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Abstract:
Number is processed in a specific system in human brain. We
recorded event-related potentials (ERPs) in 15 subjects. Following
a warning signal, numbers and symbols were presented in sequence to
subjects on a monitor, which constituted a mental arithmetic
problem. Subjects were asked to make mental arithmetic following
the visual stimuli, and to match their arithmetic outcome to a
presented answer. The answer may be true (condition 1) or false
(condition 2 and 3). In condition 2 the deviation of the presented
answer from the outcome was less than or equal to two, and in
condition 3 the deviation of presented answer from the outcome was
more than or equal to 3. Subjects had to indicate if the answer was
true or not. When a false answer was presented to the subject, a
negative component can be recorded on the scalp with the maximal
amplitude at central-parietal areas and with mean peak latency of
268.6 ~{!@~} 29.0 ms (condition 2) and 278.0 ~{!@~} 19.0 ms
(condition 3) at Cz. This negative component is considered to be
the corresponding component of N4 for number processing. The same
mechanism may exist for semantic evaluation of numerical and verbal
processing, though they may be processed in different parts of the
brain.
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