Effects of haloperidol on selective attention - A combined whole-head MEG and high-resolution EEG study

We used 122-channel magnetoencephalography (MEG) and 64-channel electroence phalogrphy (EEG) simultaneously to study the effects of dopaminergic transm ission on human selective attention in a randomized, double-blind placebo-c ontrolled cross-over design. A single dose of dopamine D2 receptor antagoni st haloperidol (2 mg) or placebo was given orally to 12 right-handed health y volunteers 3 hours before measurement. In a dichotic selective attention task, subjects were presented with two trains of standard (700 Hz to the le ft ear, 1,100 Hz to the right ear) and deviant (770 and 1,210 Hz, respectiv ely) tones. Subjects were instructed to count the tones presented to one ea r; whereas, the tones presented to the other ear were to be ignored. Halope ridol significantly attenuated processing negativity (PN), an event-related potential (ERP) component elicited by selectively attended standard tones at 300-500 ins after stimulus presentation. These results, indicating impai red selective attention by a blockade of dopamine D2 receptors, were furthe r accompanied with increased mismatch negativity (MMN), elicited by involun tary detection of task-irrelevant deviants. Taken together, haloperidol see med to induce functional changes in neural networks accounting for both sel ective and involuntary attention, suggesting modulation of these functions by dopamine D2 receptors.