P300 in neglect.

OBJECTIVE

Attentional deficits have been thought to underlie hemispatial neglect. The present study investigates this using the P300 component of the event-related potential, which is assumed to reflect the allocation of attention.

METHODS

We recorded the P300 and oddball detection performance from patients with neglect. Infrequent targets appeared either in the affected contralesional or the unaffected ipsilesional visual hemifield.

RESULTS

Contralesional targets produced weaker average P300 responses than ipsilesional ones, but stronger responses than when only distractors were presented. In the affected hemifield, the difference in P300 amplitude between identified and missed targets was correlated with the miss rate. The number of missed contralesional targets for a given participant was positively correlated with the time required for completion of standard neglect tests.

CONCLUSIONS

The P300 not only reflects a general attentional impairment in neglect, but also varies as a function of the participants' awareness of individual stimuli.

SIGNIFICANCE

The findings reflect an important link between attentional dysfunction and impaired stimulus processing in neglect and extinction.