Objectives:

This study was undertaken to identify neural substrates for simple focused attention and more highly-focused working memory in normal people and investigate their characteristics and differences.

Method:

Fourteen normal subjects were studied with [`50]H20 positron emission tomography during a visual processing baseline task, simple focused attention task and working memory task.Results were analyzed with the subtraction analysis to map the neural correlates of focused attention and working memory.

Results:

Activated areas during focused attention tended to be lateralized to the left and scattered over various regions including the anterior cingulate, motor area, and primary and secondary visual cortices. While the areas activated during working memory also show the left lateralization and scattered distribution, activation prevailed more in the frontal lobe than in the visual cortex, and was particularly remarkable in the right anterior cingulate.

Conclusion:

Focused attention and working memory do not have only conceptually com­monalties and differences but also have common and specific areas in their neural substrates. The anterior cingulate may commonly play an important role in both cognitive functions, whereas secondary visual cortex and prefrontal cortex seem to be predominantly implicated in each function, respectively.