The voluntary control of visual attention allows people to selectively process information in the environment that is relevant to their current behavioral goals, whereas stimulus-driven re-orienting of attention allows people to respond appropriately to unexpected contingencies. Previous work has indicated that brain regions play different roles in these two functions. Regions in dorsal parietal, near/at the intraparietal sulcus (IPS), and frontal cortex, near/at human frontal eye field (FEF), play a major role in voluntary orienting to stimuli and responses. A right hemisphere ventral network, consisting of the temporo-parietal junction (TPJ) and inferior frontal cortex, are inactive during task preparation, suggesting minimal involvement in the voluntary control of attention, but are strongly activated by re-orienting to unexpected but behaviorally important stimuli. In this grant we ask several questions concerning the functional significance of signals in dorsal and ventral fronto-parietal regions. A first question is whether preparatory orienting signals are predictive of behavioral performance for targets that are either attended or unattended. The topography of these signals in IPS and visual cortex as function of task (motion, shape discrimination), stimulus feature (location, motion), or effector (eye, arm) is considered. A second question is how information is coded within the ventral network in terms of topography, hemispheric asymmetries, stimulus modality, and relationship to behavioral performance. A third question is how the input to this ventral network is controlled by signals coming from the dorsal network. Prior work has indicated that TPJ activity is decreased in the presence of a task set. We propose that this decreased activity reflects a filtering of the input from unattended sensory areas to TPJ, which prevents it from inappropriately responding to salient stimuli that are not task-relevant. Several experiments are proposed that test predictions of this hypothesis. ? ?
Showing the most recent 10 out of 41 publications
