In ecological situations, threatening stimuli often come out from the peripheral vision. Such aggressive messages must trigger rapid attention to the periphery to allow a fast and adapted motor reaction... Fearful and neutral faces were briefly presented in the central or peripheral visual field, and were followed by target faces stimuli. An event-related beamformer source analysis model was applied in three time windows following the first face presentations: 80 to 130 ms, 140 to 190 ms, and 210 to 260 ms. The frontal lobe and the right internal temporal lobe part, including the amygdala, reacted as soon as 80 ms of latency to fear occurring in the peripheral vision. For central presentation, fearful faces evoked the classical neuronal activity along the occipito-temporal visual pathway between 140 and 190 ms...Thus, the high spatio-temporal resolution of MEG allowed disclosing a fast response of a network involving medial temporal and frontal structures in the processing of fear related stimuli occurring unconsciously in the peripheral visual field.A related study is offered by Sabatinelli et al., who examine the timing of emotional discrimination in the amygdala and ventral visual cortex.
Wednesday, December 16, 2009
Rapid amygdala activation by fearful objects in our peripheral vision
Bayle et al. use Magnetoencephalography (MEG) to show that fearful objects presented to our peripheral field of vision while we are consciously looking at a central object cause rapid (80 msec) activation of the amygdala. If the fearful stimulus is presented to our central field of view and processed by the classical occipito-temporal visual pathway, it takes between 140 and 190 ms to register. Some clips: