Access

Blue, Shala Natasha (2009)

Permanent URL: https://etd.library.emory.edu/concern/etds/6t053g573?locale=en
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Abstract

Previous studies have suggested that the protracted development of certain spatial memory processes in primates may be correlated with the protracted neural maturation of the hippocampus. However, due to a lack of evidence in non-human primates regarding normal structural and functional maturation of the hippocampus, the present study investigated whether: 1) hippocampal-dependent spatial memory had a protracted development, 2) early damage to the hippocampus resulted in delayed impairments in spatial memory that correspond to the timing at which the hippocampal-dependent spatial memory abilities emerge, and 3) the effects of early damage to the hippocampus mimicked the effects of adult damage or whether significant sparing of spatial memory functions occurred after the neonatal hippocampal lesions. Rhesus macaque monkeys that received neonatal ibotenic acid lesions of the hippocampus (N=5) and controls (N=6), were tested on two versions of a VPC paradigm measuring spatial location memory and object-place associations at 8-months, 18-months and 5-6 years. Performance was evaluated throughout development and adult performance of animals with neonatal hippocampal lesions was compared to the performance of animals with adult lesions of the hippocampus, using the same paradigm, from a previous study. We found evidence for a protracted development of spatial memory abilities in normally developing rhesus monkeys with regards to both spatial location and object-place association. In addition, we found that animals with bilateral neonatal hippocampal lesions did not show a preference for novelty throughout development and that their performance as adults was similar to animals with bilateral adult lesions.

Table of Contents

CHAPTER 1. INTRODUCTION.................................................................. 1 CHAPTER 2. METHODS......................................................................... 18 CHAPTER 3. RESULTS & DISCUSSION (NORMAL DEVELOPMENT).................... 29 CHAPTER 4. RESULTS & DISCUSSION (EARLY HIPPOCAMPAL AMAGE)............. 47 CHAPTER 5. RESULTS & DISCUSSION (TIME OF DAMAGE)............................ 76 CHAPTER 6. GENERAL DISCUSSION.......................................................... 89 REFERENCES....................................................................................... 92 LIST OF FIGURES AND TABLES TABLE 1. VIEWING BEHAVIORS AND NOVELTY PREFERENCE IN SHAM-OPERATED

ANIMALS............................................................................................ 30-31 TABLE 2. PERCENT DAMAGE FOR MEMBERS OF GROUP NEO-H-IBO................. 48 TABLE 3. VIEWING BEHAVIORS AND NOVELTY PREFERENCE IN ANIMALS WITH NEONATAL HIPPOCAMPAL LESIONS.......................................................... 52-53 TABLE 4. INTENDED DAMAGE TO THE HIPPOCAMPAL FORMATION AND UNINTENDED DAMAGE TO ADJACENT AREAS.............................................. 77 FIGURE 1. NEUROANATOMY OF THE PRIMATE HIPPOCAMPUS....................... 6-7 FIGURE 2. SPATIAL AND NON-SPATIAL VISUAL PAIRED COMPARISON (VPC) TASKS............................................................................................... 23-24 FIGURE 3. NOVELTY PREFERENCE IN VPC TASKS....................................... 33-34 FIGURE 4. NOVELTY PREFERENCE IN THE VPC-OBJECT-IN-PLACE AND VPC- OBJECT-CONTROL TASKS...................................................................... 36 FIGURE 5. REPRESENTATIVE CASE NEO-H-IBO 4....................................... 50 FIGURE 6. NOVELTY PREFERENCE IN VPC-SPATIAL-LOCATION TASK............. 55 FIGURE 7. BETWEEN GROUP DIFFERENCES IN NOVELTY PREFERENCE IN THE VPC-SPATIAL-LOCATION TASK.............................................................. 57 FIGURE 8. NOVELTY PREFERENCE IN THE VPC-OBJECT-IN-PLACE TASK......... 59 FIGURE 9. BETWEEN GROUP DIFFERENCES IN NOVELTY PREFERENCE IN THE VPC-OBJECT-IN-PLACE TASK................................................................. 61 FIGURE 10. NOVELTY PREFERENCE IN THE VPC-OBJECT-CONTROL TASK....... 63 FIGURE 11. NOVELTY PREFERENCE IN THE VPC-OBJECT-IN-PLACE AND VPC-OBJECT-CONTROL TASKS IN ANIMALS WITH BILATERAL HIPPOCAMPAL

LESIONS............................................................................................ 64 FIGURE 12. EXTENT OF LESION............................................................. 78-79 FIGURE 13. NOVELTY PREFERENCE IN VPC-SPATIAL-LOCATION (A) AND VPC-OBJECT IN PLACE (B) TASKS........................................................... 82-83

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