Simple methods have been devised for dissociating attentional subcomponents such as alerting, orienting, or reorienting of attention.2 In 1990, based on seminal cued target, detection (CTD) experiments in subjects with parietal lesions,3 Postier and Petersen“ described an anatomic network

responsible for visual detection which, they argued, involved mainly the right, hemisphere, with a (mainly frontal) anterior system responsible for executive attentional control, a posterior system responsible for orientation, selection, and attention focus (mainly right temporoparietal junction and intraparietal sulcus), and a general activation network (comprising the right fronto-parietal-thalamic Inhibitors,research,lifescience,medical network) responsible for alertness and vigilance. Since our basic aim was to improve rapid response to an Inhibitors,research,lifescience,medical elementary stimulus and prepare for motor action, we decided to incorporate a gap procedure

into our CTD paradigm to release fixation and hence attentional engagement (the gap also acted as a warning signal). In addition, we combined this task with a choice reaction time (CRT) incorporating a warning signal and variable preparation times: a short, (0.5 s) interstimulus interval (ISI) for optimal preparation in healthy subjects, and a long (2 s) ISI predisposing to poor preparation. The purpose of introducing these various procedures was to maximize the attention deficits and distractibility found in schizophrenic patients. Inhibitors,research,lifescience,medical Study 1: visuospatial orientation and disengagement difficulty schizophrenics treated with second-generation antipsychotics Applying their CTD paradigm in treated and

untreated schizophrenics, Posner et al5 observed longer attentional disengagement (invalid cues), mainly in the left hemisphere for stimuli occurring on the right. Based on similarity Inhibitors,research,lifescience,medical between these results and those in subjects with parietal lesions, they suggested there might be left parietal dysfunction in schizophrenia. Other groups tried Inhibitors,research,lifescience,medical to confirm these results with mixed success, in that not. all found hemispheric asymmetry.6 No study had been performed on visuospatial orientation abnormalities in schizophrenics treated with antipsychotics. Studies of simple reaction times (RTs) have shown that these are prolonged in both treated and untreated patients.7 In addition, studies incorporating attention gap procedures have been undertaken in schizophrenia using oculomotor Mephenoxalone paradigms; they have shown impaired control of inhibitory mechanisms, with an increased check details number of express saccades (extremely short. RTs, eg, 100 ms) versus controls. No study has used manual RTs. Aims To determine whether the abnormal disengagement, observed with first-generation neuroleptics is also observed in patients who have been on a stable dose of single second-generation antipsychotic therapy for several months without, concomitant treatment. To confirm/disprove the attentional asymmetry reported in other studies.