The functional neural architecture of components of attention in language-processing tasks

Using functional magnetic resonance imaging we examined three important dim ensions of attentional control (selective attention, divided attention, and executive function) in 25 neurologically normal, right-handed men and wome n, using tasks involving the perception and processing of printed words, sp oken words, or both. In the context of language-processing manipulations: s elective attention resulted in increased activation at left hemisphere pari etal sites as well as at inferior frontal sites, divided attention resulted in additional increases in activation at these same left hemisphere sites and was also uniquely associated with increased activation of homologous si tes in the right hemisphere, and executive function (measured during a comp lex task requiring sequential decision-making) resulted in increased activa tion at frontal sites relative to all other conditions. Our findings provid e support for the belief that specific functional aspects of attentional co ntrol in language processing involve widely distributed but distinctive cor tical systems, with mechanisms associated with the control of perceptual se lectivity involving primarily parietal and inferior frontal sites and execu tive function engaging specific sites in frontal cortex. (C) 2001 Academic Press.