Neuroleptics reverse attentional effects in schizophrenia patients.
Patients with schizophrenia show attention deficit characterized by a larger validity effect (fast responses to cued than uncued stimuli) in the right visual field than in the left visual field. In addition, schizophrenia patients do not show inhibition of return (IOR--a mechanism that enables efficient visual search), unless attention is summoned back to the center after the peripheral cue. The present study examined the short-term effect of neuroleptic medications on these two components of visual spatial attention in schizophrenia patients. In order to do this we tested schizophrenia patients that were treated with long-acting neuroleptic medication. These patients were treated once a month, which allowed us to test them with either low or high levels of medication. Here we show that neuroleptic medications reverse the attentional hemispheric asymmetry. In the group with a high level of medication fast RTs to cued trials were found in the right visual field, while in the group with a low level of medication the opposite pattern was found - fast RTs to cued trials were found in the left visual field. In addition, level of medication did not influence IOR - regardless of the level of medication, IOR was observed only when attention was summoned back to the center, unlike control group. These finding suggest an imbalance in dopaminergic activity, possibly in subcortical structures such as the basal ganglia. This study also shows a dissociation between the two components of visual orienting of attention and suggests that facilitation and inhibition are independent processes.
Sapir
Ayelet
A
Department of Behavioral Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel. sayelet@netscape.net
Dobrusin
Michael
M
Ben-Bashat
Guy
G
Henik
Avishai
A
D000328:Adult; D000704:Analysis of Variance; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000209:etiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000187:drug effects; D012559:Schizophrenia / Q000150:complications*; D013028:Space Perception / Q000187:drug effects; D013997:Time Factors; D014794:Visual Fields / Q000187:drug effects
D014150:Antipsychotic Agents