Association of ideas

Transcription and translation of proteins are required for the consolidation of episodic memory. Arc, an effector immediate early gene, has been linked to synaptic plasticity following learning and memory. It is well established that the rodent hippocampus is essential for processing spatial memory, but its role in processing object memory is a point of contention. Using immunohistochemical techniques, hippocampal sections were stained for arc proteins in the CA1 region of the dorsal hippocampus in mice following two variations of the novel object recognition (NOR) task. Results suggest mice that acquired strong object memory showed significant hippocampal activation. In mice that acquired weak object memory, hippocampal activation was not significantly different from controls. Arc expression was also examined in other hippocampal sub-regions, as well as in the perirhinal cortex. These results suggest that the mice must acquire a threshold amount of object information before the hippocampal CA1 region is engaged.

Cognitive theorists hypothesize two types of cognitive processes
(e.g., automatic and effortful) which may influence human information
processing. This thesis investigates age differences in when children
use intralist associative relationships (thought to be automatic in
nature) to identify other (categorical) relations. Use of conceptual/
categorical relations to organize recall is thought to be effortful in
nature. Sixty children each from grades 3, 5, 7, and 9 were presented
orally with lists of 20 words under free-recall instructions. Results
provide support for the position that recall memory of young children
is mediated primarily by associative rather than conceptual
relationships. Also, partial support was obtained for the three stage model of the development of organization proposed by Bjorklund and
Zeman (1982). However, the model's prediction of when children will
optimally use associative relationships to identify categorized
relations was inaccurate. These results indicate that older childrens'
recall can be facilitated by automatic cognitive processes resulting in
higher levels of clustering (organization) and recall.