Twelve healthy subjects underwent investigation of averaged (electroencephalogram) EEG potentials during preparation for motor activity and in the latent period (LP) of visually evoked saccades by presentation of stimuli using Posner's (1980) design of “cost-benefit.” It has been shown that covert spatial attention orientation leads to an increase in amplitude and decrease in latency of presaccadic initiation potential peaks within the saccadic latent period (LP) (P-100, N –50). Processes of covert orientation of attention during the interstimulus interval period of anticipation of the target stimulus correlate with the increase of slow negativity of fronto-parietal-temporal localization. Spatial-temporal changes of presaccadic potentials are evidence of the fact that orientation of attention during motor preparation and saccadic initiation is reflected in intensification of fronto-parietal networks of saccadic control and attention, activating the fronto-medio-thalamic and thalamo-parietal modulating systems.

Clinical, experimental, and functional imaging studies suggest overlapping neuronal networks and functional interactions of alertness and visuospatial attention within the right hemisphere of the brain. To examine the interaction of arousal and visuospatial attention in peripersonal and extrapersonal virtual space, we tested 20 healthy male adults during 24 hr of sleep deprivation at four points during the night (9 p.m., 1 a.m., 5 a.m., and 9 a.m.). The main finding concerning covert orienting in a virtual environment is a highly significant slowing of reorientation toward the left visual hemifield in extrapersonal space due to decreased arousal. The results provide additional evidence for the proposed anatomical and functional overlap of the two attentional systems and indicate a modulation of visuospatial attention by the level of arousal in extrapersonal space. (JINS, 2008, 14, 309–317.)