A Specific Role for the Thalamus in Mediating the Interaction of Attention and Arousal in Humans

ies, 1984) distinguishes sustained from selective attention; the first is defined as maintaining attention to a single source of information for an unbroken period of time, whereas the second is defined as attending to one source of information and excluding the others. Both sustained and selective attention are affected by the level of arousal (Das et al., 1994). The link between attention and arousal is related to their mutual dependency and complementary behavioral expression (Lynn, 1966). A correlation between performance of attentional tasks and level of arousal has been reported (Babkoff et al., 1991). However, arousal and attention are related in a nonlinear manner: attentional performance improves with a moderate increase of arousal but drops dramatically when a state of high excitement is reached (Easterbrook, 1959). On the other hand, sustained attention reduces arousal and induces drowsiness (Babkoff et al., 1991). Arousal and attention rely on distinct anatomical system