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Ten normal adult right-handed subjects receive phonemic combinations (/epik/, /epak/, /a/, /pi/, /pa/) and pure tones (2500 and 8000 Hz) binaurally through matched earphones. Fifty responses from electrodes at P5, P6, C5, C6, F7 and F8 (referenced to linked mastoids) were summated, and evoked potentials from homologous areas were measured separately and superimposed in order to observe differences. Visual inspection of superimposed responses showed no consistent gross asymmetries that lateralized to either hemisphere. Comparison between amplitude of evoked potentials (N1, P2) at P5 and P6 were not significant (P < 0.05; paired t test). We suggest that our technique may not be a useful clinical test for cerebral dominance.

In 10 female subjects, power-spectrum analysis was performed on the alpha activity elicted during the resting state, 4 right hemispheric tasks, and 3 left hemispheric tasks. The data were treated in 3 ways: approach 1, comparing the right and left hemispheric alpha activity; approach 2, comparing the right and left hemispheric alpha activity adjusted for the resting state; and approach 3, comparing the right and left hemispheric alpha activity adjusted for the previous task. Approaches 1 and 2 revealed few significant differences in the alpha activity of the hemispheres, but approach 3 provided data that better fit the theory of decreased power spectrum of attenuation of activity in the activated hemisphere. Thus, approach 3 may be useful in developing an electroencephalographic test for determining cerebral dominance for language.

We studied the feasibility of adapting the method of Wood et al. (1971) for determining cerebral dominance for language and did not obtain consistent asymmetries of evoked responses in the left hemisphere to stop consonant task (SCT) as compared with fundamental frequency task (FFT). Likewise, the right hemisphere-evoked potentials for SCT and FFT did not show consistent asymmetries. However, we did find that the evoked responses at T3 were attenuated as compared with those at T4, regardless of the task performed (FFT or SCT). These findings may be useful in developing a test for cerebral dominance for language.