Adrenocorticotropin widens the focus of attention in humans. A nonliner electroencephalographic analysis.
OBJECTIVE
This study examined the effects of ACTH 4-10, a fragment of adrenocorticotropin (ACTH) with known central nervous system (CNS) activity, on the dimensional complexity of the ongoing electroencephalographic (EEG) activity. Stressful stimuli cause ACTH to be released from the pituitary, and as a neuropeptide ACTH may concurrently exert adaptive influences on the brain's processing of these stimuli. Previous studies have indicated an impairing influence of ACTH on selective attention.


METHODS
Dimensional complexity of the EEG, which indexes the brain's way of stimulus processing, was evaluated while subjects performed tasks with different attention demands. Sixteen healthy men (23 to 33 years) were tested once after placebo and another time after administration of ACTH 4-10 (1.25 mg intravenously (i.v.), 30 minutes before testing). The EEG was recorded while subjects were presented with a dichotic listening task (consisting of the concurrent presentation of tone pips to the left and right ear). Subjects either a) listened to pips in both ears (divided attention), or b) listened selectively to pips in one ear (selective attention), or c) ignored all pips.


RESULTS
Dimensional complexity of the EEG was higher during divided than selective attention. ACTH significantly increased the EEG complexity during selective attention, in particular over the midfrontal cortex (Fz, Cz).


CONCLUSIONS
The effects support the view of a de-focusing action of ACTH during selective attention that could serve to improve the organism's adaptation to stress stimuli.
Mölle
M
M
Department of Clinical Neuroendocrinology, Medical University of Lübeck, Germany.
Albrecht
C
C
Marshall
L
L
Fehm
H L
HL
Born
J
J
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology* / Q000502:physiology; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000187:drug effects* / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects*; D005072:Evoked Potentials, Auditory / Q000187:drug effects; D005625:Frontal Lobe / Q000187:drug effects; D006801:Humans; D008297:Male; D012647:Self-Assessment; D013647:Task Performance and Analysis; D014836:Volition / Q000187:drug effects* / Q000502:physiology
D000324:Adrenocorticotropic Hormone