| Abstrakt: |
Studies in 20 healthy right-handed subjects analyzed evoked EEG synchronization and desynchronization in the δ, θ1, θ2, α1, α2, β1, β2, β3, and γ ranges in response to sequential presentation of stimuli from the International Affective Picture System (IAPS) with low, medium, and high emotional activation impact. Each signal presentation was accompanied by subjective scaling of the extent of its emotional impact. EEG traces were recorded in 62 channels as signals were presented. These experiments showed that the degree of emotional impact of the signal was significantly associated with increases in evoked synchronization in the δ, θ1, θ2, β1, β3, and γ ranges and with the effects of combined changes in evoked synchronization and desynchronization in the α2frequency range. The interhemisphere distribution of evoked changes in power provided evidence that not only the posterior areas of the right hemisphere were involved in analyzing the emotional significance of images, as indicated by changes in evoked θ1and θ2synchronization and α2desynchronization, but also the anterior areas of the left hemisphere, as indicated by changes in evoked θ2synchronization. From the standpoint of affective chronometry, the earliest discrimination of the emotional content of stimuli, regardless of the sign of the emotion, occurred in the lower θ range and was seen at 0–600 msec after the start of stimulus presentation. This process was delayed to 600–1000 msec in the θ2, α2, and γ ranges. |
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