Evoked and induced magnetic brain activity measured
over the left hemisphere were tested for their specificity
to language-related processing. Induced activity refers
to oscillatory alterations time locked but not phase locked
to the stimulus. Words, false font stimuli, and two types
of nonverbal patterns were presented visually while subjects
performed a nonlinguistic visual feature detection task.
The comparison of evoked and induced brain activity around
200 ms after stimulus onset revealed differential sensitivity
to the stimuli. The M180 component of the evoked magnetic
field was larger at the processing of words and false font
stimuli compared with nonverbal stimuli. The induced magnetic
brain activity in the 60-Hz band at a compatible latency
range was correlated with the familiarity of the visual
Gestalt. Sensitivity to language-specific information processing
can be concluded if a parameter differentiates the word
condition from the nonlexical conditions. Such a difference
was observed at sensors located over the frontal-temporal
scalp regions for induced but not evoked magnetic brain
activity. Thus, evoked and induced magnetic brain activity
revealed a differential sensitivity to elements of cognitive
processing during the given task.