Sequential information processing during a mental arithmetic is reflected in the time course of event-related brain potentials.
OBJECTIVE
We hypothesized that mental arithmetic is a complex of sequential information processing. In order to test the hypothesis, event-related potentials (ERPs) were measured during 3 mental tasks.


METHODS
Fifteen normal human subjects performed the following tasks; (1) subjects added up every digit delivered successively on a computer display, (2) subjects counted the number of presented digits, or (3) subjects counted the number of meaningless patterns. Spatiotemporal differences between ERP waveforms under the 3 tasks were studied within the period of 1200 ms post-stimulus.


RESULTS
During the adding task, N120-P180-N220 complex advanced in latency in the left frontal, central and parietal regions. P300 increased in amplitude in the frontal and temporal regions during adding and counting digits, which was specific to the digit presentation. A positive slow potential depended on the adding task and showed two spatiotemporal distributions; one was a widespread brain activity over the frontal, central, temporal and parietal regions observed within 400-820 ms, and another was a brain activity restricted to the frontal region lasting up to 1150 ms.


CONCLUSIONS
The results suggest that the early portion of ERPs reflects identification of physical attributes of stimuli and numeric meaning of digits, and that the positive slow potential reflects processes associated with calculation.
Iguchi
Y
Y
Department of Psychophysiology, Tokyo Institute of Psychiatry, Tokyo Metropolitan Organization for Medical Research, Japan.
Hashimoto
I
I
D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008606:Mental Processes / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D011930:Reaction Time; D013647:Task Performance and Analysis