Mechanisms of Primate Working Memory

One of the defining features of the behavior of many animal species is the ability to retain and utilize information from the environment even after it is gone. The encoding and utilization of information on short time scales is referred to as working memory. It is not yet fully understood how the brain accomplishes working memory. This dissertation presents three studies that help to characterize the working memory system of primates. All three studies involve primates performing saccades during a spatial memory task. The first study demonstrates that while the local field potential power is contralaterally tuned (i.e., power is greater for contralateral targets), overall power gradually decreases. The second study characterizes how, over 15 s of memory, if a cell will exhibit tuning during memory, it will do so within a couple seconds. Then, after some number of seconds, the cell will become untuned and stay untuned for the remainder of memory. Finally, the last study presents behavioral data demonstrating that primates represent simultaneously presented memoranda as a chunk. In contrast, when memoranda are presented sequentially, their representations compete in memory