Caffeine effects on ERPs and performance in an auditory Go/NoGo task.
OBJECTIVE
Previous research has shown that caffeine produces a general increase in arousal. The present study examined caffeine-induced arousal effects on performance and auditory ERPs. We sought components showing amplitude changes without topography changes, as would be expected of a pure arousal amplification of source activity.


METHODS
The effects of a single oral dose of caffeine (250 mg) were examined in a randomised double-blind placebo-controlled repeated-measures cross-over study. Subjects abstained from caffeine for 4h before the testing sessions, which were conducted, in the afternoon, one week apart. A simple auditory Go/NoGo task was used, with a random mix of 75 tones at 1000 Hz and 75 at 1500 Hz. All tones were 60 dB SPL, 50 ms duration (rise/fall time 5 ms), with SOA 1100 ms.


RESULTS
There was a reduction in RT, but no effects on omission or commission errors. The major ERP effects of caffeine were focal rather than global increases in P1, P2 and P3b amplitudes to Go stimuli, with no changes in latency. There were no effects on N1 or N2 to Go stimuli, and no effects on any components in response to NoGo stimuli.


CONCLUSIONS
The results suggest that caffeine differentially improves aspects of the processing related to response production and task performance, contrary to the widespread amplification of ERP component amplitudes, and latency reductions, expected of an increase in general arousal.


CONCLUSIONS
These results add auditory ERP data to the list of complex effects of caffeine on brain function and behaviour. They appear to rule out a simple arousal interpretation, and suggest directions for future research.
Barry
Robert J
RJ
Brain & Behaviour Research Institute and School of Psychology, University of Wollongong, Wollongong, NSW, Australia. robert_barry@uow.edu.au
Johnstone
Stuart J
SJ
Clarke
Adam R
AR
Rushby
Jacqueline A
JA
Brown
Christopher R
CR
McKenzie
David N
DN
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001143:Arousal / Q000187:drug effects* / Q000502:physiology; D001307:Auditory Perception / Q000187:drug effects* / Q000502:physiology; D001931:Brain Mapping; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology; D003071:Cognition / Q000187:drug effects* / Q000502:physiology; D004311:Double-Blind Method; D004569:Electroencephalography; D005071:Evoked Potentials / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008606:Mental Processes / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010919:Placebos; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology
D000697:Central Nervous System Stimulants; D010919:Placebos; D002110:Caffeine