[Emotional stimuli: sensory processing and motor responses].
Emotion can be functionally considered as action dispositions preparing the organism for either avoidance- or approach- related behaviors. In order to prepare an appropriate behavioral output, the organism has to be efficient in the encoding of relevant stimuli. We herein present evidence from neuroimaging studies that seeing emotional and arousing pictures leads to greater activation in visual cortex than seeing neutral ones. In addition to this facilitation of sensory processing, emotional stimuli prompt somatic and vegetative reactions. Recordings of postural oscillations and heart rate while participants visualized a block of unpleasant pictures, revealed a significant reduction of body sway and bradycardia. A parallel investigation showed that reaction time also slows down after the visualization of negative pictures. Taken together, immobility, bradycardia and slower reaction time in the laboratory experimental set may reflect the engagement of the defensive system, resembling the defensive reactions to distant threatening stimuli in natural contexts. In summary, the affective system operates at an early level of sensory encoding and at the motor output favoring dispositions for appropriate actions.
Volchan
Eliane
E
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil. evolchan@biof.ufrj.br
Pereira
Mirtes G
MG
Oliveira
Letícia de
Ld
Vargas
Cláudia
C
Mourão-Miranda
Janaína
J
Azevedo
Tatiana Maia de
TM
Machado-Pinheiro
Walter
W
Pessoa
Luiz
L
D001931:Brain Mapping; D004644:Emotions / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D010775:Photic Stimulation; D011930:Reaction Time; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*