Optical Imaging of Short–Term Working Memory in Prefrontal Cortex of the Macaque Monkey
Prefrontal cortex is an area critical for cognitive functions such as planning, decision-making, and reasoning. Working memory is a key aspect to the execution of these functions and has been strongly associated with prefrontal function. This chapter reviews the functional organization of a prefrontal area, area 46, that has been associated with working memory in monkeys. Anatomical and optical imaging studies indicate the presence of a clustered organization within area 46, similar in nature to clustered organizations found in sensory cortical areas. Although the relationship of these clusters to working memory function is unknown, optical imaging studies suggest a spatial organization for mnemonic function. This ‘spatial memory map’ is topographically consistent with electrophysiologically established maps for visual and eye movement response. Interestingly, in trials in which response suppression is required, optical imaging reveals a possible suppressive signal; lack of this signal may underly the perseveration seen in diseases such as schizophrenia. In sum, I suggest that clustered organization in prefrontal cortex provides a scaffold upon which visual, mnemonic, and motor response are organized.
KeywordsPrefrontal Cortex Delay Period Macaque Monkey Saccadic Response Blank Trial
This chapter is written in memory of Dr. Patricia Goldman-Rakic. Much of the optical imaging work described here was conducted in collaboration with Dr. Goldman-Rakic at Department of Neurobiology at Yale University School of Medicine, New Haven CT. Dr. Goldman-Rakic was a pioneer in prefrontal function and encouraged me to explore and extend ideas regarding functional organization to prefrontal areas. I am grateful to have had her support and mentorship. Others who contributed to this work were E Sybirska and Douglas Walled. Supported by Packard Foundation, NIMH P50MH068789, NEI EY11744, NIDA DA023002.
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