ATTENTION TO ACTION

The paper considers the question of why subjects are poor at performin g two tasks simultaneously if both require attention. It is shown usin g positron emission tomography (PET) that during new learning of a mot or sequence task the prefrontal and anterior cingulate cortex are exte nsively activated, but that they are no longer activated when a motor sequence has been practiced for an hour until it is automatic. It is a lso shown that early in motor learning there is interference if subjec ts are required to generate verbs at the same time, but that the inter ference is much less if they are required to do this late in motor lea rning. The prefrontal and anterior cingulate cortex are activated duri ng verb generation. It is therefore suggested that the interference oc curs centrally, and that it occurs in either prefrontal or anterior ci ngulate cortex.