Modulation of startle and the startle-elicited P300 by the conditions of the cued continuous performance task in school-age boys.
OBJECTIVE
This study compares the modulation of the startle response by conditions requiring response preparation, production, and inhibition during a cued continuous performance task (CPT) in children to the results of previous studies in adults and evaluates the modulation of the startle-elicited P300 under the same conditions. The latter variable, reflecting the cognitive processing of the startling stimulus (SS), has not been studied under these conditions.


METHODS
Normal boys completed a cued CPT in which the cue was the letter T, the go condition requiring a button press was an X following the T, and the no-go condition requiring response inhibition was a letter other than X following the T. SS were presented 450 ms following the letter of interest in each condition. The amplitudes of the startle-elicited P300 at Fz, Cz, and Pz and the startle blink were compared in the different CPT conditions.


RESULTS
The startle blink, measured by orbicularis oculi electromyography, was not inhibited by the no-go CPT condition as is the case in adults. The vertical electro-oculogram was actually largest in the no-go condition. The startle-elicited P300 showed a central predominance and was significantly larger in the no-go condition and in the cue condition than in the go condition.


CONCLUSIONS
The absence of inhibition of the startle response during the no-go condition probably reflects a relative inefficiency of prefrontal cortical mechanisms that mediate response inhibition in children compared to adults. The enhanced startle-elicited P300 in the no-go and cue conditions of the CPT reflects cognitive processing of the SS that has been influenced by response inhibition or its anticipation.
Ornitz
E M
EM
Division of Child Psychiatry, Department of Psychiatry, University of California at Los Angeles (UCLA), 760 Westwood Plaza, Los Angeles, CA 90024, USA. eornitz@mednet.ucla.edu
Gehricke
J G
JG
Russell
A T
AT
Pynoos
R
R
Siddarth
P
P
D001767:Blinking / Q000502:physiology; D002648:Child; D003463:Cues; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time; D013216:Reflex, Startle / Q000502:physiology*