Trait anxiety impact on the EEG theta band power changes during appraisal of threatening and pleasant visual stimuli.

The main objective of the present investigation was to examine whether trait anxiety construct would influence EEG event-related synchronization (ERS) of the theta power during viewing of visual threatening stimuli. The 62-channel EEG was recorded while low (LA, n= 18) and high (HA, n= 18) trait-anxious subjects viewed sequentially presented neutral, threatening and pleasant pictures. Between-group differences, related to stimulus emotionality, were linked to the test period of 0-1000 ms after stimulus onset. In the low theta (4-6 Hz) at prefrontal sites HA exhibited deficient ERS in response to both threatening and pleasant stimuli in the right hemisphere, whereas LA yielded larger right than left hemisphere ERS in response to all the three stimulus categories. In the upper theta (6-8 Hz) group differences were associated with posterior cortical regions: HA exhibited the largest ERS to threatening and the lowest to pleasant stimuli, whereas LA prompted the largest ERS to pleasant and the lowest to neutral pictures. It is suggested that low theta right prefrontal hypoactivation favoring left hemispheric (i.e. more analytical) activity along with higher upper theta ERS of posterior cortical regions (i.e. enhanced higher order visual processing) to threatening stimuli could form the basis for neuropsychologically observed general bias towards threatening information in HA.