Absence of neglect for mental representations during the intracarotid amobarbital procedure

D. S. Manoach, M. O'Connor and S. Weintraub
Behavioral Neurology Unit, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts, USA.

BACKGROUND: The unilateral suppression of right-hemisphere electrophysiological activity during the intracarotid amobarbital procedure results in left neglect on visuomotor search tasks. OBJECTIVE: To investigate whether right-hemisphere inactivation during the intracarotid amobarbital procedure also results in left neglect of the mental representation of a remembered scene. DESIGN: Before the intracarotid amobarbital procedure, 16 subjects were asked to draw a room from their homes. Following the right-hemisphere injection, subjects wee tested for the presence of left neglect of extrapersonal space using a Random Letter Cancellation Test. To test for neglect of the mental representation of a remembered scene, they were then asked to report items from the room they had drawn. RESULTS: While 10 of the 16 subjects showed left neglect on the Random Letter Cancellation Test, only one subject showed left neglect of the mental representation. The other 15 subjects recalled approximately equal numbers of items from the left and the right hemispaces. CONCLUSIONS: These results replicate previous findings of left neglect of extra personal space during the intracarotid amobarbital procedure and fail to show concurrent neglect for mental representations. They provide further evidence for the multiplicity and dissociability of the behavioral manifestations of neglect.