Evoked Potential Correlates of Verbal Versus Imagery Coding in Hypnosis
In our previous works it has been demonstrated that late components of midline evoked potentials recorded in the associative cortical areas do reflect significant modifications of selective attention caused by hypnosis. More and more data can be found in the literature indicating that subdominant hemispheric functions — significant in imagery coding — are more expressed in hypnosis as compared to the waking state.
The purpose of the present experiment was to study how the motor reactions and the bilaterially recorded evoked potentials reflect the hypnotic modifications in processing visually exposed verbal vs. imagery commands. A warning tone signal was followed by a tachisto-scopically exposed verbal or imagery command to push a button either by the right or the left hand, according to the content of the command. Correct and incorrect responses and their reaction time were recorded together with the registration of EEG, EMG, ECG, EOG and evoked potentials in frontal, central and occipital right and left monopolar leads. The alterations of the motor responses and of the negative evoked potential peak appearing with 120 ms latency and of the positive peaks with 200 and 300 ms latencies showed characteristic differences as functions of verbal vs. imagery task (i.e. dominant vs. subdominant hemispheric processing) as a result of hypnosis.
KeywordsEvoke Potential Verbal Command Imagery Task Ambiguous Stimulus Empty Column
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